Fluke 281, 282, 284 User Manual

®

281, 282, 284

40 MS/s Arbitrary Waveform Generators

Users Manual

January 2005

© 2005 Fluke Corporation, All rights reserved. Printed in USA
All product names are trademarks of their respective companies.

LIMITED WARRANTY AND LIMITATION OF LIABILITY

Each Fluke product is warranted to be free from defects in material and workmanship under normal use and
service. The warranty period is one year and begins on the date of shipment. Parts, product repairs, and
services are warranted for 90 days. This warranty extends only to the original buyer or end-user customer of
a Fluke authorized reseller, and does not apply to fuses, disposable batteries, or to any product which, in
Fluke's opinion, has been misused, altered, neglected, contaminated, or damaged by accident or abnormal
conditions of operation or handling. Fluke warrants that software will operate substantially in accordance
with its functional specifications for 90 days and that it has been properly recorded on non-defective media.
Fluke does not warrant that software will be error free or operate without interruption.

Fluke authorized resellers shall extend this warranty on new and unused prod ucts to end-user customers
only but have no authority to extend a greater or different warranty on behalf of Fluke. Warranty support is
available only if product is purchased through a Fluke authorized sales outlet or Buyer has paid the
applicable international price. Fluke reserves the right to invoice Buyer for importation cost s of
repair/replacement parts when product purchased in one country is submitted for repair in another countr y.

Fluke's warranty obligation is limited, at Fluke's option, to refund of the purchase price, free of charge repair,
or replacement of a defective product which is returned to a Fluke authorized service center within the
warranty period.

To obtain warranty service, contact your nearest Fluke authorized service center to obtain return
authorization information, then send the product to that service center, with a description of the difficulty,
postage and insurance prepaid (FOB Destination). Fluke assumes no risk for damage in transit. Following
warranty repair, the product will be returned to Buyer, transportation prepaid (FOB Destination). If Fluke
determines that failure was caused by neglect, misuse, contamination, alteration, accident, or abnormal
condition of operation or handling, including overvoltage failures caused by use outsid e th e product’s
specified rating, or normal wear and tear of mechanical components, Fluke will provide an estimate of repair
costs and obtain authorization before commencing the work. Following repair, the product will be returned to
the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges
(FOB Shipping Point).

THIS WARRANTY IS BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. FLUKE SHALL NOT BE LIABLE
FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES OR LOSSES,
INCLUDING LOSS OF DATA, ARISING FROM ANY CAUSE OR THEORY.

Since some countries or states do not allow limitation of the term of an implied warranty, or exclusion or
limitation of incidental or consequential damages, the limitations and exclusions of this warranty may not
apply to every buyer. If any provision of this Warranty is held invalid or unenforceable by a court or other
decision-maker of competent jurisdiction, such holding will not affect the validity or enforceability of any other
provision.

Fluke Corporation
P.O. Box 9090
Everett, WA 98206-9090
U.S.A.

Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands

11/99
To register your product online, visit register.fluke.com

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 °C and -10 °C without degradation
of its safety. Do not operate the instrument 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

To avoid the possibility of electric shock:

• 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.

• 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.

• 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.

Caution

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.

i

Note

This instrument uses a Lithium button cell for non-volatile memory battery
back-up. Typical battery life is 5 years. In the event of replacement
becoming necessary, replace only with a cell of the correct type, a 3 V
Li/Mn0

20 mm button cell type 2032. Do not mix with solid waste stream.

2

Do not cut open, incinerate, expose to temperatures above 60 °C or attempt
to recharge. Used batteries should be disposed of by a qualified recycler or
hazardous materials handler. Contact your authorized Fluke Service
Center for recycling information.

Caution

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:

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.

Warning - hazardous voltages may be present.

ii

EMC Compliance

This instrument meets the requirements of the EMC Directive 89/336/EEC.
Compliance was demonstrated by meeting the test limits of the following standards:

Emissions

EN61326 (1998) 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:

Immunity

EN61326 (1998) EMC product standard for Electrical Equipment for Measurement,
Control and Laboratory Use. Test methods, limits and performance achieved were:

a) EN61000-4-2 (1995)

b) EN61000-4-3 (1997)

c) EN61000-4-11 (1994)

d) EN61000-4-4 (1995)

e) EN61000-4-5 (1995)

f) EN61000-4-6 (1996)

According to EN61326 the definitions of performance criteria are:

The instrument is Class A by product category.

EN61000-3-2 (2000) Class A

Electrostatic Discharge: 4 kV air, 4 kV contact

Electromagnetic Field: 3 V/m, 80 % AM at 1 kHz

Voltage Interrupt: 1 cycle, 100 %

Fast Transient: 1 kV peak (ac line), 0.5 kV peak (signal lines
and RS232/GPIB ports)

Surge: 0.5 kV (line to line), 1 kV (line to ground)

Conducted RF: 3 V, 80 % AM at 1kHz (AC line only; signal
connections <3 m not tested)

Performance A.

Performance A.

Performance A.

Performance A.

Performance A.

Performance A.

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.’

To ensure continued compliance with the EMC directive the
following precautions should be observed:

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

iii

Cautions

b) after opening the case for any reason ensure that all signal
and ground connections are remade correctly before replacing
the cover. Always ensure all case screws are correctly refitted
and tightened.

c) In the event of part replacement becoming necessary, only
use components of an identical type. Refer to the Service
Manual.

iv

Table of Contents

Chapter Title Page

1 Introduction and Specifications......................................................... 1-1

Introduction........................................................................................................ 1-2

Overview ....................................................................................................... 1-2

Features ......................................................................................................... 1-2

Specifications..................................................................................................... 1-4

Waveforms .................................................................................................... 1-4

Standard Waveforms................................................................................. 1-4

Sine, Cosine, Haversine, Havercosine ...................................................... 1-4

Square........................................................................................................ 1-4

Triangle..................................................................................................... 1-4

Ramps and Sin(x)/x................................................................................... 1-4

Pulse and Pulse Train................................................................................ 1-4

Arbitrary.................................................................................................... 1-5

Sequence ................................................................................................... 1-5

Output Filter.............................................................................................. 1-5

Operating Modes........................................................................................... 1-5

Triggered Burst ......................................................................................... 1-5

Gated......................................................................................................... 1-6

Sweep........................................................................................................ 1-6

Tone Switching ......................................................................................... 1-6

Trigger Generator...................................................................................... 1-7

Outputs .......................................................................................................... 1-7

Main Output.............................................................................................. 1-7

Sync Out.................................................................................................... 1-7

Cursor/Marker Out.................................................................................... 1-8

Inputs............................................................................................................. 1-8

Trig In ....................................................................................................... 1-8

Modulation In............................................................................................ 1-8

Sum In....................................................................................................... 1-8

Hold........................................................................................................... 1-8

Ref Clock In/Out....................................................................................... 1-8

Inter-channel Operation................................................................................. 1-9

Inter-channel Modulation.......................................................................... 1-9

Inter-channel Analog Summing................................................................ 1-9

Inter-channel Phase Locking..................................................................... 1-9

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Inter-channel Triggering ........................................................................... 1-10

Interfaces ....................................................................................................... 1-10

General .......................................................................................................... 1-10

2 Installation ........................................................................................... 2-1

Mains Operating Voltage................................................................................... 2-2

Fuse.................................................................................................................... 2-2

Mains Lead ........................................................................................................ 2-2

Mounting............................................................................................................ 2-2

3 Connections......................................................................................... 3-1

Introduction........................................................................................................ 3-2

Front Panel Connections.................................................................................... 3-2

MAIN OUT................................................................................................... 3-2

SYNC OUT................................................................................................... 3-2

TRIG IN ........................................................................................................ 3-3

SUM IN......................................................................................................... 3-3

MODULATION IN....................................................................................... 3-3

Rear Panel Connections..................................................................................... 3-3

REF CLOCK IN/OUT................................................................................... 3-3

HOLD IN....................................................................................................... 3-4

CURSOR/MARKER OUT............................................................................ 3-4

RS232............................................................................................................ 3-4

GPIB (IEEE-488) .......................................................................................... 3-5

4 Initial Operation................................................................................... 4-1

Introduction........................................................................................................ 4-2

Initial Operation................................................................................................. 4-2

Switching On................................................................................................. 4-2

Display Contrast............................................................................................ 4-2

Keyboard ....................................................................................................... 4-2

Principles of Editing...................................................................................... 4-3

Principles of Operation...................................................................................... 4-5

Clock Synthesis Mode................................................................................... 4-5

DDS Mode..................................................................................................... 4-6

5 Standard Waveform Operation........................................................... 5-1

Introduction........................................................................................................ 5-2

Standard Waveform Operation.......................................................................... 5-2

Setting Generator Parameters ............................................................................ 5-2

Waveform Selection...................................................................................... 5-2

Frequency...................................................................................................... 5-2

Amplitude...................................................................................................... 5-3

DC Offset ...................................................................................................... 5-4

Warning and Error Messages............................................................................. 5-5

SYNC Output..................................................................................................... 5-6

6 Sweep Operation................................................................................. 6-1

Introduction........................................................................................................ 6-2

Principles of Sweep Operation...................................................................... 6-2

Connections for Sweep Operation................................................................. 6-2

Setting Sweep Parameters.................................................................................. 6-3

vi

Contents (continued)

Sweep Range................................................................................................. 6-3

Sweep Time................................................................................................... 6-4

Sweep Type................................................................................................... 6-4

Manual Sweep............................................................................................... 6-5

Sweep Spacing............................................................................................... 6-6

Sweep Marker................................................................................................ 6-6

Sweep Hold ................................................................................................... 6-6

7 Triggered Burst and Gate................................................................... 7-1

Introduction........................................................................................................ 7-2

Internal Trigger Generator............................................................................. 7-2

External Trigger Input................................................................................... 7-3

Adjacent Channel Trigger Output ................................................................. 7-3

Triggered Burst.................................................................................................. 7-3

Trigger Source............................................................................................... 7-4

Trigger Edge.................................................................................................. 7-4

Burst Count.................................................................................................... 7-4

Start Phase..................................................................................................... 7-5

Manual Initialization of Inter-channel Triggering......................................... 7-5

Gated Mode........................................................................................................ 7-6

Gate Source ................................................................................................... 7-6

Gate Polarity.................................................................................................. 7-6

Start Phase..................................................................................................... 7-6

Sync Out in Triggered Burst and Gated Mode .................................................. 7-7

8 Tone Mode ........................................................................................... 8-1

Introduction........................................................................................................ 8-2

Tone Frequency ................................................................................................. 8-2

Tone Type.......................................................................................................... 8-2

Tone Switching Source...................................................................................... 8-3

DTMF Testing with a Multi-Channel Generator............................................... 8-4

9 Arbitrary Waveform Generation......................................................... 9-1

Introduction........................................................................................................ 9-2

Arb Waveform Terms........................................................................................ 9-2

Arb Waveform Creation and Modification – General Principles ...................... 9-2

Selecting and Outputting Arbitrary Waveforms................................................ 9-3

Creating New Waveforms.................................................................................. 9-4

Create Blank Waveform................................................................................ 9-4

Create Waveform Copy................................................................................. 9-5

Modifying Arbitrary Waveforms....................................................................... 9-6

Waveform Edit Cursor .................................................................................. 9-6

Resize Waveform .......................................................................................... 9-6

Rename Waveform........................................................................................ 9-7

Waveform Info .............................................................................................. 9-7

Delete Waveform........................................................................................... 9-8

Edit Waveform .............................................................................................. 9-8

Point Edit....................................................................................................... 9-9

Line Edit........................................................................................................ 9-9

Wave Insert.................................................................................................... 9-9

Block Copy.................................................................................................... 9-10

Waveform Amplitude.................................................................................... 9-11

Waveform Offset........................................................................................... 9-11

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Wave Invert................................................................................................... 9-12

Position Markers............................................................................................ 9-12

Arbitrary Waveform Sequence.......................................................................... 9-13

Sequence Set-up ............................................................................................ 9-14

Frequency and Amplitude Control with Arbitrary Waveforms......................... 9-15

Frequency...................................................................................................... 9-15

Amplitude...................................................................................................... 9-16

Sync Out Settings with Arbitrary Waveforms................................................... 9-16

Waveform Hold in Arbitrary Mode................................................................... 9-16

Output Filter Setting .......................................................................................... 9-17

10 Pulse and Pulse-trains........................................................................ 10-1

Introduction........................................................................................................ 10-2

Pulse Set-up ....................................................................................................... 10-2

Pulse-Train Set-up ............................................................................................. 10-4

Waveform Hold in Pulse and Pulse-Train Modes ............................................. 10-6

11 Modulation ........................................................................................... 11-1

Introduction........................................................................................................ 11-2

External Modulation.......................................................................................... 11-2

External VCA................................................................................................ 11-2

External SCM................................................................................................ 11-3

Internal Modulation ........................................................................................... 11-3

12 Sum....................................................................................................... 12-1

Introduction........................................................................................................ 12-2

External Sum...................................................................................................... 12-2

Internal Sum....................................................................................................... 12-3

13 Synchronization .................................................................................. 13-1

Introduction........................................................................................................ 13-2

Inter-Channel Synchronization.......................................................................... 13-2

Synchronizing Principles............................................................................... 13-2

Master-Slave Allocation................................................................................ 13-2

Phase-setting between Channels.................................................................... 13-3

Other Phase-Locking Considerations............................................................ 13-4

Synchronizing Two Generators ......................................................................... 13-5

Synchronizing Principles............................................................................... 13-5

Connections for Synchronization .................................................................. 13-5

Generator Set-ups.......................................................................................... 13-5

Synchronizing................................................................................................ 13-7

14 System Operations from the Utility Menu......................................... 14-1

Introduction........................................................................................................ 14-2

Storing and Recalling Set-ups............................................................................ 14-2

Channel Waveform Information........................................................................ 14-2

Warnings and Error messages............................................................................ 14-3

Remote Interface Set-up .................................................................................... 14-3

Reference Clock In/Out Setting......................................................................... 14-3

Cursor/Marker Output........................................................................................ 14-3

Power On Setting............................................................................................... 14-4

System Information............................................................................................ 14-4

viii

Contents (continued)

Calibration ......................................................................................................... 14-5

Copying Channel Set-ups .................................................................................. 14-5

15 Calibration............................................................................................ 15-1

Introduction........................................................................................................ 15-2

Equipment Required.......................................................................................... 15-2

Calibration Procedure ........................................................................................ 15-2

Setting the Password...................................................................................... 15-2

Password Access to Calibration .................................................................... 15-3

Changing the Password ................................................................................. 15-3

Calibration Routine............................................................................................ 15-3

Remote Calibration............................................................................................ 15-5

16 Remote Operation ............................................................................... 16-1

Introduction........................................................................................................ 16-2

Address and Baud Rate Selection...................................................................... 16-2

Remote/Local Operation.................................................................................... 16-2

RS232 Interface ................................................................................................. 16-3

RS232 Interface Connector ........................................................................... 16-3

Single Instrument RS232 Connections.......................................................... 16-3

Addressable RS232 Connections................................................................... 16-3

RS232 Character Set...................................................................................... 16-4

Addressable RS232 Interface Control Codes................................................ 16-4

Full List of Addressable RS232 Interface Control Codes......................... 16-6

GPIB Interface................................................................................................... 16-6

GPIB Subsets................................................................................................. 16-6

GPIB IEEE Std. 488.2 Error Handling.......................................................... 16-6

GPIB Parallel Poll ......................................................................................... 16-7

Status Reporting................................................................................................. 16-7

Standard Event Status and Standard Event Status Enable Registers............. 16-7

Status Byte Register and Service Request Enable Register........................... 16-8

Power on Settings .............................................................................................. 16-9

Remote Commands............................................................................................ 16-10

RS232 Remote Command Formats............................................................... 16-10

GPIB Remote Command Formats................................................................. 16-10

Command List............................................................................................... 16-11

Channel Selection.......................................................................................... 16-11

Frequency and Period.................................................................................... 16-12

Amplitude and DC Offset.............................................................................. 16-12

Waveform Selection...................................................................................... 16-12

Arbitrary Waveform Create and Delete......................................................... 16-13

Arbitrary Waveform Editing ......................................................................... 16-14

Waveform Sequence Control ........................................................................ 16-17

Mode Commands........................................................................................... 16-17

Input/Output control...................................................................................... 16-18

Modulation Commands ................................................................................. 16-19

Phase Locking Commands ............................................................................ 16-19

Status Commands.......................................................................................... 16-19

Miscellaneous Commands............................................................................. 16-21

Remote Command Summary............................................................................. 16-22

17 Maintenance......................................................................................... 17-1

Introduction........................................................................................................ 17-2

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Cleaning............................................................................................................. 17-2

Appendices

A Mains Operating Voltage ............................................................................ A-1

B Warning and Error Messages...................................................................... B-1

C SYNC OUT Automatic Settings ................................................................. C-1

D Factory System Defaults ............................................................................. D-1

E Waveform Manager Plus............................................................................. E-1

F Block Diagrams........................................................................................... F-1

G Front and Rear Panel Drawings................................................................... G-1

x

List of Tables

Table Title Page

3-1. RS232 Pin Functions.............................................................................................. 3-4

7-1. Phase Range and Resolution - Triggered Burst Mode........................................... 7-5

16-1. Remote Command Summary ................................................................................. 16-22

1-1. Approved Fuse Types ............................................................................................ 1-1

List of Figures

Figure Title Page

4-1. Single-Channel Simplified Block Diagram............................................................ 4-5

4-2. Clock Synthesis Mode............................................................................................ 4-6

4-3. Direct Digital Synthesis Mode............................................................................... 4-6

8-1. Tone Waveform Types........................................................................................... 8-3

16-1. Single Instrument RS232 Connections .................................................................. 16-3

16-2. RS232 Daisy-Chained Instruments ........................................................................ 16-3

16-3. RS232 Daisy-Chain Connector Wiring.................................................................. 16-4

16-4. Status Model........................................................................................................... 16-9

1-1. Mains Transformer Connections - Model 281....................................................... 1-2

1-2. Mains Transformer Connections - Models 282 and 284........................................ 1-2

6-1. Block Diagram: Single Channel............................................................................. 6-1

6-2. Inter-Channel Block Diagram................................................................................ 6-2

7-1. Front Panel - Model 281......................................................................................... 7-1

7-2. Front Panel - Model 282......................................................................................... 7-2

7-3. Front Panel - Model 284......................................................................................... 7-2

7-4. Rear Panel - Model 281.......................................................................................... 7-3

7-5. Rear Panel - Models 282 and 284.......................................................................... 7-3

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xii

Chapter 1

Introduction and Specifications

Introduction........................................................................................................ 1-2

Overview ....................................................................................................... 1-2

Features ......................................................................................................... 1-2

Specifications..................................................................................................... 1-4

Waveforms .................................................................................................... 1-4

Standard Waveforms................................................................................. 1-4

Sine, Cosine, Haversine, Havercosine ...................................................... 1-4

Square........................................................................................................ 1-4

Triangle ..................................................................................................... 1-4

Ramps and Sin(x)/x................................................................................... 1-4

Pulse and Pulse Train ................................................................................ 1-4

Arbitrary.................................................................................................... 1-5

Sequence ................................................................................................... 1-5

Output Filter.............................................................................................. 1-5

Operating Modes ........................................................................................... 1-5

Triggered Burst ......................................................................................... 1-5

Gated ......................................................................................................... 1-6

Sweep ........................................................................................................ 1-6

Tone Switching ......................................................................................... 1-6

Trigger Generator...................................................................................... 1-7

Outputs .......................................................................................................... 1-7

Main Output .............................................................................................. 1-7

Sync Out.................................................................................................... 1-7

Cursor/Marker Out .................................................................................... 1-8

Inputs ............................................................................................................. 1-8

Trig In ....................................................................................................... 1-8

Modulation In............................................................................................ 1-8

Sum In ....................................................................................................... 1-8

Hold........................................................................................................... 1-8

Ref Clock In/Out ....................................................................................... 1-8

Inter-channel Operation................................................................................. 1-9

Inter-channel Modulation.......................................................................... 1-9

Inter-channel Analog Summing ................................................................ 1-9

Inter-channel Phase Locking..................................................................... 1-9

Inter-channel Triggering ........................................................................... 1-10

Interfaces ....................................................................................................... 1-10

General .......................................................................................................... 1-10

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Introduction

Overview

This manual describes the features and operation of the Fluke models 281, 282 and 284
single-, two- and four-channel arbitrary waveform generators.

The physical differences between the two and four-channel generators are
straightforward: the two-channel instrument has no set-up keys or output connections for
channels three and four.

The single-channel instrument has essentially the same keys but they are arranged quite
differently to suit the half-rack case. There are drawings of all three models at the end of
this manual.

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, phase­locking, 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 two- and
four-channel instruments in the text; it is obvious when the description applies only to a
multi-channel instrument.

Features

These synthesized programmable arbitrary waveform generators have the following
features:

• 1, 2 or 4 independent 'arb' channels

• Sampling frequency up to 40 MHz

• Sine waves and square waves up to 16 MHz

• 12-bit vertical resolution

• 64K points horizontal resolution per channel

• 256K point non-volatile waveform memory

• Waveform linking, looping and sequencing

• Inter-channel triggering, summing, modulation and phase control

• GPIB and RS232 interfaces

A combination of direct digital synthesis and phase lock loop techniques provides high
performance and extensive facilities in compact instruments. These instruments can
generate a wide variety of waveforms between 0.1 mHz and 16 MHz with high resolution
and accuracy.

You can define arbitrary waveforms with 12 bit vertical resolution and from 4 to 65,536
horizontal points. In addition a number of standard waveforms are available including
sine, square, triangle, ramp and pulse.

1-2

You can replay arbitrary waveforms at a user specified waveform frequency or period, or
you can define the sample rate in terms of period or frequency.

The instruments provide extensive waveform editing features between defined start and
end points, including waveform insert, point edit, line draw, amplitude adjust and invert.

Introduction and Specifications

Introduction 1

The supplied Windows™-based arbitrary waveform creation software gives access to
more comprehensive features, allowing you 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, each with a user-specified length and name.
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 32,768.

All waveforms can be swept over their full frequency range at a rate variable between 30
milliseconds and 15 minutes. Sweeps can be linear or logarithmic, single or continuous.
Single sweeps can be triggered from the front panel, the trigger input, or from 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 driven 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 1,048,575.

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 (0.005 Hz to 100 kHz), from an external source (dc to
1 MHz) or by a key press or remote command.

Any number of channels can be phase locked with the phase angle under user control.
You can use this feature to generate multi-phase waveforms or locked waveforms of
different frequencies.

If you need more signals than one instrument provides you can use the signals from the

REF IN/OUT and SYNC OUT sockets to phase lock two instruments.

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

You can enter all parameters directly from the numeric keypad. Most parameters can
also 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 you can link up to 32 instruments to a single PC serial port.

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Specifications

Waveforms

Standard Waveforms

Sine, Cosine, Haversine, Havercosine

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

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

Range: 0·1 mHz to 16 MHz
Resolution: 0·1 mHz or 7 digits
Accuracy: 10 ppm for 1 year
Temperature stability: Typically <1 ppm/ºC.
Output level: 2.5 mV to 10 V p-p into 50 
Harmonic distortion: <0.1% THD to 100 kHz

<–65 dBc to 20 kHz
<–50 dBc to 300 kHz
<–35 dBc to 10 MHz
<–30 dBc to 16 MHz

Non-harmonic spurious: <–65 dBc to 1 MHz,

<–65 dBc + 6dB/octave 1 MHz to 16 MHz

Square

Range: 1 mHz to 16 MHz
Resolution: 1 mHz (4 digits)
Accuracy: ±1 digit of setting
Output level: 2.5 mV to 10 V p-p into 50 
Rise and fall times: <25 ns

Triangle

Range: 0.1 mHz to 100 kHz
Resolution: 0.1 mHz or 7 digits
Accuracy: 10 ppm for 1 year
Output level: 2.5 mV to 10 V p-p into 50 
Linearity error: <0.1 % to 30 kHz

Ramps and Sin(x)/x

Range: 0.1 mHz to 100 kHz
Resolution: 0.1 mHz (7 digits)
Accuracy: 10 ppm for 1 year
Output level: 2.5 mV to 10 V p-p into 50 
Linearity error: <0.1 % to 30 kHz

Pulse and Pulse Train

Output level: 2.5 mV to 10 V p-p into 50 
Rise and fall times: <25 ns
Period:
range:
resolution:
accuracy:

100 ns to 100 s
4-digit
±1 digit of setting

1-4

Introduction and Specifications

Specifications 1

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.

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

Vertical resolution: 12 bits
Sample clock range: 100 mHz to 40 MHz
Resolution: 4 digits
Accuracy: ± 1 digit of setting

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

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

points, minimum waveform size is 4 points

Sequence

Up to 16 waveforms may be linked.
Each waveform may 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 16 MHz elliptic, 10 MHz elliptic, 10 MHz Bessel, or none.

Operating Modes

Triggered Burst

Each active edge of the trigger signal produces one burst of the waveform.

Carrier waveforms: All standard and arbitrary
Maximum carrier
frequency:

Number of cycles: 1 to 1,048,575
Trigger repetition rate: 0.005 Hz to 100 kHz internal

Trigger signal source: Internal from keyboard, previous channel, next channel or

Trigger start/stop phase: ± 360 ° settable with 0.1 ° resolution, subject to waveform

The smaller of 1 MHz or the maximum for the selected
waveform.
40 M samples/s for arb and sequence.

DC to 1 MHz external.

trigger generator.
External from

TRIG IN or remote interface.

frequency and type.

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Gated

Sweep

Waveform runs while the gate signal is true and stops while false.

Carrier waveforms: All standard and arbitrary.
Maximum carrier
frequency:

The smaller of 1 MHz or the maximum for the selected
waveform.
40 M samples/s for arb and Sequence.

Trigger repetition rate: 0.005 Hz to 100 kHz internal

DC to 1 MHz external.

Gate signal source: Internal from keyboard, previous channel, next channel or

trigger generator.
External from

TRIG IN or remote interface.

Gate start/stop phase: ± 360 ° settable with 0.1 ° resolution, subject to waveform

frequency and type.

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

sequence.
Sweep mode: Linear or logarithmic, triggered or continuous.
Sweep direction: Up, down, up/down or down/up.
Sweep range: From 1 mHz to 16 MHz in one range.

Phase continuous.

Independent setting of start and stop frequency.
Sweep time: 30 ms to 999 s (3 digit resolution).
Marker: Variable during sweep.
Sweep trigger source: The sweep may be free run, triggered manually from the

keyboard, or triggered externally from the

TRIG IN input or

the remote interface.
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 sweep parameters will be the same for all channels.

Amplitude, offset and waveform can be set independently

for each channel.

1-6

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 1 mHz to 10 MHz.
Trigger repetition rate: 0.005 Hz to 100 kHz internal

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

DC to 1 MHz external.

Usable repetition rate and waveform frequency depend on

the tone switching mode.

trigger generator.

External from

TRIG IN or remote interface.

Introduction and Specifications

Specifications 1

Tone switching modes:
gated:

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.
triggered: The tone is output when the trigger signal goes true.

The next tone is output, at the end of the current waveform

cycle, when the trigger signal goes true again.
FSK: The tone is output when the trigger signal goes true.

The next tone is output, immediately, when the trigger

signal goes true again.
You can generate DTMF test signals by summing the outputs of two channels.

Trigger Generator

Internal source 0.005 Hz to 100 kHz square wave, adjustable in 10 µs steps. 3 digit
resolution. Available for external use from any

SYNC OUT socket.

Outputs

Main Output - one for each channel

Output impedance: 50 
Amplitude: 5 mV to 20 V p-p open circuit

(2.5 mV to 10 V p-p into 50 ).
Amplitude can be specified open circuit (hi Z) or into an

assumed load of 50  or 600  in V p-p, V rms or dBm.
Amplitude accuracy: 2 % ±1 mV at 1 kHz into 50 .
Amplitude flatness: ±0.2 dB to 200 kHz;

±1 dB to 10 MHz;

±2.5 dB to 16 MHz.
DC offset range: ±10 V

(DC offset plus signal peak limited to ±10 V from 50 )
DC offset accuracy: Typically 3% ±10 mV, unattenuated.
Resolution: 3 digits for both amplitude and dc offset.

Sync Out - one for each channel

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

Waveform sync:
(all waveforms)

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.
Position markers:
(arbitrary only)

Any point(s) on the waveform may have associated marker

bit(s) set high or low.
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 gated signals.
Sweep sync: Outputs a pulse at the start of a sweep to synchronize an

oscilloscope or recorder.
Phase lock out: Used to phase lock two generators. Produces a positive edge

at the 0 ° phase point.

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Cursor/Marker Out

Inputs

Trig In

Output signal level: TTL/CMOS logic levels from typically 50 

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 oscilloscope channel.

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

adjustable width as a cursor.
Output Impedance: 600  typical

Frequency range: DC to 1 MHz.
Signal range: Threshold nominally TTL level; max input ±10 V
Minimum pulse width: 50 ns, for trigger and gate modes;

50 µs for sweep mode.
Polarity: Selectable as high/rising edge or low/falling edge.
Input impedance: 10 k

Modulation In

Frequency range: DC to 100 kHz.
Signal range: VCA: Approximately 1 V p-p for 100 % level change at

Input impedance: Typically 1 k

Sum In

Frequency range: DC to 8 MHz
Signal range: Approximately 2 V p-p input for 20 V p-p output.
Input impedance: Typically 1 k

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
key or a remote command may also be used to control the hold function. While held the
front panel
the start. The

Input impedance: 10 k

Ref Clock In/Out

Set to input: Input for an external 10MHz reference clock.

Set to output: Buffered version of the internal 10 MHz clock.

Set to phase lock:

maximum output.

SCM: Approximately ± 1 V pk for maximum output.

MAN HOLD

MAN TRIG key or remote command may be used to return the waveform to

HOLD input may be enabled independently for each channel.

TTL/CMOS threshold level.

Output levels nominally 1 V and 4 V from 50 

Used together with

SYNC OUT on a master and TRIG IN

on a slave to synchronize (phase lock) two separate

generators.

1-8

Introduction and Specifications

Specifications 1

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:

Double sideband with carrier.

Double sideband suppressed carrier.
Modulation source: Internal from the previous channel.

External from the modulation input socket.

The external modulation signal may be applied to any

number of channels simultaneously.
Frequency range: DC to >100 kHz.
Internal AM:
depth:
resolution:
carrier suppression:
External modulation
signal range:

0 % to 105 %

1 %

SCM: better than -40 dB.

VCA: Approximately 1 V p-p for 100 % level change at

maximum output.

SCM: Approximately ± 1 V pk 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
socket.

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

Frequency range: DC to >8 MHz.
External signal range: Approximately 5 V p-p input for 20 V p-p 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. This
allows easy generation of multi-phase waveforms at the same frequency.

DDS waveforms are those with seven digits of frequency setting resolution, while non­DDS waveforms have four digits

Phase resolution:
DDS waveforms:
non-DDS waveforms:

Phase error:
all waveforms:

External from

SUM IN socket.

0.1 °

0.1 ° or 360 ° divided by the number of points,
whichever is the greater

<±10 ns

SUM IN

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Inter-channel Triggering

Interfaces

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.

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.

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

General

RS232 Variable Baud rate, 9600 Baud maximum.

9-pin D-connector.
IEEE-488 Conforms with IEEE488.1 and IEEE488.2

Display: 20 character x 4 row alphanumeric LCD.
Data Entry: Keyboard selection of mode, waveform etc.

Value entry direct by numeric keys or by rotary control.
Stored Settings: 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.
Operating Range: +5 °C to +40 °C, 20-80 % RH
Storage Range: -20 °C to +60 °C.
Environmental: Indoor use at altitudes up to 2000 m,

Pollution Degree 2.
Options: 19 inch rack mounting kit.
Safety: Complies with EN61010-1.
EMC: Complies with EN61326.
Power: 100 V, 110 V-120 V or 220 V-240 V AC ±10 %, 50/60 Hz,

adjustable internally; Installation category II

Size: height 3U (130 mm)

Model 281
40 VA maximum

width 212 mm
depth 335mm

Model 282
75 VA maximum
height 3U (130 mm)
width 350 mm
depth 335 mm

Model 284
100 VA maximum
height 3U (130 mm)
width 350 mm
depth 335 mm

Weight: 4.1kg (9lb) 7.2 kg (16 lb) 7.2 kg (16 lb)

1-10

Chapter 2

Installation

Mains Operating Voltage................................................................................... 2-2

Fuse.................................................................................................................... 2-2

Mains Lead ........................................................................................................ 2-2

Mounting............................................................................................................ 2-2

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Mains Operating Voltage

Fuse

Mains Lead

Check that the instrument operating voltage marked on the rear panel is correct for the
local supply. If it is necessary to change the operating voltage, follow the procedure
described in appendix A.

Ensure that the correct mains fuse is fitted for the set operating voltage. The correct
mains fuse types are listed in Appendix A.

Warning

To avoid the possibility of electric shock, 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 a three core mains lead with bare ends is provided it should be connected as
follows:-

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.

Brown Mains Live
Blue Mains Neutral
Green / Yellow Mains Earth

2-2

Chapter 3

Connections

Introduction........................................................................................................ 3-2

Front Panel Connections.................................................................................... 3-2

MAIN OUT ................................................................................................... 3-2

SYNC OUT ................................................................................................... 3-2

TRIG IN ........................................................................................................ 3-3

SUM IN ......................................................................................................... 3-3

MODULATION IN....................................................................................... 3-3

Rear Panel Connections ..................................................................................... 3-3

REF CLOCK IN/OUT................................................................................... 3-3

HOLD IN....................................................................................................... 3-4

CURSOR/MARKER OUT............................................................................ 3-4

RS232 ............................................................................................................ 3-4

GPIB (IEEE-488) .......................................................................................... 3-5

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Introduction

Front Panel Connections

MAIN OUT (1 per channel)

SYNC OUT (1 per channel)

This chapter describes the front- and rear-panel connections and their functions.

MAIN OUT is the 50 Ω output from the channel’s main generator. It provides up to 20 V

p-p into an open circuit or 10 V p-p into a matched 50 Ω load. It can tolerate a short
circuit for 60 seconds.

Caution

To avoid risk of damage to the instrument, do not apply
external voltages to these outputs.

SYNC OUT provides a TTL/CMOS level output which may be set to any of the

following signals from the

SYNC OUT screen.

waveform sync A sync marker phase-coincident with the MAIN OUT

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

position marker When pos’n marker is selected, the instrument generates

a pulse marker pattern for arbitrary waveforms. The pulse
pattern is programmable from the
on the

When the MAIN OUT waveform is a standard waveform

pos'n marker automatically changes to phase zero
which is a narrow (1 clock) pulse output at the start of each
standard waveform cycle.

Burst done Provides a signal during gate or trigger modes which is low

while the waveform is active at the main output, high at all
other times.

Sequence sync Provides a signal which is low during the last cycle of the last

waveform in a sequence, high at all other times.

Trigger Provides a positive going version of the trigger signal.

Internal, external, manual and remote all produce a trigger
sync.

MODIFY screen.

edit waveform menu

3-2

Sweep sync Goes high at the start of the sweep, goes low at the end of the

sweep.

Phase lock Produces a positive edge coincident with the start of the

current waveform. This is used for phase locking instruments.

Connections

Rear Panel Connections 3

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

Caution

To avoid risk of damage to the instrument, do not apply
external voltages to this output.

TRIG IN

TRIG IN is the external input for trigger, gate, sweep and sequence operations. It is also

the input used to synchronize the generator as a slave to another generator which is the
master.

Caution

To avoid risk of damage to the instrument, do not apply
external voltages exceeding ±10 V to this input.

SUM IN

SUM IN 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.

To avoid risk of damage to the instrument, do not apply
external voltages exceeding ±10 V to this input.

MODULATION IN

MODULATION IN is the input socket for external modulation. Any number of channels

may be amplitude or suppressed-carrier modulated with this signal; the target channels
are selected on the

To avoid risk of damage to the instrument, do not apply
external voltages exceeding ±10 V to this input.

MODULATION screen.

Rear Panel Connections

REF CLOCK IN/OUT

The function of the REF CLOCK IN/OUT socket is set from the ref clock i/o

menu on the
Menu".

input This is the default setting. The socket becomes an input for an

UTILITY screen, as described under "System Operations from the Utility

external 10 MHz reference clock. The system automatically switches
over from the internal clock when the external reference is applied.

Caution

Caution

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

phase lock When two or more generators are synchronized the slaves are set to

phase lock slave and the master is set to phase lock
master

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HOLD IN

CURSOR/MARKER OUT

As an output the logic levels are nominally 1 V and 4 V from typically 50 Ω.

REF CLOCK IN/OUT will withstand a short-circuit.

As an input the threshold is TTL/CMOS compatible.

Caution

To avoid risk of damage to the instrument, do not apply
external voltages exceeding ±10 V to this socket.

HOLD IN controls the waveform hold function. The input impedance is nominally

10 kΩ.

Caution

To avoid risk of damage to the instrument, do not apply
external voltages exceeding ±10 V to this input.

The CURSOR/MARKER OUT socket provides an output pulse for use as a marker in

sweep mode or as a cursor in arbitrary waveform editing mode. It can be used to
modulate the Z-axis of an oscilloscope or can be displayed on a second oscilloscope
channel. The output impedance is nominally 600 Ω and the signal level is adjustable from
2 to14 V (nominal) from the

cursor/marker menu on the UTILITY screen, as

described in chapter 14, System Operations from the Utility Menu.

RS232

Caution

To avoid risk of damage to the instrument, do not apply
external voltages to this output.

The

RS232 interface is on a 9-pin D-connector and is compatible with addressable

RS232 use. The pin connections are shown below:

Table 3-1. RS232 Pin Functions

Pin number Signal 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
8 TXD2 Secondary transmitted data

3-4

9 GND Signal ground

Connections

Rear Panel Connections 3

Pin 2, 3 and 5 may be used as a conventional RS232 interface with XON/XOFF
handshaking. Pins 7, 8 and 9 are used when the instrument is operated in addressable
RS232 mode. Signal grounds are connected to the instrument ground. The RS232 address
is set from the

remote menu on the UTILITY screen, as described in chapter 14,

System Operations from the Utility Menu.

GPIB (IEEE-488)

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, as described

chapter 14, System Operations from the Utility Menu.

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3-6

Chapter 4

Initial Operation

Introduction........................................................................................................ 4-2

Initial Operation................................................................................................. 4-2

Switching On................................................................................................. 4-2

Display Contrast............................................................................................ 4-2

Keyboard ....................................................................................................... 4-2

Principles of Editing...................................................................................... 4-3

Principles of Operation...................................................................................... 4-5

Clock Synthesis Mode................................................................................... 4-5

DDS Mode..................................................................................................... 4-6

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Introduction

This section is a general introduction to the organization and principles 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 chapter 5, Standard Waveform Operation.

In this Users Manual front panel keys and sockets are shown in capitals, e.g.
SYNC OUT; all soft-key labels, entry fields and messages displayed on the LCD are
shown in the Courier type-font, e.g.

Initial Operation

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

CHECK BATTERY

and Error Messages.
Loading takes a few seconds, after which the status screen is displayed, showing the

generator parameters set to their default values, with the
The power-up settings may be preset to those at power-down or to any of the stored

settings; chapter 14, System Operations from the Utility Menu explains how to do this.
You can recall the status screen at any time with the

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. You can change the basic
generator parameters for the selected channel as described in chapter 5, and you can
switch the output on with the
output is on.

CREATE,

STANDARD WAVEFORMS, sine.

SYSTEM RAM ERROR,

will be displayed. If this happens, refer to appendix B, Warnings

MAIN OUT outputs set to off.

STATUS key; a second press

MAIN OUT key; the ON lamp will light to show that

4-2

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 optimized for a particular environment by using the front panel
contrast control. Insert a small screwdriver or trimmer tool through the adjustment
aperture marked

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. Numeric values
are changed using either the numeric keys or the rotary control, as described later in this
chapter under Principles of Editing.

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.

LCD and rotate the control for optimum contrast.

Initial Operation

Initial Operation 4

• 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 (
exponential (

2 EXP 1).

20), floating point (20·0) and

For example, to set a new frequency of 50 kHz, press

ENTER

or 5 EXP 4 ENTER.

FREQ followed by 50000

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.

•

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 synchronizing two or more generators when suitably connected together.

HOLD

held at the level it was at when

is used to manually pause arbitrary waveform output and sweep; the output is

MAN HOLD was pressed.

MAN

• 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 controlled.

• 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 generator's 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.

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Note

On multi-channel instruments 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 (
press

MODE to get the screen shown below:

) denote selected items. For example,

)

MODE:

continuous
gated setup…
triggered setup…

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 hollow. This
screen also 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
illustrated, pressing the

SETUP

menu; note that selecting this item does not change the continuous /

gated / triggered

Some screen items are marked with a double-headed arrow (

setup… soft-key on the bottom line brings up the TRIGGER

selection.

) when selected to indicate

MODE screen

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
settings of

type soft-key (or cursor keys or use of the rotary control) will step the selection

the

auto and manual. Similarly, when type is selected, repeated presses of

mode soft-key will toggle the mode between its two possible

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 the 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

UTILITY

screens.

STD (standard waveform) and

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.

4-4

Initial Operation

Principles of Operation 4

Thus for STANDARD FREQUENCY set to 1.000000 MHz rotating the control will
change the frequency in 1 kHz 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 1 kHz to
the 1 kHz increment would be lost. If, however, the starting frequency had been set to

1.0000

to

900.0000 Hz and could then be decremented further to 000.0000 Hz without

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

00 MHz, i.e. a 100 Hz increment, the display would have autoranged at 1 kHz

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. Direct digital synthesis (DDS) mode is used for sine, cosine, haversine, triangle,
sin(x)/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

Figure 4-1. Single-Channel Simplified Block Diagram

The main differences between DDS and clock synthesis modes are the way in which the
addresses are generated for the RAM and the length of the waveform data.

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 40 MHz to 0·1 Hz. The frequency of the
waveform is the clock frequency divided by the waveform length, thus allowing short
waveforms to be played out at higher repetition rates than long waveforms.

For example the maximum frequency of a 4 point waveform is 40,000,000÷4 or 10 MHz,
but a 1000 point waveform has a maximum frequency of 40,000,000÷1000 or 40 kHz.

Arbitrary waveforms have a user defined length of 4 to 65,536 points. Square waves use
a fixed length of 2 points and pulse and pulse train have their length defined by the user
selected period value.

MAIN OUT connector.

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DDS Mode

In DDS mode 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 (360 º)
of the waveform; each sequential address change corresponds to a phase increment of the
waveform of 360/4096 degrees. Instead of using a counter to generate sequential RAM
addresses, a phase accumulator is used to increment the phase.

Figure 4-2. Clock Synthesis Mode

Figure 4-3. Direct Digital Synthesis Mode

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4-6

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 being 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

(approximately 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 equal to the clock frequency divided by 4096, approximately
6·7 kHz, 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.

Chapter 5

Standard Waveform Operation

Introduction........................................................................................................ 5-2

Standard Waveform Operation .......................................................................... 5-2

Setting Generator Parameters ............................................................................ 5-2

Waveform Selection ...................................................................................... 5-2

Frequency ...................................................................................................... 5-2

Amplitude...................................................................................................... 5-3

DC Offset ...................................................................................................... 5-4

Warning and Error Messages............................................................................. 5-5

SYNC Output..................................................................................................... 5-6

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Introduction

Standard Waveform Operation

This section deals with the use of the instrument as a standard function generator, i.e.
generating sine, square, triangle, dc, ramp, haversine, cosine, havercosine and sin(x)/x
waveforms. All but the square wave are generated by DDS which gives 7-digit frequency
precision; the square wave is generated by clock synthesis which results in only 4-digit

frequency resolution. Refer to Principles of Operation in the previous chapter for an

explanation of the differences.

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
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 this manual.

Most 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 the appropriaite sections.

ARB and SEQUENCE respectively) and are

Setting Generator Parameters

Waveform Selection

Pressing the STD key gives the STANDARD WAVEFORMS screen which lists all the

waveforms available:

STANDARD WAVEFORMS

sine
square
triangle

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 soft­key beside the required waveform.

Frequency

Pressing the FREQ key gives the STANDARD FREQUENCY screen:

STANDARD FREQUENCY

10.00

freq period

000 kHz

5-2

With

freq selected as shown above, the frequency can be entered directly from the

keyboard in integer, floating point or exponential format. For example, 12·34 kHz can be
entered as

12340, 12340·00, or 1·234 exp 4, etc. However, the display will

Standard Waveform Operation

Setting Generator Parameters 5

always show the entry in the most appropriate engineering units, in this case

12·34000 kHz

With

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

for example 123·4µs can be entered as

.

·0001234 or 123·4 exp -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 is always zero. The hardware is programmed in terms of frequency, so that
when you make a period entry the synthesized 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.

Square waves, generated by clock synthesis, provides 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

The waveform amplitude can be set in terms of peak-to-peak volts (
(

Vrms) or dBm (referenced to a 50 Ω or 600 Ω load). For Vpp and Vrms the level can be

set assuming that the output is open-circuit (

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 50 Ω; the displayed amplitude values for 600 Ω
termination take this into account.

AMPL key gives the AMPLITUDE screen:

AMPLITUDE:
+2

0.0 Vpp

Vpp Vrms
dBm load:hiZ

load:hiZ) or terminated (load:50Ω or

Vpp), rms volts

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. For example 250 mV can be entered as

·250 exp -3 or 250, etc.

The display will always show the entry in the most appropriate engineering units, in this
case

250 mV.

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.

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DC Offset

Alternate presses of the ± key will invert the signal at the MAIN OUT socket; if the
DC OFFSET is non-zero the signal is inverted about the same offset. The exception to

this occurs when the amplitude is specified in dBm. Since low level signals are specified
in dBm (0 dBm = 1 mW into 50 Ω = 0.224 mV rms) the

- sign is interpreted as part of a

new amplitude entry and not as a command to invert the signal.

Note that for dc, sin(x)/x, pulse train, arbitrary and sequence, the 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.

Pressing the OFFSET key gives the DC OFFSET screen:

DC OFFSET:

program +0.00 mVdc
(actual +0.00 mVdc)

load:hiZ

The offset can be entered directly from the keyboard in integer, floating point or
exponential format, for example 100 mV can be entered as

·1 or 100 exp -3, etc. 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 invert the offset;

alternate presses toggle the sign between

+ and -.

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. Because the 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 = +205· mVdc

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

program = +205· mVdc
program = +105· mVdc
program = +5·00 mVdc
program = -95·0 mVdc
program = -195· mVdc

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.

5-4

For example, if the amplitude is set to 2·5 V p-p 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:

Standard Waveform Operation

Warning and Error Messages 5

DC OFFSET:

program +1.50 Vdc
(actual +1.50 Vdc)

load:hiZ

If the amplitude is now reduced to, say, 250 mV pp, this introduces the attenuator and 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.

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 250 mV p-p exactly
and takes account of the small error in the fixed attenuator; the offset is 151
mV (to three significant figures) and takes account of the effect of the
calibrated attenuation error on the set offset of 1.50 V.

Whenever the set dc offset is modified by a subsequent change in output level the display
shows a warning message. Similarly, settings which would result in peak offset+signal
levels outside the range ±10 V (and therefore clipping) generate a similar warning

message. There is additional information on these messages in the Warnings and Error
Messages section below.

The output attenuation is controlled intelligently to minimize 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 150 mV, for example, the amplitude can
be reduced to nominally 50 mV pp before the fixed attenuator causes the actual offset to
be different from the programmed value.

Warning 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, as in the following two examples:

Note

1. Changing the amplitude from, for example, 2·5 V p-p to 25 mV p-p brings in the step
attenuator; if a non-zero offset has been set then this will also be attenuated. The message
DC OFFSET CHANGED BY AMPLITUDE will be shown temporarily on the 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 10 V p-p, increasing the dc offset beyond ± 5 V will
cause the message OFFSET + SUM + LEVEL MAY CAUSE CLIPPING. The
offset change will be accepted (producing a clipped waveform) and the user may then

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choose to change the output level or the offset to produce a signal which is not clipped.
The word (clip?) will show in the display beside AMPLITUDE or DC OFFSET
while the clipped 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, as in the following three examples:

1. Entering a frequency of 1 MHz for a triangle waveform. The error message:
Frequency out of range for the selected waveform is shown.

2. Entering an amplitude of 25 V pp. The error message:
Maximum output level exceeded is shown.

3. Entering a DC offset of 20 V. The error message:
Maximum DC offset exceeded is shown.

The messages remain 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

Each message has a number and the full list appears in appendix B.

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… menu on the

UTILITY

screen.

screen. The error menu is shown below:

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

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

position marker: Can be selected for arbitrary waveforms only. Any point(s)

error beep: ON
error message: ON
warn beep: ON
warn message: ON

UTILITY screen to restore last setup.

frequency, or a pulse coincident with the first few points of
an arbitrary waveform. Can be selected for all waveforms.

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

MAIN OUT waveform is a

5-6

Standard Waveform Operation

SYNC Output 5

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 synchronizing
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 0 º phase point.

The setting up of the signals themselves is discussed in the relevant sections later in this

manual, e.g. trigger is covered in chapter 7, Triggered Burst and Gate and position
markers in chapter 9, Arbitrary Waveform Generation.

Pressing the

SYNC OUT key calls the SYNC OUT set-up 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 soft-key. In automatic mode
the

SYNC OUT waveform most appropriate for the current main waveform is selected.

For example, waveform sync is automatically selected for all continuous standard
and 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 C.

The automatic selection can still be changed manually by the src soft-key even when
auto 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. You must select manual with 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, for example waveform sync for all continuous main
waveforms, but you will need to use manual for any special requirements, such as
position markers on arbitrary waveforms.

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5-8

Chapter 6

Sweep Operation

Introduction........................................................................................................ 6-2

Principles of Sweep Operation...................................................................... 6-2

Connections for Sweep Operation................................................................. 6-2

Setting Sweep Parameters.................................................................................. 6-3

Sweep Range................................................................................................. 6-3

Sweep Time................................................................................................... 6-4

Sweep Type................................................................................................... 6-4

Manual Sweep............................................................................................... 6-5

Sweep Spacing............................................................................................... 6-6

Sweep Marker................................................................................................ 6-6

Sweep Hold ................................................................................................... 6-6

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Introduction

Principles of Sweep Operation

All standard and arbitrary waveforms can be swept with the exception of pulse, pulse­train 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

10

:1). However it must be remembered that the frequency is actually
stepped, not swept linearly, 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
compressed in software to 4096 points when sweep is turned on. The expansion or
compression leaves the original data unaffected.

Sweep mode is turned on and off by the
screen (accessed by pressing the

MODE screen. In multi-channel instruments two or more channels can be swept

on the
at once but one set of sweep parameters applies to all the swept channels.

When sweep is switched on the software creates a table of 2048 frequencies between, and
including, the specified start and stop values. For sweep times of 1·03 s and above the
sweep will step through all 2048 frequency values. Below 1·03 s, however, the frequency
sweep will contain fewer steps because of the minimum 0·5 ms dwell at each step; at the
shortest sweep time (30 ms) 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 frequencies. The frequency
resolution of the steps will be at its most coarse with wide sweeps at the fastest sweep
rate.

Connections for Sweep Operation

Sweeps are generally used with an oscilloscope or hard-copy device to investigate the
frequency response of a device. The
device 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 socket. This defaults to sweep sync when sweep is turned

on, going high at the start of sweep and low at the end of the sweep. The low period is
sufficiently long to allow an oscilloscope to retrace.

on or off soft-key on the SWEEP SETUP

SWEEP front panel key), or by the sweep soft-key

MAIN OUT is connected to the device input and the

6-2

To show a marker on the display instrument the rear panel

CURSOR/MARKER OUT

socket should be connected to a second channel. It can also be used in the case of an
oscilloscope to modulate the Z-axis. See the Sweep Marker section below for information
on setting the marker frequency. The cursor/marker polarity and level is set up on the

cursor/marker…

menu of the UTILITY screen, as described in chapter 14,

System Operations from the Utility Menu.
For triggered sweeps you must provide a trigger signal, either electrically at the front

panel

TRIG IN socket, by a remote command or by manually pressing the MAN TRIG

key. The TRIG IN function automatically defaults to external when you select triggered
sweep. A sweep is initiated on the rising edge of the trigger signal.

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

Sweep Operation

Setting Sweep Parameters 6

Setting Sweep Parameters

Pressing the SWEEP key (or the sweep setup… soft-key on the MODE screen)
displays the

Menus for setting up the range, time (sweep rate), type (continuous, triggered, etc.)
spacing (linear or logarithmic) 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

Sweep can also be turned on by the sweep soft-key on the MODE screen. In multi­channel instruments two or more channels can be swept at once using the same sweep
parameters. The channels to be swept are set on or off by selecting them in turn with the
appropriate
screen.

SWEEP SETUP screen:

SWEEP SETUP: off

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

on/off soft-key.

SETUP key and then using the on/off soft-key of the SWEEP SETUP

On all the following menus, pressing the

SWEEP SETUP

Sweep Range

Pressing the range… soft-key calls the SWEEP RANGE screen:

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

You can define the sweep range in terms either of the start and stop frequencies or of the
centre frequency and span.
the sweep to be set directly from the keyboard or by using the rotary control; the start
frequency must be lower than the stop frequency (but see Sweep Type below for selecting
the sweep direction).

Pressing the
center frequency and sweep span about that frequency; pressing the
soft-key on that screen returns the display to the start and stop frequency form of entry.

done soft-key returns the display to this

screen.

SWEEP RANGE:

start: 100.0 kHz
stop: 10.00 MHz
centr/span done

start and stop soft-keys permit the two end points of

centr/span soft-key changes the screen to permit entry in terms of

start/stop

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, as
described in the section above, Principles of Sweep Operation.

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Sweep Time

Sweep Type

Pressing the time… soft-key calls the SWEEP TIME screen:

SWEEP TIME:

0.05

sec
(steps=100)
done

The sweep time can be set from 0·03 to 999 s with 3-digit resolution by direct keyboard
entry or by using the rotary control. As explained above, sweeps lasting less than 1·03
seconds will contain less than the maximum 2048 steps because of the minimum 0·5 ms
dwell at each step. For this reason the number of steps in the sweep is displayed as a non­editable field below the sweep time.

Pressing the type soft-key calls the

SWEEP TYPE screen:

SWEEP TYPE:

continuous

direction: up
sync: on done

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:

up start frequency to stop frequency.
down stop frequency to start frequency.
up/down start frequency to stop frequency and back to start frequency.

down/up

stop frequency to start frequency and back to stop frequency.

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
descriptions which follow the direction is assumed to be

up/down and down/up operation. In the sweep mode

up but all modes can be used

with all sweep directions.
In

continuous mode the generator sweeps continuously between the start and stop
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 (nominally long enough for an oscilloscope to retrace), and
begins a new sweep.

6-4

If

sync is set to on (the default) the generator steps from the stop frequency to zero
frequency and then starts the next sweep from the first point of the waveform,
synchronized to the internally generated trigger signal.

Sweep Operation

Setting Sweep Parameters 6

This is useful because it forces the sweep always to start from the same point in the
waveform. You should be aware that in this case the waveform discontinuity may be
undesirable in some circumstances, for example in filter evaluation.

With

sync is set to off the frequency steps directly and phase continuity is
maintained from the stop frequency to the start frequency. Note, however, that the sweep
is not synchronized to the software-generated trigger signal.

In

triggered mode the generator holds the output at the start frequency until it
recognizes a trigger, at which the frequency sweeps to the stop frequency, resets, and
awaits the next trigger. If

sync is set to on the frequency resets to zero frequency
(i.e. no waveform) and starts a new sweep at the first point of the waveform when the
next trigger is recognized. If

sync is set to off the waveform resets to the start

frequency and continues at that frequency until the next trigger initiates a new sweep.
In

trig’d, hold/reset mode the generator holds the output at the start frequency
until it recognizes a trigger; at which point 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
operates exactly as described above; if

sync is set to on the frequency goes to zero at

sync is set to off the output

the start and begins each new sweep at the first point of the waveform.
For both

automatically set to external. The trigger source can be the rising edge of an external
signal applied to
command.

In

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

Manual Sweep

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

Before manual control can be used, you must select
screen. 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

frequency table is stepped through if
then the frequency changes in multiple step increments. You can not select
when the number of steps in the table is small.

triggered and trig’d, hold/reset modes the TRIG IN input is

TRIG IN, a press of the MAN TRIG key on the front panel, or a remote

screen:

MANUAL SWEEP FREQ:

1.630 MHz

step fast wrap
step slow done

manual on the SWEEP TYPE

screen, by using the rotary control or cursor keys. Every point of the

step slow is selected; if step fast is set

step fast

If

wrap is set the sweep wraps-round from start frequency to

stop frequency
start

or stop frequency depending on the direction of the rotary control or cursor

and vice-versa; if no wrap is set the sweep finishes at either the

keys.

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Sweep Spacing

Sweep Marker

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

screen:

SWEEP SPACING:

logarithmic
linear

done

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.

Pressing the marker… soft-key on the SWEEP SETUP screen calls the

SWEEP MARKER FREQ

screen:

SWEEP MARKER FREQ:
program: 5.0

00 MHz

actual: 4.977 MHz

done

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 100 kHz to 10 MHz in 50 ms (which is
completed in 400 steps), the actual frequency of a 5 MHz marker is 4·977 MHz.

The marker duration is for the number of 0·5 ms intervals that the frequency remains at
the marker value; for fast and/or wide sweeps this will often be the 0·5 ms minimum but
for slow and/or narrow spans the marker may last many 0·5 ms 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. For full details

refer chapter 14, System Operations from the Utility Menu.
You can change the marker frequency can be changed while the sweep is 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. You can achieve the same result more quickly by
switching the sweep off, changing the marker, then switching the sweep back on.

6-6

Sweep Hold

The sweep can be held or restarted at any time at or from its current frequency by
alternate presses of the
sweep controls, pressing
sweep has been set on.

MAN HOLD key or by a remote command. As with all other

MAN HOLD will halt the sweep on all channels for which

Chapter 7

Triggered Burst and Gate

Introduction........................................................................................................ 7-2

Internal Trigger Generator............................................................................. 7-2

External Trigger Input................................................................................... 7-3

Adjacent Channel Trigger Output ................................................................. 7-3

Triggered Burst.................................................................................................. 7-3

Trigger Source............................................................................................... 7-4

Trigger Edge.................................................................................................. 7-4

Burst Count.................................................................................................... 7-4

Start Phase..................................................................................................... 7-5

Manual Initialization of Inter-channel Triggering......................................... 7-5

Gated Mode........................................................................................................ 7-6

Gate Source ................................................................................................... 7-6

Gate Polarity.................................................................................................. 7-6

Start Phase..................................................................................................... 7-6

Sync Out in Triggered Burst and Gated Mode .................................................. 7-7

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Introduction

Triggered burst and gated modes are selected from the MODE screen, called by the
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 internally-generated trigger out signal from an adjacent channel
on a multi-channel instrument, by the front panel

key, as alternatives to the default continuous mode.

MODE:

continuous
gated setup…
triggered setup…

MAN TRIG key or by remote control.

Gated mode can be controlled by the internal trigger generator or by 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

TRIGGER IN

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

When triggered burst or gated modes are selected the
defaults to
triggering or gating is specified.

set-up screen called by the TRIG IN key:

0·109ms is rounded to 0·11ms.

trigger which is the output of the internal trigger generator when internal

period soft-key on the

TRIGGER IN: force

source: internal
slope: positive
period: 2.00ms

SYNC OUT source automatically

7-2

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 0·01 ms to 200 s as set by the
generator period.

In gated mode the output of the main generator is gated on while the internal trigger
generator output is true; the duration of the gate is therefore 0·005 ms to 100 s, in step
with trigger generator periods of 0·01 ms to 200 s.

Triggered Burst and Gate

Triggered Burst 7

External Trigger Input

External trigger or gate signals are applied to the front panel TRIG IN socket which has a
TTL level (+1·5 V) 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
mode is 50 ns and the maximum repetition rate is 1 MHz. The maximum signal level that
can be applied without damage is ±10 V.

When triggered burst or gated modes are selected the
defaults to
or gate signal when external triggering or gating is specified.

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’ such that
channel 1 follows channel 4.

The source of the trigger out signal is selected by the

TRIGGER OUT

The

trigger which is always a positive-edged version of the external trigger

screen called by the TRIG OUT key.

TRIGGER OUT:

mode: auto
source: wfm end

source choices are as follows:

TRIG IN in triggered burst and gated

SYNC OUT source automatically

source soft-key on the

wfm end: Waveform end; a positive-going pulse coincident with the end

pos’n marker: Position marker; arbitrary waveforms only. Any point(s) on

seq sync: Sequence sync; a positive-going pulse coincident with the end

burst done: A positive-going pulse coincident with the end of the last

The default choice is
which case it becomes
default it is necessary to change the mode from
soft-key.

Trigger out is an internal signal but, as with the other trigger sources, a positive-edged
version is available at the triggered channel’s

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

of a waveform cycle (and the start of the next).

the main waveform may have marker bit(s) set high or low.
No output if selected for a standard waveform.

of a waveform sequence.

cycle of a burst.

wfm end except when the channel is running a sequence in

seq sync. To set the trigger out to anything other than its

auto to manual using the mode

SYNC OUT with its default source of

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Trigger Source

screen on which the burst count and start phase are set. The other trigger parameters are
set on the

TRIGGER IN set-up screen called by pressing the TRIG IN key.

TRIGGER IN: force

source: internal
slope: positive
period: 2.00ms

The trigger source can be selected with the source soft-key on the TRIGGER IN
set-up screen to be internal, external, manual or (in the case of multi­channel instruments) 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 (multi-channel instruments only) 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 the only ways to initiate a burst are by pressing
the

MAN TRIG key or sending a remote command. In multi-channel instruments,

pressing
selected as the source.

Trigger Edge

The slope soft-key is used to select the edge (positive or negative) of the
external trigger signal used to initiate a burst. The default setting of
should be used for triggering by the internal trigger generator or an adjacent channel’s
trigger out.

Note that the
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:.

MAN TRIG will trigger all those channels for which manual has been

positive

trigger signal from SYNC OUT, used for synchronizing the display of

screen, called by selecting setup… on the MODE

7-4

TRIGGER/GATE SETUP:

burst cnt: 0000001
phase: +000.0°

(actual +000.0°)

Triggered Burst and Gate

Triggered Burst 7

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 1,048,575 (2

20

-1).

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 frequency
resolution to 4 digits for all waveforms although the waveforms normally generated by
DDS 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, and this can cause a slight lag if the parameters are changed quickly using
the rotary control.

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

Square waves, pulse, pulse trains and sequences have no start phase adjustment. Their
phase is always fixed at 0°.

The start phase capabilities in triggered burst mode are summarized below:

Table 7-1. Phase Range and Resolution - Triggered Burst Mode

Waveform Maximum Waveform

Frequency

Sine, cosine,
haversine, havercosine

Square 1 MHz 0 ° only
Triangle, Ramp, sin(x)/x 100 kHz ± 360 °, 0.1 °
Pulse, Pulse Train 10 MHz 0 ° only
Arbitrary 40 Msamples/s clock ± 360 °, 360 °divided by length or 0.1 °
Sequence 40 Msamples/s clock 0 ° only

1 MHz ± 360 °, 0.1 °

Phase Control
Range and Resolution

Manual Initialization 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

7-5

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Gated Mode

Gate Source

channel’s TRIGGER IN screen. Select the channel to start the sequence with the
appropriate
press the

Gated mode is turned on with the gated soft-key on the MODE screen. The

setup…

which the start phase is set. The other parameters associated with gated mode are set on
the

TRIGGER IN set-up screen called by pressing the TRIG IN key.

The gate signal source can be selected with the source soft-key on the

TRIGGER IN

channel instrument) an adjacent channel.

SETUP key, select the TRIGGER IN screen with the TRIG IN key and

force soft-key.

soft-key on this screen accesses the TRIGGER/GATE SETUP screen on

TRIGGER IN: force

source: internal
slope: positive
period: 2.00ms

set-up screen to be internal, external, or (in the case of a multi-

With

internal selected the internal trigger generator is used to gate the waveform;
the duration of the gate is half the generator period. Refer to the section on the Internal
Trigger Generator above for more information.

With

external selected the gate duration is from the point (nominally +1.5 V) on the
specified edge of the signal at the
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 set-up 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. In other words the gate signal is true when the
is high. If the
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.

Start Phase

Press

setup… on the MODE screen to access the TRIGGER/GATE SETUP screen

on which the start phase can be set.

TRIG IN socket until the same level on the opposite

TRIG IN signal

slope is set negative the gate signal is true when the TRIG IN

7-6

TRIGGER/GATE SETUP:

burst cnt: 0000001
phase: +000.0°

(actual +000.0°)

Triggered Burst and Gate

Sync Out in Triggered Burst and Gated Mode 7

The start phase, i.e. the point on the waveform cycle at which the gated waveform starts,
can be selected by pressing 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.

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 gated mode is specified. This limits frequency
resolution to 4 digits for all waveforms although the waveforms normally generated by
DDS 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, and this can cause a slight lag if the parameters are changed quickly using
the rotary control.

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 greater than 3600
points will have a resolution of 0.1 °, but below this number of points the maximum
resolution becomes 360 ° divided by the number of points.

phase soft-key followed by direct entries from the

Square waves, pulse, pulse trains and sequences have no start phase adjustment. Their
phase is always fixed at 0°.

Refer to the table in the Triggered Burst section above 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
used whether internal (from the internal trigger generator or an adjacent channel) or
external of either polarity.

Alternatively,
screen; this provides a
and high at all other times.

trigger; this is a positive-edged signal synchronized to the actual trigger

SYNC OUT can be set to burst done on the SYNC OUT set-up

SYNC OUT signal which is low while the waveform is running

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7-8

Chapter 8

Tone Mode

Introduction........................................................................................................ 8-2

Tone Frequency ................................................................................................. 8-2

Tone Type.......................................................................................................... 8-2

Tone Switching Source...................................................................................... 8-3

DTMF Testing with a Multi-Channel Generator............................................... 8-4

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Introduction

Tone Frequency

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
set-up screen. This signal can be the internal trigger generator, an external trigger input,
the front panel
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 mode 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 1 mHz to 10 MHz
in tone mode, including triangle, ramp and square wave, which have different limits in
continuous operation.

Press the tone setup… soft-key on the MODE screen, called by pressing the

MODE

MAN TRIG key or a remote command. On multi-channel instruments the

key. The TONE set-up screen will be displayed:

source soft-key on the TRIGGER IN

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
the end of the list by selecting
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 set-up 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
only after completing the last cycle of the current frequency.

TONE type: trig

2.000000 kHz #2

3.000000 kHz del

end of list #4

del (delete) soft-key. Additional frequencies can be added to

end of list with the appropriate soft-key and

source and slope fields on the TRIGGER IN screen, but

8-2

With

type set to gate the frequency changes when the signal specified in the
source

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 point the next frequency in the list is gated on.

field goes to the level specified in the slope field on the TRIGGER IN

Tone Mode

Tone Switching Source 8

Thus the difference between triggered and gated tone changes is 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 (no signal) period between successive frequencies while the gate signal is not
true.

With

type set to fsk the frequency changes instantaneously (and phase­continuously) at each occurrence of the signal edge specified in the

slope

fields on the TRIGGER IN screen, without completing the current waveform

source and

cycle; this is true FSK (frequency shift keying) tone switching.
The following diagrams demonstrate the differences between trigger, gate and FSK tone

switching for a list of two frequencies switched by a square wave (positive slope
specified on the

TRIGGER IN set-up).

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

GATE: Maximum tone frequency 50 kHz;

maximum switching frequency < lowest tone frequency.

TRIGGER: Maximum tone frequency 50 kHz;

maximum switching frequency 1 MHz.

FSK: Maximum tone frequency 1 MHz;

maximum switching frequency 1 MHz.

Figure 8-1. Tone Waveform Types

Tone Switching Source

The signal which controls the frequency switching is that set by the source soft-key

TRIGGER IN set-up screen. The slope field on the same screen sets the

on the
active polarity of that signal; when set to
signal is active or the high level of the gating signal is true. The reverse is true for a

negative

internal trigger generator, an external trigger input, the front panel
remote command and, for multi-channel instruments, the trigger output from an adjacent
channel. A full explanation for each of these can be found in chapter 7, Triggered Burst
and Gate.

setting. The signal selections available on the source soft-key are the

positive the rising edge of the trigger

MAN TRIG key, a

shb0008f.emf

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DTMF Testing with a Multi-Channel Generator

An important use of tone mode is DTMF (Dual Tone Multiple Frequency) testing in
which two channels are set up with equal length lists of different frequencies, triggered
from a common signal. The outputs are summed together using the internal sum facility
(see chapter 12, Sum). DTMF testing generally uses sine waves in the frequency range
600 Hz to 1.6 kHz.

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.

8-4

Chapter 9

Arbitrary Waveform Generation

Introduction........................................................................................................ 9-2

Arb Waveform Terms........................................................................................ 9-2

Arb Waveform Creation and Modification – General Principles ...................... 9-2

Selecting and Outputting Arbitrary Waveforms................................................ 9-3

Creating New Waveforms.................................................................................. 9-4

Create Blank Waveform................................................................................ 9-4

Create Waveform Copy................................................................................. 9-5

Modifying Arbitrary Waveforms....................................................................... 9-6

Waveform Edit Cursor .................................................................................. 9-6

Resize Waveform .......................................................................................... 9-6

Rename Waveform........................................................................................ 9-7

Waveform Info .............................................................................................. 9-7

Delete Waveform........................................................................................... 9-8

Edit Waveform .............................................................................................. 9-8

Point Edit....................................................................................................... 9-9

Line Edit........................................................................................................ 9-9

Wave Insert.................................................................................................... 9-9

Block Copy.................................................................................................... 9-10

Waveform Amplitude.................................................................................... 9-11

Waveform Offset........................................................................................... 9-11

Wave Invert................................................................................................... 9-12

Position Markers............................................................................................ 9-12

Arbitrary Waveform Sequence.......................................................................... 9-13

Sequence Set-up ............................................................................................ 9-14

Frequency and Amplitude Control with Arbitrary Waveforms......................... 9-15

Frequency...................................................................................................... 9-15

Amplitude...................................................................................................... 9-16

Sync Out Settings with Arbitrary Waveforms................................................... 9-16

Waveform Hold in Arbitrary Mode................................................................... 9-16

Output Filter Setting .......................................................................................... 9-17

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Introduction

Arb Waveform Terms

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 65,536 horizontal points. The vertical
range is -2048 to +2047, corresponding to a maximum peak-peak output of 20 V. Up to
100 waveforms can be stored in the 256 kByte non-volatile RAM and each waveform
may be given a name; the exact 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. The appendix includes information about
the software tools available.

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 65,536 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 The arb frequency is the clock rate of the data RAM address

counters and has a range of 0·1 Hz to 40 MHz on these
instruments.

Waveform frequency. The waveform frequency depends on both the arb frequency

and the horizontal size; for example a 1000 point waveform
clocked at an arb frequency of 40 MHz has a waveform
frequency of 40e6/1000 = 40 kHz.

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-to­peak 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

9-2

Principles

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

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

Arbitrary Waveform Generation

Selecting and Outputting Arbitrary Waveforms 9

2. 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:

1. Creating the waveform using the software on a PC.

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

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 summarized
here.

1. On multi-channel instruments all the channels must be running in continuous mode to
allow arb creation or modification. Summing and modulation of channels is allowed.

2. 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 256 kBytes. 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 65,536 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 non­volatile back-up memory (and then to any other channels using that waveform) when
the parameter edit is confirmed with the

save soft-key.

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

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

5. If an arb waveform sequence is running no waveforms can be deleted from that
channel, whether they are used in the sequence or not.

6. 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.

You will be reminded of the above constraints by a warning or error message in the
display if you attempt an illegal operation.

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
in back-up memory.

ARB key to see the list, on the ARBS screen, of all arbitrary waveforms held

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ARBS: backup mem

wv00 01024
wv01 03782
wv02 00500

The rotary control or cursor keys can be used to scroll the full list backwards and
forwards through the display. With the appropriate channel selected using its
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
screen; this causes the channel memory to be displayed instead of the backup

mem

ory, for example:

SETUP

ARBS

ARBS: chan mem

wv00 03872
wv01 00128

If the power-on setting has been set to

POWER ON SETTING

at power-on. Refer to chapter 14, System Operations from the Utility Menu for more
information.

The same arbitrary waveform can be selected to run on more than one channel; in this
case, when it is edited in backup memory, the changes will also be applied to all copies of
the waveform.

The following sections give full details as to how arbitrary waveforms are created and
modified.

screen the waveforms will be restored to the channel’s memory

Creating New Waveforms

Pressing the CREATE key calls the CREATE NEW WAVEFORM screen.

restore last setup on the

9-4

Create Blank Waveform

Pressing the

create blank… soft-key calls the menu:

CREATE NEW WAVEFORM
free memory: 258972

create blank…
create from copy…

Arbitrary Waveform Generation

Creating New Waveforms 9

create: "wv00 "
size: 01024

cancel create

The top line contains the user-defined waveform name which can be up to 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. 1024 points is the default size
and the range is from 4 to 65,536 points. Screen messages will tell you if you have
attempted to set values less than 4 or greater than the remaining available backup
memory. The waveform ‘blank’ is created in the non-volatile backup memory and the

free memory

The

cancel soft key causes the name to be kept without any allocation of memory

field shows the remaining unused backup memory.

space. Pressing the
calls the

MODIFY screen to permit waveform editing.

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
and size soft-keys respectively, exactly as described in the previous section.

create soft key allocates both the name and the memory, and

create: "wv00 "
from: sine
size: 01024
cancel create

create

The source waveform which is to be copied can be selected by the

from soft key;
repeated presses of the 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 it is possible to lose significant waveform, particularly from arb waveforms
with narrow spikes if the compression ratio is large.

The

cancel soft key causes the name to be kept without any allocation of memory
space. Pressing the
calls the

9-5

MODIFY screen to permit waveform editing.

create soft key allocates both the name and the memory, and

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Modifying Arbitrary Waveforms

Certain restrictions apply to waveform modification. They are summarized at the head of
this chapter.

Pressing the

CREATE NEW 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

Waveform Edit Cursor

During any arbitrary waveform modify procedure which involves setting waveform
addresses, one or more waveform cursors can be output from the rear panel

CURSOR/MARKER OUT

output currently selected by the channel
of the cursor is set on the
described chapter 14, System Operations from the Utility Menu. The cursors are
positioned at the start and stop addresses used for the various edit operations described
below (one address per cursor only for point edit). The cursor signal can be displayed on
a second channel of the oscilloscope or used to modulate the Z-axis to highlight the stop
and start addresses.

MODIFY front panel key, or the create soft-key on either of the

menus calls the MODIFY screen:

MODIFY: vwv01
resize… rename…
delete… info…
edit waveform

MODIFY.

socket. The waveform being edited must be running on the

SETUP keys. The amplitude, polarity and width

cursor/marker… menu of the UTILITY screen as

9-6

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 be
changed subsequently.

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 new size is smaller points are removed. Reducing the
waveform size may cause the waveform to lose significant data; be careful, because there
is no "undo" for resize.

Resize: vwv01
(old size: 01024)

new size: 0

cancel resize

1024

Arbitrary Waveform Generation

Modifying Arbitrary Waveforms 9

Resize is implemented by pressing the resize soft-key. The cancel soft-key
leaves the size unchanged. Both soft keys return the display to the

MODIFY screen.

Rename Waveform

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

Rename: vwv01
as: "myWave01

"

cancel rename

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 eight
characters long.

Rename is completed by pressing the
the name unchanged. Both soft keys return the display to the

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 important when executing
waveform management operations such as delete.

Pressing
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

rename soft-key. The cancel soft-key leaves

MODIFY screen.

Info vwv03 exit
length: 00128
chan: 3 4
seq:

exit returns the display to the MODIFY screen.

chan wfm info… soft-key to get the CHANNEL WFM INFO: screen:

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

9-7

soft-key to return to the UTILITY MENU.

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Delete Waveform

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

Delete waveform
"wv01 "
?

cancel delete

Confirm deletion by pressing the

MODIFY

screen with the next arb waveform automatically selected; the cancel soft

delete soft-key which will return the display to the

key aborts the deletion.
A waveform cannot be deleted from the backup memory until it has first been deleted

from all channel memories.
A waveform cannot be deleted from a channel’s memory if it is being output on that

channel. The waveform must first be deselected by selecting an alternative waveform.
Make the new selection using either the

STANDARD WAVEFORMS or the ARBS

screen.
You will then be able to delete the waveform from the channel memory by selecting the

ARBS

screen for that channel.

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. You can then complete the deletion from backup memory as described above.

9-8

Edit Waveform

Pressing the

From this menu you can select functions which permit you to edit the waveform point­by-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 their baseline can be changed using wave offset. Sections of the

edit waveform… soft-key calls the EDIT FUNCTIONS menu:

EDIT FUNCTIONS:

point edit…
line draw…
wave insert…

Arbitrary Waveform Generation

Modifying Arbitrary Waveforms 9

waveform can be copied into itself (block copy) and position markers for use at

SYNC OUT

can also be defined.

Pressing the

EDIT FUNCTIONS

Point Edit

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

To see the data value at a point, press the soft-key on the left adjacent to the numeric
address and enter the point address directly from the keyboard or by using the rotary
control. The current data value is displayed to the right of the address.

To change the value press the soft key on the right adjacent to the numeric value and
enter the new value directly from the keyboard or by using the rotary control. Changing
the data value automatically updates the waveform.

Pressing the

Line Edit

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

exit soft-key on any of these edit screens will return the display to the

menu.

POINT EDIT
(addrs, value)

(00512, +0500)
exit next point

next point soft-key automatically advances the address by one point.

The display shows a frm (from) and to address which will be the points between
which a straight line will be created when the
default
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 linear interpolations will be calculated for the addresses between the two selected
points when the

Wave Insert

Pressing wave insert… calls the wave insert screen:

LINE (addrs, value)

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

draw line soft-key is pressed. The

frm address is the first point on the waveform or the point most recently edited

draw line soft-key is pressed.

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wv01 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.

You can insert a section of an arbitrary waveform, defined by the left-hand
and

stop addresses, for example points 00000 to 00512 of wv01 on the
screen above. These start and stop addresses default to the start and stop addresses of the
entire waveform being inserted, but you can adjust the addresses 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
pressing the appropriate soft-key and making entries from the keyboard or by rotary
control.

The insertion is completed by pressing the
If there is a size difference between the two sections of waveform then the software will

expand or compress the source address space to fit the new waveform. As before,
compressing the waveform may cause you to lose some significant data.

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

Block Copy

Pressing

strt (start)

strt and stop addresses. Again, change the addresses by

insert soft-key.

block copy… calls the BLOCK COPY screen:

9-10

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.

Arbitrary Waveform Generation

Modifying Arbitrary Waveforms 9

Block copy edit operates on the version of the waveform in the channel currently selected
by the channel

SETUP keys, and the effect of the edit can be seen by selecting the

waveform to run on that channel.
When your waveform is ready it can be saved by pressing the

of saving modifies the waveform in the backup memory and also any other copies of the
waveform in other channel memories. After the edited waveform has been saved the
original waveform cannot be recovered.

Pressing the

exit soft key returns to the EDIT FUNCTIONS screen without saving

any changes.

Waveform Amplitude

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

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.
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
appropriate soft-key and make entries directly from the keyboard or by using the rotary
control. The amplitude changes on completion of the entry. Note that entries greater
than 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.

save soft-key; the action

AMPLITUDE: 001.00

start: 00400
stop: 01000 undo
exit save

AMPLITUDE field. Press the

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 soft key; the action of saving modifies
the waveform in the backup memory and also any other copies of the waveform in other
channel memories. After the edited waveform has been saved the original waveform
cannot be recovered.

Pressing the

exit soft key returns to the EDIT FUNCTIONS screen without

saving any changes.

Waveform Offset

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

WAVE OFFSET: +0000

start: 00400
stop: 01000 undo
exit save

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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 using the 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 directly
from the keyboard or by using the 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, although 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 soft key; the action of saving modifies the
waveform in the backup memory and also any other copies of the waveform in other
channel memories. After the edited waveform has been saved the original waveform
cannot be recovered.

Pressing the
saving any changes.

Wave Invert

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

The inversion can be applied to a section of the waveform defined by the

stop

addresses. Set the addresses by pressing the appropriate soft-key and making

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

time the
Press

invert soft-key is pressed.

exit to return to the EDIT FUNCTIONS screen.

Position Markers

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

exit soft key returns to the EDIT FUNCTIONS screen without

INVERT: wv02

start adrs: 00512
stop adrs: 00750
exit invert

start and

9-12

POSITION MARKER EDIT
adrs: 00000 <0>

patterns…
exit clear all

Position markers are output from the

pos’n marker

on the SYNC OUTPUT SETUP screen.

SYNC OUT socket when the source src is set to

Arbitrary Waveform Generation

Arbitrary Waveform Sequence 9

Position markers can be set at any or all of the addresses of a waveform either
individually, using the

patterns…

adrs (address) soft-key, or as a pattern, using the

menu.

A marker can be set directly at an address by pressing the
keyboard entry. Pressing the right-hand soft-key on the
marker setting between
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

The start and stop addresses of the markers within the waveform are set using the

start

using the rotary control.
The pattern itself is set in the top line of the display; press the soft-key to the right of

PATTERN:

(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.

and stop soft-keys respectively followed by a direct keyboard entry or by

and enter the sequence of 1s and 0s using 1 and 0 from the keyboard

<1> and <0>. The address can be changed by incrementing with

PATTERN: 00000000…

start: 00000
stop: 01023
exit: do pattern

adrs soft-key followed by a

adrs line then toggles the

patterns… sub-menu:

The pattern is entered repeatedly across the whole range defined by the start and stop
addresses when the

POSITION MARKER EDIT

Pressing the
should be cleared from the waveform. Pressing
returns the display to
clear.

clear all soft-key displays a request for confirmation that all markers

do pattern soft-key is pressed; pressing exit returns to the

screen without implementing the pattern.

POSITION MARKER EDIT; pressing cancel aborts the

Arbitrary Waveform Sequence

Up to 16 arbitrary waveforms may be linked in a sequence. Each waveform can have a
loop count of up to 32,768 and the whole sequence can run continuously or be looped up
to 1,048,575 times using the triggered burst mode.

Pressing the

SEQUENCE key calls the initial SEQUENCE screen:

SEQUENCE (segs= 1)

sequence setup…

stop run

clear cancels all the markers and

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Sequence Set-up

A previously defined sequence can be run and stopped from this screen using the run
and stop soft-keys. The sequence can also be switched on from the

STANDARD WAVEFORMS

The

segs= field shows the number of segments in the sequence; there is always at

screen with the sequence soft-key.

least 1 segment.

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
stepped through with repeated presses of the

wfm (waveform) soft-key; the list of all arbitrary waveforms already created is

wfm soft-key or by using the rotary

control.
The criterion for stepping between waveform segments is set by the

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

step on soft-

cnt

(count) field; up to 32,768 cycles can be set with cnt selected, using direct keyboard
entries or by rotary control.

Alternatively, the

step on criterion 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
subsequent trigger. The trigger source can be any of the settings selected on the

TRIGGER IN

set-up screen (called by the TRIG IN key); these are described fully in

run and steps to the following segments in turn at each

chapter 7, Triggered Burst and Gate. At each trigger the current waveform cycle plus one
further whole cycle are completed before the waveform of the next segment is started.

9-14

If

trig level is selected the sequence runs continuously through each segment in
turn (one 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 again runs continuously through each segment in turn. The
trigger level source can be any of the settings selected on the

TRIGGER IN set-up

Arbitrary Waveform Generation

Frequency and Amplitude Control with Arbitrary Waveforms 9

screen with the exception of the MAN TRIG key (which when pressed can only produce
an edge, not a level).

Providing the
sequence can also be run in gated and triggered burst modes in the same way as simple
waveforms. Refer to chapter 7, Triggered Burst and Gate for full details.

The individual segments of the sequence can be turned on or off with the
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
soft-key which returns the display to the initial SEQUENCE screen. The sequence can
be run and stopped from this screen with the

step on: field is set to count for all segments the waveform

on-off soft-

done

run and stop soft-keys respectively.

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

ARBITRARY FREQUENCY
40·00 MHz

screen:

sample waveform
freq period

You can set either the frequency or the period, as before, by pressing the

period

mode is only 4 digits because clock synthesis generation is used. The Principles of
Operation section in chapter 4, Initial Operation, provides an explanation of the synthesis

technique used.
Additionally, for arbitrary waveforms, frequency or period can be set in terms of the

sample clock frequency, by pressing the
frequency, by pressing the

waveform frequency = sample frequency divided by waveform size.
Frequency and period entries are made directly from the numeric keypad or by using the

rotary control in the usual way.
Pressing the

SEQ CLOCK FREQUENCY

soft-key respectively. Note that the frequency and period resolution in arbitrary

sample soft-key, or in terms of the waveform

waveform soft-key. The relationship between them is

FREQuency key with sequence selected calls the

screen:

SEQ CLOCK FREQUENCY
40·00 MHz

freq period

freq or

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Amplitude

Frequency or period can now only be set in terms of the clock frequency. Frequency and
period entries are made directly from the numeric keypad or by using the rotary control in
the usual way.

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

AMPLITUDE:
+20·0 Vpp

Vpp

load:hiZ

This differs from the
now only be entered in volts peak-to-peak.

Note that the peak-to-peak amplitude set on this screen will only 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 output range with the instrument set
to 20 V p-p will only be 10 V p-p.

AMPLITUDE screen for standard waveforms in that amplitude can

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
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.

Waveform Hold in Arbitrary Mode

Arbitrary waveforms can be paused and restarted on any channel by using the front panel
MAN HOLD

On multi-channel instruments the channels which are to be held by the
or

HOLD IN socket must first be enabled using the ARB HOLD INPUT screen,

accessed by pressing the

key or a signal applied to the rear panel HOLD IN socket.

HOLD key:

sequence sync;

MAN HOLD key

9-16

ARB HOLD INPUT:

status: no hold

mode: disabled

Each channel is selected in turn using the channel

mode

key presses.

soft-key; the mode changes between disabled and enabled with alternate

SETUP keys and set using the

Arbitrary Waveform Generation

Output Filter Setting 9

Pressing the front panel MAN HOLD key stops the waveform at the current level on all
enabled channels; pressing
level. If the
change from

ARB HOLD INPUT screen is currently selected the status field will

no hold to manual hold while the waveform is paused.

MAN HOLD a second time restarts the waveform from that

A logic low or switch closure at the rear panel
at the current level on all enabled channels; a logic high or switch opening restarts the
waveform from that level. If the

status

paused.
If, while the waveform is held by either of the above means, the

pressed the waveform is reset to its first point; the waveform will restart from this point
when
socket.

field will change from no hold to ext. hold while the waveform is

MAN HOLD is pressed again or a high is applied to the rear panel HOLD IN

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 may be a frequent requirement with arbitrary waveforms.

To change the filter settings, press the
screen:

HOLD IN socket also stops the waveform

ARB HOLD INPUT screen is currently selected the

MAN TRIG key is

FILTER key to call the FILTER SETUP

FILTER SETUP

mode: auto
type: 10MHz eliptic

The default
filter. With the setting on
revert to the automatic selection as soon as any relevant parameter is changed.

To override the automatic choice press the

mode is auto which means that the software selects the most appropriate

auto the type can be changed manually but the choice will

mode soft-key to select manual.

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

10 MHz elliptic: The automatic choice up to 10 MHz for sine, cosine, haversine,

havercosine, sin(x)/x and triangle. Would be the better choice for arb
waveforms with an essentially sinusoidal content.

16 MHz elliptic: The automatic choice above 10 MHz for sine, cosine, haversine and

havercosine. Not recommended for any other waveforms.

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

sequence.

No filter: The automatic choice for square ware, pulse and pulse trains. May be

the best choice for arb waveforms with an essentially rectangular
content.

9-18

Pulse and Pulse-trains

Introduction10

Chapter 10

Pulse and Pulse-trains

Introduction........................................................................................................ 10-2

Pulse Set-up ....................................................................................................... 10-2

Pulse-Train Set-up ............................................................................................. 10-4

Waveform Hold in Pulse and Pulse-Train Modes ............................................. 10-6

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Introduction

Pulse Set-up

Pulse and pulse-trains are both selected and set-up from independent menus on the
STANDARD WAVEFORMS

trains have similar timing set-ups and considerations but pulses are always unipolar, with
a maximum amplitude of 10 V p-p, whereas pulse-trains can be bipolar, with a maximum
amplitude of 20 V p-p.

Pulse waveforms are turned on with the pulse soft-key on the

STANDARD WAVEFORMS

calls the first of the pulse set-up screens:

screen called by pressing the STD key. Pulse and pulse-

screen. Pressing the setup… soft-key beside pulse

Enter pulse period:
1

exit next

00·0 us

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

Enter pulse width:
program 5
(actual 50·00 us)

exit next

The width can be entered directly from the numeric keypad or by using the rotary control.
Any value in the range 25·00 ns to 99·99 s can be programmed but the
may differ because of the considerations discussed below; for this reason the
pulse width is shown below the program width.

Pressing the

next soft-key calls the pulse delay screen:

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

exit done

0·00 us

·000 ns

next soft-

actual value

actual

10-2

This is very similar to the pulse width screen and, again, the
below the
(pulse period -1 point); positive values delay the pulse output with respect to waveform
sync from
waveform sync.

Pressing the

STANDARD WAVEFORMS

program delay. The delay value that can be entered must be in the range ±

SYNC OUT; negative values cause the pulse to be output before the

done soft-key on this screen returns the display to the

screen.

actual delay is shown

Pulse and Pulse-trains

Pulse Set-up10

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 25.00 ns corresponding to the fastest clock frequency of 40
MHz.

At short pulse periods, i.e. for waveforms with a small number of points, the setting
resolution is, however, much better than 25.00 ns 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 500 ns, the minimum pulse width, when set to 25.00
ns, will in fact be 25.00 ns; 20 points at 25.00 ns each exactly defines the 500 ns period.
However, if the period is set to 499·0 ns, 20 points at the minimum point time of 25.00 ns
will be too long so 19 points are used and the point time is adjusted to 26.26 ns
(499·0/19); 26.26 ns is now the increment size used when changing the pulse width and
delay.

For periods above 1·25 ms 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 100 ms, the smallest pulse width and delay increment is 2 µs (100
ms/50,000). This may appear to cause significant errors at extreme settings (for example,
setting 100 ns in the above case will still give an actual width of 2 µs) but in practical
terms a 1 in 50,000 resolution (0·002%) is normally acceptable.

The pulse period can be adjusted irrespective of the pulse width and delay setting (for
example it 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 100 µs period and
50 µs width, the period is changed to 60 µs the pulse width
even though the

program width is still 50µs. To get a 50µs width with the period at 60

actual changes to 30 µs

µs the width must be re-entered as 50 µs 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
1

00·0 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
frequency from this screen is slightly different from changing period on the

setup

screen. When changing from this screen the number of points in the waveform is

freq soft-key. However, changing the period or

pulse

never changed (just as with a true arb) which means that the shortest period that can be
set is the number of waveform points times 25.00 ns. 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 less than 1·25 ms).

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Pulse-Train Set-up

Pulse-trains are turned on with the pulse-train soft key on the
STANDARD WAVEFORMS
train

The number of screens used for the set-up depends on the number of pulses in the pulse­train. 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 (three screens for pulse 1,
then three screens for pulse 2, etc.).

calls the first of the set-up screens:

screen; pressing the setup… soft-key beside pulse-

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

done next

Pressing the
the display to the
turned on and off.

Pressing the

STANDARD WAVEFORMS

The pulse-train is built only after the
parameter set-up screen, or whenever
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 numeric keypad or by using the rotary control.

Pressing

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

Pressing

next soft key on any screen calls the next set-up screen, finally returning

STANDARD WAVEFORMS screen from which pulse-train can be

done soft key returns the display directly to the

screen from any set-up screen.

next soft key is pressed following the final

done is pressed (always assuming a change has

next calls the pulse train period screen:

Enter pulse train
period:
1

done next

next calls the baseline voltage screen, the last of the general set-up screens:

00·0us

10-4

Enter the baseline
voltage:
+0

done next

·000 V

Pulse and Pulse-trains

Pulse-Train Set-up10

The baseline is the signal level between the end of one pulse and the start of the next, i.e.
it is the level at which all pulses start and finish. The baseline can be set between -5·0 V
and +5·0 V by direct numeric keypad 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 (10 V p-p into 50 Ω) on the

AMPLITUDE screen

and terminated in 50 Ω. The amplitude control scales the baseline setting, so that if, for
example, the amplitude were set to 5 V p-p into 50 Ω then the actual baseline range
would be -2·5 V to +2·5 V for set values of -5·0 V to +5·0 V.

Note also that the output levels are doubled when the output is not terminated.

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 -5·0 V and +5·0 V by direct numeric
keypad 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 (10 V p-p
into 50 Ω) on the

AMPLITUDE screen and terminated in 50 Ω. Adjusting the amplitude

scales both the peak pulse levels and the baseline together, thus keeping the pulse shape
in proportion as the amplitude is changed, exactly as for arb waveforms.

Note also that the output levels are doubled when the output is not terminated.

By pressing the

Pulse soft-key on this (and subsequent) screens, the pulse to be edited

can be directly selected using the numeric keypad or the rotary control. This is useful for
editing a particular pulse in a long pulse train without needing to step through all the
earlier pulses.

Pressing

next then 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 numeric keypad or by using the rotary control.
Any value in the range 25.00 ns to 99·99 s can be programmed but the
may differ; for this reason the

actual pulse width is shown below the program

actual value

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 Set-up section.

Pressing

next calls the pulse delay screen for the first pulse:

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Pulse 1 delay
program +0·000 ns

(actual +0·000 ns)

done next

The pulse delay is entered in the same way as the 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
pulse to be output before the waveform sync.

SYNC OUT; negative values cause the

Pressing
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
last screen of the last pulse or when

You must be careful to ensure that the set widths and delays of the individual pulses are
compatible with each other and with the overall pulse-train period. Thus delays must not
be such that pulses overlap each other and the delays plus 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
the

next on this screen calls the first of the three screens for setting the

next is pressed on the

done is pressed on any screen.

PULSE-TRN PERIOD screen called by pressing

FREQ key with pulse-train mode selected:

PULSE-TRN PERIOD
1

done next

00·0us

10-6

The new setting can be entered either as a period in the way already described, or as a
frequency by first pressing the
frequency from this screen is slightly different from changing the period on the

pulse-train setup

in the waveform is never changed (just as with a true arb) which means that the shortest
period that can be set is the number of waveform points times 25.00 ns. To achieve
higher 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 less than 1·25 ms).

freq soft-key. However, changing the period or

screen. When changing from this screen the number of points

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

On multi-channel instruments the channels which are to be held by the
or

HOLD IN socket must first be enabled using the ARB HOLD INPUT screen,

accessed by pressing the

MAN HOLD key or a signal applied to the rear panel HOLD IN socket.

HOLD key:

MAN HOLD key

Pulse and Pulse-trains

Waveform Hold in Pulse and Pulse-Train Modes10

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
enabled channels; pressing
level. If the
change from

ARB HOLD INPUT screen is currently selected the status field will

no hold to manual hold while the waveform is paused.

MAN HOLD key stops the waveform at the current level on all

MAN HOLD a second time restarts the waveform from that

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

status

field will change from no hold to ext hold while the waveform is

ARB HOLD INPUT screen is currently selected the

paused.

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10-8

Chapter 11

Modulation

Introduction........................................................................................................ 11-2

External Modulation .......................................................................................... 11-2

External VCA ................................................................................................ 11-2

External SCM ................................................................................................ 11-3

Internal Modulation ........................................................................................... 11-3

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Introduction

You can use both internal and external modulation sources. External modulation can be
applied to any or all channels. Internal modulation uses the previous channel as the
modulation source; for example channel 2 can be used to modulate channel 3. Clearly,
internal modulation is not available on channel 1 or on a single channel instrument.

The external modulation mode can be either VCA (voltage controlled amplitude) or SCM
(suppressed carrier modulation). The internal modulation mode can be either 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
they are generally outside the range of common-sense applications. To better understand

these constraints the following sections (and chapter 12, Sum) should be read with

reference to the block diagrams in appendix F. These show the control signals in a single
channel and the inter-channel connections.

The block diagrams also show the inter-channel trigger connections described in chapter

7, Triggered Burst and Gate; in general, inter-channel triggering is possible

simultaneously with modulation but few combinations are of real use.

External 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; this last choice is not available on

single channel instruments or on channel 1 of multi-channel instruments.

With

ext selected the modulation can be switched between VCA and SCM with
alternate presses of the
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
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 20 V p-p
open-circuit voltage.

type soft-key. Both types of external modulation can be used

MODULATION

source: ext
type: VCA

EXT MODULATION socket (nominally 1 kΩ input

11-2

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 must also be changed to maintain the same
modulation depth.

Modulation

Internal Modulation11

The VCA signal is applied to the amplifier chain prior to the output attenuators. The
amplifier itself is controlled over a limited range (approximately 10 dB); the full
amplitude range of the channel is achieved by switching in up to five 10 dB 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 below), it is up to the user to

observe the waveforms when using externally-driven VCA and to make adjustments to
prevent clipping. Note that it is not possible to give a simple guide as to where the range
clipping limits are because the use of dc offset, for example, changes them.

Within each 10 dB attenuator step the maximum output setting of the channel at which
clipping is avoided is reduced from the range maximum to half this value as the
modulation is increased from 0 to 100 %. 100 % modulation will be achieved at this
mid-range setting with an external VCA signal of approximately 1 V p-p. The frequency
range for the modulating signal is DC to 100 kHz.

It is also possible to modulate a dc level from the generator with a signal applied to the

EXT MODULATION

Set the generator to external trigger on the
apply a trigger signal to the

WAVEFORMS

the peak positive voltage defined by the current amplitude setting. Pressing the ± key

AMPLITUDE displayed will set the level to the peak negative voltage. This DC

with
level can now be modulated by the signal applied to the

External SCM

Select SCM with the type soft-key on the MODULATION screen. Connect the
modulating signal to the
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 20 V p-p open-circuit voltage
limit.

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

When external SCM is selected for a channel the amplitude control of that channel is
disabled. The

socket, as follows:

TRIGGER IN set-up screen but do not

TRIG IN socket; select square in the STANDARD

screen. The MAIN OUT socket now provides a constant voltage which is

EXT MODULATION input.

EXT MODULATION input (nominally 1 kΩ input impedance).

AMPLITUDE set-up screen shows the message fixed by SCM.

Internal Modulation

Only the multi-channel instruments (models 282 and 284) can make use of internal
modulation; the single-channel model 281 has no internal modulation capability.

Pressing the

11-3

MODULATION key calls the MODULATION set-up screen.

MODULATION

source: Ch3
type: SCM
level

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The source soft-key steps the modulation choice between off, external and
CHx

where x is the number of the previous channel.

With

CHx selected the modulation can be switched between AM and SCM with

alternate presses of the

When

AM is selected the screen has an additional soft-key labeled depth; selecting

type soft-key.

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 one of the two parameters must be
changed to eliminate clipping.

When

SCM is selected the screen has an additional soft-key labeled 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 10 V p-p.

When internal SCM is selected for a channel both the amplitude control of that channel
and of the previous channel (which is the modulation source) are disabled. The

AMPLITUDE
fixed by SCM.

message

set-up screen of the channel being modulated shows the message

The AMPLITUDE screen of the previous channel shows the

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 can not be used with internal or external sum.

11-4

Chapter 12

Introduction........................................................................................................ 12-2

External Sum...................................................................................................... 12-2

Internal Sum....................................................................................................... 12-3

Sum

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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 source, so that for example channel 2 can be added 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 the modulation
modes; as a result neither internal nor external sum can be used with internal modulation
but external modulation is still possible with sum.

To better understand the constraints, the following sections (and chapter 11, Modulation)
should be read with reference to the block diagrams in appendix F. These show the
control signals in a single channel and the inter-channel connections.

These diagrams also show the inter-channel trigger connections described in chapter 7,
Triggered Burst and Gate; 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

Pressing the

CHx

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
knob or cursor keys to set the
10 dB steps. This facility permits the same
each channel.

Clipping will occur if the sum input level attempts to drive the channel amplitude above
the maximum 20 V p-p open-circuit voltage. However, the relationship between the

SUM

but also on the channel's own 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 (approximately10 dB) and the full amplitude range of the channel is
achieved by switching in up to five 10 dB 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 below), it is the responsibility of the user to observe the waveforms when using
external sum and to make adjustments if the waveform is clipped. Note that it is not

SUM key calls the SUM set-up screen:

source soft-key steps the sum sources between off, external and

where x is the number of the previous channel.

input and the maximum summed output depends not only on the sum input level

SUM source: ext

ratio: 0dB
CH2 +2.00 Vpp

ratio soft-key; use the rotary

SUM input attenuation for that channel from 0 to –50 dB in

SUM signal to be used at different levels with

12-2

Sum

Internal Sum12

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
from the range minimum to the range max imum; if the channel amplitude is set to mid­range then the
approximately 1 V p-p.

To facilitate the setting of appropriate sum and amplitude levels the output amplitude of
the selected channel can also be changed from the
soft-key and adjust the amplitude with direct keyboard entries or by using the rotary
control.

External sum cannot be used with internal modulation.

Internal Sum

Only the multi-channel instruments (models 282 and 284) can make use of internal sum;
the single-channel model 281 has no internal sum capability.

Pressing the

SUM signal of approximately 2 V p-p will force the channel output

SUM signal needed to force the output to range maximum is halved to

SUM set-up screen. Press the CHx

SUM key calls the SUM set-up screen:

SUM source: CH1

ratio: 1.00000
CH2 +2.00 Vpp
CH1 +2.00 Vpp

Pressing the

CHx (

internal sum signal.
With

CHx selected for internal sum the screen is as shown above. The amplitude of
both the summing channel,
the display, together with the
can be selected with the appropriate soft-key and set directly from the keyboard or by
using the rotary control. Changing any one parameter will also adjust one of the other
two; for example adjusting the amplitude of either channel will cause the displayed ratio
to change.

The value shown in the
amplitude. Adjusting the ratio value directly changes the amplitude of the sum input
signal, CHx, not the channel’s output amplitude. When a value is entered into the

ratio

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's 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 less than or equal to 1; ratio values can be set from
very small signal levels up to unity. If the sum input is greater than the channel amplitude
there will be combinations when the ratio can be set to a little greater 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 its last legitimate setting.

source soft-key steps the sum source between off, external and

where x is the number of the previous channel). CHx is the source of the

CHx+1, and the internal sum signal, CHx, are shown in

ratio in which they are combined. All three parameters

ratio field is the CHx amplitude divided by the CHx+1

field it is initially accepted as entered but may then change slightly to reflect the

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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.

12-4

Chapter 13

Synchronization

Introduction........................................................................................................ 13-2

Inter-Channel Synchronization.......................................................................... 13-2

Synchronizing Principles............................................................................... 13-2

Master-Slave Allocation................................................................................ 13-2

Phase-setting between Channels.................................................................... 13-3

Other Phase-Locking Considerations............................................................ 13-4

Synchronizing Two Generators ......................................................................... 13-5

Synchronizing Principles............................................................................... 13-5

Connections for Synchronization .................................................................. 13-5

Generator Set-ups.......................................................................................... 13-5

Synchronizing................................................................................................ 13-7

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Introduction

Inter-Channel Synchronization

Synchronizing Principles

Two or more channels in one multi-channel generator can be synchronized together and
precise phase differences can be set between the channels. Two separate generators can
also be synchronized, giving a maximum of 8 channels that can be operated
synchronously.

This section covers the use of a multi-channel instrument to produce two or more
synchronous signals, and certain restrictions which apply to some specific waveform and
frequency combinations.

Frequency locking is achieved by using the clock output from a master channel to drive
the clock inputs of one or more slave channels. Any one channel can be the master 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, an 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 in appendix F. Channels to be locked together must all be
operated in continuous mode.

For DDS-generated waveforms (refer to Principles of Operation in chapter 4) it is the

27.4878 MHz signal that is distributed from the master to the 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; for example a 2 kHz signal could be locked usefully with 10 kHz,
50 kHz, 100 kHz, etc., but not with 2.001 kHz.

For clock synthesized waveforms 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 synthesized slaves can be locked to a clock synthesized master. In practice the
constraints described are not severe as the most common use of synchronization is to
provide outputs of the same waveform at the same frequency, or a harmonic of it, often
with controlled phase offsets.

Master-Slave Allocation

Press the front panel

INTER CHannel key to call up the inter-channel set-up screen.

mode: indep
phase: +000.0º

(actual: +000.0º

status: off view

13-2

The

mode soft-key can be used to select between independent, master,

master/freq

and slave; the default mode is independent. Only one