TTI tga1240 schematic

THURLBY THANDAR INSTRUMENTS

TGA1240 SERIES

40MHz ARBITRARY WAVEFORM GENERATORS

INSTRUCTION MANUAL

Table of Contents

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

1

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

2

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.

3

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.

4

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

2.5mV to 10Vp−p into 50Ω

2.5mV to 10Vp−p into 50Ω

5

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

6

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.

7

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.

8

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

9

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

10

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.

11

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.

12

CHRIS WILDING
TECHNICAL DIRECTOR

1 May 2009

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.

13

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

2

14

l

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.

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.

15

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:−

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.

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.

16

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.

17

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.

18

Do not apply external voltages to this output.

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

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.

19

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.

20

• 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.

21

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

1

.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.

22

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

38

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.

23

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.

24

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.

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.

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 −.

25

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

26

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.

27

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

28

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

10

).

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

29