TTI tga1240 schematic

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THURLBY THANDAR INSTRUMENTS

TGA1240 SERIES

40MHz ARBITRARY WAVEFORM GENERATORS

INSTRUCTION MANUAL

Page 2

Overview 3

Specifications 5

EMC 13

Safety 14

Installation 15

Connections 17

Front Panel Connections 17

Rear Panel Connections 18

General 20

Initial Operation 20

Principles of Operation 22

Standard Waveform Operation 24

Setting Generator Parameters 24

Warnings and Error Messages 27

SYNC Output 28

Sweep Operation 29

General 29

Setting Sweep Parameters 30

Triggered Burst and Gate 34

General 34

Triggered Burst 35

Gated Mode 37

Sync Out in Triggered Burst and Gated Mode 38

Tone Mode 39

Arbitrary Waveform Generation 41

Introduction 41

Creating New Waveforms 43

Modifying Arbitrary Waveforms 44

Arbitrary Waveform Sequence 49

Frequency and Amplitude Control with Arbitrary Waveforms 51

Sync Out Settings with Arbitrary Waveforms 51

Waveform Hold in Arbitrary Mode 52

Output Filter Setting 52

Pulse and Pulse-trains 53

Pulse Set-up 53

Pulse-train Setup 54

Waveform Hold in Pulse and Pulse-Train Modes 56

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Modulation 58

Introduction 58

External Modulation 58

Internal Modulation 59

Sum 60

Inter-Channel Synchronisation 62

Synchronising Two Generators 65

System Operations from the Utility Menu 67

Calibration 70

Equipment Required 70

Calibration Procedure 70

Calibration Routine 71

Remote Calibration 72

Remote Operation 74

Power on Settings 81

Remote Commands 82

Channel Selection 83

Frequency and Period 83

Amplitude and DC Offset 84

Waveform Selection 84

Arbitrary Waveform Create and Delete 84

Arbitrary Waveform Editing 85

Waveform Sequence Control 87

Mode Commands 87

Input/Output control 88

Modulation Commands 88

Phase Locking Commands 88

Status Commands 89

Miscellaneous Commands 90

Remote Command Summary 91

Maintenance 95

Appendix 1. Warning and Error Messages 96

Appendix 2. SYNC OUT Automatic Settings 99

Appendix 3. Factory System Defaults 100

Appendix 4 : Waveform Manager Plus Arbitrary Waveform Creation and Management Software 101

Block Diagrams 102

Front Panel Diagrams 103

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Overview

This manual describes the features and operation of 1, 2 and 4 channel arbitrary waveform generators. The physical differences between the 2 and 4−channel generators are straightforward:− the 2−channel instrument has no set−up keys or output connections for channels 3 and 4. The single−channel instrument has essentially the same keys but they are arranged quite differently to suit the ½−rack case. The diagram at the end of the manual shows all 3 models.

The set−up and operation of an individual channel in any of the instruments is identical and therefore no distinction is made between the different models when describing the functions associated with any single channel. Those features associated with multi−channel operation (inter−channel summing, phase−locking, etc.) self−evidently apply only to the multi−channel instruments; the relevant chapters are mostly grouped together towards the end of the manual (but before Remote Operation) although some mention of multi−channel operation is made when appropriate in earlier sections. To avoid repetition specific reference is not always made to 2− and 4−channel instruments in the text; it is obvious when the description applies only to a multi−channel instrument.

Introduction

This synthesised programmable arbitrary waveform generator has the following features:

• 1, 2 or 4 independent arb channels

• Up to 40MHz sampling frequency

• Sinewaves and square waves up to 16MHz

• 12 bit vertical resolution

• 64k points horizontal resolution per channel

• 256k point non−volatile waveform memory

• Waveform linking, looping and sequencing

• Interchannel triggering, summing, modulation and phase control

• GPIB and RS232 interfaces

The instrument uses a combination of direct digital synthesis and phase lock loop techniques to provide high performance and extensive facilities in a compact instrument. It can generate a wide variety of waveforms between 0·1mHz and 16MHz with high resolution and accuracy.

Arbitrary waveforms may be defined with 12 bit vertical resolution and from 4 to 65536 horizontal points. In addition a number of standard waveforms are available including sine, square, triangle, ramp and pulse.

Arbitrary waveforms may be replayed at a user specified waveform frequency or period, or the sample rate may be defined in terms of period or frequency.

Extensive waveform editing features between defined start and end points are incorporated, including waveform insert, point edit, line draw, amplitude adjust and invert. More comprehensive features are available using the arbitrary waveform creation software supplied. This is a powerful Windows−based design tool that enables the user to create waveforms from mathematical expressions, from combinations of other waveforms, freehand, or using a combination of all three techniques. Waveforms created in this way are downloaded via the RS232 or GPIB interface.

Up to 100 waveforms may be stored with the length and name specified by the user. Waveforms may be strung together to form a sequence of up to 16 steps. Each waveform may have a user defined repeat count from 1 to 32768.

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All waveforms can be swept over their full frequency range at a rate variable between 30 milliseconds and 15 minutes. Sweep can be linear or logarithmic, single or continuous. Single sweeps can be triggered from the front panel, the trigger input, or the digital interfaces. A sweep marker is provided.

Amplitude Modulation is available for all waveforms and is controlled from the previous channel or from an external generator via the MODULATION input socket.

Signal Summing is available for all waveforms and is controlled from the previous channel or from an external generator via the SUM input socket.

All waveforms are available as a Triggered Burst whereby each active edge of the trigger signal will produce one burst of the carrier. The number of cycles in the burst can be set between 1 and

1048575. The Gated mode turns the output signal On when the gating signal is true and Off when it is false. Both Triggered and Gated modes can be operated from the previous or next channel, from the internal Trigger Generator (0.005Hz to 100kHz), from an external source (dc to 1MHz) or by a key press or remote command.

Any number of channels can be phase locked with user defined phase angle. This can be used to generate multi−phase waveforms or locked waveforms of different frequencies.

The signals from the REF IN/OUT socket and the SYNC OUT socket can be used to phase lock two instruments where more than 4 channels are required.

The generator parameters are clearly displayed on a backlit LCD with 4 rows of 20 characters. Soft−keys and sub menus are used to guide the user through even the most complex functions.

All parameters can be entered directly from the numeric keypad. Alternatively most parameters can be incremented or decremented using the rotary control. This system combines quick and easy numeric data entry with quasi−analogue adjustment when required.

The generator has RS232 and GPIB interfaces as standard which can be used for remote control of all of the instrument functions or for the down−loading of arbitrary waveforms.

As well as operating in conventional RS232 mode the serial interface can also be used in addressable mode whereby up to 32 instruments can be linked to a single PC serial port.

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Specifications apply at 18−28ºC after 30 minutes warm−up, at maximum output into 50Ω

WAVEFORMS

Standard Waveforms

Sine, square, triangle, DC, positive ramp, negative ramp, sin(x)/x, pulse, pulse train, cosine, haversine and havercosine.

Sine, Cosine, Haversine, Havercosine

Range: 0·1mHz to 16 MHz Resolution: 0·1mHz or 7 digits Accuracy: 10 ppm for 1 year Temperature Stability: Typically <1 ppm/ºC. Output Level:

Harmonic Distortion: <0.1% THD to 100kHz; <–65dBc to 20kHz <–50dBc to 300kHz,

Non−harmonic Spurii:

2.5mV to 10Vp−p into 50Ω

<−35dBc to 10MHz

<−30dBc to 16MHz <–65dBc to 1MHz, <–65dBc + 6dB/octave 1MHz to 16MHz

Specifications

Square

Range: 1mHz to 16MHz Resolution: 1mHz (4 digits) Accuracy: ± 1 digit of setting Output Level:

Rise and Fall Times: <25ns

Triangle

Range: 0.1mHz to 100kHz Resolution: 0.1mHz or 7 digits Accuracy: 10 ppm for 1 year Output Level:

Linearity Error: <0.1% to 30 kHz

Ramps and Sin(x)/x

Range: 0.1mHz to 100kHz Resolution: 0.1mHz (7 digits) Accuracy: 10 ppm for 1 year Output Level:

Linearity Error: <0.1% to 30 kHz

2.5mV to 10Vp−p into 50Ω

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Pulse and Pulse Train

Output Level:

Rise and Fall Times: <25ns Period: Range: 100ns to 100s Resolution:

Accuracy: ±1 digit of setting Delay: Range:

Resolution:

Width: Range:

Resolution:

Note that the pulse width and absolute value of the delay may not exceed the pulse period at any time.

Pulse trains of up to 10 pulses may be specified, each pulse having independently defined width, delay and level. The baseline voltage is separately defined and the sequence repetition rate is set by the pulse train period.

2.5mV to 10Vp−p into 50Ω

4−digit

−99·99s to + 99·99s 0·002% of period or 25ns, whichever is greater

25ns to 99·99s 0·002% of period or 25ns, whichever is greater

Arbitrary

Up to 100 user defined waveforms may be stored in the 256K point non−volatile RAM. Waveforms can be defined by front panel editing controls or by downloading of waveform data via RS232 or GPIB.

Waveform Memory Size: 64k points per channel. Maximum waveform size is 64k points,

Vertical Resolution: 12 bits Sample Clock Range: 100mHz to 40MHz Resolution: 4 digits Accuracy: ± 1 digit of setting

Sequence

Up to 16 waveforms may be linked. Each waveform can have a loop count of up to 32,768. A sequence of waveforms can be looped up to 1,048,575 times or run continuously.

Output Filter

Selectable between 16MHz Elliptic, 10MHz Elliptic, 10MHz Bessel or none.

minimum waveform size is 4 points

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OPERATING MODES Triggered Burst

Each active edge of the trigger signal will produce one burst of the waveform.

Carrier Waveforms: All standard and arbitrary Maximum Carrier Frequency: The smaller of 1MHz or the maximum for the selected waveform.

Number of Cycles: 1 to 1,048,575 Trigger Repetition Rate: 0.005Hz to 100kHz internal

Trigger Signal Source: Internal from keyboard, previous channel, next channel or trigger

Trigger Start/Stop Phase:

Gated

Waveform will run while the Gate signal is true and stop while false.

Carrier Waveforms: All standard and arbitrary. Maximum Carrier Frequency: The smaller of 1MHz or the maximum for the selected

Trigger Repetition Rate: 0.005Hz to 100kHz internal

Gate Signal Source: Internal from keyboard, previous channel, next channel or trigger

Gate Start/Stop Phase:

Sweep

Frequency sweep capability is provided for both standard and arbitrary waveforms. Arbitrary waveforms are expanded or condensed to exactly 4096 points and DDS techniques are used to perform the sweep.

Carrier Waveforms: All standard and arbitrary except pulse, pulse train and

Sweep Mode: Linear or logarithmic, triggered or continuous. Sweep Direction: Up, down, up/down or down/up. Sweep Range: From 1mHz to 16 MHz in one range. Phase continuous.

Sweep Time: 30ms to 999s (3 digit resolution). Marker: Variable during sweep. Sweep Trigger Source: The sweep may be free run or triggered from the following

Sweep Hold: Sweep can be held and restarted by the HOLD key. Multi channel sweep: Any number of channels may be swept simultaneously but the

40Msamples/s for ARB and Sequence.

dc to 1MHz external.

generator. External from TRIG IN or remote interface.

± 360° settable with 0.1° resolution, subject to waveform frequency and type.

waveform.

40Msamples/s for ARB and Sequence.

dc to 1MHz external.

generator. External from TRIG IN or remote interface.

± 360° settable with 0.1° resolution, subject to waveform frequency and type.

sequence.

Independent setting of the start and stop frequency.

sources: Manually from keyboard. Externally from TRIG IN input or remote interface.

sweep parameters will be the same for all channels. Amplitude, Offset and Waveform can be set independently for each channel.

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Tone Switching

Capability provided for both standard and arbitrary waveforms. Arbitrary waveforms are expanded or condensed to exactly 4096 points and DDS techniques are used to allow instantaneous frequency switching.

Carrier Waveforms: All waveforms except pulse, pulse train and sequence. Frequency List: Up to 16 frequencies from 1mHz to 10MHz. Trigger Repetition Rate: 0.005Hz to 100kHz internal

Source: Internal from keyboard, previous channel, next channel or trigger

Tone Switching Modes: Gated:

Triggered:

FSK: The tone is output when the trigger signal goes true and the next

Using 2 channels with their outputs summed together it is possible to generate DTMF test signals.

dc to 1MHz external. Usable repetition rate and waveform frequency depend on the

tone switching mode.

generator. External from TRIG IN or remote interface.

The tone is output while the trigger signal is true and stopped, at the end of the current waveform cycle, while the trigger signal is false. The next tone is output when the trigger signal is true again.

The tone is output when the trigger signal goes true and the next tone is output, at the end of the current waveform cycle, when the trigger signal goes true again.

tone is output, immediately, when the trigger signal goes true again.

Trigger Generator

Internal source 0.005 Hz to 100kHz square wave adjustable in 10us steps. 3 digit resolution. Available for external use from any SYNC OUT socket.

OUTPUTS

Main Output - One for each channel

Output Impedance:

Amplitude:

Amplitude Accuracy:

Amplitude Flatness: ±0.2dB to 200 kHz; ±1dB to 10 MHz; ±2.5dB to 16 MHz. DC Offset Range:

DC Offset Accuracy: Typically 3% ±10mV, unattenuated. Resolution: 3 digits for both Amplitude and DC Offset.

50Ω

5mV to 20Vp−p open circuit (2.5mV to 10Vp−p into 50Ω). Amplitude can be specified open circuit (hi Z) or into an assumed load of 50Ω or 600Ω in Vpk−pk, Vrms or dBm.

2% ±1mV at 1kHz into 50Ω.

±10V. DC offset plus signal peak limited to ±10V from 50Ω.

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Sync Out - One for each channel

Multifunction output user definable or automatically selected to be any of the following: Waveform Sync:

(all waveforms) Position Markers:

(Arbitrary only) Burst Done: Produces a pulse coincident with the last cycle of a burst. Sequence Sync: Produces a pulse coincident with the end of a waveform sequence. Trigger: Selects the current trigger signal. Useful for synchronizing burst or

Sweep Sync: Outputs a pulse at the start of sweep to synchronize an oscilloscope or

Phase Lock Out: Used to phase lock two generators. Produces a positive edge at the 0°

Output Signal Level:

A square wave with 50% duty cycle at the main waveform frequency, or a pulse coincident with the first few points of an arbitrary waveform.

Any point(s) on the waveform may have associated marker bit(s) set high or low.

gated signals.

recorder.

phase point.

TTL/CMOS logic levels from typically 50Ω.

Cursor/Marker Out

Adjustable output pulse for use as a marker in sweep mode or as a cursor in arbitrary waveform editing mode. Can be used to modulate the Z−axis of an oscilloscope or be displayed on a second ‘scope channel.

Output Signal Level: Adjustable from nominally 2V to 14V, normal or inverted; adjustable

width as a cursor.

Output Impedance:

600Ω typical

INPUTS Trig In

Frequency Range:

Signal Range: Threshold nominally TTL level; maximum input ±10V. Minimum Pulse Width: 50ns, for Trigger and Gate modes; 50us for Sweep mode. Polarity: Selectable as high/rising edge or low/falling edge. Input Impedance:

Modulation In

Frequency Range: DC – 100kHz. Signal Range:

Input Impedance:

Sum In

Frequency Range:

Signal Range:

Input Impedance:

Hold

Holds an arbitrary waveform at its current position. A TTL low level or switch closure causes the waveform to stop at the current position and wait until a TTL high level or switch opening which allows the waveform to continue. The front panel MAN HOLD key or remote command may also be used to control the Hold function. While held the front panel MAN TRIG key or remote command may be used to return the waveform to the start. The Hold input may be enabled independently for each channel.

Input Impedance:

DC − 1MHz.

10kΩ

VCA: Approximately 1V pk−pk for 100% level change at maximum output.

SCM: Approximately ± 1Vpk for maximum output.

Typically 1 kΩ.

DC − 8 MHz.

Approximately 2 Vpk−pk input for 20Vpk−pk output.

Typically 1kΩ.

10kΩ

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Ref Clock In/Out

Set to Input: Input for an external 10MHz reference clock. TTL/CMOS threshold

level.

Set to Output: Buffered version of the internal 10MHz clock. Output levels nominally

1V and 4V from 50Ω.

Set to Phase Lock: Used together with SYNC OUT on a master and TRIG IN on a slave

to synchronise (phase lock) two separate generators.

INTER-CHANNEL OPERATION

Inter-channel Modulation:

The waveform from any channel may be used to Amplitude Modulate (AM) or Suppressed Carrier Modulate (SCM) the next channel. Alternatively any number of channels may be Modulated (AM or SCM) with the signal at the MODULATION input socket.

Carrier frequency: Entire range for selected waveform. Carrier waveforms: All standard and arbitrary waveforms. Modulation Types:

AM: SCM:

Modulation source: Internal from the previous channel.

Frequency Range: DC to >100 kHz. Internal AM:

Depth: Resolution:

Carrier Suppression (SCM):

External Modulation Signal Range:

Double sideband with carrier. Double sideband suppressed carrier.

External from Modulation input socket. The external modulation signal may be applied to any number of channels simultaneously.

0% to 105% 1%.

> −40dB.

VCA: Approximately 1V pk−pk for 100% level change at maximum output.

SCM: Approximately ± 1Vpk for maximum output.

Inter-channel Analog Summing:

Waveform Summing sums the waveform from any channel into the next channel. Alternatively any number of channels may be summed with the signal at the SUM input socket.

Carrier frequency: Entire range for selected waveform. Carrier waveforms: All standard and arbitrary waveforms. Sum source: Internal from the previous channel.

External from SUM IN socket. Frequency Range: DC to >8MHz. External Signal Range:

Approximately 5Vpk−pk input for 20Vpk−pk output.

Inter-channel Phase locking:

Two or more channels may be phase locked together. Each locked channel may be assigned a phase angle relative to the other locked channels. Arbitrary waveforms and waveform sequences may be phase locked but certain constraints apply to waveform lengths and clock frequency ratios. With one channel assigned as the Master and other channels as Slaves a frequency change on the master will be repeated on each slave thus allowing multi−phase waveforms at the same frequency to be easily generated.

DDS waveforms are those with 7 digits of frequency setting resolution, while Non−DDS waveforms have 4 digits

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Phase Resolution: DDS waveforms: Non−DDS waveforms:

Phase Error: All waveforms:

The signals from the REF IN/OUT socket and the SYNC OUT socket can be used to phase lock two instruments where more than 4 channels are required.

Inter-channel Triggering:

Any channel can be triggered by the previous or next channel. The previous/next connections can be used to ’daisy chain’ a trigger signal from a ‘start’ channel,

through a number of channels in the ‘chain’ to an ‘end’ channel. Each channel receives the trigger out signal from the previous (or next) channel, and drives its selected trigger out to the next (or previous) channel. The ‘end’ channel trigger out can be set up to drive the ‘start’ channel, closing the loop.

In this way, complex and versatile inter−channel trigger schemes may be set up. Each channel can have its trigger out and its output waveform set up independently. Trigger out may be selected from Waveform End, Position Markers, Sequence Sync or Burst Done.

Using the scheme above it is possible to create a sequence of up to 64 waveform segments, each channel producing up to 16 segments and all channels being summed to produce the complete waveform at the output of channel 4.

0.1 degree

0.1 degree or 360 degrees/number of points whichever is the greater

<±10ns

INTERFACES

Full remote control facilities are available through the RS232 or GPIB interfaces.

RS232:

IEEE−488:

GENERAL

Display: 20 character x 4 row alphanumeric LCD. Data Entry: Keyboard selection of mode, waveform etc.; value entry direct by numeric

Stored Settings:

Size: 3U (130mm) height; 350mm width (2 and 4 channels),

Weight: 7.2 kg. (16 lb), 2 and 4 channels; 4.1kg (9lb) 1 channel. Power: 100V, 110V-120V, 220V-240V AC ±10%, 50/60Hz, adjustable internally;

Operating Range:

Storage Range:

Environmental: Indoor use at altitudes up to 2000m, Pollution Degree 2. Options: 19 inch rack mounting kit. Safety:

EMC: Complies with EN61326.

Variable Baud rate, 9600 Baud maximum. 9−pin D−connector. Conforms with IEEE488.1 and IEEE488.2

keys or by rotary control.

Up to 9 complete instrument set−ups may be stored and recalled from battery−backed memory. Up to 100 arbitrary waveforms can also be stored independent of the instrument settings.

212mm (½−rack) single channel; 335mm long.

100VA max. for 4 channels, 75VA max. for 2 channels, 40VA max. for 1 channel. Installation Category II.

+5°C to 40°C, 20−80% RH.

−20°C to + 60°C.

Complies with EN61010−1.

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EC Declaration of Conformity

We Thurlby Thandar Instruments Ltd Glebe Road Huntingdon Cambridgeshire PE29 7DR England

declare that the

TGA1241/42/44 40MHz Synthesised Arbitrary Waveform Generators with GPIB

meet the intent of the EMC Directive 2004/108/EC and the Low Voltage Directive 2006/95/EC. Compliance was demonstrated by conformance to the following specifications which have been listed in the Official Journal of the European Communities.

EMC

Emissions: a) EN61326-1 (2006) Radiated, Class B

b) EN61326-1 (2006) Conducted, Class B

c) EN61326-1 (2006) Harmonics, referring to EN61000-3-2 (2006)

Immunity: EN61326-1 (2006) Immunity Table 1, referring to:

a) EN61000-4-2 (1995) Electrostatic Discharge

b) EN61000-4-3 (2006) Electromagnetic Field

c) EN61000-4-11 (2004) Voltage Interrupt

d) EN61000-4-4 (2004) Fast Transient

e) EN61000-4-5 (2006) Surge

f) EN61000-4-6 (2007) Conducted RF

Performance levels achieved are detailed in the user manual.

Safety EN61010-1 Installation Category II, Pollution Degree 2.

CHRIS WILDING TECHNICAL DIRECTOR

1 May 2009

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This instrument has been designed to meet the requirements of the EMC Directive 2004/108/EC. Compliance was demonstrated by meeting the test limits of the following standards:

Emissions

EN61326-1 (2006) EMC product standard for Electrical Equipment for Measurement, Control and Laboratory Use. Test limits used were:

a) Radiated: Class B

b) Conducted: Class B

c) Harmonics: EN61000-3-2 (2006) Class A; the instrument is Class A by product category.

Immunity

EN61326-1 (2006) EMC product standard for Electrical Equipment for Measurement, Control and Laboratory Use.

Test methods, limits and performance achieved are shown below (requirement shown in brackets):

a) EN61000-4-2 (1995) Electrostatic Discharge : 4kV air, 4kV contact, Performance A (B).

EMC

b) EN61000-4-3 (2006) Electromagnetic Field:

c) EN61000-4-11 (2004) Voltage Interrupt: ½ cycle and 1 cycle, 0%: Performance A (B);

d) EN61000-4-4 (2004) Fast Transient, 1kV peak (AC line), 0·5kV peak (signal connections), Performance A (B).

e) EN61000-4-5 (2006) Surge, 0·5kV (line to line), 1kV (line to ground), Performance A (B).

f) EN61000-4-6 (2007) Conducted RF, 3V, 80% AM at 1kHz (AC line only; signal connections <3m, therefore not tested), Performance A (A).

According to EN61326-1 the definitions of performance criteria are:

Performance criterion A: ‘During test normal performance within the specification limits.’

Performance criterion B: ‘During test, temporary degradation, or loss of function or

performance which is self-recovering’.

Performance criterion C: ‘During test, temporary degradation, or loss of function or performance which requires operator intervention or system reset occurs.’

Cautions

To ensure continued compliance with the EMC directive observe the following precautions:

3V/m, 80% AM at 1kHz, 80MHz – 1GHz: Performance A (A) and 1.4GHz to 2GHz: Performance A (A); 1V/m, 2.0GHz to 2.7GHz: Performance A (A).

25 cycles, 70% and 250 cycles, 0%: Performance B (C).

a) Connect the generator to other equipment using only high quality, double−screened cables.

b) After opening the case for any reason ensure that all signal and ground connections are

remade correctly and that case screws are correctly refitted and tightened.

c) In the event of part replacement becoming necessary, only use components of an identical

type, see the Service Manual.

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Safety

This generator is a Safety Class I instrument according to IEC classification and has been designed to meet the requirements of EN61010−1 (Safety Requirements for Electrical Equipment for Measurement, Control and Laboratory Use). It is an Installation Category II instrument intended for operation from a normal single phase supply.

This instrument has been tested in accordance with EN61010−1 and has been supplied in a safe condition. This instruction manual contains some information and warnings which have to be followed by the user to ensure safe operation and to retain the instrument in a safe condition.

This instrument has been designed for indoor use in a Pollution Degree 2 environment in the temperature range 5°C to 40°C, 20% − 80% RH (non−condensing). It may occasionally be subjected to temperatures between +5° and −10°C without degradation of its safety. Do not operate while condensation is present.

Use of this instrument in a manner not specified by these instructions may impair the safety protection provided. Do not operate the instrument outside its rated supply voltages or environmental range.

WARNING! THIS INSTRUMENT MUST BE EARTHED

Any interruption of the mains earth conductor inside or outside the instrument will make the instrument dangerous. Intentional interruption is prohibited. The protective action must not be negated by the use of an extension cord without a protective conductor.

When the instrument is connected to its supply, terminals may be live and opening the covers or removal of parts (except those to which access can be gained by hand) is likely to expose live parts. The apparatus shall be disconnected from all voltage sources before it is opened for any adjustment, replacement, maintenance or repair.

Any adjustment, maintenance and repair of the opened instrument under voltage shall be avoided as far as possible and, if inevitable, shall be carried out only by a skilled person who is aware of the hazard involved.

If the instrument is clearly defective, has been subject to mechanical damage, excessive moisture or chemical corrosion the safety protection may be impaired and the apparatus should be withdrawn from use and returned for checking and repair.

Make sure that only fuses with the required rated current and of the specified type are used for replacement. The use of makeshift fuses and the short−circuiting of fuse holders is prohibited.

This instrument uses a Lithium button cell for non−volatile memory battery back−up; typical life is 5 years. In the event of replacement becoming necessary, replace only with a cell of the correct type, i.e. 3V Li/Mn0 in accordance with local regulations; do not cut open, incinerate, expose to temperatures above 60°C or attempt to recharge.

Do not wet the instrument when cleaning it and in particular use only a soft dry cloth to clean the LCD window. The following symbols are used on the instrument and in this manual:−

20mm button cell type 2032. Exhausted cells must be disposed of carefully

Caution −refer to the accompanying documentation, incorrect operation may

damage the instrument.

terminal connected to chassis ground.

mains supply OFF.

mains supply ON.

alternating current.

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Mains Operating Voltage

Check that the instrument operating voltage marked on the rear panel is suitable for the local supply. Should it be necessary to change the operating voltage, proceed as follows:

1) Disconnect the instrument from all voltage sources.

2) Remove the screws which retain the top cover and lift off the cover.

3) Change the transformer connections following the appropriate diagrams below.

4) Refit the cover and the secure with the same screws.

5) To comply with safety standard requirements the operating voltage marked on the rear panel must be changed to clearly show the new voltage setting.

6) Change the fuse to one of the correct rating, see below.

Single Channel

Installation

for 230V operation connect the live (brown) wire to pin 15 for 115V operation connect the live (brown) wire to pin 14 for 100V operation connect the live (brown) wire to pin 13

2 and 4 Channel

for 230V operation link pins 15 & 16. for 115V operation link pins 13 & 16 and pins 15 & 18. for 100V operation link pins 13 & 16 and pins 14 & 17.

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Fuse

Ensure that the correct mains fuse is fitted for the set operating voltage. The correct mains fuse types are:

Single channel

2 & 4 channel

To replace the fuse, disconnect the mains lead from the inlet socket and withdraw the fuse drawer below the socket pins. Change the fuse and replace the drawer.

The use of makeshift fuses or the short−circuiting of the fuse holder is prohibited.

Mains Lead

When a three core mains lead with bare ends is provided it should be connected as follows:−

for 230V operation: 250 mA (T) 250V HRC for 100V or 115V operation: 500 mA (T) 250V HRC

for 230V operation: 1A(T) 250V HRC for 100V or 115V operation: 2A(T) 250V HRC

Brown

Blue

Green / Yellow

WARNING! THIS INSTRUMENT MUST BE EARTHED

Mains Live

− Mains Neutral

− Mains Earth

−

Mounting

This instrument is suitable both for bench use and rack mounting. It is delivered with feet for bench mounting. The front feet include a tilt mechanism for optimal panel angle.

A rack kit for mounting in a 19” rack is available from the Manufacturers or their overseas agents.

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Front Panel Connections

MAIN OUT (1 per channel)

This is the 50Ω output from the channel’s main generator. It will provide up to 20V peak−to−peak e.m.f. which will yield 10V peak−to−peak into a matched 50Ω load. It can tolerate a short circuit for 60 seconds.

Do not apply external voltages to these outputs.

SYNC OUT (1 per channel)

This is a TTL/CMOS level output which may be set to any of the following signals from the SYNC OUT screen.

Connections

waveform sync

position marker

Burst done

Sequence sync

Trigger

Sweep sync

A sync marker phase coincident with the MAIN OUT waveform of that channel. For standard waveforms, (sine, cosine, haversines, square, triangle, sinx/x and ramp), the sync marker is a squarewave with a 1:1 duty cycle with the rising edge at the 0º phase point and the falling edge at the 180º phase point. For arbitrary waveforms the sync marker is a positive pulse coincident with the first few points (addresses) of the waveform.

When position (pos’n) marker is selected, the instrument generates a pulse marker pattern for arbitrary waveforms. The pulse pattern is programmable from the edit waveform screen. When the MAIN OUT waveform is a standard waveform position marker automatically changes to phase zero which is a narrow (1 clock) pulse output at the start of each standard waveform cycle.

Provides a signal during Gate or Trigger modes which is low while the waveform is active at the main output and high at all other times.

Provides a signal which is low during the last cycle of the last waveform in a sequence and high at all other times.

Provides a positive going version of the actual trigger signal; internal, external, manual and remote all produce a trigger sync.

Goes high at the start of the sweep and low at the end of the sweep.

menu on the MODIFY

Phase lock

SYNC OUT logic levels are nominally 0V and 5V from typically 50 Ω. SYNC OUT will withstand a short circuit.

Do not apply external voltage to this output.

Produces a positive edge coincident with the start of the current waveform; this is used for phase locking instruments.

TRIG IN

This is the external input for Trigger, Gate, Sweep and Sequence operations. It is also the input used to synchronise the generator (as a slave) to another (which is the master).

Do not apply external voltages exceeding ±10V.

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SUM IN

This is the input socket for external signal summing. The channel(s) with which this signal is to be summed are selected on the SUM screen.

Do not apply external voltages exceeding ±10V.

MODULATION IN

This is the input socket for external modulation. Any number of channels may be AM or SCM modulated with this signal; the target channels are selected on the MODULATION screen.

Do not apply external voltages exceeding ±10V.

Rear Panel Connections

REF CLOCK IN/OUT

The function of the CLOCK IN/OUT socket is set from the ref clock i/o menu on the UTILITY screen, see System Operations section.

input

This is the default setting. The socket becomes an input for an external 10MHz reference clock. The system automatically switches over from the internal clock when the external reference is applied.

output

phase lock

The internal 10MHz clock is made available at the socket.

When two or more generators are synchronised the slaves are set to phase lock slave and the master is set to phase lock master.

As an output the logic levels are nominally 1V and 4V from typically 50Ω. CLOCK OUT will withstand a short−circuit. As an input the threshold is TTL/CMOS compatible.

Do not apply external voltages exceeding +7.5V or –2.5V to this signal connection.

HOLD IN

Controls the waveform hold function. The input impedance is nominally 10kΩ.

Do not apply external voltages exceeding ±10V.

CURSOR/MARKER OUT

Output pulse for use as a marker in sweep mode or as a cursor in arbitrary waveform editing mode. Can be used to modulate the Z−axis of an oscilloscope or be displayed on a second ‘scope channel. The output impedance is nominally 600Ω and the signal level is adjustable from 2V−14V nominal from the cursor/marker menu on the UTILITY screen, see System Operations section.

Do not apply external voltages to this output.

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RS232

9−pin D−connector compatible with addressable RS232 use. The pin connections are shown below:

Pin 2, 3 and 5 may be used as a conventional RS232 interface with XON/XOFF handshaking. Pins 7, 8 and 9 are additionally used when the instrument is used in addressable RS232 mode. Signal grounds are connected to instrument ground. The RS232 address is set from the remote menu on the UTILITY screen, see System Operations section.

GPIB (IEEE−488)

Pin Name Description

1 2 TXD Transmitted data from instrument 3 RXD Received data to instrument 4 5 GND Signal ground 6 7 RXD2 Secondary received data 8 TXD2 Secondary transmitted data 9 GND Signal ground

−

No internal Connection

No internal connection

The GPIB interface is not isolated; the GPIB signal grounds are connected to the instrument ground.

The implemented subsets are:

SH1 AH1 T6 TE0 L4 LE0 SR1 RL1 PP1 DC1 DT1 C0 E2

The GPIB address is set from the remote menu on the UTILITY screen, see System Operations section.

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Initial Operation

This section is a general introduction to the organisation of the instrument and is intended to be read before using the generator for the first time. Detailed operation is covered in later sections starting with Standard Waveform Operation.

In this manual front panel keys and sockets are shown in capitals, e.g. CREATE, SYNC OUT; all soft−key labels, entry fields and messages displayed on the LCD are shown in a different type−font, e.g. STANDARD WAVEFORMS, sine.

Switching On

The power switch is located at the bottom left of the front panel. At power up the generator displays the installed software revision whilst loading its waveform

RAM; if an error is encountered the message SYSTEM RAM ERROR, CHECK BATTERY displayed, see the Warnings and Error Messages section.

Loading takes a few seconds, after which the status screen is displayed, showing the generator parameters set to their default values, with the MAIN OUT outputs set off. Refer to the System Operations section for how to change the power up settings to either those at power down or to any one of the stored settings. Recall the status screen at any time with the STATUS key; a second press returns the display to the previous screen.

On multi−channel instruments the status shown is that of the channel selected by the SETUP keys; this is the channel currently enabled for editing and is always the last channel selected, whether power has been switched off or not. Change the basic generator parameters for the selected channel as described in the Standard Waveform Operation section and switch the output on with the MAIN OUT key; the ON lamp will light to show that output is on.

General

will be

Display Contrast

All parameter settings are displayed on the 20 character x 4 row backlit liquid crystal display (LCD). The contrast may vary a little with changes of ambient temperature or viewing angle but can be optimised for a particular environment by using the front panel contrast control. Insert a small screwdriver or trimmer tool through the adjustment aperture marked LCD and rotate the control for optimum contrast.

Keyboard

Pressing the front panel keys displays screens which list parameters or choices relative to the key pressed. Selections are then made using the display soft−keys and numeric values are changed using the numeric keys or rotary control, see the Principles of Editing section.

The keys are grouped as follows:

• WAVE SELECT keys call screens from which all standard or already defined arbitrary waveforms can be selected.

• WAVE EDIT keys call screens from which arbitrary waveforms can be created and modified.

• FREQuency, AMPLitude, OFFSET and MODE keys display screens which permit their

respective parameters to be edited either from the numeric keypad or using the rotary control/cursor keys.

• Numeric keys permit direct entry of a value for the parameter currently selected. Values are accepted in three formats: integer (20), floating point (20·0) and exponential (2 EXP 1). For example, to set a new frequency of 50kHz press FREQ followed by 50000 ENTER or 5 EXP 4 ENTER. ENTER confirms the numeric entry and changes the generator setting to the new value. CE (Clear Entry) undoes a numeric entry digit by digit. ESCAPE returns a setting being edited to its last value.

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• MODULATION, SUM, TRIG IN and SYNC OUT call screens from which the parameters of those input/outputs can be set, including whether the port is on or off. SWEEP similarly calls a screen from which all the sweep parameters an be set.

• Each channel has a key which directly switches the MAIN OUT of that channel on and off.

• MAN TRIG is used for manual triggering (when TRIG IN is appropriately set) and for

synchronising two or more generators when suitably connected together. MAN HOLD is used to manually pause arbitrary waveform output and sweep; the output is held at the level it was at when MAN HOLD was pressed.

• UTILITY gives access to menus for a variety of functions such as remote control interface set−up, power−up parameters, error message settings and store/recall set-ups to/from non−volatile memory; the STORE and RECALL keys can also be used to directly access the non−volatile stores.

• The INTER CHannel and COPY CHannel keys (multi−channel instruments only) directly call screens from which channel−to−channel phase locking and set−up copying can be set.

• The SETUP keys (multi−channel instruments only) select the channel to be edited; the lamp lights beside the channel currently enabled for editing.

• Eight soft−keys around the display are used to directly set or select parameters from the currently displayed menu; their operation is described in more detail in the next section.

• The STATUS key always returns the display to the default start−up screen which gives an overview of the generators status. Pressing STATUS again returns the display to the previous screen.

Further explanations will be found in the detailed descriptions of the generator’s operation.

Principles of Editing

Each screen called up by pressing a front panel key shows parameter value(s) and/or a list of choices. Parameter values can be edited by using the ROTARY CONTROL in combination with the left and right arrowed CURSOR keys, or by direct numeric keyboard entry; choices are made using the soft−key associated with the screen item to be selected. The examples which follow assume factory default settings.

The channel to be edited must first be selected by pressing the appropriate SETUP key; the lamp lights beside the SETUP key of the channel currently enabled for editing.

A diamond beside a screen item indicates that it is selectable; hollow diamonds identify deselected items and filled diamonds denote selected items. For example, press MODE to get the screen shown below:

The filled diamond indicates that the selected mode is continuous. Gated or

Triggered modes are selected by pressing the associated soft−key which will make the diamond beside that item filled and the diamond beside continuous illustrates how an ellipsis (three dots following the screen text) indicates that a further screen follows when that item is selected. In the case of the MODE screen illustrated, pressing the setup… soft−key on the bottom line brings up the TRIGGER SETUP menu; note that selecting this item does not change the continuous/gated/triggered

MODE:

♦continuous ◊gated setup…◊ ◊triggered setup…◊

hollow. This screen also

selection.

Page 23

Some screen items are marked with a double−headed arrow (a split diamond) when selected to indicate that the item’s setting can be changed by further presses of the soft−key, by pressing either cursor key or by using the rotary control. For example, pressing FILTER brings up the screen shown below.

FILTER SETUP

mode: auto

◊type: 10MHz eliptic

Repeated presses of the mode soft−key will toggle the mode between its two possible settings of auto and manual. Similarly, when type is selected, repeated presses of the type

soft−key (or cursor keys or use of the rotary control) will step the selection through all possible settings of the filter type.

In addition to their use in editing items identified by a double−headed arrow as described above, the CURSOR keys and ROTARY CONTROL operate in two other modes.

In screens with lists of items that can be selected (i.e. items marked with a diamond) the cursor keys and rotary control are used to scroll all items through the display if the list has more than three items; look, for example at the STD (standard waveform) and UTILITY screens.

In screens where a parameter with a numeric value is displayed the cursor keys move the edit cursor (a flashing underline) through the numeric field and the rotary control will increment or decrement the value; the step size is determined by the position of the edit cursor within the numeric field.

Thus for STANDARD FREQUENCY set to 1.000

00 MHz rotating the control will change the

frequency in 1kHz steps. The display will auto−range up or down as the frequency is changed, provided that autoranging permits the increment size to be maintained; this will in turn determine the lowest or highest setting that can be achieved by turning the control. In the example above, the lowest frequency that can be set by rotating the control is 1 kHz, shown on the display as

.000000 kHz.

This is the limit because to show a lower frequency the display would need to autorange below 1kHz to x

xx.xxx Hz in which the most significant digit represents 100Hz, i.e. the 1kHz

increment would be lost. If, however, the starting frequency had been set to 1.000000 MHz, i.e. a 100 Hz increment, the display would have autoranged at 1kHz to 900.0000 Hz and could then be decremented further right down to 0

00.0000 Hz without losing the 100 Hz

increment. Turning the control quickly will step numeric values in multiple increments.

Principles of Operation

The instrument operates in one of two different modes depending on the waveform selected. DDS mode is used for sine, cosine, haversine, triangle, sinx/x and ramp waveforms. Clock Synthesis mode is used for square, pulse, pulse train, arbitrary and sequence.

In both modes the waveform data is stored in RAM. As the RAM address is incremented the values are output sequentially to a Digital−to−Analogue Converter (DAC) which reconstructs the waveform as a series of voltages steps which are subsequently filtered before being passed to the main output connector.

The main difference between DDS and Clock Synthesis modes is the way in which the addresses are generated for the RAM and the length of the waveform data.

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Clock Synthesis Mode

In Clock Synthesis mode the addresses are always sequential (an increment of one) and the clock rate is adjusted by the user in the range 40MHz to 0·1Hz. The frequency of the waveform is clock frequency ÷ waveform length, thus allowing short waveforms to be played out at higher repetition rates than long waveforms, e.g. the maximum frequency of a 4 point waveform is 40e6÷4 or 10MHz but a 1000 point waveform has a maximum frequency of 40e6÷1000

Arbitrary waveforms have a user defined length of 4 to 65536 points. Squarewaves use a fixed length of 2 points and pulse and pulse train have their length defined by the user selected period value.

DDS Mode

In DDS mode (Direct Digital Synthesis) all waveforms are stored in RAM as 4096 points. The frequency of the output waveform is determined by the rate at which the RAM addresses are changed. The address changes are generated as follows:

The RAM contains the amplitude values of all the individual points of one cycle (360º) of the waveform; each sequential address change corresponds to a phase increment of the waveform of 360º/4096. Instead of using a counter to generate sequential RAM addresses, a phase accumulator is used to increment the phase.

or 40kHz.

On each clock cycle the phase increment, which has been loaded into the phase increment register by the CPU, is added to the current result in the phase accumulator; the 12 most significant bits of the phase accumulator drive the lower 12 RAM address lines, the upper 4 RAM address lines are held low. The output waveform frequency is now determined by the size of the phase increment at each clock. If each increment is the same size then the output frequency is constant; if it changes, the output frequency changes as in sweep mode.

The generator uses a 38 bit accumulator and a clock frequency which is 2

x 10−4(~27·4878

MHz); this yields a frequency resolution of 0·1 mHz. Only the 12 most significant bits of the phase accumulator are used to address the RAM. At a

waveform frequency of F

CLK/4096 (~6·7kHz), the natural frequency, the RAM address increments

at every clock. At all frequencies below this (i.e. at smaller phase increments) one or more addresses are output for more than one clock period because the phase increment is not big enough to step the address at every clock. Similarly at frequencies above the natural frequency the larger phase increment causes some addresses to be skipped, giving the effect of the stored waveform being sampled; different points will be sampled on successive cycles of the waveform.

Page 25

Standard Waveform Operation

This sections deals with the use of the instrument as a standard function generator, i.e. generating sine, square, triangle, dc, ramp, haversine, cosine, havercosine and sinx/x waveforms. All but squarewave are generated by DDS which gives 7−digit frequency precision; squarewave is generated by Clock Synthesis which results in only 4−digit frequency resolution. Refer to Principles of Operation in the previous section for a fuller explanation of the differences involved.

The STANDARD WAVEFORMS screen also includes arbitrary and sequence for simplicity of switching between these and standard waveforms; they do, however, have their own screens (accessed by pressing ARB and SEQUENCE respectively) and are described in detail in their appropriate sections. Pulse and pulse−train are also accessed from the ‘standard waveforms’ screen but are sufficiently different to justify their own section in the manual.

Much of the following descriptions of amplitude and offset control, as well as of Mode, Sweep, etc., in following sections, apply to arbitrary and sequence as well as standard waveforms; for clarity, any differences of operation with arbitrary, sequence, pulse and pulse−train are described only in those sections.

Setting Generator Parameters

Waveform Selection

Pressing the STD key gives the STANDARD WAVEFORMS screen which lists all the waveforms available; the rotary control or cursor keys can be used to scroll the full list back and forward through the display. The currently selected waveform (sine with the factory defaults setting) is indicated by the filled diamond; the selection is changed by pressing the soft−key beside the required waveform.

Frequency

Pressing the FREQ key gives the STANDARD FREQUENCY screen. With freq selected as shown above, the frequency can be entered directly from the keyboard in integer, floating point or exponential format, e.g. 12·34 kHz can be entered as 12340, 12340·00, or 1·234 exp 4 etc. However, the display will always show the entry in the most appropriate engineering units, in this case 12·34000 kHz.

With period 123·4µs can be entered as ·0001234 or 123·4e−6; again the display will always show the entry in

the most appropriate engineering units. Note that the precision of a period entry is restricted to 6 digits; 7 digits are displayed but the least significant one is always zero. The hardware is programmed in terms of frequency; when a period entry is made the synthesised frequency is the nearest equivalent value that the frequency resolution and a 6−digit conversion calculation gives. If the frequency is displayed after a period entry the value may differ from the expected value because of these considerations. Further, once the setting has been displayed as a frequency, converting back again to display period will give an exact 6−digit equivalent of the 7−digit frequency, but this may differ from the period value originally entered.

STANDARD WAVEFORMS

♦sine ◊square ◊triangle

STANDARD FREQUENCY 10·00000 kHz

♦freq period ◊

selected instead of freq the frequency can be set in terms of a period, e.g.

Page 26

Squarewave, generated by Clock Synthesis has 4−digit resolution for both frequency and period entry but the hardware is still programmed in terms of frequency and the same differences may occur in switching the display from period to frequency and back to period.

Turning the rotary control will increment or decrement the numeric value in steps determined by the position of the edit cursor (flashing underline); the cursor is moved with the left and right arrowed cursor keys.

Note that the upper frequency limits vary for the different waveform types; refer to the Specifications section for details.

Frequency setting for arbitrary, sequence pulse and pulse−train is explained in the relevant sections.

Amplitude

Pressing the AMPL key gives the AMPLITUDE screen.

The waveform amplitude can be set in terms of peak−to−peak Volts (Vpp), r.m.s. Volts (Vrms) or dBm (referenced to a 50Ω or 600Ω load). For Vpp and Vrms the level can be set assuming that the output is open−circuit (load:hiZ) or terminated (load:50Ω or load:600Ω); when dBm is selected termination is always assumed and the load:hiZ setting is automatically changed to load:50Ω. Note that the actual generator output impedance is always 50Ω; the displayed amplitude values for 600Ω termination take this into account.

With the appropriate form of the amplitude selected (indicated by the filled diamond) the amplitude can be entered directly from the keyboard in integer, floating point or exponential format, e.g. 250mV can be entered as ·250 or 250 exp −3, etc., However, the display will always show the entry in the most appropriate engineering units, in this case 250mV.

Alternate presses of the ± key will invert the MAIN OUT output; if DC OFFSET is non−zero, the signal is inverted about the same offset. The exception to this is if the amplitude is specified in dBm; since low level signals are specified in −dBm (0dBm = 1mW into 50Ω = 224mVrms) the

− sign is interpreted as part of a new amplitude entry and not as a command to invert the signal.

Note that for DC, sinx/x, pulse train, arbitrary and sequence amplitude can only be displayed and entered in the Vpp form; further limitations on pulse−train, arbitrary and sequence amplitude are discussed in the appropriate sections.

AMPLITUDE: +20·0 Vpp

♦Vpp Vrms ◊ ◊dBm load:hiZ ◊

DC Offset

DC OFFSET: program +0·00 mVdc (actual +0·00 mVdc)

load:hiZ ◊

Pressing the OFFSET key gives the DC OFFSET screen. The offset can be entered directly from the keyboard in integer, floating point or exponential format, e.g. 100mV can be entered as

·1 or 100 exp −3 etc. However, the display will always show the entry in the most appropriate

engineering units, in this case 100mV. During a new offset entry the ± key can be used at any time to set the offset negative; alternate presses toggle the sign between + and −.

Page 27

Turning the rotary control will increment or decrement the numeric value in steps determined by the position of the edit cursor (flashing underline); the cursor is moved by the left and right arrowed cursor keys. Because DC offset can have negative values, the rotary control can take the value below zero; although the display may autorange to a higher resolution if a step takes the value close to zero, the increment size is maintained correctly as the offset is stepped negative. For example, if the display shows

program = +2

with the cursor in the most significant digit, the rotary control will decrement the offset in 100mV steps as follows:

program = +2

program = +1 program = +5

05· mVdc

05· mVdc 05· mVdc

·00 mVdc

program = −9

program = −1

The actual DC offset at the MAIN OUT socket is attenuated by the fixed−step output attenuator when this is in use. Since it is not obvious when the signal is being attenuated the actual offset is shown in brackets as a non−editable field below the programmed value.

For example, if the amplitude is set to 2·5Vpp the output is not attenuated by the fixed attenuator and the actual DC offset (in brackets) is the same as that set. The DC OFFSET display shows:

DC OFFSET: program +1.50 Vdc (actual +1.50 Vdc)

load: hiZ ◊

If the amplitude is now reduced to 250mVpp which introduces the attenuator, the actual DC offset changes by the appropriate factor:

DC OFFSET: program +1.50 Vdc (actual +151. mVdc)

load: hiZ ◊

The above display shows that the set DC offset is +1.50V but the actual offset is +151mV. Note that the actual offset value also takes into account the true attenuation provided by the fixed attenuator, using the values determined during the calibration procedure. In the example displayed the output signal is 250mVpp exactly and takes account of the small error in the fixed attenuator; the offset is 151.mV exactly, taking account of the effect of the known attenuation (slightly less than the nominal) on the set offset of 1.50V.

Whenever the set DC offset is modified by a change in output level in this way a warning message that this has happened will be displayed. Similarly, because the DC offset plus signal peak is limited to ± 10V to avoid waveform clipping, a warning message will be displayed if this condition is set. This is explained more fully in the Warnings and Error Messages section.

The output attenuation is controlled intelligently to minimise the difference between the programmed and actual offset when the combination of programmed amplitude and offset allows this. Thus when the offset is set to 150mV, for example, the amplitude can be reduced to nominally 50mVpp before the fixed attenuator causes the actual offset to be different from the programmed value.

5·0 mVdc

95· mVdc

Page 28

Warnings and Error Messages

Two classes of message are displayed on the screen when an illegal combination of parameters is attempted.

WARNING messages are shown when the entered setting causes some change which the user might not necessarily expect. Examples are:

1. Changing the amplitude from, for example, 2·5 Volts pk−pk to 25mV pk−pk brings in the

step attenuator; if a non−zero offset has been set then this will now be attenuated too. The message DC OFFSET CHANGED BY AMPLITUDE screen but the setting will be accepted; in this case the actual, attenuated, offset will be shown in brackets below the set value.

2. With the output level set to 10V pk−pk, increasing the DC offset beyond ± 5V will cause

the message OFFSET + SUM + LEVEL MAY CAUSE CLIPPING change will be accepted (producing a clipped waveform) and the user may then choose to

change the output level or the offset to produce a signal which is not clipped. (clip?) will show in the display beside AMPLITUDE or DC OFFSET condition exists.

ERROR messages are shown when an illegal setting is attempted, most generally a number outside the range of values permitted. In this case the entry is rejected and the parameter setting is left unchanged. Examples are:

1. Entering a frequency of 1MHz for a triangle waveform. The error message:

Frequency out of range for the selected waveform is shown.

2. Entering an amplitude of 25Vpp. The error message:

Maximum output level exceeded is shown.

3. Entering a DC offset of 20V. The error message:

Maximum DC offset exceeded is shown.

The messages are shown on the display for approximately two seconds. The last two messages can be viewed again by pressing the last error… soft−key on the UTILITY screen, see System Operations section.

Each message has a number and the full list appears in Appendix 1.

The default set−up is for all warning and error messages to be displayed and for a beep to sound with each message. This set−up can be changed on the error… The error menu is shown below:

will be shown temporarily on the

. The offset

while the clipped

menu on the UTILITY screen.

◊ error beep: ON ◊ error message: ON

warn beep: ON

◊ warn message: ON

Each feature can be turned ON and OFF with alternate presses of the associated soft−key; the factory default is for all features to be ON. If the setting is changed and is required for future use it should be saved by changing the POWER ON SETTING

on the power on… menu of the

UTILITY screen to restore last setup.

Page 29

SYNC Output

SYNC OUT is a multifunction CMOS/TTL level output that can be automatically or manually set to be any of the following:

• waveform sync : A square wave with 50% duty cycle at the main waveform frequency, or a pulse coincident with the first few points of an arbitrary waveform. Can be selected for all waveforms.

• position marker : Can be selected for arbitrary waveforms only. Any point(s) on the main waveform may have associated marker bit(s) set high or low.

• burst done : Produces a pulse coincident with the last cycle of the burst.

• sequence sync : Produces a pulse coincident with the end of a waveform sequence.

• trigger : Selects the current trigger signal (internal, external, adjacent

channel or manual). Useful for synchronising burst or gated signals.

• sweep sync : Outputs the sweep trigger signal.

• phase lock : Used to lock two or more generators. Produces a positive edge at

the 0º phase point.

The setting up of the signals themselves is discussed in the relevant sections later in this manual, e.g. trigger the Arbitrary Waveform Generation.

Pressing the SYNC OUT key calls the SYNC OUT

When the MAIN OUT waveform is a standard waveform position marker is not available and this choice on the list automatically becomes phase zero; if selected, phase zero produces a narrow (1 clock) pulse at the start of each standard waveform cycle.

is described in the Triggered Burst/Gate section and position marker under

setup screen.

SYNC OUT:

output: on

◊ mode: auto

src: waveform sync

SYNC OUT is turned on and off by alternate presses of the output soft−key.

The selection of the signal to be output from the SYNC OUT socket is made using the src (source) soft−key; repeated presses of src cycle the selection through all the choices (waveform sync, position marker, etc.) listed above. Alternatively, with the src selected (double−headed arrow) the rotary control or cursor keys can be used to step backwards

and forwards through the choices. The source selection of the SYNC OUT waveform can be made automatic (auto) or

user−defined (manual) with alternate presses of the mode SYNC OUT waveform most appropriate for the current main waveform is selected.

For example, waveform sync

arbitrary waveforms, but trigger is selected in trigger or gated waveform modes. The

automatic selection will be mentioned in each of the appropriate main waveform mode sections and a full table is given in Appendix 2.

The automatic selection can still be changed manually by the src mode has been selected but the selection will immediately revert to the automatic choice as soon as any relevant parameter (e.g. main waveform frequency or amplitude) is adjusted. Manual must be selected by the mode soft−key for a source other than the automatic choice to remain set. The auto selection will generally set the most frequently used signal, e.g. waveform

sync

for all continuous main waveforms, but manual will need to be used for special

requirements, e.g. position markers on arbitrary waveforms.

is automatically selected for all continuous standard and

soft−key. In automatic mode the

soft−key even when auto

Page 30

General

Principles of Sweep Operation

All standard and arbitrary waveforms can be swept with the exception of pulse, pulse−train and sequence. During Sweep all waveforms are generated in DDS mode because this offers the significant advantage of phase−continuous sweeps over a very wide frequency range (up to 10 However, it must be remembered that the frequency is actually stepped, not truly linearly swept, and thought needs to be given as to what the instrument is actually doing when using extreme combinations of sweep range and time.

For DDS operation during Sweep all waveforms must be 4096 points in length; this is the natural length for standard waveforms but all arbitrary waveforms are expanded or condensed in software to 4096 points when Sweep is turned on. This does not affect the original data.

Sweep mode is turned on and off either by the on or off soft−key on the SWEEP SETUP screen accessed by pressing the SWEEP front panel key, or by the sweep soft−key on the

MODE

sweep parameters are the same for all channels. When sweep is turned on the software creates a table of 2048 frequencies between, and

including, the specified start and stop values. For sweep times of 1·03s and greater the sweep will step through all 2048 frequency values. Below 1·03s, however, the frequency sweep will contain fewer steps because of the minimum 0·5ms dwell at each step; at the shortest sweep time (30ms) the sweep will contain only 60 steps.

Because any frequency used in sweep mode must be one of the tabled values, the centre frequency displayed (see Sweep Range) may not be the exact mid−point and markers (see Sweep Marker) may not be exactly at the programmed frequency. The frequency resolution of the steps will be particularly coarse with wide sweeps at the fastest sweep rate.

screen. In multi−channel instruments two or more channels can be swept at once but the

Sweep Operation

Connections for Sweep Operation. Sync Out and Trig In

Sweeps are generally used with an oscilloscope or hard−copy device to investigate the frequency response of a circuit. The MAIN OUT is connected to the circuit input and the circuit output is connected to an oscilloscope or, for slow sweeps, a recorder.

An oscilloscope or recorder can be triggered by connecting its trigger input to the generator’s SYNC OUT; SYNC OUT defaults to sweep sync goes high at the start of sweep and low at the end of sweep. At the end of sweep it is low long enough for an oscilloscope to retrace, for example.

To show a marker on the display instrument the rear panel CURSOR/MARKER OUT socket should be connected to a second channel. Alternatively, for an oscilloscope the signal can be used to modulate the Z−axis. See Sweep Marker section for setting marker frequency. The cursor/marker polarity and level is set up on the cursor/marker… screen, see System Operations section.

For triggered sweeps, a trigger signal must be provided at the front panel TRIG IN socket or by pressing the MAN TRIG key or by a remote command. The function of TRIG IN is automatically defaulted to external when triggered sweep is selected; a sweep is initiated by the rising edge of the trigger signal.

The generator does not provide a ramp output for use with X−Y displays or recorders.

when sweep is turned on. sweep sync

menu of the UTILITY

Page 31

Setting Sweep Parameters

Pressing the SWEEP key (or the sweep setup soft−key on the MODE screen) displays the SWEEP SETUP screen.

Menus for setting up the range, time (sweep rate), type (continuous, triggered, etc.) spacing (lin/log) and marker position are all accessed from this screen using the appropriate soft−key. In addition the control screen for manual sweep (i.e. sweeping using the rotary control or cursor keys) is selected from this screen and Sweep Mode itself is turned on and off with alternate presses of the on/off the MODE using the same sweep parameters. The channels to be swept are set on or off by selecting them in turn with the appropriate SETUP key and then using the on/off soft−key of the SWEEP SETUP screen. On all the following menus, pressing the done display to this SWEEP SETUP screen.

Sweep Range

Pressing the range… soft−key calls the SWEEP RANGE screen.

SWEEP SETUP: off

◊range… type… ◊ ◊time… spacing… ◊ ◊manual… marker… ◊

soft−key; sweep can also be turned on by the sweep soft−key on

screen. In multi−channel instruments two or more channels can be swept at once

soft−key returns the

SWEEP RANGE:

♦start: 100·0 kHz ◊stop: 10·00 MHz ◊centr/span done ◊

The maximum sweep range for all waveforms is 1mHz to 16MHz, including triangle, ramp and squarewave which have different limits in unswept operation.

Sweep range can be defined by start and stop frequencies or in terms of a centre frequency and span. Start from the keyboard or by using the rotary control; the start frequency must be lower than the stop frequency (but see Sweep Type for selecting sweep direction).

Pressing the centr/span soft−key changes the screen to permit entry in terms of centr frequency and sweep span about that frequency; pressing the start/stop soft−key on that screen returns the display to the start and stop frequency form of entry.

Note that when the sweep is displayed in terms of centre frequency and span the span will always be the exact difference between start and stop frequencies but the centre frequency shown will be that of the frequency step nearest the true centre frequency, see Principles of Sweep Operation section.

Sweep Time

Pressing the time… soft−key calls the SWEEP TIME screen.

The sweep time can be set from 0·03 to 999s with 3−digit resolution by direct keyboard entry or by using the rotary control. As explained in the Principles of Sweep Operation section, sweeps with a sweep time less than 1·03 seconds will contain less than the maximum 2048 steps because of the minimum 0·5ms dwell at each step. For this reason the number of actual steps in the sweep is shown (in brackets) as a non−editable field below the sweep time.

and Stop soft−keys permit the two end points of the sweep to be set directly

SWEEP TIME: 0·05 sec (steps=100)

done ◊

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Sweep Type

Pressing the type soft−key calls the SWEEP TYPE screen.

This screen is used to set the sweep mode (continuous; triggered; triggered, hold and reset; manual) and sweep direction.

Successive presses of the direction soft−key select one of the following sweep directions:

down

up/down

down/up

The total sweep time is always that set on the SWEEP TIME screen, i.e. for up/down and down/up operation the sweep time in each direction is half the total. Similarly the total number

of steps is the same for all choices, i.e. there will be half the number of steps in each direction for up/down and down/up operation. In the sweep mode descriptions which follow the direction is assumed to be up but all modes can be used with all sweep directions.

In continuous frequencies, triggered repetitively by an internal trigger generator whose frequency is determined by the sweep time setting. At the stop frequency the generator resets to the start frequency after a delay long enough for an oscilloscope to retrace, for example, and begins a new sweep. If

sync

is set to on (the default) the generator actually steps from the stop frequency to zero

frequency and then starts the next sweep from the first point of the waveform, synchronised to the (internally generated) trigger signal.

This is useful because the sweep always starts from the same point in the waveform but the waveform discontinuity can be undesirable in some circumstances, e.g. filter evaluation. With

sync

set to off, the frequency steps directly and phase continuously from the stop frequency

to the start frequency but is not synchronised to the software−generated trigger signal. In triggered

trigger. When triggered, the frequency sweeps to the stop frequency, resets, and awaits the next trigger. If sync starts a new sweep at the first point of the waveform when the next trigger is recognised. If sync is set to off the waveform resets to the start frequency and runs at that frequency until the next trigger initiates a new sweep.

In trig’d, hold/reset recognises a trigger; when triggered, the frequency sweeps to the stop frequency and holds. At the next trigger the output is reset to the start frequency where it is held until the next sweep is initiated by a further trigger. If sync above; if sync is set to on the frequency actual goes to zero at the start and begins each new sweep at the first point of the waveform.

For both triggered and trig’d, hold/reset set to external. The trigger source can be an external signal applied to TRIG IN (positive edge triggers), pressing the MAN TRIG key on the front panel, or a remote command.

In manual

SWEEP TYPE:

continuous

◊direction: up ◊sync: on done ◊

start frequency to stop frequency. stop frequency to start frequency. start frequency to stop frequency and back to start frequency. stop frequency to start frequency and back to stop frequency.

mode the generator sweeps continuously between the start and stop

mode the generator holds the output at the start frequency until it recognises a

if set to on the frequency resets to zero frequency (i.e. no waveform) and

mode the generator holds the output at the start frequency until it

is set to off the output operates exactly as described

modes the TRIG IN input is automatically

mode the whole sweep process is controlled from the MANUAL SWEEP screen.

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Manual Sweep

Pressing the manual… soft−key on the SWEEP SETUP screen calls the MANUAL SWEEP FREQ screen.

Before manual control can be used, manual must be selected on the SWEEP TYPE screen, see above; if manual has not been set, the message mode is not manual will be displayed instead of the frequency.

In manual mode the frequency can be stepped through the sweep range, defined on the SWEEP

RANGE

stepped through if step slow is selected; if step fast is set then the frequency changes in multiple step increments. Step fast cannot be set when the number of steps in the table is small.

If wrap vice−versa; if no wrap depending on the direction of the rotary control or cursor keys.

screen, using the rotary control or cursor keys. Every point of the frequency table is

is set the sweep wraps−round from start frequency to stop frequency and

MANUAL SWEEP FREQ: 1·630 MHz

◊step fast wrap ◊ ♦step slow done ◊

is set the sweep finishes at either the start or stop frequency

Sweep Spacing

Pressing the spacing… soft−key on the SWEEP SETUP screen calls the SWEEP SPACING screen.

With linear selected the sweep changes the frequency at a linear rate; with logarithmic selected the sweep spends an equal time in each frequency decade.

Sweep Marker

Pressing the marker… soft−key on the SWEEP SETUP screen calls the SWEEP MARKER FREQ screen.

A new marker frequency can be programmed directly from the keyboard or by using the rotary control and cursor keys. Note that the marker frequency can only be one of the values in the sweep frequency table; any value in the sweep range can be entered but the actual value will be the nearest frequency in the table. When sweep is turned on, the actual marker frequency is shown in the non−editable field below the programmed frequency. For the default sweep setting of 100kHz to 10MHz in 50ms (400 steps), the actual frequency of a 5MHz marker is 4·977 MHz.

The marker duration is for the number of 0·5ms intervals that the frequency remains at the marker value; for fast and/or wide sweeps this will often be the 0·5ms minimum but for slow and/or narrow spans the marker may last many 0·5ms intervals. To avoid anomalous conditions the marker will not be exactly placed at the start and stop frequencies even though it can be programmed to be so. The marker polarity and level is set up on the cursor/marker… menu of the UTILITY screen, see System Operations section.

SWEEP SPACING:

♦logarithmic ◊linear

done ◊

SWEEP MARKER FREQ: progrm: 5·000 MHz actual: 4·977 MHz

done ◊

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The marker frequency can be changed with sweep on but since the table of frequency values is rebuilt with each change this can be a slow process, especially if the rotary control is used. It is faster to switch sweep off, change the marker and switch sweep back on again.

Sweep Hold

The sweep can be held/restarted at any time at/from its current frequency by alternate presses of the MAN HOLD key or remote command. As with all other sweep control, pressing MAN HOLD will halt the sweep on all channels for which sweep has been set on.

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General

Triggered Burst and Gated modes are selected from the MODE screen, called by the MODE key, as alternatives to the default continuous mode.

In Triggered Burst mode a defined number of cycles are generated following each trigger event. This mode is edge triggered.

In gated mode the generator runs whenever the gating signal is true. This mode is level sensitive.

Triggered Burst mode can be controlled by either the Internal Trigger Generator, an external trigger input, the (internal) Trigger Out signal from an adjacent channel on a multi−channel instrument, by the front panel MAN TRIG key or by remote control. Gated mode can be controlled by the Internal Trigger Generator or on external trigger input.

In both modes the start phase, i.e. the starting point on the waveform cycle, can be specified.

Internal Trigger Generator

The period of the Internal Trigger Generator is set with the period soft−key on the TRIGGER IN setup screen called by the TRIG IN key.

Triggered Burst and Gate

MODE:

♦continuous ◊gated setup…◊ ◊triggered setup…◊

The Internal Trigger Generator divides down a crystal oscillator to produce a 1:1 square wave with a period from 0·01ms (100kHz) to 200s (·005Hz). Generator period entries that cannot be exactly set are accepted and rounded up to the nearest available value, e.g. ·109ms is rounded to ·11ms.

When Triggered Burst or Gated modes are selected the SYNC OUT source automatically defaults to trigger which is the output of the internal trigger generator when internal triggering or gating is specified.

In Triggered Burst mode the selected edge of each cycle of the trigger generator is used to initiate a burst; the interval between bursts is therefore 0·01ms to 200s as set by the generator period.

In Gated mode the output of the main generator is gated on whilst the Internal Trigger Generator output is true; the duration of the gate is therefore ·005ms to 100s in step with trigger generator periods of ·01ms to 200s.

External Trigger Input

External trigger or gate signals are applied to the front panel TRIG IN socket which has a TTL level (1·5V) threshold. In Triggered Burst mode the input is edge sensitive; the selected edge of each external trigger initiates the specified burst. In Gated mode the input is level sensitive; the output of the main generator is on whilst the gate signal is true.

The minimum pulse width that can be used with TRIG IN in Triggered Burst and Gated mode is 50ns and the maximum repetition rate is 1MHz. The maximum signal level that can be applied without damage is ±10V.

When Triggered Burst or Gated modes are selected the SYNC OUT source automatically defaults to trigger which is always a positive−edged version of the external trigger or gate signal when external triggering or gating is specified.

TRIGGER IN: force

◊source: internal ◊slope: positive ♦period: 2·00ms

◊

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Adjacent Channel Trigger Output

On multi−channel instruments the Trigger Out signal of an adjacent channel can be used as the control signal for a Triggered Burst. The channel numbering ‘wraps round’, i.e. channels 1 and 3 are obviously adjacent to channel 2 but so are channels 2 and 4 adjacent to channel 1.

The source of the Trigger Out signal is selected by the source soft−key on the TRIGGER OUT screen called by the TRIG OUT key.

TRIGGER OUT:

◊ source: wfm end

The Trigger Out choices are as follows:

wfm end:

pos’n marker:

seq sync:

burst done:

The default choice is wfm end except when the channel is running a sequence in which case it becomes seq sync. To set the Trigger Out to anything other than its default it is necessary to change the mode from auto to manual using the mode soft−key.

Waveform end; a positive−going pulse coincident with the end of a waveform cycle (and the start of the next).

Position marker; arbitrary waveforms only. Any point(s) on the main waveform may have marker bit(s) set high or low. No output if selected for a standard waveform.

Sequence sync; a positive−going pulse coincident with the end of a waveform sequence.

A positive−going pulse coincident with the end of the last cycle of a burst.

mode: auto

Trigger Out is an internal signal but, as with the other trigger sources, a positive−edged version is available at the triggered channel’s SYNC OUT with its default source of trigger selected.

Triggered Burst

Triggered Burst mode is turned on with the triggered soft−key on the MODE screen. The setup… soft−key on this screen accesses the TRIGGER/GATE SETUP screen on which the burst count and start phase are set. The other trigger parameters are set on the

TRIGGER IN setup screen called by pressing the TRIG IN key.

Trigger Source

The trigger source can be selected with the source soft−key on the TRIGGER IN setup screen to be internal, external, manual or either of the adjacent channels.

With internal selected the internal trigger generator is used to initiate a burst; this generator is set up as described in the previous section.

With external selected the specified edge of the signal at TRIG IN is used to initiate a burst.

With chan x selected the Trigger Out signal from adjacent channel x is used to initiate a burst; the source of the Trigger Out signal on that channel x is set up as described in the previous section.

With manual selected as the source only pressing the MAN TRIG key or a remote command can be used to initiate a burst. In multi−channel instruments, pressing MAN TRIG will trigger all

those channels for which manual has been selected as the source.

TRIGGER IN: force

◊source: internal ◊slope: positive ♦period: 2·00ms

◊

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Trigger Edge

The slope soft−key is used to select the edge ( positive or negative ) of the external trigger signal that is used to initiate a burst. The default setting of positive should be used for triggering by the Internal Trigger Generator or an adjacent channel’s Trigger Out.

Note that the trigger signal from SYNC OUT, used for synchronising the display of a triggered burst on an oscilloscope for example, is always positive−going at the start of the burst.

Burst Count

The number of complete cycles in each burst following the trigger is set from the TRIGGER/GATE SETUP screen called by pressing setup on the MODE screen.

The required count can be set by pressing the burst cnt soft−key followed by direct entries from the keyboard or by using the rotary control. The maximum number of waveform cycles that can be counted is 1048575 (2

Start Phase

The start phase, i.e. the point on the waveform cycle at which the burst starts, can be selected by pressing the phase soft−key followed by direct entries from the keyboard or by using the rotary control. Since the waveform cycle is always completed at the end of the burst the start phase is also the stop phase.

The phase can be set with a precision of 0.1° but the actual resolution is limited with some waveforms and at certain waveform frequencies as detailed below. To indicate when this is the case the actual phase is shown in brackets as a non−editable field below the programmed value.

To achieve start phase precision all waveforms are run in Clock Synthesis mode, i.e. as if they were arbitrary waveforms, when Triggered Burst is specified; this limits actual frequency resolution to 4 digits for all waveforms although the normally DDS generated waveforms are still entered with 7−digit precision. Sine/cosine/haversine/etc. waveforms are created as if they were arbitrary waveforms with the first point of the waveform exactly at the start phase; each time the phase or frequency is changed the waveform is recalculated which can cause a slight lag if these parameters are being changed quickly with the rotary knob.

The phase resolution of true arbitrary waveforms is limited by the waveform length since the maximum resolution is 1 clock; thus waveforms with a length >3600 points will have a resolution of 0.1° but below this number of points the maximum resolution becomes 360° ÷ number of points.

Square waves, pulse, pulse trains and sequences have no start phase adjustment; phase is fixed at 0°. A summary of start phase capabilities in Triggered Burst mode is shown in the table below:

Waveform Max Wfm Freq Phase Control Range & Resolution

Sine, cosine, haversine, havercosine 1MHz

Square 1MHz

Triangle 100kHz

Ramp 100kHz

Sin(x)/x 100kHz

Pulse & Pulse Train 10MHz

Arbitrary 40MS/s clock

Sequence 40MS/s clock

TRIGGER/GATE SETUP:

♦burst cnt: 0000001 ◊phase: +000.0º

(actual: +000.0º)

−1).

± 360°, 0.1°

0° only

± 360°, 0.1°

0° only

± 360°, 300 ÷ length or 0.1°

0° only

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Manual Initialisation of Inter−channel Triggering

If a multi−channel instrument is set up such that all channels are triggered by an adjacent one it is possible to have a stable condition where all channels are waiting for a trigger and the sequence of triggered bursts never starts. To overcome this problem any channel can be triggered manually and independently using the force soft−key on that channel’s TRIGGER IN screen; select the channel to start the sequence with the appropriate SETUP key, select the

TRIGGER IN screen with the TRIG IN key and press the force soft−key.

Gated Mode

Gated mode is turned on with the gated soft−key on the MODE screen. The setup… soft−key on this screen accesses the TRIGGER/GATE SETUP screen on which the start phase is set. The other parameters associated with Gated are set on the TRIGGER IN setup screen called by pressing the TRIG IN key.

Gate Source

The gate signal source can be selected with the source soft−key on the TRIGGER IN setup screen to be internal, external, or either of the adjacent channels.

With internal selected the internal trigger generator is used to gate the waveform; the duration of the gate is half the generator period, see Internal Trigger Generator section.

With external selected the gate duration is from the point (nominally 1.5 Volts) on the specified edge of the signal at TRIG IN until the same level on the opposite edge.

With chan x selected the Trigger Out signal from the adjacent channel x is used to gate the waveform; the source of the Trigger Out signal on that channel x is set up as described in the previous section.

Gate Polarity

If slope on the TRIGGER IN setup screen is set to positive the gate will open at the threshold on the rising edge and close on the threshold of the falling edge of an external gating signal, i.e. the gate signal is true when the TRIG IN signal is high. If the slope is set negative the gate signal is true when the TRIG IN signal is low. The default setting of positive should be used for gating with the Internal Trigger Generator or an adjacent channel’s Trigger Out.

TRIGGER IN: force

◊source: internal ◊slope: positive ♦period: 2·00ms

◊

Start Phase

Press setup… on the MODE screen to access the TRIGGER/GATE SETUP screen on which the start phase can be set.

TRIGGER/GATE SETUP:

♦BURST CNT: 0000001 ◊PHASE: +000.0° (actual: +000.0°)

The start phase, i.e. the point on the waveform cycle at which the gated waveform starts, can be selected by pressing the phase soft−key followed by direct entries from the keyboard or by using the rotary control. Since the waveform cycle is always completed at the end of the gated period the start phase is also the stop phase.

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To achieve start phase precision all waveforms are run in Clock Synthesis mode, i.e. as if they were arbitrary waveforms, when Gated mode is specified; this limits actual frequency resolution to 4 digits for all waveforms although the normally DDS generated waveforms are still entered with 7−digit precision. Sine/cosine/haversine/etc. waveforms are created as if they were arbitrary waveforms with the first point of the waveform exactly at the start phase; each time the phase or frequency is changed the waveform is recalculate which can cause a slight lag if these parameters are being changed quickly with the rotary knob.

Square waves, pulse, pulse trains and sequences have no start phase adjustment; phase is fixed at 0°. Refer to the table in the Triggered Burst section for a summary of start phase capabilities.

Sync Out in Triggered Burst and Gated Mode

When Triggered Burst or Gated modes are selected the SYNC OUT source automatically defaults to trigger; trigger is a positive−edged signal synchronised to the actual trigger used whether internal (from the Internal Trigger Generator or an adjacent channel) or external of either polarity.

Alternatively, SYNC OUT can be set to burst done on the SYNC OUT setup screen; sync out then provides a signal which is low while the waveform is running and high at all other times.

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General

In Tone mode the output is stepped through a user−defined list of up to 16 frequencies under the control of the signal set by the source soft−key on the TRIGGER IN setup screen. This signal can be the Internal Trigger Generator, an external trigger input, the front panel MAN TRIG key or a remote command. On multi−channel instruments the control signal can also be the Trigger Out from an adjacent channel.

All standard and arbitrary waveforms can be used in Tone mode with the exception of pulse, pulse−train and sequence. During Tone all waveforms are generated in DDS mode for fast phase−continuous switching between frequencies. For DDS operation all waveforms must be 4096 points in length; this is the natural length for standard waveforms but all arbitrary waveforms are expanded or condensed in software to 4096 points when the Tone list is built. This does not affect the original data.

Because DDS mode is used the frequency range for all waveforms is 1mHz to 10MHz in Tone mode, including triangle, ramp and squarewave which have different limits in continuous operation.

Tone Frequency

Press the tone setup… soft−key on the MODE screen, called by pressing the MODE key, to get the TONE setup screen:

Tone Mode

Each frequency in the list can be changed by pressing the appropriate soft−key and entering the new value from the keyboard. The selected frequency can be deleted from the list by pressing the

del (delete) soft−key. Additional frequencies can be added to the end of the list by selecting end of list with the appropriate soft−key and entering the new frequency from the

keyboard.

The whole list can be scrolled back and forward through the display using the rotary control.

Tone Type

The type soft−key on the TONE setup screen permits three types of tone switching to be specified.

With type set to trig the frequency changes after each occurrence of the signal edge specified in the source and slope fields on the TRIGGER IN screen but only after completing the last cycle of the current frequency.

With type set to gate the frequency changes when the signal specified in the source field goes to the level specified in the slope field on the TRIGGER IN screen and continues until the level changes again at which point the current cycle is completed; the output is then gated off until the next occurrence of the gating signal at which time the next frequency in the list is gated on. The difference between triggered and gated tone changes is therefore that in triggered mode the signal changes phase−continuously from one frequency to the next at the waveform zero−crossing point immediately after the trigger signal whereas in gated mode there can be an ‘off’ period between successive frequencies whilst the gate signal is not true.

TONE type: trig◊ ◊2·000000 kHz #2 ♦3·000000 kHz del◊ ◊end of list #4

With type set to fsk the frequency changes instantaneously (and phase−continuously) at each occurrence of the signal edge specified in the source and slope fields on the TRIGGER IN screen without completing the current waveform cycle; this is true FSK (Frequency Shift Keying) tone switching.

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The following diagrams demonstrate the differences between trigger, gate and FSK tone switching for a list of 2 frequencies switched by a square wave (positive slope specified on TRIGGER IN setup).

The maximum recommended tone frequencies and trigger/gate switching frequencies for the three modes are as follows:

GATE: Maximum tone frequency 50kHz; maximum switching frequency

<lowest tone frequency.

TRIGGER: Maximum tone frequency 50kHz; maximum switching frequency 1MHz.

FSK: Maximum tone frequency 1MHz; maximum switching frequency 1MHz.

Tone Switching Source

The signal which controls the frequency switching is that set by the source soft−key on the TRIGGER IN setup screen. The slope field on the same screen sets the active polarity of

that signal; when set to positive the rising edge of the trigger signal is active or the high level of the gating signal is true and the reverse is true for a negative setting. The signal that can be selected by the source soft−key can be the Internal Trigger Generator, an external trigger input, the front panel MAN TRIG key, a remote command and, for mutli−channel instruments, Trigger Out of an adjacent channel; a full explanation for each of these can be found in the Triggered Burst and Gate chapter.

DTMF Testing with a Multi−Channel Generator

An important use of Tone mode is DTMF (Dual Tone Multiple Frequency) testing in which 2 channels are set up with equal length lists of different frequencies and are triggered from a common signal. The outputs are summed together using the internal sum facility, see SUM chapter. DTMF testing generally uses sinewaves in the frequency range 600Hz to 1.6kHz.

It is also possible to set up DTMF testing using two single channel instruments triggered by a common external signal and summed using the external SUM capability.

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Arbitrary Waveform Generation

Introduction

Arbitrary (Arb) waveforms are generated by sequentially addressing the RAM containing the waveform data with the arbitrary clock. The frequency of the arb waveform is determined both by the arb clock and the total number of data points in the cycle.

In this instrument an arb waveform can have up to 65536 horizontal points. The vertical range is

−2048 to +2047, corresponding to a maximum peak−peak output of 20 Volts. Up to 100 waveforms can be stored in the 256k non−volatile RAM and each given a name; the number that can be stored depends on the number of points in each waveform.

Arb waveforms can be created using basic front panel editing capabilities (particularly useful for modifying existing standard or arb waveforms) or by using waveform design software that enables the user to create waveforms from mathematical expressions, from combinations of other waveforms, or freehand, see Appendix 4.

Arb Waveform Terms

The following terms are used in describing arb waveforms:

• Horizontal Size. The number of horizontal points is the time component of the waveform. The minimum size is 4 points and the maximum is 65536 points.

• Waveform Address. Each horizontal point on an arb waveform has a unique address. Addresses always start at 0000, thus the end address is always one less than the horizontal size.

• Arb Frequency and Waveform Frequency. The arb frequency is the clock rate of the data RAM address counters and has a range of 0·1Hz to 40MHz on this instrument. The waveform frequency depends on both the arb frequency and horizontal size. A 1000 point waveform clocked at an arb frequency of 40MHz has a waveform frequency of 40e6÷1000 = 40kHz.

• Data Value. Each horizontal point in the waveform has an amplitude value in the range −2048 to +2047.

• Arb Waveform Amplitude. When playing arb waveforms the maximum output amplitude will depend on both the range of data values and the output amplitude setting. A waveform that contains data values ranging from −2048 to +2047 will produce a maximum output which is 100% of the programmed peak−to−peak amplitude; if the maximum range of the data values is only −1024 to +1023, for example, the maximum output will only be 50% of the programmed level.

Arb Waveform Creation and Modification – General Principles

Creating arb waveforms with the instrument alone consists of two main steps:

• Creating a new blank waveform, or a copy of an existing one, and giving it a size and a name

• Modifying that waveform using the various editing capabilities to get exactly the waveform

required. These steps are fully described in the Creating New Waveforms and Modifying Arbitrary

Waveforms sections which follow.

Waveform creation using waveform design software also consists of two steps:

• Creating the waveform using the software on a PC.

• Downloading the waveform to the generator via the RS232 or GPIB interface.

This process is described in Appendix 4.

Certain constraints apply to the overall operation of the generator during creation and modification of an arb waveform on the instrument; these ensure proper management of the arb waveforms and avoid contentions, particularly in multi−channel instruments. The constraints are mentioned in the individual sections which follow but are summarised here.

• No arb creation or modification is possible unless all channels are running in continuous

mode; summing and modulation of channels is allowed.

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• Arb waveforms are created and mostly edited in the non−volatile backup memory; up to 100 waveforms can be stored subject to the memory limitation of 256k. Any of these waveforms can be called into a channel’s memory by selecting them to run as an arb or as part of an arb sequence, up to the channel’s limit of 64k points. During editing, changes are made to the waveform in non−volatile memory and are then copied to all the channels where that waveform is used. The exceptions to this are amplitude, offset and block copy changes which are initially made only to the waveform copy of the channel currently selected; the changes are copied to the non−volatile back−up memory (and then to any other channels using that waveform) when the parameter edit is confirmed with the save soft−key.

• A waveform cannot be deleted from a channel’s memory if it is running on that channel.

• Waveforms must be deleted from the channel’s memory before they can be deleted from the back−up memory.

• If an arb waveform sequence is running no waveforms can be deleted from that channel,

whether they are used in the sequence or not.

• A waveform used by a non−active sequence can be deleted but the sequence will not subsequently run properly and should be modified to exclude the deleted waveform.

The user is reminded of the above constraints by warning/error messages in the display when illegal operations are attempted.

Selecting and Outputting Arbitrary Waveforms

At switch−on, assuming factory default settings, any arbitrary waveforms already created will only be stored in the non−volatile back−up memory. To run an arbitrary waveform it is necessary to select it from the list in back−up memory.

Press the ARB key to see the list, on the ARBS screen, of all arbitrary waveforms held in back−up memory.

ARBS: backup mem◊ ◊wv00 01024 ◊wv01 03782 ◊wv02 00500

The rotary knob or cursor keys can be used to scroll the full list backwards and forwards through the display. With the appropriate channel selected using its SETUP key press the soft−key beside the required waveform to load it into that channel’s memory. Many waveforms can be loaded into and held in the channel’s memory in this way, up to the 64k point limit; the last one selected will be the one currently output on that channel.

Once an arb waveform has been loaded into a channel it can also be selected to run from the STANDARD WAVEFORMS screen, accessed by pressing the STD key, by pressing the arb

soft−key; if more than one arb waveform is held in the channel’s memory the last one selected will be the one that is output. The complete list of waveforms held in a channel’s memory can be viewed by pressing the top right soft−key on the ARBS screen; this causes the channel memory to be displayed instead of the backup memory, e.g.

ARBS: chan mem◊ ◊wv01 03872 ◊wv03 00128

If the power−on setting has been set to restore last setup on the POWER ON SETTING screen the waveforms will be restored to the channel’s memory at power−on, see

System Operations chapter. The same arbitrary waveform can be selected to run on more than one channel and when it is

edited, in backup memory, the changes will be made to all copies of the waveform too. The following sections give full details as to how arbitrary waveforms are created and modified.

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Creating New Waveforms

Pressing the CREATE key calls the CREATE NEW WAVEFORM screen.

Create Blank Waveform

Pressing the create blank… soft−key calls the menu:

The top line contains the user−defined waveform name which can be 8 characters long. The instrument allocates a default name of wv(n) starting at wv00; the name can be edited by selecting the appropriate character position with the cursor keys and then setting the character with the rotary control which scrolls through all alphanumeric characters in sequence.

Pressing the size soft−key permits the waveform length to be entered directly from the keyboard or by using the rotary control and cursor keys; the default size is 1024. The minimum size is 4 and the maximum 65536; appropriate warnings are given if attempts are made to set a waveform size less than 4 or greater than the remaining available backup memory. The waveform ‘blank’ is being created in the non−volatile backup memory; the free memory field shows the remaining unused backup memory.

This menu can be exited either by pressing the cancel soft−key which keeps the name but does not allocate the memory space, or by pressing the create soft−key which builds a “blank” waveform and directly calls the MODIFY screen to permit waveform editing.

CREATE NEW WAVEFORM free memory: 258972

◊create blank… ◊create from copy…

♦create: “wv00 ” ◊size: 01024

◊cancel create ◊

Create Waveform Copy

Pressing the create from copy… soft−key calls the following menu:

The user−defined name and waveform size can be entered after pressing the create and size soft−keys respectively, exactly as described in the previous section.

The source waveform which is to be copied can be selected by the from soft−key; repeated presses of the soft−key, cursor keys or using the rotary control will scroll through the list of all the

available waveforms, including any other arbitrary waveforms already created. The horizontal size of the waveform being copied does not have to be the same as the waveform

being created. When the waveform is copied, by pressing the create key, the software compresses or expands the source waveform to create the copy. When the source is expanded the copy has additional interpolated points; when the source is compressed, significant waveform data may be lost, particularly from arb waveforms with narrow spikes if the compression ratio is large.

The menu can be exited by pressing the cancel soft−key, which keeps the name but does not implement the copy, or by pressing the create soft−key, which makes the copy and directly calls the MODIFY screen to permit waveform editing.

♦create: “wv01 ” ◊from: sine ◊size: 01024 ◊cancel create ◊

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Modifying Arbitrary Waveforms

Read the Arb Waveform Creation and Modification General Principles section for a summary of the general restrictions applying to waveform modification.

Pressing the MODIFY front panel key, or the create soft−key on either of the CREATE NEW

WAVEFORM menus calls the MODIFY screen.

MODIFY: wv01 ◊ resize… rename…◊ ◊delete… info…◊ ◊edit waveform…

This screen gives access to a number of menus which permit the selected waveform to be resized, renamed, edited, etc. The arb waveform to be modified is selected using the rotary control or cursor keys to step through all possible choices; the current choice is displayed on the top line beside MODIFY.

Waveform Edit Cursor

During any arbitrary waveform modify procedure which involves setting waveform addresses, waveform cursor(s) can be output from the rear panel CURSOR/MARKER OUT socket. For this to happen the waveform being edited must be running on the output currently selected by the channel SETUP keys. The amplitude, polarity and width of the cursor is set on the cursor/marker… menu of the UTILITY screen, see System Operations section. The cursors are positioned at the start and stop addresses used for the various edit operations described below (one address/cursor only for point edit). The cursor signal can be displayed on a second channel of the ‘scope or used to modulate the Z−axis to bright−up the stop and start addresses.

Note that the addresses are retained when moving between edit functions. Thus if the stop and start addresses are set for waveform insert, the same addresses appear as the defaults when wave amplitude edit is selected, for example; the addresses can of course subsequently be changed.

Resize Waveform

Pressing the resize… soft−key on the MODIFY screen calls the Resize screen.

Resize changes the number of points in the waveform; the new size can be larger or smaller

than the old size. When the new size is larger, the software adds additional interpolated points. When the size is smaller, points are removed. Reducing the waveform size may cause the waveform to lose significant data. There is no “undo” for resize.

Resize is implemented by pressing the resize soft−key or aborted by pressing the cancel soft−key; both return the display to the MODIFY screen.

Rename Waveform

Pressing the rename… soft−key on the MODIFY screen calls the Rename screen:

The new name can be entered below the original by selecting the appropriate character position with the cursor keys and then setting the character with the rotary control which scrolls through all the alphanumeric characters in sequence. The name can be up to 8 characters long.

Resize: wv01 (old size: 01024) new size: 01024

◊cancel resize ◊

Rename: wv01 as “y ”

◊cancel rename ◊

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Return to the MODIFY screen by pressing rename (which implements the new name) or cancel.

Waveform Info

Pressing the info… soft−key on the MODIFY screen calls the info screen.

The screen gives the name of the waveform, its length and the channels and sequences where it is used; the where used information is particularly useful when executing waveform management operations such as delete.

Pressing exit returns the display to the MODIFY screen.

To view what waveforms are held in a particular channel memory select the channel with its SETUP key, press the UTILITY key to view the UTILITY MENU and then press the

chan wfm info… soft−key to get the CHAN WFM INFO: screen.

Info wv03 exit◊ length: 00128 chan: 3 4 seq:

CHANNEL WFM INFO: waveforms: 1 free mem: 65436

exit◊

This shows the number of waveforms and the free memory on that channel. Press the exit soft−key to return to the UTILITY MENU.

Delete Waveform

Pressing the delete… soft−key displays a request for confirmation that the selected waveform is to be deleted from the backup memory.

Confirm deletion by pressing the delete soft−key which will return the display to the MODIFY screen with the next arb waveform automatically selected; cancel aborts the deletion.

Waveforms cannot be deleted from the backup memory until they have first been deleted from all channel memories; waveforms cannot be deleted from a channel’s memory if it is being output on that channel. The waveform must first be deselected on each channel by selecting alternative waveforms on those channels (from the STANDARD WAVEFORMS or ARBS screens). The waveform can then be deleted from each channel memory in turn by selecting the ARBS screen for that channel.

Delete waveform “wv01 ” ?

◊cancel delete ◊

ARBS: chan mem◊

◊wv00 01024 del◊ ♦wv01 03872 ◊wv02 00500 del◊

A del soft−key will appear against those waveforms in the channels memory which are not in use; press the appropriate del soft−key to delete the waveform from channel memory. The deletion from backup memory described above can then be actioned.

Edit Waveform

Pressing the edit waveform… soft−key calls the EDIT FUNCTIONS menu:

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From this menu can be selected functions which permit the waveform to be edited point−by−point (point edit), by drawing lines between two points (line draw) or by inserting all or part of an existing waveform into the waveform being edited (wave insert). In addition, sections of the waveform can be selected and their peak−to−peak level changed using wave amplitude, or baseline changed using wave offset. Sections of the waveform can be copied into itself (block copy) and position markers for use at Sync Out can also be defined.

Pressing the exit soft−key on any of these edit screens will return the display to the EDIT FUNCTIONS menu.

Point Edit

Press the point edit… soft−key to call the POINT EDIT screen:

EDIT FUNCTIONS:

◊point edit… ◊line draw… ◊wave insert…

POINT EDIT (addrs, value)

♦ (00512, +0500) ◊ ◊exit next point◊

To modify a point, press the addrs soft−key and enter the address directly from the keyboard or by using the rotary control; the current data value will be displayed to the right of the address. To change the value press value and enter the new value directly from keyboard or by using the rotary control. Changing the data value automatically updates the waveform.

Pressing the next point soft−key automatically advances the address by one point; alternatively press addrs to re−select address and permit entries from the keyboard or by rotary control.

Line Edit

Press the line draw… soft−key to call the LINE screen:

The display shows a frm (from) and to address which will be the points between which a straight line will be created when the draw line soft−key is pressed. The default frm address is the first point on the waveform or the point most recently edited if point edit has been used. Set the “from” address and value by pressing the appropriate soft−key and making an entry

direct from the keyboard or by using the rotary control; repeat for the “to” address and value.

The line will be drawn between the two selected points when the draw line soft−key is pressed.

Wave Insert

Pressing wave insert… calls the wave insert screen:

LINE (addrs, value)

♦frm (00512, +0500)◊ ◊to (00750, +0412)◊ ◊exit draw line◊

wv01 Æ wv02

◊ 00000 strt 00400 ◊ ◊ 00512 stop 01000 ◊ ◊exit insert◊

Wave Insert places waveforms between programmable start and stop points. Both standard and arbitrary waveforms can be inserted in the new waveform, with the exception of pulse, pulse−train and sequence.

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A section of an arbitrary waveform can be inserted, as defined by the left−hand strt (start) and stop addresses, e.g. 00000 and 00512 of wv01 on the screen above; these addresses default to the start and stop of the whole waveform but can be reset to define any section of the waveform. Change the addresses by pressing the appropriate soft−key and making entries from the keyboard or by rotary control. The destination of the selected section of the source waveform in the new waveform is defined by the right−hand strt (start) and stop addresses. Change the addresses by pressing the appropriate soft−key and making entries from the keyboard or by rotary control.

The insert is actioned by pressing the insert soft−key. If there is a size difference between the two sections of waveform then the software will expand or compress the source to fit the new waveform. Compressing the waveform may lose some significant data.

To insert sections of the current waveform within itself see Block Copy.

Block Copy

Pressing block copy… calls the BLOCK COPY screen:

BLOCK COPY: execute

◊

♦start: 00400 exit ◊ ◊stop: 01000 undo ◊ ◊dest: 00000 save ◊

Block copy allows a section of the current waveform to be inserted within itself. The block to be inserted is defined by the start and stop addresses. Change the addresses by pressing

the appropriate soft−key and making entries from the keyboard or by rotary control.

The destination address for the start of the section is set by pressing the dest soft−key and entering the address. The effect of making the block copy can then by previewed by pressing the execute soft−key.

Note that if there are not enough waveform points between the destination address and end of waveform to accommodate the copied section, the waveform being copied will simply be truncated. The copy can be removed by pressing the undo soft−key or by entering a new destination address.

Block copy edit operates on the version of the waveform in the channel currently selected by the channel SETUP keys; the effect of the edit can be seen by selecting the waveform to run on that channel. When the block copy is as required it can be saved by pressing the save soft−key; the action of saving modifies the waveform in the backup memory and then any other copies of the waveform in other channel memories. Once saved the original waveform cannot be recovered.

Pressing exit returns to the EDIT FUNCTIONS screen without change.

Waveform Amplitude

Pressing the wave amplitude soft−key calls the AMPLITUDE screen:

AMPLITUDE: 0

◊start: 00400 ◊stop: 01000 undo◊ ◊exit save◊

The waveform amplitude can be changed on a section of the waveform defined by the start and stop addresses. Set the addresses by pressing the appropriate soft−key and making entries directly from the keyboard or by rotary control.

01·00♦

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The data values over the specified section of the waveform can be multiplied by a factor of between 0·01 and 100·0 by making entries in the AMPLITUDE field. Press the appropriate

soft−key and make entries direct from the keyboard or by using the rotary control; the amplitude changes on completion of the entry. Note that entries >1·0 will cause clipping if the waveform already uses the full −2048 to +2047 data value range; the result is, however, still treated as a valid waveform. The original waveform can be restored by pressing the undo soft−key.

Amplitude edit operates on the version of the waveform in the channel currently selected by the channel SETUP keys; the effect of the edit can be seen by selecting the waveform to run on that channel. When the amplitude has been modified as required the new waveform can be saved by pressing the save key; the action of saving modifies the waveform in the backup memory and then any other copies of the waveform in other channel memories. Once saved the original waveform cannot be recovered.

Pressing exit returns to the EDIT FUNCTIONS screen without change.

Waveform Offset

Pressing the wave offset soft−key calls the WAVE OFFSET screen.

WAVE OFFSET: +0

◊start: 00400 ◊stop: 01000 undo ◊ ◊exit save ◊

The waveform offset can be changed on a section of the waveform defined by the start and stop addresses. Set the addresses by pressing the appropriate soft−key and making entries

directly from the keyboard or by rotary control. The data values over the specified section of the waveform are offset by the value entered in the

WAVE OFFSET field. Press the appropriate soft−key and make entries direct from the keyboard or by using rotary control. Entries in the range −4096 to +4095 will be accepted; this permits, in the extreme, waveform sections with values at the −2048 limit to be offset to the opposite limit of

+2047. Warnings are given when the offset causes clipping but the entry is still accepted. The original waveform can be restored by pressing the undo soft−key.

Offset edit operates on the version of the waveform in the channel currently selected by the channel SETUP keys; the effect of the edit can be seen by selecting the waveform to run on that channel. When the offset has been modified as required the new waveform can be saved by pressing the save key; the action of saving modifies the waveform in the backup memory and then any other copies of the waveform in other channel memories. Once saved the original waveform cannot be recovered.

Pressing exit returns to the EDIT FUNCTIONS screen without change.

000♦

Wave Invert

Pressing the wave invert soft−key calls the INVERT screen:

The waveform can be inverted on a section of the waveform defined by the start and stop addresses. Set the addresses by pressing the appropriate soft−key and making entries directly

from the keyboard or by rotary control. The data values over the specified section of the waveform are inverted about 0000 each time the

invert soft−key is pressed.

Press exit to return to the EDIT FUNCTIONS screen.

INVERT: wv02

♦start adrs: 00512 ◊stop adrs: 00750 ◊exit invert ◊

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Position Markers

Pressing the position markers… soft−key calls the POSITION MARKER EDIT screen:

Position markers are output from SYNC OUT when the source (src) is set to pos’n marker on the SYNC OUTPUT SETUP screen.

Position markers can be set at any or all of the addresses of a waveform either individually, using the adrs (address) soft−key, or as a pattern, using the patterns… menu.

A marker can be set directly at an address by pressing the adrs soft−key followed by a keyboard entry; pressing the right−hand soft−key on the adrs line then toggles the marker setting between <1> and <0> as shown in the arrowed brackets. The address can be changed by

incrementing with the adrs key, by using the rotary control, or by further keyboard entries; marker settings are changed at each new address with the right−hand soft−key. Markers show

immediately they are changed.

Alternatively, markers can be input as patterns by using the patterns… sub−menu.

POSITION MARKER EDIT

adrs: 00000 <0> ◊

◊patterns… ◊exit clear all ◊

PATTERN: 0

◊start: 00000 ◊stop: 01023 ◊exit: do pattern ◊

The start and stop addresses of the markers within the waveform are set using the start and stop soft−keys respectively followed by a direct keyboard entry or by rotary control. The pattern itself is set in the top line of the display; press the soft−key to the right of PATTERN: and enter the sequence of 1s and 0s using 1 and 0 from the keyboard (which auto−increments to

the next character) or with the rotary control (using the cursor keys to move the edit cursor along the pattern). The pattern consists of 16 values; if the cursor keys are used to skip over some character positions these will automatically be filled with the value of the last one specified to the left. The pattern is entered repeatedly across the whole range defined by the start and stop addresses when the do pattern soft−key is pressed; pressing exit returns to POSITION MARKER EDIT screen without implementing the pattern.

Pressing the clear all soft−key displays a request for confirmation that all markers should be cleared from the waveform. Pressing clear cancels all the markers and returns the display to POSITION MARKER EDIT; pressing cancel aborts the clear.

Arbitrary Waveform Sequence

Up to 16 arbitrary waveforms may be linked in a sequence. Each waveform can have a loop count of up to 32768 and the whole sequence can run continuously or be looped up to 1048575 times using the Triggered Burst mode. Pressing the SEQUENCE key calls the initial SEQUENCE screen:

0000000…♦

SEQUENCE (segs= 1)

◊sequence setup…

♦stop run ◊

A previously defined sequence can be run and stopped from this screen using the run and stop soft−keys; sequence can also be switched on from the STANDARD WAVEFORMS

screen with the sequence soft−key. The segs= field shows the number of segments in the sequence; there is always at least 1 segment.

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Sequence Set−up

Pressing the sequence setup… soft−key on the SEQUENCE screen (or the setup… soft−key next to sequence on the STANDARD WAVEFORMS screen) calls the sequence set up screen:

◊seg: 2 off

◊

♦wfm wv03 ◊step on: count ◊cnt: 00001 done ◊

Repeated presses of the seg soft−key steps the display through the set−ups of each of the 16 segments of the sequence. With the exception of segment 1 which is always on (and therefore has no on−off soft−key) the 16 segment set−ups are identical in format. When segment 1 is displayed the segs= field shows the total number of segments in the current sequence.

The segment to be set−up is selected with the seg soft−key; the 16 segments can be selected in sequence with repeated presses of the soft−key or by using the rotary control.

Once the segment to be edited has been set the waveform for that segment is selected with the wfm (waveform) soft−key; the list of all arbitrary waveforms already created is stepped through with repeated presses of the wfm soft−key or by using the rotary control.

The criteria for stepping between waveform segments is set by the step on soft−key. The default setting is step on: count which means that the waveform will step on to the next segment after the number of waveform cycles specified in the cnt (count) field; up to 32768 cycles can be set with cnt selected, using direct keyboard entries or by rotary control.

Alternatively, the step on criteria can be set to trig edge or trig level in the step on field; trigger edge or trigger level can be mixed with count (i.e. some segments can step on

count, others on the specified trigger condition) but trigger edge cannot be mixed with trigger level in the same sequence.

If trig edge is selected the sequence starts running at the first waveform segment when sequence is set to run and steps to the following segments in turn at each subsequent trigger. The trigger source can be any of the settings selected on the TRIGGER IN setup screen (called by the TRIG IN key); these are described fully in the Triggered Burst and Gate section. At each trigger the current waveform cycle plus one further whole cycle are completed before the waveform of the next segment is started.

If trig level is selected the sequence runs continuously through each segment in turn (1 cycle per segment) while the trigger level is true. When the trigger level goes false the waveform currently selected runs continuously until the level goes true again at which point the sequence runs continuously through each segment in turn again. The trigger level source can be any of the settings selected on the TRIGGER IN setup screen with the exception of the MAN TRIG key which can only produce an edge, not a level, when pressed.

Providing the step on: field is set to count for all segments the waveform sequence can also be run in Gated and Triggered Burst modes in the same way as simple waveforms; refer to the Triggered Burst and Gated section for full details.

The individual segments of the sequence can be turned on or off with the on−off soft−key. Note that turning a segment off will automatically set all subsequent segments off; turning a segment on will also turn on any others between segment 1 and itself that were previously off. Segment 1 is always on.

When the whole sequence is defined the set−up is constructed by pressing the done soft−key which returns the display to the initial SEQUENCE screen. The sequence can be run and stopped from this screen with the run and stop soft−keys respectively.

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Frequency and Amplitude Control with Arbitrary Waveforms

Frequency and Amplitude control work in essentially the same way as for standard waveforms with the following minor differences.

Frequency

Pressing the FREQuency key with an arbitrary waveform selected calls the ARBITRARY FREQUENCY screen:

ARBITRARY FREQUENCY 40·00 MHz

♦sample waveform ◊ ♦freq period ◊

Frequency can be set in terms of frequency or period as before by pressing the freq or period soft−key respectively. Note that the frequency and period resolution in arbitrary mode is

only 4 digits because Clock Synthesis generation is used, see Principles of Operation section. Additionally, for arbitrary waveforms, frequency/period can be set in terms of the sample clock

frequency, by pressing the sample soft−key, or in terms of the waveform frequency, by pressing the waveform soft−key. The relationship between them is

waveform frequency = sample frequency ÷ waveform size. Frequency/period entries are made direct from the keyboard or by using the rotary control in the

usual way. Pressing the FREQuency key with Sequence selected calls the SEQ CLOCK FREQUENCY

screen:

SEQ CLOCK FREQUENCY 40·00 MHz

♦freq period ◊

Frequency/period can now only be set in terms of the clock frequency. Frequency/period entries are made direct from the keyboard or by using the rotary control in the usual way.

Amplitude

Pressing the AMPLitude key with an arbitrary waveform selected calls the AMPLITUDE screen.

AMPLITUDE: +20·0 Vpp

♦Vpp

load:hiZ ◊

This differs from the AMPLITUDE screen for standard waveforms in that amplitude can now only be entered in volts peak−to−peak.

Note that the peak−to−peak amplitude set will only actually be output if the arbitrary waveform has addresses with values which reach −2048 and +2047; if the maximum value range is −1024 to +1023 for example then the maximum peak−to−peak voltage will only be 10Vpp for the instrument set to 20Vpp.

Sync Out Settings with Arbitrary Waveforms

The default setting for Sync Out when arbitrary waveforms are selected is waveform sync; this is a pulse that starts coincident with the first point of the waveform and is a few points wide.

If a waveform sequence has been selected then Sync Out defaults to sequence sync; this is a waveform which goes low during the last cycle of the last waveform in a sequence and is high at all other times. When sequence is used in Triggered Burst mode the burst count is a count of the number of complete sequences.

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Waveform Hold in Arbitrary Mode

Arbitrary waveforms can be paused and restarted on any channel by using the front panel MAN HOLD key or a signal applied to the rear panel HOLD IN socket.

On multi−channel instruments the channels which are to be held by the MAN HOLD key or HOLD IN socket must first be enabled using the ARB HOLD INPUT screen, accessed by pressing the HOLD key.

ARB HOLD INPUT:

status: no hold

mode: disabled

Each channel is selected in turn using the channel SETUP keys and set using the mode soft−key; the mode changes between disabled and enabled with alternate key presses.

Pressing the front panel MAN HOLD key stops the waveform at the current level on all enabled channels; pressing MAN HOLD a second time restarts the waveform from that level. If the ARB

HOLD INPUT screen is currently selected the status field will change from no hold to manual hold while the waveform is paused.

A logic low or switch closure at the rear panel HOLD IN socket also stops the waveform at the current level on all enabled channels; a logic high or switch opening restarts the waveform from that level. If the ARB HOLD INPUT screen is currently selected the status field will change from no hold to ext. hold while the waveform is paused.

If, while the waveform is held by either of the above means, the MAN TRIG key is pressed the waveform is reset to its first point; the waveform will restart from this point when MAN HOLD is pressed again or a high is applied to the rear panel HOLD IN socket.

Output Filter Setting

The output filter type is automatically chosen by the software to give the best signal quality for the selected waveform. The choice can, however, be overridden by the user and this is most probably a requirement with arbitrary waveforms.

To change the filter, press the FILTER key to call the FILTER SETUP screen.

The default mode is auto which means that the software selects the most appropriate filter. With the setting on auto the type can be changed manually but the choice will revert to the automatic selection as soon as any relevant parameter is changed. To override the automatic choice press the mode soft−key to select manual.

The four filter choices, which are either automatically selected or set manually with the type soft−key, are as follows:

• 10MHz elliptic: The automatic choice up to 10MHz for sine, cosine, haversine, havercosine, sinx/x and triangle. Would be the better choice for arb waveforms with an essentially sinusoidal content.

• 16MHz elliptic: The automatic choice above 10MHz for sine, cosine, haversine and havercosine. Not recommended for any other waveforms.

• 10MHz Bessel: The automatic choice for positive and negative ramps, arb and sequence.

• No filter: The automatic choice for squareware, pulse and pulse−trains. May be the

better choice for arb waveforms with an essentially rectangular content.

FILTER SETUP

◊mode: auto

type: 10MHz eliptic

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Pulse and pulse−trains are both selected and set−up from independent menus on the STANDARD WAVEFORMS screen called by pressing the STD key. Pulse and pulse−trains have similar timing set−ups and considerations but pulses are only unipolar, with a maximum amplitude of 10Vpp, whereas pulse−trains can be bipolar, with a maximum peak−to−peak of 20Vpp.

Pulse Set-up

Pulse waveforms are turned on with the pulse soft−key on the STANDARD WAVEFORMS screen; pressing the setup… soft−key beside pulse calls the first of the pulse set−up screens:

The pulse period can be set between 100·0ns and 100s, with 4−digit resolution, by direct entries from the keyboard or by using the rotary control. Pressing the next soft−key calls the pulse width screen:

Pulse and Pulse-trains

Enter pulse period: 100·0 us

◊exit next ◊

Enter pulse width: program 50·00 us (actual 50·00 us)

◊exit next ◊

The width can be entered directly from the keyboard or by using the rotary control. Any value in the range 25.00ns to 99·99s can be programmed but the actual value may differ because of the considerations discussed below; for this reason the actual pulse width is shown (in brackets) below the program width.

Pressing the next soft−key calls the pulse delay screen:

Enter pulse delay: program +0·000 ns (actual +0·000 ns)

◊exit done ◊

This is very similar to the pulse width screen and, again, the actual delay is shown below the program delay. The delay value that can be entered must be in the range ± (pulse period

−1 point); positive values delay the pulse output with respect to waveform sync from SYNC OUT; negative values cause the pulse to be output before the waveform sync. Pressing the done

soft−key on this screen returns the display to the STANDARD WAVEFORMS screen.

The means by which pulse period is set−up in the hardware requires an understanding because it affects the setting resolution of both pulse width and delay. Pulse is actually a particular form of arbitrary waveform made up of between 4 and 50,000 points; each point has a minimum time of

25.00ns corresponding to the fastest clock frequency of 40MHz. At short pulse periods, i.e. only a few points in the waveform, the setting resolution is, however,

much better than 25.00ns because the time−per−point is adjusted as well as the number of points; since the pulse width and delay are also defined in terms of the same point time, varying the time−per−point affects their resolution. For example, if the period is set to 500ns, the minimum pulse width, when set to 25.00ns, will actually be 25.00ns; 20 points at 25.00ns each exactly define the 500ns period. However, if the period is set to 499·0ns, 20 points at the minimum point time of 25.00ns will be too long so 19 points are used and the point time is adjusted to 26.26ns

(499·0

÷19); 26.26ns is now the increment size used when changing the pulse width and delay.

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For periods above 1·25ms the maximum number of points in the waveform (50,000) becomes the factor determining pulse width and delay resolution. For example, with the period set to 100ms, the smallest pulse width and delay increment is 2µs (100ms÷50,000). This may appear to cause significant “errors” at extreme settings (e.g. setting 100ns in the above example will still give an actual width of 2µs) but in practical terms a 1 in 50,000 resolution (0·002%) is quite acceptable.

Pulse period can be adjusted irrespective of the pulse width and delay setting (e.g. can be set smaller than the programmed pulse width) because, unlike a conventional pulse generator, pulse width and delay are adjusted proportionally as the period is changed. For example, if, from the default pulse settings of 100µs period/50µs width, the period is changed to 60µs the pulse width actual changes to 30µs even though the program width is still 50µs; to get a 50µs width

with the period at 60µs the width must be re−entered as 50µs after the period has been changed. Period can also be changed from the PULSE PERIOD screen called by pressing the FREQ

key with Pulse mode selected.

PULSE PERIOD 100·0 us

◊freq period♦

The new setting can be entered either as a period in the way already described or as a frequency by first pressing the freq soft−key. However, changing the period/frequency from this screen is slightly different from changing period on the pulse setup screen. When changing from this screen the number of points in the waveform is never changed (just as with a true arb) which means that the shortest period/highest frequency that can be set is number of waveform points x25.00ns. To achieve faster frequencies (up to the specification limit) the period must be changed from the pulse set−up screen; changing the frequency from this screen causes the number of points to be reduced as the period is reduced (for periods <1·25ms).

Pulse-train Setup

Pulse−trains are turned on with the pulse-train softkey on the STANDARD WAVEFORMS screen; pressing the setup… soft−key beside pulse-train calls the first of the setup screens:

The number of screens used for the setup depends on the number of pulses in the pulse−train. The first three screens define the parameters that apply to the whole pattern (number of pulses, overall pulse−train period and baseline voltage); subsequent screens define the pulse level, width and delay for each pulse in turn (3 screens for pulse 1, then 3 screens for pulse 2, etc.). Pressing

next on any screen calls the next setup screen, finally returning the display to the STANDARD WAVEFORMS screen from which pulse−train can be turned on and off; pressing done returns

the display directly to the STANDARD WAVEFORMS screen from any setup screen. The pulse−train is built only after next is pressed after the last parameter setup or whenever done is pressed, assuming a change has been made. The first screen, shown above, sets the number of pulses (1−10) in the pattern; enter the number of pulses directly from the keyboard or

by using the rotary control.

Enter no of pulses in train (1-10): 2

◊done next ◊

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Pressing next calls the pulse train period screen:

Enter pulse train period: 100·0us

◊done next◊

The period can be set, with 4−digit resolution, from 100.00ns to 100s by direct keyboard entries or by using the rotary control.

Pressing next calls the baseline voltage screen, the last of the general setup screens:

Enter the baseline voltage: +0·000 V

◊done next◊

The baseline is the signal level between the end of one pulse and the start of the next, i.e. it is the level all pulses start and finish at. The baseline can be set between −5·0V and +5·0V by direct keyboard entries or by using the rotary control. Note that the actual baseline level at the output will only be as set in this field if the output amplitude is set to maximum (10Vpp into 50Ω) on the AMPLITUDE screen and terminated in 50Ω. If the amplitude was set to 5Vpp into 50Ω then the actual baseline range would be −2·5V to +2·5V for set values of −5·0 to +5·0V, i.e. the amplitude control “scales” the baseline setting. The actual output levels are doubled when the output is unterminated.

Pressing next on this screen calls the first of 3 screens for the first pulse in the pattern:

◊Pulse 1 level

♦ +5·000 V ◊done next◊

The pulse level can be set on this screen between −5·0V and +5·0V by direct keyboard entries or by using the rotary control. As with the baseline level described above the set pulse levels are only output if the amplitude setting is set to maximum (10Vpp into 50Ω) on the AMPLITUDE screen and terminated in 50Ω. Adjusting the amplitude “scales” both the peak pulse levels and baseline together, thus keeping the pulse shape in proportion as the amplitude is changed, exactly as for arb waveforms. Actual output levels are doubled when the output is unterminated.

Note that by pressing the Pulse soft−key on this (and subsequent screens) the pulse to be edited can be directly set from the keyboard or by using the rotary control; this is useful in directly accessing a particular pulse in a long pulse train instead of having to step through the whole sequence.

Pressing next calls the pulse width screen for the first pulse:

◊Pulse 1 width ♦program 25·00 us

(actual 25·00 us) ◊done next◊

The width can be entered directly from the keyboard or by using the rotary control. Any value in the range 25.00ns to 99·99s can be programmed but the actual value may differ; for this reason the actual pulse width is shown (in brackets) below the program width. The variation between program and actual will only really be noticeable for very short

pulse−train periods (only a few points in the pulse−train) and very long periods (each of the 50,000 points has a long dwell time) for exactly the same reasons as described in the Pulse Setup section; refer to that section for a detailed explanation.

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Pressing next calls the pulse delay screen for the first pulse:

◊Pulse 1 delay ♦program +0·000 ns

(actual +0·000 ns) ◊done next◊

The pulse delay is entered in the same way as pulse width and, again, the actual delay is shown below the program delay for the same reasons. The delay value that can be entered must be in the range ± (pulse−train period −1 point); positive values delay the pulse with respect to waveform sync from SYNC OUT; negative values cause the pulse to be output before the waveform sync.

Pressing next on this screen calls the first of the 3 screens for setting the parameters of Pulse 2, and so on through all the pulses in the pulse−train. In this way all parameters of all pulses are set. The pulse−train is built when next is pressed on the last screen of the last pulse or if done is pressed on any screen.

Care must be taken that the set widths and delays of the individual pulses are compatible with each other and the overall pulse−train period, i.e. delays must not be such that pulses overlap each other and delays + widths must not exceed the pulse−train period; unpredictable results will occur if these rules are not followed.

Once the pulse−train has been defined the period can be adjusted irrespective of the pulse width and delay settings for the individual pulses because, unlike a conventional pulse generator, the individual pulse widths and delays are adjusted proportionally to the period as the period is changed.

Period can also be changed from the PULSE-TRN PERIOD screen called by pressing the FREQ key with pulse−train mode selected:

PULSE-TRN PERIOD 100·0 us

◊freq period♦

The new setting can be entered either as a period in the way already described or as a frequency by first pressing the freq soft−key. However, changing the period/frequency from this screen is slightly different from changing period on the pulse-train setup screen. When changing from this screen the number of points in the waveform is never changed (just as with a true arb) which means that the shortest period/highest frequency that can be set is the number of waveform points x 25.00ns. To achieve faster frequencies (up to the specification limit) the period must be changed from the pulse setup screen; changing the frequency from this screen causes the number of points to be reduced as the period is reduced (for period <1·25ms).

Waveform Hold in Pulse and Pulse-Train Modes

Pulse and Pulse−Train waveforms can be paused and re−started on any channel by using the front panel MAN HOLD key or a signal applied to the rear panel HOLD IN socket.

On multi−channel instruments the channels which are to be held by the MAN HOLD key or HOLD IN socket must first be enabled using the ARB HOLD INPUT screen, accessed by pressing the HOLD KEY.

ARB HOLD INPUT:

status: no hold

mode: disabled

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Each channel is selected in turn using the channel SETUP keys and set using the mode soft−key; the mode changes between disabled and enabled with alternate key presses.

Pressing the front panel MAN HOLD key stops the waveform at the current level on all enabled channels; pressing MAN HOLD a second time restarts the waveform from that level. If the

ARB HOLD INPUT screen is currently selected the status field will change from no hold to manual hold while the waveform is paused.

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Introduction

Both internal and external modulation can be selected. External modulation can be applied to any or all channels. Internal modulation uses the previous channel as the modulation source, e.g. channel 2 can be used to modulate channel 3; internal modulation is not available on channel 1 or on a single channel instrument.

The external modulation mode can be set to VCA (Voltage Controlled Amplitude) or SCM (Suppressed Carrier Modulation) modes. Internal modulation can be set to true AM (Amplitude Modulation) or SCM.

Modulation modes share some of the generator’s inter−channel resources with Sum modes; as a result there are some restrictions on using Modulation and Sum together but these are generally outside the range of common−sense applications. To better understand these constraints the following sections (and the SUM chapter) should be read with reference to the fold−out block diagrams at the end of the manual which show the control signals of a single channel and the inter−channel connections.

These diagrams also show the inter−channel trigger connections described in the Triggered Burst and Gate chapter; in general, inter−channel triggering is possible simultaneously with modulation but few combinations are of real use.

External Modulation

Modulation

Pressing the MODULATION key calls the MODULATION set−up screen.

The source soft−key steps the modulation choice between off, external and CHx where x is the number of the previous channel; note that channel 1 does not have a previous channel, refer to the Inter−Channel Block Diagram.

With ext selected the modulation can be switched between VCA and SCM with alternate presses of the type soft−key. Both types of external modulation can be used with internal or external Sum.

External modulation can be applied to any or all channels.

External VCA

Select VCA with the type soft−key on the MODULATION screen. Connect the modulating signal to the EXT MODULATION socket (nominally 1kΩ input impedance); a positive

voltage increases the channel output amplitude and a negative voltage decreases the amplitude. Note that clipping will occur if the combination of channel amplitude setting and VCA signal attempts to drive the output above 20Vpp open−circuit voltage.

External AM is achieved by setting the channel to the required output level and applying the modulation signal (which can be AC coupled if required) at the appropriate level to obtain the modulation depth required. If the channel output level is changed the amplitude of the modulating signal will have to be changed to maintain the same modulation depth.

The VCA signal is applied to the amplifier chain prior to the output attenuators. The amplifier itself is controlled over a limited range (~10dB) and the full amplitude range of the channel is achieved by switching in up to five –10dB attenuation stages. Peak modulation cannot exceed the maximum of the “range” within which the channel output has been set by choice of amplitude setting. Whereas with internal AM the generator gives warnings when the combination of modulation depth and amplitude setting cause waveform clipping (see Internal Modulation section), it is up to the user to observe the waveforms when using external VCA and to make adjustments if the waveform is clipping. Note that it is not possible to give a simple guide as to

MODULATION

source: ext

◊ type: VCA

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where the “range” breakpoints are because the use of DC Offset, for example, changes these points.

Within each “range” the maximum output setting of the channel at which clipping is avoided is reduced from range maximum to half this value as modulation is increased by 0% to 100%; 100% modulation will be achieved at this mid−range setting with an external VCA signal of approximately 1Vpp. Modulation frequency range is DC to 100kHz.

It is also possible to modulate a DC level from the generator with a signal applied to the EXT MODULATION socket, as follows. Set the generator to external trigger on the TRIGGER IN setup screen but do not apply a trigger signal to TRIG IN; select squarewave. The MAIN OUT is now set at the peak positive voltage defined by the amplitude setting; pressing the ± key with AMPLITUDE displayed will set the level to the peak negative voltage. This DC level can now be modulated by the signal applied to the EXT MODULATION input.

External SCM

Select SCM with the type soft−key on the MODULATION screen. Connect the modulating signal to the EXT MODULATION input (nominally 1kΩ input impedance). With no signal the

carrier is fully suppressed; a positive or negative level change at the modulation input increases the amplitude of the carrier. Note that clipping will occur if the SCM signal attempts to drive the output above the 20Vpp open−circuit voltage.

Peak modulation, i.e. maximum carrier amplitude (20Vpp), is achieved with an external SCM level of approximately ±1V, i.e. a 2Vpp signal. Modulation frequency range is DC to 100kHz.

When external SCM is selected for a channel the amplitude control of that channel is disabled; the AMPLITUDE setup screen shows the message fixed by SCM.

Internal Modulation

Pressing the MODULATION key calls the MODULATION setup screen.

The source soft−key steps the modulation choice between off, external and CHx¸ where x is the number of the previous channel; CHx is the source for internal modulation. Note that channel 1 and single channel instruments do not have a previous channel, i.e. they have no internal modulation capability; refer to the Inter−Channel Block Diagram.

With CHx selected the modulation mode can be switched between AM and SCM with alternate presses of the type soft−key.

When AM is selected the screen has an additional soft−key labelled depth; selecting this key permits the modulation depth to be set directly from the keyboard or by the rotary control.

Warnings are given when either a modulation depth or output amplitude change has caused clipping; the new setting is accepted but it must either be changed back or the other parameter must also be changed to avoid the contention.

When SCM is selected the screen has an additional soft−key labelled level; selecting this key permits the peak carrier output level to be set directly from the keyboard or by the rotary control. The maximum output level that can be set is 10Vpp.

When internal SCM is selected for a channel both the amplitude control of that channel and the previous channel (used as the modulation source) are disabled. The AMPLITUDE setup screen of the channel being modulated shows the message fixed by SCM. The AMPLITUDE screen of the previous channel shows the message Set by CHx mod. and its status screen

shows the message →x to indicate that it is being used as a source for channel x.

Internal modulation cannot be used with internal or external Sum.

MODULATION

source: ext

◊ type: VCA

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Introduction

Both internal and external Sum can be selected; summing can be used to add ‘noise’ to a waveform, for example, or to add two signals for DTMF (Dual Tone Multiple Frequency) testing.

External Sum can be applied to any or all channels. Internal sum uses the previous channel as the modulation source, e.g. channel 2 can be summed into Channel 3; internal Sum is not available on channel 1 or on a single channel instrument.

Summing shares some of the generator’s inter−channel resources with Modulation modes; as a result neither internal nor external Sum can be used with internal modulation but external modulation is possible.

To better understand the constraints, the following sections (and the Modulation chapter) should be read with reference to the fold−out block diagrams at the end of the manual which show the control signals of a single channel and the inter−channel connections.

These diagrams also show the inter−channel trigger connections described in the Triggered Burst and Gate chapter; in general, inter−channel triggering is possible simultaneously with summing.

External Sum

In Sum mode an external signal applied to the SUM input is summed with the waveform(s) on the specified channel(s). The same Sum input signal can be used at different amplitudes with each of the channels with which it is summed.

Pressing the SUM key calls the SUM set−up screen.

Sum

SUM source: ext

◊ratio: 0dB ◊CH2 +2.00 Vpp

Pressing the source soft−key steps the Sum sources between off, external and CHx where x is the number of the previous channel, refer to the Inter−Channel Block Diagram.

With ext selected the screen is as shown above. The level of the SUM can be adjusted independently for the selected channel by pressing the ratio soft−key; use the rotary knob or cursor keys to set the SUM input attenuation for that channel from 0 to –50dB in –10dB steps.

This facility permits the same SUM signal to be used at different levels with each channel. Clipping will occur if the Sum input level attempts to drive the channel amplitude above the

maximum 20Vpp open−circuit voltage. However, the relationship between the SUM input and the maximum summed output depends not only on the Sum input level but also on the channel amplitude setting. This is because the Sum input is applied to the amplifier chain prior to the output attenuators; the amplifier itself is controlled over a limited range (~10dB) and the full amplitude range of the channel is achieved by switching in up to five –10dB attenuation stages. The summed output cannot exceed the maximum of the “range” within which the channel output has been set by choice of amplitude setting. Whereas with internal Sum the generator gives warnings when the combination of Sum input and amplitude would cause waveform clipping (see Internal Sum section), it is up to the user to observe the waveforms when using external sum and to make adjustments if the waveform is clipping. Note that it is not possible to give a simple guide as to where the “range” breakpoints are because the use of DC Offset, for example, changes these points.

Within each “range” a SUM signal of ~2Vpp will force the channel output from range minimum to range maximum; if the channel amplitude is set to mid−range the SUM signal needed to force the output to range maximum is about half, i.e. ~1Vpp.

To facilitate the setting of appropriate Sum and amplitude levels the output amplitude of the selected channel can also be changed from the SUM set−up screen. Press the CHx soft−key and adjust the amplitude with direct keyboard entries or by using the rotary knob.

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External Sum cannot be used with internal modulation.

Internal Sum

Pressing the SUM key calls the SUM set−up screen.

SUM source: CH1

◊ratio: 1.00000 ◊CH2: 2.00 Vpp ◊CH1: 2.00 Vpp

Pressing the source soft−key steps the Sum source between off, external and CHx where x is the number of the previous channel; CHx is the source of the internal Sum signal. Note that channel 1 and single channel instruments do not have a previous channel, refer to the Inter−Channel Block Diagram.

With CHx selected for internal Sum the screen is as shown above. The amplitude of both the summing channel ( CHx+1 ) and the internal Sum signal ( CHx ) are shown in the display, together with the ratio between them. All three parameters can be selected with the appropriate soft−key and set directly from the keyboard or by the rotary control Changing any one parameter will also adjust the interdependent one, e.g. adjusting the amplitude of either channel will cause the displayed ratio to change.

Note that the value shown in the ratio field is CH(x) amplitude ÷ CH(x+1) amplitude. Adjusting the ratio value directly changes the amplitude of the Sum input signal, i.e. CH(x), never the channel’s output amplitude. When a value is entered into the ratio field it is initially accepted as entered but may then change slightly to reflect the actual ratio achieved with the nearest Sum input amplitude that could be set for the given channel output amplitude.

Warnings are given when either a ratio, Sum input or output amplitude change is attempted which would cause the channel output to be driven into “clipping”.

In general it is recommended that the amplitude of the Sum input is smaller than the channel amplitude, i.e. the ratio is ≤1; most ratio values ≤1 can then be set, down to very small signal levels. If the Sum input is greater than the channel amplitude there will be combinations when the ratio can be set to a little more than 1. Note that the software will always accept an entry, make the calculation and, if the combination is not possible, return the instrument to the original setting.

The amplitude of the channel being used for the internal Sum signal can still be adjusted on its own Amplitude set−up screen; its status screen shows the message →x to indicate that it is being used as a source for channel x.

Internal sum cannot be used with internal modulation.

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Two or more channels can be synchronised together and precise phase differences can be set between the channels. Two generators can also be synchronised (see Synchronising Two Generators chapter) giving a maximum of 8 channels that can be operated in synchronisation. Restrictions apply to certain waveform and frequency combinations; these are detailed in the following sections.

Synchronising Principles

Frequency locking is achieved by using the clock output from a ‘master’ channel to drive the clock inputs of ‘slaves’. Any channel can be a master (only 1 master allowed) and any or all the others can be slaves; master/slaves and independent channels can be mixed on the same instrument. When frequency locking is switched on, the internal lock signal (from the CPU) locks the channels at the specified inter−channel phase and re−locks them automatically every time the frequency is changed. The clock and internal lock signals are shown in the Inter−Channel Block Diagram at the end of the manual. Channels to be locked together must all be operating in continuous mode.

For DDS−generated waveforms (see Principles of Operation in the General chapter) it is the

27.4878 MHz signal that is distributed from master to slaves and channels can in principle be

frequency−locked with any frequency combination. However, the number of cycles between the phase−referenced points will be excessively large unless the ratio is a small rational number, e.g. 2kHz could be locked usefully with 10kHz, 50kHz, 100kHz, etc., but not with 2.001kHz, for example.

For Clock Synthesised waveforms (see Principles of Operation in the General chapter) it is the PLL clock of the master which is distributed from master to slaves; the clock frequency for master and slaves is therefore always the same. The number of points comprising the waveforms should also be the same to ensure that the waveforms themselves appear locked.

From the foregoing it is clear that only DDS ‘slaves’ can be locked to a DDS ‘master’ and only Clock Synthesised ‘slaves’ can be locked to a Clock Synthesised ‘master’. In practice the constraints described are not severe as the most common use of synchronisation is to provide outputs of the same waveform at the same frequency, or maybe a harmonic frequency, but with phase differences.

Inter-Channel Synchronisation

Master-Slave Allocation

Press the front panel INTERCHannel key to call up the inter−channel set−up screen.

The mode soft−key can be used to select between independent, master, master/freq and slave; the default mode is independent. Only one master can be set; more than one master can be selected but when locking is turned on with the status soft−key the set−up will be rejected. Master/freq selects the master and sets frequency−tracking; for this to be operational the master and slave(s) must be set to the same frequency when locking is turned on. In this mode, when the frequency of the master is changed the frequency of the slaves also change and the slaves are re−locked to the master.

Master/freq is the default mode when the waveforms are Clock Synthesised (arbs, pulses, etc); if master has been set instead, the mode will automatically change to master/freq when locking is turned on. The frequency of Clock Synthesised waveform slaves always therefore tracks the master. Finally, slave selects those channel(s) which are to be locked to the master.

mode: indep ◊phase: +000.0° (actual: +000.0°) ◊status: off view◊

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At any time, pressing the view soft−key gives a graphical view of the master−slave set−up, see below for an example.

CH→ indep - - - Υ master Υ- - slave - ΥΥ- exit◊

Channel locking is turned on or off with the status soft−key. Any illegal setting combinations will result in an error message when an attempt is made to turn status on. Any of the following conditions will cause an error (see also the Synchronising Principles section for a discussion of the set−up constraints):

1. More than one master channel is enabled.

2. No master channel is enabled.

3. The locked channels contain a mixture of DDS and PLL generated waveforms.

4. Frequency tracking is enabled (mode: master/freq) but the frequencies are not the same on all channels. If PLL waveforms are locked the mode will be forced to frequency tracking.

5. A locked channel is not set to continuous mode.

6. An attempt is made to turn on phase lock with a frequency set too high. Note that the maximum frequency for phase−locked DDS operation is 10MHz.

7. An attempt is made to set the frequency too high during phase lock. This error does not set phase lock to off, the system simply inhibits the setting of the incorrect frequency.

In addition to the illegal setting combinations there are further considerations which affect the phase resolution and accuracy between channels, see below.

1 2 3 4

Phase-setting between Channels

The inter−channel set−up screen also has a field for setting up the phase of the slaves with respect to the master.

◊phase: +000.0° (actual: +000.0°) ◊status: off view◊

Selecting the phase soft−key allows the phase to be set by direct keyboard entry or by rotary control. Setting the phase of a slave positive advances the waveform of the slave with respect to the master; setting it negative delays the slave with respect to the master. The phase of each slave channel can be set independently. The phase of the master can also be set; this is intended primarily for use in phase−locking between two generators. If both the master and the slaves are set to +90°, say, on the same generator then the waveforms will all be in phase again; if the master is set to +90° and the slaves set to −90° the master and slave wavefoms will be 180° out of phase.

DDS−generated waveforms can be phase−locked with 0.1° resolution up to their maximum available frequency; sine, cosine, haversine and havercosine are limited to 10MHz in phase−locked mode.

The phase−locking resolution of arbitrary waveforms will be less than 0.1° for waveforms of less than 3600 points. The phase is fixed at 0° for pulses, pulse−trains and sequences.

mode: indep

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The table below summarises the phase control and frequency range for different waveforms.

Waveform Max Wfm Freq Phase Control Range & Resolution

Sine, cosine, haversine, havercosine 10MHz

Square 16MHz

Triangle 100kHz

Ramp 100kHz

Sin(x)/x 100kHz

Pulse & Pulse Train 10MHz

Arbitrary 40MS/s clock

Sequence 40MS/s clock

When phase−locking is turned on with the status soft−key the slaves are re−locked automatically after every phase or frequency setting change.

See also the Other Phase−Locking considerations section.

Other Phase-Locking Considerations

The Master−Slave Allocation and Phase−Setting sections contain tables of specific limitations on the selection of frequency, waveform type and phase−setting range and resolution. The following further points should also be considered.

• The waveform filters introduce a frequency−dependent delay above ~1MHz; this will affect the accuracy of the phase between locked waveforms at different frequencies, e.g. 500kHz and 5MHz.

± 360°, 0.1°

± 0° only

± 360°, 0.1°

± 360°, 360° ÷ length or 0.1°

0° only

• Square waves, which are 2−point Clock Synthesised waveforms will not reliably lock to other Clock Synthesised waveforms.

• Pulse and Pulse train waveforms will lock to other Pulse and Pulse−trains (and each other) but should be built with equal periods.

• Arb waveforms should be the same length (although this is not forced and does not create an error message).

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Two generators can be synchronised together following the procedure outlined below. It is possible to link more than two generators in this way but results are not guaranteed.

Synchronising Principles

Frequency locking is achieved by using the clock output from the ‘master’ generator to drive the clock inputs of a slave. The additional connection of an initialising SYNC signal permits the slave to be synchronised such that the phase relationship between master and slave outputs is that specified on the slave generator’s Inter−channel set−up screen.

Synchronisation is only possible between generators when the ratio of the master and slave frequencies is rational, e.g. 3kHz can be synchronised with 2kHz but not with 7kHz. Special considerations arise with waveforms generated by Clock Synthesis mode (squarewave, arbitrary, pulse, pulse−train and sequence) because of the relatively poor precision with which the frequency is actually derived in the hardware. With these waveforms, frequencies with an apparently rational relationship (e.g. 3:1) may be individually synthesised such that the ratio is not close enough to e.g. 3:1 to maintain phase lock over a period of time; the only relationships guaranteed to be realised precisely are 2 mode are binary. A further complication arises with arb waveforms because waveform frequency depends on both waveform size and clock frequency (waveform frequency = clock frequency

÷ waveform size). The important relationship with arbs is the ratio of clock frequencies and

the above considerations on precision apply to them. The most practical use of synchronisation will be to provide outputs at the same frequency, or maybe harmonics, but with phase differences.

Synchronising Two Generators

:1 because the division stages in Clock Synthesis

Connections for Synchronisation

The clock connection arrangement is for the rear panel REF CLOCK IN/OUT of the master (which will be set to phase lock master) to be connected directly to the REF CLOCK IN/OUT socket of the slave (which will be set to phase lock slave).

Similarly the synchronising connection is from any SYNC OUT of the master, which all default to phase lock, to the TRIG IN input of the slave.

Generator Set-ups

Each generator can have its main parameters set to any value, with the exception that the ratio of frequencies between master and slave must be rational and each generator can be set to any waveform, but see Synchronising Principles section above. Best results will be achieved if the constraints forced on inter−channel synchronisation are adopted for inter−generator synchronisation.

The master has its CLOCK IN/OUT set to phase lock master on the REF. CLOCK I/O SETUP menu called by the ref. clock i/o soft−key on the UTILITY screen, see System Operations section.

REF CLOCK I/O SETUP ◊input ◊output

Repeated presses of the phase lock soft−key toggle between master and slave.

The slave is set to slave. Setting the slave generator to phase lock slave forces the slave’s mode to continuous and defaults all the SYNC OUT outputs to phase lock. Only one of the SYNC OUTs is needed for inter−generator synchronisation; the others may be reset to other

functions if required. The phase relationship between the slave and the master is set on the Inter−channel set−up screen of the slave, accessed by pressing the INTERCHannel key.

phase lock slave

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mode: indep ◊phase: +000.0° (actual: +000.0°) ◊status: off view◊

The phase of the slave generator is set by adjusting the phase of the master channel on the slave generator’s Inter−channel set−up screen exactly as described in the Phase−setting between Channels section of the inter−channel Synchronisation chapter. The phase(s) of slave channel(s) on the slave generator are set up with respect to the master in the way described in that same section.

When a single generator, which has no Inter−channel set−up key or screen, is the slave, its phase is set on the TRIGGER/GATE SETUP screen, see Trigger Phase section of the Triggered Burst and Gate chapter.

The convention adopted for the phase relationship between generators is the same as that used between channels, i.e. a positive phase setting advances the slave generator with respect to the master and a negative setting delays the slave generator. The status of the slave generator on the inter−channel set−up screen must be set to on (automatic on a single channel generator).

Hardware delays become increasingly significant as frequency increases causing additional phase delay between the master and slaves. However, these delays can be largely nulled−out by ‘backing−off’ the phase settings of the slaves.

Typically these hardware delays are as follows:

DDS waveforms: <± 25ns; <1° to 100kHz

Clock Synthesised waveforms: <300ns; <1° to 10kHz.

Clearly a multi−channel generator gives much closer inter−channel phase−locking and is the recommended method for up to 4 channels.

Synchronising

Having made the connections and set up the generators as described in the preceding paragraphs, synchronisation is achieved by pressing the MAN TRIG key of the slave. Once synchronised any change to the setup will require resynchronisation with the MAN TRIG key again.

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System Operations from the Utility Menu

Pressing the UTILITY key calls a list of menus which give access to various system operations including storing/recalling set−ups from non−volatile memory, error messages, power on settings and calibration.

Storing and Recalling Set-ups

Complete waveform set−ups can be stored to or recalled from non−volatile RAM using the menus called by the store and recall soft−keys.

Pressing store… (or the STORE front panel key) calls the store screen:

Nine stores, numbered 1 to 9 inclusive, are available. Select the store using the rotary control or direct keyboard entry and press execute to implement the store function.

Pressing recall… (or the RECALL front panel key) calls the recall screen:

In addition to the user−defined stores, the factory defaults can be reloaded by pressing the set defaults soft−key. Note that loading the defaults does not change any arbitrary waveforms, the set−ups stored in memories 1 to 9, or the RS232/GPIB interface settings.

Channel Waveform Information

Information about each channel’s waveform memory can be viewed by pressing the

chan wfm info… soft−key.

Save to store No: 1

◊execute

Recall store No: 1

◊set defaults ◊execute

CHANNEL WFM INFO: waveforms: 1 free mem: 65436

exit◊

For each channel, selected using the channel SETUP keys, the number of waveforms and the free memory on that channel are shown.

Warnings and Error messages

The default setup is for all warning and error messages to be displayed and for a beep to sound with each message. This setup can be changed on the error… menu:

◊error beep: ON ◊error message: ON

warn beep: ON

◊warn message: ON

Each feature can be turned ON or OFF with alternate presses of the appropriate soft−key.

The last two error messages can be viewed by pressing the last error… soft−key. Each message has a number and the full list appears in Appendix 1. See also Warnings and Error Messages in the Standard Waveform Operation section.

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Remote Interface Setup

Pressing remote… calls the REMOTE SETUP screen which permits RS232/GPIB choice and selection of address and Baud rate. Full details are given in the Remote Operation section.

Reference Clock In/Out Setting

The function of the rear panel REF CLOCK IN/OUT socket is set on the REF. CLOCK I/O screen, called by pressing the ref. clock i/o soft−key.

The default setting is for the socket to be set to input, i.e. an input for an external 10MHz reference clock. When set to input the system is automatically switched over to the external reference when an adequate signal level (TTL/CMOS threshold) is detected at REF CLOCK IN/OUT but will continue to run from the internal clock in the absence of such a signal.

With the clock set to output a buffered version of the internal 10MHz clock is made available at the socket.

With phase lock selected the socket can be set to be a master or slave when used for synchronising (phase−locking) multiple generators. See Synchronising Generators

section for full details.

REF. CLOCK I/O:

♦input ◊output ◊phase lock

Cursor/Marker Output

Pressing the cursor/marker… soft−key calls the CURSOR/MARKER OUTPUT screen.

The cursor/marker signal is output from the rear panel CURSOR/MARKER OUT socket. It is used as a marker in sweep mode or as a cursor in arbitrary waveform mode. It can be used to modulate the Z−axis of an oscilloscope or be displayed on a second ‘scope channel.

With amplitude selected the cursor/marker level can be set between 2 and 14V in 2V steps. With polarity selected the polarity can be set positive or negative. With polarity set to positive the cursor/marker is a positive−going pulse from the 0V baseline; with polarity set to negative the cursor/marker is a negative−going pulse from the 2 − 14V set amplitude level, i.e. negative gives an inverted signal.

When used as a sweep marker (i.e. Sweep mode selected) the width is determined by the time spent at the marker frequency, see Sweep Marker in the Sweep Operation section for details.

When used as a cursor during arbitrary waveform editing (i.e. edit waveform selected on the MODIFY screen) the width can be adjusted by repeated presses of the cursor width soft−key or by using the rotary control. The width is adjustable so that the cursor can still be made visible even with long arbitrary waveforms. The width is always an odd number of waveform points increasing in steps of 2 points from 1 to 3, 5, 7, etc. A width setting of 1 corresponds to 1 waveform point, width 2 is 3 points, width 3 is 5 points and so on up to width

30 which is 59 points.

CURSOR/MARKER OUTPUT

amplitude: 2V

◊polarity: negative ◊cursor width: 1

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Power On Setting

Pressing the power on… soft−key calls the POWER ON SETTING screen:

The setting loaded can be selected with the appropriate soft−key to be default values (the default setting), restore last setup (i.e. the settings at power down are restored at power up) or any of the settings stored in non−volatile memories 1 to 9. Default values restores the factory default settings, see Appendix 3.

System Information

The system info… soft−key calls the SYSTEM INFO screen which shows the instrument name and software revision. When system info… is pressed a checksum is also made of the firmware EPROM and the result displayed; this can be used when a software fault is suspected to check that the EPROM has not got corrupted.

Calibration

Pressing calibration calls the calibration routine, see Calibration section.

POWER ON SETTING ◊default values ◊restore last setup

recall store no. 1

Copying Channel Set−ups

An easy way of copying complete channel set−ups (waveform, frequency, amplitude, etc.) is accessed by pressing the COPY CHannel key.

The top line of the screen shows which channel is currently selected with the channel SETUP keys. Pressing the to channel soft−key steps the channel number through all the other channels of the instrument.

Select the channel to be changed and make the copy by pressing the execute soft−key.

copy channel: 1

to channel: 2

◊execute

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All parameters can be calibrated without opening the case, i.e. the generator offers ‘closed−box’ calibration. All adjustments are made digitally with calibration constants stored in EEPROM. The calibration routine requires only a DVM and a frequency counter and takes no more than a few minutes.

The crystal in the timebase is pre−aged but a further ageing of up to ±5ppm can occur in the first year. Since the ageing rate decreases exponentially with time it is an advantage to recalibrate after the first 6 month’s use. Apart from this it is unlikely that any other parameters will need adjustment.

Calibration should be carried out only after the generator has been operating for at least 30 minutes in normal ambient conditions.

Equipment Required

• 3½ digit DVM with 0·25% DC accuracy and 0·5% AC accuracy at 1kHz.

• Frequency counter capable of measuring 10·00000MHz.

The DVM is connected to the MAIN OUT of each channel in turn and the counter to any SYNC OUT.

Frequency meter accuracy will determine the accuracy of the generator’s clock setting and should ideally be ±1ppm.

Calibration

Calibration Procedure

The calibration procedure is accessed by pressing the calibration… soft−key on the UTILITY screen.

The software provides for a 4−digit password in the range 0000 to 9999 to be used to access the calibration procedure. If the password is left at the factory default of 0000 no messages are shown and calibration can proceed as described in the Calibration Routine section; only if a non−zero password has been set will the user be prompted to enter the password.

Setting the Password

On opening the Calibration screen press the password… soft−key to show the password screen:

Enter a 4−digit password from the keyboard; the display will show the message NEW PASSWORD STORED! for two seconds and then revert to the UTILITY menu. If any keys other than 0−9 are pressed while entering the password the message ILLEGAL PASSWORD! will be shown.

CALIBRATION SELECTED Are you sure ?

◊password… tests…◊ ◊exit continue◊

ENTER NEW PASSWORD

−−−−

Using the Password to Access Calibration or Change the Password

With the password set, pressing calibration… on the UTILITY screen will now show:

ENTER PASSWORD

----

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When the correct password has been entered from the keyboard the display changes to the opening screen of the calibration routine and calibration can proceed as described in the Calibration Routine section. If an incorrect password is entered the message INCORRECT PASSWORD! is shown for two seconds before the display reverts to the UTILITY menu.

With the opening screen of the calibration routine displayed after correctly entering the password, the password can be changed by pressing password... soft−key and following the procedure described in Setting the Password. If the password is set to 0000 again, password protection is removed.

The password is held in EEPROM and will not be lost when the memory battery back−up is lost. In the event of the password being forgotten, contact the manufacturer for help in resetting the instrument.

Calibration Routine

The calibration procedure proper is entered by pressing continue on the opening Calibration screen; pressing exit returns the display to the UTILITY menu. Pressing tests… calls a menu of basic hardware checks used at production test; these are largely self−explanatory but details can be found in the Service Manual if required. At each step the display changes to prompt the user to adjust the rotary control or cursor keys, until the reading on the specified instrument is at the value given. The cursor keys provide coarse adjustment, and the rotary control fine adjustment. Pressing next increments the procedure to the next step; pressing CE decrements back to the previous step. Alternatively, pressing exit returns the display to the last CAL screen at which the user can choose to either save new values, recall old values or calibrate again.

The first two displays (CAL 00 and CAL 01) specify the connections and adjustment method. The next display (CAL 02) allows the starting channel to be chosen; this allows quick access to any particular channel. To calibrate the complete instrument choose the default setting of CH1. The subsequent displays, CAL 03 to CAL 55, permit all adjustable parameters to be calibrated.

The full procedure is as follows:

CAL 03 CH1. DC offset zero. Adjust for 0V ± 5mV. CAL 04 CH1. DC offset at + full scale. Adjust for + 10V ± 10mV. CAL 05

CAL 06 CH1. Multiplier zero. Adjust for minimum Volts AC CAL 07 CH1. Multiplier offset. Adjust for 0V ± 5mV. CAL 08 CH1. Waveform offset. Adjust for 0V ± 5mV. CAL 09

CAL 10 CH1. 20dB attenuator Adjust for 1V ± 1mV. CAL 11 CH1. 40dB attenuator Adjust for 0·1V ± ·1mV. CAL 12 CH1. 10dB attenuator Adjust for 2·236V AC ± 10mV. CAL 13 CH1. Not used. CAL 14 CH1. Not used. CAL 15 CH1. Not used. CAL 16 CH2. DC offset zero. Adjust for 0V ± 5mV. CAL 17

CAL 18

CAL 19 CH2. Multiplier zero. Adjust for minimum Volts AC CAL 20 CH2. Multiplier offset. Adjust for 0V ± 5mV. CAL 21 CH2. Waveform offset. Adjust for 0V ± 5mV. CAL 22

CAL 23 CH2. 20dB attenuator Adjust for 1V ± 1mV.

CH1. DC offset at − full scale.

CH1. Output level at full−scale

CH2. DC offset at + full−scale.

CH2. DC offset at − full−scale.

CH2. Output level at full−scale

Check for –10V ± 3%

Adjust for 10V ± 10mV.

Adjust for +10V ± 10mV.

Check for –10V ± 3%

Adjust for 10V ± 10mV.

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CAL 24 CH2. 40dB attenuator Adjust for 0·1V ± ·1mV. CAL 25 CH2. 10dB attenuator Adjust for 2·236V AC ± 10mV. CAL 26 CH2. Sum offset. Adjust for 0V ± 5mV. CAL 27

CAL 28

CAL 29 CH3. DC offset zero. Adjust for 0V ± 5mV. CAL 30 CH3. DC offset at + full scale. Adjust for +10V ± 10mV. CAL 31

CAL 32 CH3. Multiplier zero. Adjust for minimum Volts AC CAL 33 CH3. Multiplier offset. Adjust for 0V ± 5mV. CAL 34 CH3. Waveform offset. Adjust for 0V ± 5mV. CAL 35

CAL 36 CH3. 20dB attenuator Adjust for 1V ± 1mV. CAL 37 CH3. 40dB attenuator Adjust for 0·1V ± ·1mV. CAL 38 CH3. 10dB attenuator Adjust for 2·236V AC ± 10mV. CAL 39 CH2. Sum offset. Adjust for 0V ± 5mV. CAL 40

CAL 41

CAL 42 CH4. DC offset zero. Adjust for 0V ± 5mV. CAL 43 CH4. DC offset at + full scale. Adjust for +10V ± 10mV. CAL 44

CAL 45 CH4. Multiplier zero. Adjust for minimum Volts AC CAL 46 CH4. Multiplier offset. Adjust for 0V ± 5mV. CAL 47 CH4. Waveform offset. Adjust for 0V ± 5mV. CAL 48

CAL 49 CH4. 20dB attenuator Adjust for 1V ± 1mV. CAL 50 CH4. 40dB attenuator Adjust for 0·1V ± ·1mV. CAL 51 CH4. 10dB attenuator Adjust for 2·236V AC ± 10mV. CAL 52 CH4. Sum offset. Adjust for 0V ± 5mV. CAL 53

CAL 54

CAL 55 Clock calibrate Adjust for 10·00000 MHz at SYNC OUT.

CH2. SCM level at full−scale.

CH2. AM level at full−scale.

CH3. DC offset at − full scale. Check for −10V ± 3%

CH3. Output level at full−scale

CH3. SCM level at full−scale.

CH3. AM level at full−scale.

CH4. DC offset at − full scale. Check for −10V ± 3%

CH4. Output level at full−scale

CH4. SCM level at full−scale.

CH4. AM level at full−scale.

Adjust for 5V ± 5mV.

Adjust for 10V ± 10mV.

Adjust for 5V ± 5mV.

Adjust for 10V ± 10mV.

Adjust for 5V ± 5mV.

Adjust for 10V ± 10mV.

Remote Calibration

Calibration of the instrument may be performed over the RS232 or GPIB interface. To completely automate the process the multimeter and frequency meter will also need to be remote controlled and the controller will need to run a calibration program unique to this instrument.

The remote calibration commands allow a simplified version of manual calibration to be performed by issuing commands from the controller. The controller must send the CALADJ command repeatedly and read the dmm or frequency meter until the required result for the selected calibration step is achieved. The CALSTEP command is then issued to accept the new value and move to the next step.

While in remote calibration mode very little error checking is performed and it is the controllers responsibility to ensure that everything progresses in an orderly way. Only the following commands should be used during calibration.

WARNING: Using any other commands while in calibration mode may give unpredictable results and could cause the instrument to lock up, requiring the power to be cycled to regain control.

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CALIBRATION <cpd> [,nrf]

START Enter calibration mode; this command must be issued before any

SAVE Finish calibration, save the new values and exit calibration mode. ABORT Finish calibration, do not save the new values and exit calibration

CALADJ <nrf> Adjust the selected calibration value by <nrf>. The value must be in

CALSTEP Step to the next calibration point. For general information on remote operation and remote command formats, refer to the following

sections.

The calibration control command. <cpd> can be one of three

sub−commands:−

other calibration commands will be recognised.

mode.

<nrf> represents the calibration password. The password is only

required with CALIBRATION START and then only if a non−zero

password has been set from the instrument’s keyboard. The

password will be ignored, and will give no errors, at all other times.

It is not possible to set or change the password using remote

commands.

the range −100 to +100. Once an adjustment has been completed

and the new value is as required the CALSTEP command must be

issued for the new value to be accepted.

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The instrument can be remotely controlled via its RS232 or GPIB interfaces. When using RS232 it can either be the only instrument connected to the controller or it can be part of an addressable RS232 system which permits up to 32 instruments to be addressed from one RS232 port.

Some of the following sections are general and apply to all 3 modes (single instrument RS232, addressable RS232 and GPIB); others are clearly only relevant to a particular interface or mode. It is only necessary to read the general sections plus those specific to the intended remote control mode.

Remote command format and the remote commands themselves are detailed in the Remote Commands chapter.

Address and Baud Rate Selection

For successful operation, each instrument connected to the GPIB or addressable RS232 system must be assigned a unique address and, in the case of addressable RS232, all must be set to the same Baud rate.

The instrument’s remote address for operation on both the RS232 and GPIB interfaces is set via the remote

menu on the UTILITY screen, see System Operations section.

REMOTE:

interface: RS232

◊address: 05 ◊baud rate: 9600

Remote Operation

With interface selected with the interface soft−key, the selection can be toggled between RS232 and GPIB with alternate presses of the soft−key, the cursor keys or by using the

rotary control.

With address

selected, the soft−key, cursor keys or rotary control can be used to set the

address.

With baud rate selected, the soft−key, cursor keys or rotary control can be used to set the baud rate for the RS232 interface.

When operating on the GPIB all device operations are performed through a single primary address; no secondary addressing is used.

NOTE: GPIB address 31 is not allowed by the IEEE 488 standards but it is possible to select it as an RS232 address.

Remote/Local Operation

At power−on the instrument will be in the local state with the REMOTE lamp off. In this state all keyboard operations are possible. When the instrument is addressed to listen and a command is received the remote state will be entered and the REMOTE lamp will be turned on. In this state the keyboard is locked out and remote commands only will be processed. The instrument may be returned to the local state by pressing the LOCAL key; however, the effect of this action will remain only until the instrument is addressed again or receives another character from the interface, when the remote state will once again be entered.

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RS232 Interface

RS232 Interface Connector

The 9−way D−type serial interface connector is located on the instrument rear panel. The pin connections are as shown below:

Pin Name Description

1 − No internal connection 2 TXD Transmitted data from instrument 3 RXD Received data to instrument 4 − No internal connection 5 GND Signal ground 6 − No internal connection 7 RXD2 Secondary received data (addressable RS232 only) 8 TXD2 Secondary transmitted data (addressable RS232 only) 9 GND Signal ground (addressable RS232 only)

Single Instrument RS232 Connections

For single instrument remote control only pins 2, 3 and 5 are connected to the PC. However, for correct operation links must be made in the connector at the PC end between pins 1, 4 and 6 and between pins 7 and 8, see diagram. Pins 7 and 8 of the instrument must not be connected to the PC, i.e. do not use a fully wired 9–way cable.

Baud Rate is set as described above in Address and Baud Rate Selection; the other parameters are fixed as follows:

Start Bits: 1 Parity: None Data Bits: 8 Stop Bits: 1

Addressable RS232 Connections

For addressable RS232 operation pins 7, 8 and 9 of the instrument connector are also used. Using a simple cable assembly, a 'daisy chain' connection system between any number of instruments, up to the maximum of 32 can be made, as shown below:

The daisy chain consists of the transmit data (TXD), receive date (RXD) and signal ground lines only. There are no control/handshake lines. This makes XON/XOFF protocol essential and allows the inter−connection between instruments to contain just 3 wires. The wiring of the adaptor cable is shown below:

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All instruments on the interface must be set to the same baud rate and all must be powered on, otherwise instruments further down the daisy chain will not receive any data or commands.

The other parameters are fixed as follows:

Start Bits: 1 Parity: None Data Bits: 8 Stop Bits: 1

RS232 Character Set

Because of the need for XON/XOFF handshake it is possible to send ASCII coded data only; binary blocks are not allowed. Bit 7 of ASCII codes is ignored, i.e. assumed to be low. No distinction is made between upper and lower case characters in command mnemonics and they may be freely mixed. The ASCII codes below 20H (space) are reserved for addressable RS232 interface control. In this manual 20H, etc. means 20 in hexadecimal

Addressable RS232 Interface Control Codes

All instruments intended for use on the addressable RS232 bus use the following set of interface control codes. Codes between 00H and 1FH which are not listed here as having a particular meaning are reserved for future use and will be ignored. Mixing interface control codes inside instrument commands is not allowed except as stated below for CR and LF codes and XON and XOFF codes.

When an instrument is first powered on it will automatically enter the Non− Addressable mode. In this mode the instrument is not addressable and will not respond to any address commands. This allows the instrument to function as a normal RS232 controllable device. This mode may be locked by sending the Lock Non−Addressable mode control code, 04H. The controller and instrument can now freely use all 8 bit codes and binary blocks but all interface control codes are ignored. To return to addressable mode the instrument must be powered off.

To enable addressable mode after an instrument has been powered on the Set Addressable Mode control code, 02H, must be sent. This will then enable all instruments connected to the addressable RS232 bus to respond to all interface control codes. To return to Non−Addressable mode the Lock Non−Addressable mode control code must be sent which will disable addressable mode until the instruments are powered off.

Before an instrument is sent a command it must be addressed to listen by sending the Listen Address control code, 12H, followed by a single character which has the lower 5 bits corresponding to the unique address of the required instrument, e.g. the codes A−Z or a−z give the addresses 1−26 inclusive while @ is address 0 and so on. Once addressed to listen the instrument will read and act upon any commands sent until the listen mode is cancelled.

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Because of the asynchronous nature of the interface it is necessary for the controller to be informed that an instrument has accepted the listen address sequence and is ready to receive commands. The controller will therefore wait for Acknowledge code, 06H, before sending any commands, The addressed instrument will provide this Acknowledge. The controller should time−out and try again if no Acknowledge is received within 5 seconds.

Listen mode will be cancelled by any of the following interface control codes being received:

12H Listen Address followed by an address not belonging to this instrument.

14H Talk Address for any instrument.

03H Universal Unaddress control code.

04H Lock Non−Addressable mode control code.

18H Universal Device Clear.

Before a response can be read from an instrument it must be addressed to talk by sending the Talk Address control code, 14H, followed by a single character which has the lower 5 bits corresponding to the unique address of the required instrument, as for the listen address control code above. Once addressed to talk the instrument will send the response message it has available, if any, and then exit the talk addressed state. Only one response message will be sent each time the instrument is addressed to talk.

Talk mode will be cancelled by any of the following interface control codes being received:

12H Listen Address for any instrument.

14H Talk Address followed by an address not belonging to this instrument.

03H Universal Unaddress control code.

04H

18H Universal Device Clear.

Talk mode will also be cancelled when the instrument has completed sending a response message or has nothing to say.

The interface code 0AH (LF) is the universal command and response terminator; it must be the last code sent in all commands and will be the last code sent in all responses.

The interface code 0DH (CR) may be used as required to aid the formatting of commands; it will be ignored by all instruments. Most instruments will terminate responses with CR followed by LF.

The interface code 13H (XOFF) may be sent at any time by a listener (instrument or controller) to suspend the output of a talker. The listener must send 11H (XON) before the talker will resume sending. This is the only form of handshake control supported by the addressable RS232 mode.

Lock Non−Addressable mode control code.

Full List of Addressable RS232 Interface Control Codes

02H Set Addressable Mode.

03H Universal Unaddress control code.

04H

06H Acknowledge that listen address received.

Lock Non−Addressable mode control code.

0AH Line Feed (LF); used as the universal command and response terminator.

0DH Carriage Return (CR); formatting code, otherwise ignored.

11H Restart transmission (XON).

12H

13H Stop transmission (XOFF).

14H

18H Universal Device Clear.

Listen Address − must be followed by an address belonging to the required instrument.

Talk Address − must be followed by an address belonging to the required instrument.

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GPIB Interface

The 24−way GPIB connector is located on the instrument rear panel. The pin connections are as specified in IEEE Std. 488.1−1987 and the instrument complies with IEEE Std. 488.1−1987 and IEEE Std. 488.2−1987.

GPIB Subsets

This instrument contains the following IEEE 488.1 subsets:

Source Handshake SH1 Acceptor Handshake AH1 Talker T6 Listener L4 Service Request SR1 Remote Local RL1 Parallel Poll PP1 Device Clear DC1 Device Trigger DT1 Controller C0 Electrical Interface E2

GPIB IEEE Std. 488.2 Error Handling

The IEEE 488.2 UNTERMINATED error (addressed to talk with nothing to say) is handled as follows.

If the instrument is addressed to talk and the response formatter is inactive and the input queue is empty then the UNTERMINATED error is generated. This will cause the Query Error bit to be set in

the Standard Event Status Register, a value of 3 to be placed in the Query Error Register and the parser to be reset. See the Status Reporting section for further information.

The IEEE 488.2

send a response message and a or the input queue contains more than one END message then the instrument has been

INTERRUPTED and an error is generated. This will cause the Query Error bit to be set in the

Standard Event Status Register, a value of 1 to be placed in the Query Error Register and the response formatter to be reset thus clearing the output queue. The parser will then start parsing the next

<PROGRAM MESSAGE UNIT> from the input queue. See the Status Reporting section for

further information. The IEEE 488.2

a response message and the input queue becomes full then the instrument enters the

state and an error is generated. This will cause the Query Error bit to be set in the Standard Event Status Register, a value of 2 to be placed in the Query Error Register and the response formatter to be reset thus clearing the output queue. The parser will then start parsing the next

MESSAGE UNIT> from the input queue. See the Status Reporting section for further information.

INTERRUPTED error is handled as follows. If the response formatter is waiting to

<PROGRAM MESSAGE TERMINATOR> has been read by the parser

DEADLOCK error is handled as follows. If the response formatter is waiting to send

DEADLOCK

<PROGRAM

GPIB Parallel Poll

Complete parallel poll capabilities are offered on this generator. The Parallel Poll Enable Register is set to specify which bits in the Status Byte Register are to be used to form the The Parallel Poll Enable Register is set by the *PRE <nrf> command and read by the *PRE? command. The value in the Parallel Poll Enable Register is ANDed with the Status Byte Register; if the result is zero then the value of

The instrument must also be configured so that the value of during a parallel poll operation. The instrument is configured by the controller sending a Parallel Poll Configure command (PPC) followed by a Parallel Poll Enable command (PPE). The bits in the PPE command are shown below:

ist local message

ist is 0 otherwise the value of ist is 1.

ist can be returned to the controller

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bit 7 = X don't care

bit 6 = 1

bit 5 = 1 Parallel poll enable

bit 4 = 0

bit 3 = Sense sense of the response bit; 0 = low, 1 = high

bit 2 = ?

bit 1 = ? bit position of the response

bit 0 = ?

Example. To return the RQS bit (bit 6 of the Status Byte Register) as a 1 when true and a 0 when

false in bit position 1 in response to a parallel poll operation send the following commands

*PRE 64

The parallel poll response from the generator will then be 00H if RQS is 0 and 01H if RQS is 1.

During parallel poll response the DIO interface lines are resistively terminated (passive termination). This allows multiple devices to share the same response bit position in either wired−AND or wired−OR configuration, see IEEE 488.1 for more information.

<pmt>, then PPC followed by 69H (PPE)

Status Reporting

This section describes the complete status model of the instrument. Note that some registers are specific to the GPIB section of the instrument and are of limited use in an RS232 environment.

Standard Event Status and Standard Event Status Enable Registers

These two registers are implemented as required by the IEEE std. 488.2. Any bits set in the Standard Event Status Register which correspond to bits set in the Standard Event Status Enable Register will cause the ESB bit to be set in the Status Byte Register.

The Standard Event Status Register is read and cleared by the *ESR? command. The Standard Event Status Enable register is set by the *ESE <nrf> command and read by the *ESE? command.

Bit 7 −

Bit 6 −

Bit 5 −

Power On. Set when power is first applied to the instrument.

Not used.

Command Error. Set when a syntax type error is detected in a command from the bus. The parser is reset and parsing continues at the next byte in the input stream.

Bit 4 −

Bit 3 −

Bit 2 −

1. Interrupted error

2. Deadlock error

3. Unterminated error

Bit 1 −

Bit 0 −

Execution Error. Set when an error is encountered while attempting to execute a completely parsed command. The appropriate error number will be reported in the Execution Error Register.

Not used.

Query Error. Set when a query error occurs. The appropriate error number will be reported in the Query Error Register as listed below.

Not used.

Operation Complete. Set in response to the *OPC command.

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Status Byte Register and Service Request Enable Register

These two registers are implemented as required by the IEEE std. 488.2. Any bits set in the Status Byte Register which correspond to bits set in the Service Request Enable Register will cause the RQS/MSS bit to be set in the Status Byte Register, thus generating a Service Request on the bus.

The Status Byte Register is read either by the *STB? command, which will return MSS in bit 6, or by a Serial Poll which will return RQS in bit 6. The Service Request Enable register is set by the *SRE <nrf> command and read by the *SRE? command.

Bit 7 −

Bit 6 −

Bit 5 −

Bit 4 −

Bit 3 −

Bit 2 −

Bit 1 −

Bit 0 −

Not used.

RQS/MSS. This bit, as defined by IEEE Std. 488.2, contains both the Requesting Service message and the Master Status Summary message. RQS is returned in response to a Serial Poll and MSS I−s returned in response to the *STB? command.

ESB. The Event Status Bit. This bit is set if any bits set in the Standard Event Status Register correspond to bits set in the Standard Event Status Enable Register.

MAV. The Message Available Bit. This will be set when the instrument has a response message formatted and ready to send to the controller. The bit will be cleared after the Response Message Terminator has been sent.

Not used.

Status Model

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Power on Settings

The following instrument status values are set at power on:

Status Byte Register = 0

Service Request Enable Register ✝

Standard Event Status Register = 128 (pon bit set)

Standard Event Status Enable Register ✝

Execution Error Register = 0

Query Error Register = 0

Parallel Poll Enable Register ✝

✝ Registers marked thus are specific to the GPIB section of the instrument and are of limited use

in an RS232 environment. The instrument will be in local state with the keyboard active. The instrument parameters at power on are determined on the POWER ON SETTING screen

accessed from the UTILITY menu. If restore last setup or recall store no. nn has been set and a defined state is required by the controller at start up then the command ∗RST

should be used to load the system defaults.

If for any reason an error is detected at power up in the non−volatile ram a warning will be issued and all settings will be returned to their default states as for a *RST command.

= 0

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RS232 Remote Command Formats

Serial input to the instrument is buffered in a 256 byte input queue which is filled, under interrupt, in a manner transparent to all other instrument operations. The instrument will send XOFF when approximately 200 characters are in the queue. XON will be sent when approximately 100 free spaces become available in the queue after XOFF was sent. This queue contains raw (un−parsed) data which is taken, by the parser, as required. Commands (and queries) are executed in order and the parser will not start a new command until any previous command or query is complete. In non–addressable RS232 mode responses to commands or queries are sent immediately; there is no output queue. In addressable mode the response formatter will wait indefinitely if necessary, until the instrument is addressed to talk and the complete response message has been sent, before the parser is allowed to start the next command in the input queue.

Commands must be sent as specified in the commands list and must be terminated with the command terminator code 0AH (Line Feed, LF). Commands may be sent in groups with individual commands separated from each other by the code 3BH (;). The group must be terminated with command terminator 0AH (Line Feed, LF).

Responses from the instrument to the controller are sent as specified in the commands list. Each response is terminated by 0DH (Carriage Return, CR) followed by 0AH (Line Feed, LF).

Remote Commands

<WHITE SPACE> is defined as character codes 00H to 20H inclusive with the exception of those

which are specified as addressable RS232 control codes.

<WHITE SPACE> is ignored except in command identifiers. e.g. '*C LS' is not equivalent to '*CLS'.

The high bit of all characters is ignored. The commands are case insensitive.

GPIB Remote Command Formats

GPIB input to the instrument is buffered in a 256 byte input queue which is filled, under interrupt, in a manner transparent to all other instrument operations. The queue contains raw (un−parsed) data which is taken, by the parser, as required. Commands (and queries) are executed in order and the parser will not start a new command until any previous command or query is complete. There is no output queue which means that the response formatter will wait, indefinitely if necessary, until the instrument is addressed to talk and the complete response message has been sent, before the parser is allowed to start the next command in the input queue.

Commands are sent as or more

<PROGRAM MESSAGE UNIT> elements separated by <PROGRAM MESSAGE UNIT SEPARATOR>

elements.

<PROGRAM MESSAGE UNIT> is any of the commands in the remote commands list.

<PROGRAM MESSAGE UNIT SEPARATOR> is the semi−colon character ';' (3BH).

<PROGRAM MESSAGES> are separated by <PROGRAM MESSAGE TERMINATOR> elements which may

be any of the following: NL The new line character (0AH) NL^END The new line character with the END message ^END The END message with the last character of the message Responses from the instrument to the controller are sent as

<RESPONSE MESSAGE> consists of one <RESPONSE MESSAGE UNIT> followed by a <RESPONSE MESSAGE TERMINATOR>

<RESPONSE MESSAGE TERMINATOR> is the new line character with the END message NL^END.

<PROGRAM MESSAGES> by the controller, each message consisting of zero

<RESPONSE MESSAGES>. A

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Each query produces a specific <RESPONSE MESSAGE> which is listed along with the command in the remote commands list.

<WHITE SPACE> is ignored except in command identifiers. e.g. '*C LS' is not equivalent to '*CLS'. <WHITE SPACE> is defined as character codes 00H to 20H inclusive with the exception of the NL

character (0AH). The high bit of all characters is ignored. The commands are case insensitive.

Command List

This section lists all commands and queries implemented in this instrument. The commands are listed in alphabetical order within the function groups.

Note that there are no dependent parameters, coupled parameters, overlapping commands, expression program data elements or compound command program headers; each command is completely executed before the next command is started. All commands are sequential and the operation complete message is generated immediately after execution in all cases.

The following nomenclature is used:

<rmt>

<cpd> <

<nrf>

<nr1> A number with no fractional part, i.e. an integer.

[…]

The commands which begin with a commands. All will function when used on the RS232 interface but some are of little use.

CHARACTER PROGRAM DATA>, i.e. a short mnemonic or string such as ON or OFF.

A number in any format. e.g. 12, 12.00, 1.2 e 1 and 120 e−1 are all accepted as the number 12. Any number, when received, is converted to the required precision consistent with the use then rounded up to obtain the value of the command.

ny item(s) enclosed in these brackets are optional parameters. If more than one item is

enclosed then all or none of the items are required.

Channel Selection

Most commands act on a particular channel of the generator. The following command is used to select the required channel. Subsequent commands will change only the specified parameter on the selected channel.

SETUPCH <nrf> Select channel <nrf> as the destination for subsequent commands. <nrf>

may take the range 1 to maximum channel number in the instrument.

Frequency and Period

These commands set the frequency/period of the generator main output and are equivalent to pressing the FREQ key and editing that screen.

* are those specified by IEEE Std. 488.2 as Common

WAVFREQ <nrf> Set the waveform frequency to <nrf> Hz.

WAVPER <nrf> Set the waveform period to <nrf> sec.

CLKFREQ <nrf> Set the arbitrary sample clock freq to <nrf> Hz.

CLKPER <nrf> Set the arbitrary sample clock period to <nrf> sec.

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Amplitude and DC Offset

AMPL <nrf> Set the amplitude to <nrf> in the units as specified by the AMPUNIT

command. AMPUNIT <cpd> Set the amplitude units to <VPP>, <VRMS> or <DBM>. ZLOAD <cpd> Set the output load, which the generator is to assume for amplitude

and dc offset entries, to <50> (50Ω), <600> (600Ω) or <OPEN>. DCOFFS <nrf> Set the dc offset to <nrf> Volts.

Waveform Selection

WAVE <cpd> Select the output waveform as <SINE>, <SQUARE>, <TRIANG>,

<DC>, <POSRMP>, <NEGRMP>, <COSINE>, <HAVSIN>,

<HAVCOS>, <SINC>, <PULSE>, <PULSTRN>, <ARB> or <SEQ>.

PULSPER <nrf> Set the pulse period to <nrf> sec. PULSWID <nrf> Set the pulse width to <nrf> sec. PULSDLY <nrf> Set the pulse delay to <nrf> sec. PULTRNLEN <nrf>

PULTRNPER <nrf>

PULTRNBASE <nrf>

PULTRNLEV <nrf1>,<nrf2>

PULTRNWID <nrf1>,<nrf2>

PULTRNDLY <nrf1>,<nrf2>

PULTRNMAKE

ARB <cpd> Select an arbitrary waveform for output. <cpd> must be the name of

ARBLISTCH? Returns a list of all arbitrary waveforms in the channel’s memory,

ARBLIST? Returns a list of all arbitrary waveforms in backup memory, each will

Set the number of pulses in the pulse−train to <nrf>.

Set the pulse−train period to <nrf> sec.

Set the pulse−train base line to <nrf> Volts.

Set the level of pulse−train pulse number <nrf1> to <nrf2> Volts.

Set the width of pulse−train pulse number <nrf1> to <nrf2> sec.

Set the delay of pulse−train pulse number <nrf1> to <nrf2> sec.

Makes the pulse−train and runs it − similar to the WAVE PULSTRN

command.

an existing arbitrary waveform. Backup memory is always used as

the source of the arb. The arb will be copied to the channel memory

if necessary.

each will return a name and length in the following form

<cpd>,<nr1>. The list will end with <rmt>.

return a name and length in the following form <cpd>,<nr1>. The list

will end with <rmt>.

Arbitrary Waveform Create and Delete

NOTE: Care should be take to ensure that all channels in the instrument are running in CONTINUOUS mode before using commands from this section. Failure to observe this restriction may give unexpected results.

ARBDELETE <cpd> Delete the arbitrary waveform <cpd> from backup memory. ARBCLR <cpd> Delete the arb <cpd> from channel memory. The backup memory is

not changed.

ARBCREATE <cpd>,<nrf> Create a new, blank arbitrary waveform with name <cpd> and

length <nrf> points.

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ARBDEFCSV <cpd>,<nrf>,<csv ascii data>

ARBDEF <cpd>,<nrf>,<bin data block>

Define a new or existing arbitrary waveform with name <cpd> and length <nrf> and load with the data in <csv ascii data>. If the arbitrary waveform does not exist it will be created. If it does exist the length will be checked against that specified and a warning will be issued if they are different. The edit limits will be set to the extremes of the waveform, The data consists of ascii coded values, in the range −2048 to +2047, for each point. The values are separated by a comma character and the data ends with <pmt>. If less data is sent than the number of points in the waveform the old data is retained from the point where the new data ends. If more data is sent the extra is discarded.

Define a new or existing arbitrary waveform with name <cpd> and length <nrf> and load with the data in <bin data block>. If the arbitrary waveform does not exist it will be created. If it does exist the length will be checked against that specified and a warning will be issued if they are different. The edit limits will be set to the extremes of the waveform. The data consists of two bytes per point with no characters between bytes or points. The point data is sent high byte first. The data block has a header which consists of the # character followed by several ascii coded numeric characters. The first if these defines the number of ascii characters to follow and these following characters define the length of the binary data in bytes. If less data is sent than the number of points in the waveform the old data is retained from the point where the new data ends. If more data is sent the extra is discarded. Due to the binary data block this command cannot be used over the RS232 interface.

Arbitrary Waveform Editing

ARBEDLMTS <nrf1>,<nrf2> Set the limits for the arbitrary waveform editing functions to start at

<nrf1> and stop at <nrf2>. If both values are set to 0 the commands which use them will automatically place them at the start and end points of the relevant waveform. This automatic mode will remain in effect until the ARBEDLMTS command is issued again with non zero values. The automatic mode is always selected at power up.

ARBDATACSV <cpd>,<csv ascii data>

Load data to an existing arbitrary waveform. <cpd> must be the name of an existing arbitrary waveform. The data consists of ascii coded values, in the range −2048 to +2047, for each point. The values are separated by a comma character and the data ends with <pmt>. The data is entered into the arbitrary waveform between the points specified by the ARBEDLMTS command. If less data is sent than the number of points between the limits the old data is retained from the point where the new data ends. If more data is sent the extra is discarded.

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ARBDATA <cpd>,<bin data block>

ARBDATACSV? <cpd>

ARBDATA? <cpd>

ARBRESIZE <cpd>,<nrf> Change the size of arbitrary waveform <cpd> to <nrf>. ARBRENAME <cpd1>,<cpd2> Change the name of arbitrary waveform <cpd1> to <cpd2>. ARBPOINT <cpd>,<nrf1>,<nrf2> Set the waveform point at address <nfr1> in arbitrary waveform

ARBLINE <cpd>,<nrf1>,<nrf2>,<nrf3>,<nrf4 >

ARBINSSTD <cpd1>,<cpd2>,<nrf1>,<nrf2>

ARBINSARB <cpd1>,<cpd2>,<nrf1>,<nrf2>

ARBCOPY <cpd>,<nrf1>,<nrf2>,<nrf3>

ARBAMPL <cpd>,<nrf1>,<nrf2>,<nrf3>

ARBOFFSET <cpd>,<nrf1>,<nrf2>,<nrf3>

Load data to an existing arbitrary waveform. <cpd> must be the name of an existing arbitrary waveform. The data consists of two bytes per point with no characters between bytes or points. The point data is sent high byte first. The data block has a header which consists of the # character followed by several ascii coded numeric characters. The first if these defines the number of ascii characters to follow and these following characters define the length of the binary data in bytes. The data is entered into the arbitrary waveform between the points specified by the ARBEDLMTS command. If less data is sent than the number of points between the limits the old data is retained from the point where the new data ends. If more data is sent the extra is discarded. Due to the binary data block this command cannot be used over the RS232 interface.

Returns the data from an existing arbitrary waveform. <cpd> must be the name of an existing arbitrary waveform. The data consists of ascii coded values as specified for the ARBDATACSV command. The data is sent from the arbitrary waveform between the points specified by the ARBEDLMTS command.

Returns the data from an existing arbitrary waveform. <cpd> must be the name of an existing arbitrary waveform. The data consists of binary coded values as specified for the ARBDATA command. The data is sent from the arbitrary waveform between the points specified by the ARBEDLMTS command. Due to the binary data block this command cannot be used over the RS232 interface.

<cpd> to <nrf2>. Draw a line in arbitrary waveform <cpd> from start address/data

<nrf1>/<nrf2> to stop address/data <nrf3>/<nrf4>.

Insert the standard waveform <cpd2> into the arbitrary waveform <cpd1> from start address <nrf1> to stop address <nrf2>. <cpd2> must be one of <SINE>, <SQUARE>, <TRIANG>, <DC>, <POSRMP>, <NEGRMP>, <COSINE>, <HAVSIN>, <HAVCOS>, or <SINC> and <cpd1> must be an existing arbitrary waveform.

Insert the arbitrary waveform <cpd2> into arbitrary waveform <cpd1>. Use that part of <cpd2> specified by the ARBEDLMTS command and insert from start address <nrf1> to stop address <nrf2>. <cpd1> and <cpd2> must both be existing arbitrary waveforms but they cannot be the same waveform.

Block copy in arbitrary waveform <cpd> the data from start address <nrf1> to stop address <nrf2> to destination address <nrf3>.

Adjust the amplitude of arbitrary waveform <cpd> from start address <nrf1> to stop address <nrf2> by the factor <nfr3>.

Move the data in arbitrary waveform <cpd> from start address <nrf1> to stop address <nrf2> by the offset <nrf3>.

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ARBINVERT <cpd>,<nrf1>,<nrf2> Invert arbitrary waveform <cpd> between start address <nrf1>

and stop address <nrf2>.

ARBLEN? <cpd> Returns the length, in points, of the arbitrary waveform <cpd>. If

the waveform does not exist the return value will be 0. POSNMKRCLR <cpd> Clear all position markers from arbitrary waveform <cpd>. POSNMKRSET <cpd>,<nrf>

POSNMKRRES <cpd>,<nrf> Clear the position marker at address <nrf> in arbitrary waveform

POSNMKRPAT <cpd1>,<nrf1>,<nrf2>,<cpd2>

Set the position marker at address <nrf> in arbitrary waveform

<cpd> to 1 (high).

<cpd> to 0 (low).

Put the pattern <cpd2> into the arbitrary waveform <cpd1> from

start address <nrf1> to stop address <nrf2>. The pattern may

contain up to 16 entries of '1' or '0', no other characters are

allowed.

Waveform Sequence Control

SEQWFM <nrf>,<cpd> Set the 'waveform' parameter for sequence segment <nrf> to

<cpd>. <cpd> must be the name of an existing arbitrary

waveform.

SEQSTEP <nrf>,<cpd> Set the 'step on' parameter for sequence segment <nrf> to

<COUNT>, <TRGEDGE> or <TRGLEV>.

SEQCNT <nrf1>,<nrf2> Set count for sequence segment <nrf1> to <nrf2>. SEQSEG <nrf>,<cpd> Set the status of sequence segment <nrf> to <ON> or <OFF>.

Mode Commands

MODE <cpd> Set the mode to <CONT>, <GATE>, <TRIG>, <SWEEP> or

<TONE>.

BSTCNT <nrf> Set the burst count to <nrf>. PHASE <nrf> Set the generator phase to <nrf> degrees.

This parameter is used for phase locking and trigger/gate mode

start/stop phase.

TONEEND <nrf> Delete tone frequency number <nrf> thus defining the end of the

list.

TONEFREQ <nrf1>,<nrf2>,<nrf3> Set tone frequency number <nrf1> to <nrf2> Hz. The third

parameter sets the tone type; 1 will give Trig, 2 will give FSK, any

other value gives Gate type.

SWPSTARTFRQ <nrf> Set the sweep start frequency to <nrf> Hz. SWPSTOPFRQ <nrf> Set the sweep stop frequency to <nrf> Hz. SWPCENTFRQ <nrf> Set the sweep centre frequency to <nrf> Hz. SWPSPAN <nrf> Set the sweep frequency span to <nrf> Hz. SWPTIME <nrf> Set the sweep time to <nrf> sec. SWPTYPE <cpd> Set the sweep type to <CONT>, <TRIG>, <THLDRST> or

<MANUAL>.

SWPDIRN <cpd> Set the sweep direction to <UP>, <DOWN>, <UPDN> or <DNUP>. SWPSYNC <cpd> Set the sweep sync <ON> or <OFF>. SWPSPACING <cpd> Set the sweep spacing to <LIN> or <LOG>. SWPMKR <nrf> Set the sweep marker to <nrf> Hz. SWPMANUAL <cpd> Set the sweep manual parameters to <UP>, <DOWN>, <FAST>,

<SLOW>, <WRAPON> or <WRAPOFF>.

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Input/Output control

OUTPUT <cpd> Set the main output <ON>, <OFF>, <NORMAL> or <INVERT>. SYNCOUT <cpd> Set the sync output <ON>, <OFF>, <AUTO>, <WFMSYNC>,

<POSNMKR>, <BSTDONE>, <SEQSYNC>, <TRIGGER>,

<SWPTRG> or <PHASLOC>.

TRIGOUT <cpd> Set the trig output to <AUTO>, <WFMEND>, <POSNMKR>,

<SEQSYNC> or <BSTDONE>.

TRIGIN <cpd> Set the trig input to <INT>, <EXT>, <MAN>, <PREV>, <NEXT>,

<POS> or <NEG>.

TRIGPER <nrf> Set the internal trigger generator period to <nrf> sec. FORCETRG Force a trigger to the selected channel. Will function with any

trigger source except MANUAL specified.

Modulation Commands

MOD <cpd> Set the modulation source to <OFF>, <EXT> or <PREV>. MODTYPE <cpd> Set the modulation type to <AM> or <SCM>.

AMDEPTH <nrf> Set the depth for amplitude modulation to <nrf> %. SCMLEVEL <nrf> Set the level for SCM to <nrf> Volts. SUM <cpd> Set the sum source to <OFF>, <EXT> or <PREV>. SUMATN <cpd> Set the sum input attenuator to <0dB>, <10dB>, <20dB>,

<30dB>, <40dB> or <50dB>.

SUMRATIO <nrf> Set the sum ratio to <nrf>.

Phase Locking Commands

REFCLK <cpd> Set the ref. clock bnc to <IN>, <OUT>, <MASTER> or <SLAVE>. ABORT Aborts an external phase locking operation. PHASE <nrf> Set the generator phase to <nrf> degrees.

This parameter is used for phase locking and trigger/gate mode start/stop phase.

LOCKMODE <cpd> Set the channel lock mode to <INDEP>, <MASTER>, <FTRACK>

or <SLAVE>.

LOCKSTAT <cpd>

Set the inter−channel lock status to <ON> or <OFF>.

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Status Commands

∗CLS

∗ESE <nrf>

∗ESE?

∗ESR?

∗IDN?

∗IST?

∗OPC

∗OPC?

∗PRE <nrf>

∗PRE?

∗SRE <nrf>

∗SRE?

∗STB?

∗WAI

∗TST?

EER? Query and clear execution error number register. The response

QER? Query and clear query error number register. The response

Clear status. Clears the Standard Event Status Register, Query Error Register and Execution Error Register. This indirectly clears the Status Byte Register.

Set the Standard Event Status Enable Register to the value of <nrf>.

Returns the value in the Standard Event Status Enable Register in <nr1> numeric format. The syntax of the response is <nr1><rmt>.

Returns the value in the Standard Event Status Register in <nr1> numeric format. The register is then cleared. The syntax of the response is <nr1><rmt>.

Returns the instrument identification. The exact response is determined by the instrument configuration and is of the form <NAME>, <model>, 0, <version><rmt>where <NAME> is the manufacturer’s name, <MODEL> defines the type of instrument and <VERSION> is the revision level of the software installed.

Returns ist local message as defined by IEEE Std. 488.2. The syntax of the response if 0<rmt>, if the local message false or 1<rmt>, if the local message is true.

Sets the Operation Complete bit (bit 0) in the Standard Event Status Register. This will happen immediately the command is executed because of the sequential nature of all operations.

Query operation complete status. The syntax of the response is 1<rmt>. The response will be available immediately the command is executed because of the sequential nature of all operations.

Set the Parallel Poll Enable Register to the value <nrf>.

Returns the value in the Parallel Poll Enable Register in <nr1> numeric format. The syntax of the response is <nr1><rmt>.

Set the Service Request Enable Register to <nrf>.

Returns the value of the Service Request Enable Register in <nr1> numeric format. The Syntax of the response is <nr1><rmt>.

Returns the value of the Status Byte Register in <nr1> numeric format. The syntax of the response is <nr1><rmt>.

Wait for operation complete true. As all commands are completely executed before the next is started this command takes no additional action.

The generator has no self−test capability and the response is always 0<rmt>.

format is nr1<rmt>.

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Miscellaneous Commands

∗LRN?

LRN <character data>

∗RST

∗RCL <nrf>

∗SAV <nrf>

∗TRG

COPYCHAN <nrf> Copy the parameters from the current setup chan to channel

HOLD <cpd> Set hold mode <ON>, <OFF>, <ENAB> or <DISAB>. The ON or

FILTER <cpd> Set the output filter to <AUTO>, <EL10>, <EL16>, <BESS or

BEEPMODE <cpd> Set beep mode to <ON>, <OFF>, <WARN>, or <ERROR>. BEEP Sound one beep. LOCAL Returns the instrument to local operation and unlocks the

Refer to Calibration section for remote calibration commands.

Returns the complete set up of the instrument as a hexadecimal character data block. To re−install the set up the block should be returned to the instrument exactly as it is received. The syntax of the response is LRN <Character data><rmt>. The settings in the instrument are not affected by execution of the ∗LRN? command.

Install data for a previous Resets the instrument parameters to their default values (see

DEFAULT INSTRUMENT SETTINGS). Recalls the instrument set up contained in store number <nrf>.

Valid store numbers are 0 − 9. Recalling store 0 sets all parameters to the default settings (see DEFAULT INSTRUMENT SETTINGS).

Saves the complete instrument set up in the store number <nrf>. Valid store numbers are 1 − 9.

This command is the same as pressing the MAN TRIG key. Its effect will depend on the context in which it is asserted. The interface command Group Execute Trigger (GET) will perform the same action as *TRG.

<nrf>.

OFF forms are the same as pressing the HOLD key. The ENAB and DISAB forms are channel specific and enable or disable the action of the HOLD key or HOLD input.

<NONE>.

keyboard. Will not function if LLO is in force.

∗LRN? command.

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Remote Command Summary

∗CLS

∗ESE <nrf>

∗ESE?

∗ESR?

∗IDN?

∗IST?

∗LRN?

∗OPC

∗OPC?

∗PRE <nrf>

∗PRE?

∗RCL <nrf>

∗RST

∗SAV

∗SRE <nrf>

∗SRE?

∗STB?

∗TRG

∗TST?

∗WAI

ABORT Aborts a phase locking operation. AMDEPTH <nrf> Set the depth for amplitude modulation to <nrf> %. AMPL <nrf> Set the amplitude to <nrf> in the units as specified by the AMPUNIT

AMPUNIT <cpd> Set the amplitude units to <VPP>, <VRMS> or <DBM>. ARB <cpd> Select an arbitrary waveform for output. ARBAMPL

<cpd>,<nrf1>,<nrf2>,<nrf3> ARBCLR <cpd> Delete the arb <cpd> from channel memory. ARBCOPY

<cpd>,<nrf1>,<nrf2>,<nrf3> ARBCREATE <cpd>,<nrf> Create a new, blank arbitrary waveform with name <cpd> and

ARBDATA <cpd>,<bin data block>

ARBDATA? <cpd>

Clear status.

Set the Standard Event Status Enable Register to the value of <nrf>.

Returns the value in the Standard Event Status Enable Register in <nr1> numeric format.

Returns the value in the Standard Event Status Register in <nr1> numeric format.

Returns the instrument identification.

Returns ist local message as defined by IEEE Std. 488.2.

Returns the complete set up of the instrument as a hexadecimal character data block approximately 842 bytes long.

Sets the Operation Complete bit (bit 0) in the Standard Event Status Register.

Query operation complete status.

Set the Parallel Poll Enable Register to the value <nrf>.

Returns the value in the Parallel Poll Enable Register in <nr1> numeric format.

Recalls the instrument set up contained in store number <nrf>.

Resets the instrument parameters to their default values.

Saves the complete instrument set up in the store number <nrf>. Valid store numbers are 1 − 9.

Set the Service Request Enable Register to <nrf>.

Returns the value of the Service Request Enable Register in <nr1> numeric format.

Returns the value of the Status Byte Register in <nr1> numeric format.

This command is the same as pressing the MAN TRIG key.

The generator has no self−test capability and the response is always 0<rmt>.

Wait for operation complete true. executed before the next is started

command.

Adjust the amplitude of arbitrary waveform <cpd> from start address <nrf1> to stop address <nrf2> by the factor <nfr3>.

Block copy in arbitrary waveform <cpd> the data from start address <nrf1> to stop address <nrf2> to destination address <nrf3>.

length <nrf> points.

Load data to an existing arbitrary waveform.

Returns the data from an existing arbitrary waveform.

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ARBDATACSV <cpd>,<csv ascii data>

ARBDATACSV? <cpd>

ARBDEF <cpd>,<nrf>,<bin data block>

ARBDEFCSV <cpd>,<nrf>,<csv ascii data>

ARBDELETE <cpd> Delete the arbitrary waveform <cpd>. ARBEDLMTS <nrf1>,<nrf2> Set the limits for the arbitrary waveform editing functions to start at

ARBINSARB <cpd1>,<cpd2>,<nrf1>,<nrf2>

ARBINSSTD <cpd1>,<cpd2>,<nrf1>,<nrf2>

ARBINVERT <cpd>,<nrf1>,<nrf2> Invert arbitrary waveform <cpd> between start address <nrf1> and

ARBLEN? <cpd> Returns the length, in points, of the arbitrary waveform <cpd>. ARBLINE <cpd>,<nrf1>,<nrf2>,

<nrf3>, <nrf4> ARBLIST? Returns a list of all arbitrary waveforms in backup memory, each will

ARBLISTCH? Returns a list of all arbitrary waveforms channel memory, each will

ARBOFFSET <cpd>,<nrf1>,<nrf2>,<nrf3>

ARBPOINT <cpd>,<nrf1>,<nrf2> Set the waveform point at address <nfr1> in arbitrary waveform

ARBRENAME <cpd1>,<cpd2> Change the name of arbitrary waveform <cpd1> to <cpd2>. ARBRESIZE <cpd>,<nrf> Change the size of arbitrary waveform <cpd> to <nrf>. BEEP Set beep mode to <ON>, <OFF>, <WARN>, or <ERROR>. BEEPMODE <cpd> Sound one beep. BSTCNT <nrf> Set the burst count to <nrf>. CLKFREQ <nrf> Set the arbitrary sample clock freq to <nrf> Hz. CLKPER <nrf> Set the arbitrary sample clock period to <nrf> sec. COPYCHAN <nrf> Copy the parameters from the current setup chan to channel <nrf>. DCOFFS <nrf> Set the dc offset to <nrf> Volts. EER? Query and clear execution error number register. FILTER <cpd> Set the output filter to <AUTO>, <EL10>, <EL16>, <BESS or

FORCETRG Force a trigger to the selected channel. HOLD <cpd> Set hold mode <ON>, <OFF>, <ENAB> or <DISAB>. LOCKMODE <cpd> Set the channel lock mode to <INDEP>, <MASTER>, <FTRACK>

LOCKSTAT <cpd> Set the channel lock status to <ON> or <OFF>.

LOCAL Returns the instrument to local operation and unlocks the keyboard.

Load data to an existing arbitrary waveform.

Returns the data from an existing arbitrary waveform.

Define a new or existing arbitrary waveform with name <cpd> and length <nrf> and load with the data in <bin data block>.

Define a new or existing arbitrary waveform with name <cpd> and length <nrf> and load with the data in <csv ascii data>.

<nrf1> and stop at <nrf2>. Insert the arbitrary waveform <cpd2> into arbitrary waveform

<cpd1>. Use that part of <cpd2> specified by the ARBLIMITS command and insert from start address <nrf1> to stop address <nrf2>.

Insert the standard waveform <cpd2> into the arbitrary waveform <cpd1> from start address <nrf1> to stop address <nrf2>.

stop address <nrf2>.

Draw a line in arbitrary waveform <cpd> from start address/data <nrf1>/<nrf2> to stop address/data <nrf3>/<nrf4>.

return a name and length in the following form <cpd>,<nr1>.

return a name and length in the following form <cpd>,<nr1>. Move the data in arbitrary waveform <cpd> from start address

<nrf1> to stop address <nrf2> by the offset <nrf3>.

<cpd> to <nrf2>.

<NONE>.

or <SLAVE>.

Will not function if LLO is in force.

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LRN <character data>

MOD <cpd> Set the modulation source to <OFF>, <EXT> or <PREV>. MODE <cpd> Set the mode to <CONT>, <GATE>, <TRIG>, <SWEEP> or TONE. MODTYPE <cpd> Set the modulation type to <AM> or <SCM>. OUTPUT <cpd> Set the main output <ON>, <OFF>, <NORMAL> or <INVERT>. PHASE <nrf> Set the slave generator phase to <nrf> degrees. POSNMKRCLR <cpd> Clear all position markers from arbitrary waveform <cpd>. POSNMKRPAT

<cpd1>,<nrf1>,<nrf2>,<cpd2> POSNMKRRES <cpd>,<nrf> Clear the position marker at address <nrf> in arbitrary waveform

POSNMKRSET <cpd>,<nrf> Set the position marker at address <nrf> in arbitrary waveform

PULSDLY <nrf> Set the pulse delay to <nrf> sec. PULSPER <nrf> Set the pulse period to <nrf> sec. PULSWID <nrf> Set the pulse width to <nrf> sec. PULTRNBASE <nrf>

PULTRNDLY <nrf1>,<nrf2>

PULTRNLEN <nrf>

PULTRNLEV <nrf1>,<nrf2>

PULTRNMAKE

PULTRNPER <nrf>

PULTRNWID <nrf1>,<nrf2>

QER? Query and clear query error number register. REFCLK <cpd> Set the ref. clock bnc to <IN>, <OUT>, <MASTER> or <SLAVE>. SCMLEVEL <nrf> Set the level for SCM to <nrf> Volts. SETUPCH <nrf> Select channel <nrf> SEQCNT <nrf1>,<nrf2> Set count for sequence segment <nrf1> to <nrf2>. SEQSEG <nrf>,<cpd> Set the status of sequence segment <nrf> to <ON> or <OFF>. SEQSTEP <nrf>,<cpd> Set the 'step on' parameter for sequence segment <nrf> to

SEQWFM <nrf>,<cpd> Set the 'waveform' parameter for sequence segment <nrf> to

SUM <cpd> Set the sum source to <OFF>, <EXT> or <PREV>. SUMATN <cpd> Set the sum input attenuator to <0dB>, <10dB>, <20dB>, <30dB>,

SUMRATIO <nrf> Set the sum ratio to <nrf>. SWPCENTFRQ <nrf> Set the sweep centre frequency to <nrf> Hz. SWPDIRN <cpd> Set the sweep direction to <UP>, <DOWN>, <DNUP> or <UPDN>. SWPMANUAL <cpd> Set the sweep manual parameters to <UP>, <DOWN>, <FAST>,

SWPMKR <nrf> Set the sweep marker to <nrf> Hz. SWPSPACING <cpd> Set the sweep spacing to <LIN> or <LOG>. SWPSPAN <nrf> Set the sweep frequency span to <nrf> Hz. SWPSTARTFRQ <nrf> Set the sweep start frequency to <nrf> Hz. SWPSTOPFRQ <nrf> Set the sweep stop frequency to <nrf> Hz.

Install data for a previous

Put the pattern <cpd2> into the arbitrary waveform <cpd1> from start address <nrf1> to stop address <nrf2>.

<cpd> to 0 (low).

<cpd> to 1 (high).

Set the pulse−train base line to <nrf> Volts.

Set the delay of pulse−train pulse number <nrf1> to <nrf2> sec.

Set the number of pulses in the pulse−train to <nrf>.

Set the level of pulse−train pulse number <nrf1> to <nrf2> Volts.

Makes the pulse−train and runs it − similar to the WAVE PULSTRN command.

Set the pulse−train period to <nrf> sec.

Set the width of pulse−train pulse number <nrf1> to <nrf2> sec.

<COUNT>, <TRGEDGE> or <TRGLEV>.

<cpd>.

<40dB> or <50dB>.

<SLOW>, <WRAPON> or <WRAPOFF>.

∗LRN? command.

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SWPSYNC <cpd> Set the sweep sync <ON> or <OFF>. SWPTIME <nrf> Set the sweep time to <nrf> sec. SWPTYPE <cpd> Set ten sweep type to <CONT>, <TRIG>, <THLDRST> or

<MANUAL>.

SYNCOUT <cpd> Set the sync output <ON>, <OFF>, <AUTO>, <WFMSYNC>,

<POSNMKR>, <BSTDONE>, <SEQSYNC>, <TRIGGER>, <SWPTRG> or <PHASLOC>.

TONEEND <nrf> Delete tone frequency number <nrf> thus defining the end of the

list.

TONEFREQ <nrf1>,<nrf2>,<nrf3> Set tone frequency number <nrf1> to <nrf2> Hz. The third

parameter sets the tone type; 1 will give Trig, 2 will give FSK, any other value gives Gate type.

TRIGIN <cpd> Set the trig input to <INT>, <EXT>, <MAN>, <PREV>, <NEXT>,

<POS> or <NEG>.

TRIGOUT <cpd> Set the trig output to <AUTO>, <WFMEND>, <POSNMKR>,

<SEQSYNC> or <BSTDONE>. TRIGPER <nrf> Set the internal trigger generator period to <nrf> sec. VCAIN <cpd> Set the vca/sum input to <VCA>, <SUM> or <OFF>. WAVE <cpd> Select the output waveform as <SINE>, <SQUARE>, <TRIANG>,

<DC>, <POSRMP>, <NEGRMP>, <COSINE>, <HAVSIN>,

<HAVCOS>, <SINC>, <PULSE>, <PULSTRN>, <ARB> or <SEQ>. WAVFREQ <nrf> Set the waveform frequency to <nrf> Hz. WAVPER <nrf> Set the waveform period to <nrf> sec. ZLOAD <cpd> Set the output load, which the generator is to assume for amplitude

and dc offset entries, to <50> (50Ω), <600> (600Ω) or <OPEN>.

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The Manufacturers or their agents overseas will provide a repair service for any unit developing a fault. Where owners wish to undertake their own maintenance work, this should only be done by skilled personnel in conjunction with the service manual which may be purchased directly from the Manufacturers or their agents overseas.

Cleaning

If the instrument requires cleaning use a cloth that is only lightly dampened with water or a mild detergent.

WARNING! TO AVOID ELECTRIC SHOCK, OR DAMAGE TO THE INSTRUMENT, NEVER ALLOW WATER TO GET INSIDE THE CASE. TO AVOID DAMAGE TO THE CASE NEVER CLEAN WITH SOLVENTS.

Maintenance

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Appendix 1. Warning and Error Messages

Warning messages are given when a setting may not give the expected result, e.g. DC Offset attenuated by the output attenuator when a small amplitude is set; the setting is, however, implemented.

Error messages are given when an illegal setting is attempted; the previous setting is retained. The last two warning/error messages can be reviewed by selecting LAST ERROR from the

UTILITY screen, the latest is reported first. Warning and error messages are reported with a number on the display; only the number is

reported via the remote control interfaces. The following is a complete list of messages as they appear on the display.

Warning Messages

00 No errors or warnings have been reported 13 DC offset changed by amplitude 14 Offset + SUM + level may cause clipping 23 Offset will clip the waveform 24 Instrument not calibrated 30 Amplitude will clip the waveform 42 Trigger source is fixed to external in SWP/SLAVE mode 43 Arb repeated in two seq segs so SEQ SYNC may not be correct 59 Trigger slope is fixed to positive in SWEEP/SLAVE mode 81 The programmed mod depth cannot be set 83

Error Messages

101 Frequency out of range for the selected waveform 102 Sample clock frequency required exceeds 40MHz 103 Sample clock frequency required is less than 0.1Hz 104

105 Pulse width cannot be greater than the period 106 Absolute value of pulse delay must be < period 107 Pulse width cannot be less than 25ns 108 Maximum output level exceeded 109 Minimum output level exceeded 110 Minimum dc offset value exceeded 111 Maximum dc offset value exceeded 112 The value entered is out of range 115 There are no arb waveforms defined Use WAVEFORM CREATE 116 Cannot delete arb while it is selected for any output chan 117 Arb name exists, names must be unique 118 Arb waveform length exceeds available memory 119 Arb waveform length cannot be less than four points 121 Start address error: must be in the range 0 <= n <= stop addr 122 Stop address error: must be in the range strt <= n <= wfm len 125 No GPIB available 127 System ram error check battery 128

129

Numeric value too large − switching to sample period

Pulse/pulse−train period out of range for current set−up

Point value error: must be in the range −2048 <= n <= +2047

Wave offset error: must be in the range −4096 <= n <= +4095

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131 Wave amplitude error must be in the range 0 <= n <= 100 132

133 Sequence count value exceeds the maximum of 32768 134 Sequence count value cannot be less than 1 135 Trigger generator maximum period is 200s 136 Trigger generator minimum period is 10us 138 Burst count value exceeds the maximum of 1048575 139 Burst count value cannot be less than 1 140 Trig/Gate freq too high. Max=1MHz. Continuous mode set 141 Selected function is illegal in tone mode TONE MODE CANCELLED! 144 Selected combination of function and mode is illegal 145 Selected mode is not available when phase lock master or slave 146 Cannot delete arbs while a sequence is running 147 Current setup requires an arb wfm which does not exist 148 Trig/gate mode and seq step value cause a trigger conflict 149 Seq step value can't mix edge and level between segments 150 Number of pulses in train must be between 1 and 10 151

152

153 Pulse number must be between 1 and 10 154 Sweep frequency values must be 0.001mHz to 16MHz 155 Sweep start freq must be less than stop freq 156 Sweep stop freq must be greater than start freq 157 Sweep time value is out of range 0.03s < n < 999s 158 Sweep marker value is out of range 0.001Hz < n < 16MHz 160 Not locked

161 Illegal phase value 178 SUM ratio is not possible within level constraints 179 SUM and internal MOD cannot be active together 180 Modulation depth or SCM level is out of range 182 This channel’s waveform ram is full 184 SUM or Modulation conflict 186 Inter channel lock not possible. Lock status is off.

Block dest error: must be in the range 0 <= n <= wfm len−4

Pulse train base level must be >−5.0V and <+5.0V

Pulse level must be >−5.0V and <+5.0V

This error indicates that a phase locking operation has failed.

This error may occur for several reasons. In each case there is a conflict of the phase locking settings. In most cases the status of the phase lock is set to off. Any of the following conditions will cause this error;

1. More than one master channel is enabled.

2. No master channel is enabled.

3. The locked channels contain a mixture of DDS and PLL generated waveforms.

4. Frequency tracking is enabled (mode: master/freq) but the frequencies are not the same on all channels. If PLL waveforms are locked the mode will be forced to frequency tracking.

5. A locked channel is not set to continuous mode.

6. An attempt is made to turn on phase lock with a frequency set too high. Note that the maximum frequency for phase locked DDS operation is 10MHz.

7. An attempt is made to set the frequency too high during phase lock. This error does not set phase lock to off, the system simply inhibits the setting of the incorrect frequency.

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Remote Warnings

72 Length is different to that in the ARBDEF(CSV) command

Remote Errors

120 Waveform limit value out of range 126 Illegal store number requested 162 Byte value outside the range 0 to 255 163 Specified arb name does not exist 164 Command illegal in sweep or tone mode 165 Cannot set waveform frequency or period for a sequence 166 Cannot set sample frequency or period for std waveforms 167 dBm output units assume a 50 Ohm termination 168 Specified units illegal for the selected waveform 169 Command not available for RS232 170 Length value error in binary block 171 Illegal value in arbitrary data 173 Illegal tone number 174 Illegal sequence segment number 175 Cannot insert arb into itself 176 Pattern value is illegal or pattern too long 177 Illegal remote calibration command. 185 Command not available while sweeping.

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Appendix 2. SYNC OUT Automatic Settings

The following automatic source (src) settings are made when auto mode is selected on the SYNC OUTPUT SETUP screen.

MODE

Standard

Continuous Arbitrary

Sequence

Gate/Trig All

Sweep All

Tone All

Ext. Phase Sequence Lock Master

WAVEFORM

Waveform

Sync

✔ ✔

Position

Marker

Burst

Done

Sequence

Sync

Trigger

Sweep

Trigger

✔

All other

Phase

Lock

✔

TTI tga1240 schematic

Specifications and Main Features

Frequently Asked Questions

User Manual

Table of Contents

Overview

Introduction

WAVEFORMS

Standard Waveforms

Sine, Cosine, Haversine, Havercosine

Specifications

Square

Triangle

Ramps and Sin(x)/x

Pulse and Pulse Train

Arbitrary

Sequence

Output Filter

Gated

Sweep

Tone Switching

Trigger Generator

OUTPUTS

Main Output - One for each channel

Sync Out - One for each channel

Cursor/Marker Out

Modulation In

Sum In

Hold

Ref Clock In/Out

INTER-CHANNEL OPERATION

Inter-channel Modulation:

Inter-channel Analog Summing:

Inter-channel Phase locking:

Inter-channel Triggering:

INTERFACES

GENERAL

Emissions

Immunity

Cautions

Safety

Mains Operating Voltage

Installation

2 and 4 Channel

Fuse

Mains Lead

Mounting

Front Panel Connections

MAIN OUT (1 per channel)

SYNC OUT (1 per channel)

Connections

TRIG IN

SUM IN

MODULATION IN

Rear Panel Connections

REF CLOCK IN/OUT

HOLD IN

CURSOR/MARKER OUT

RS232

Initial Operation

Switching On

General

Display Contrast

Keyboard

Principles of Editing

Principles of Operation

Clock Synthesis Mode

DDS Mode

Standard Waveform Operation

Setting Generator Parameters

Waveform Selection

Frequency

Amplitude

DC Offset

Warnings and Error Messages

SYNC Output

General

Principles of Sweep Operation

Sweep Operation

Connections for Sweep Operation. Sync Out and Trig In