271-U 115V - Fluke Electronics

271

Programmable 10 MHz DDS Function Generator

Getting Started Manual

PN 2423297

January 2005

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 products to end-user customers only but have no authority to extend a greater or differ-

ent 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 applica-

ble international price. Fluke reserves the right to invoice Buyer for importation costs of repair/replacement parts when product purchased in one country is sub-

mitted for repair in another country.

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 serv ice 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, contami-

nation, alteration, accident, or abnormal condition of operation or handling, including overvoltage failures caused by use outside the product’s specified rati ng, 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 transporta tion charges (FOB Shipping

Point).

THIS WARRANTY IS BUYER'S SOLE AND EXCLUSI V E 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 function generator is a Safety Class I instrument according to IEC classification and has been designed to meet th e re-

quirements of EN61010-1 (Safety Requirements for Electrical Equipment for Measurem ent, Control and Laboratory Use). It is

an Installation Category II instrument intende d for operati on from a normal single phase supply.

This instrument has been tested in accordance with EN61010-1 and has been supplied in a safe conditi on. This Getting

Started Manual contains some informatio n and warnings which must 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 temper ature range 5 °C to

40 °C, 20 % - 80 % RH (non-condensing). It may occasionally be subjecte d to temperatures between +5 °C and -10 °C with-

out 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 ma y impair the safety protection provided. Do not op-

erate the instrument outside its rated supply voltages or environmental range.

Warning

To avoid the possibility of electric shock:

• This instrument mu st be earthed.

• Any interruption of the mains earth conductor inside or outside the instrumen t 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 re-

moval of parts (except those to which access can be gained by hand) is likely to expose live parts.

271

Getting Started Manual

• The apparatus shall be disconnected fro m all voltage sources before it is opened for any adjustment,

replacement, maintenance or repair.

• Any adjustment, maintenance and repair of the opened instrumen t un der 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 haz-

ard involved.

• Make sure that only fuses with th e required rated current and of the specified type are used for re-

placement. 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.

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 necess ary, replace only with a cell of the correct type, a 3 V Li/Mn02 20 mm

button cell type 2032. Do not mix with solid waste stream. Do not cut open, incinerate, expose to te mperatures

above 60 °C or attempt to recharg e. Used batteries should be disposed of by a qua lified recycler or hazardous ma-

terials handler. Contact your authorized Fluke Service Center for recycling information.

Caution

Do not wet the instrumen t when cleaning it and in p articul ar use only a soft dry cloth to clean the LCD win-

dow.

Safety (continued)

The following symbols are used on the instrument and in this manual:

Caution - refer to the accompanying docume ntation, incorre ct operation may damage the instrument.

Terminal connected to chassis ground.

Mains supply OFF.

Mains supply ON.

Alternating current.

Warning - hazardous voltages may be presen t.

iii

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 produc t standard for Electrical Equipment for Measurement, Con t rol and Laborator y Use. Test limits

used were:

a) Radiated: Class B

b) Conducted: Class B

c) Harmonics:EN61000-3-2 (20 00) Class A The instrument is Class A by product category.

Immunity

EN61326 (1998) EMC produc t standard for Electrical Equipment for Measurement, Con trol and Laboratory Use. Test meth-

ods, limits and performance achieved were:

a) EN61000-4-2 (199 5) Electrostatic Discharge: 4 kV air, 4 kV contact Performance A.

b) EN61000-4-3 (199 7) Electromagnetic Field: 3 V/m, 80 % AM at 1 kHz Performance A.

c) EN61000-4-11 (1994) Voltage Interrupt: 1 cycle, 100 % Performance A.

d) EN61000-4-4 (1995) Fast Transient: 1 kV peak (ac line), 0.5 kV peak

(signal lines and RS232/GPIB ports)

Performance A.

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Getting Started Manual

e) EN61000-4-5 (1995) Surge: 0.5 kV (line to line), 1 kV (line to ground) Performance A.

f) EN61000-4-6 (1996) Conducted RF: 3 V, 80 % AM at 1kHz

(ac line only; signal connections <3 m not tested)

Performance A.

According to EN61326 the definitions of performance criteria are:

Performance criterion A: ‘During test normal performan c e within the specification limits.’

Performance criterion B: ‘During test, temporary degra dation, or loss of function or performance which is self-recovering’.

Performance criterion C: ‘During test, temporary degradation, or loss of function or performanc e which requires operator

intervention or system reset occurs.’

Table of Contents

Title Page

Introduction .................................................................................................................... 1

Before You Start............................................................................................................. 1

Mains Supply Voltage................................................................................................ 1

Externally Applied Voltages....................................................................................... 2

Controls and Connections.............................................................................................. 3

The Liquid Crystal Display......................................................................................... 4

Controls..................................................................................................................... 4

Function Keys....................................................................................................... 4

FIELD and DIGIT Keys and the Rotary Control.................................................... 5

Numeric, Units and SET Keys .............................................................................. 6

MODE Keys.......................................................................................................... 7

UTILITIES Keys.................................................................................................... 7

OUTPUT Key........................................................................................................ 7

Front Panel Inputs and Outputs................................................................................. 8

MAIN OUT............................................................................................................ 8

vii

271

Getting Started Manual

AUX OUT............................................................................................................. 8

EXT TRIG............................................................................................................. 8

Rear Panel Connectors............................................................................................. 9

CLOCK IN/OUT.................................................................................................... 9

VCA IN................................................................................................................. 9

SYNC OUT........................................................................................................... 9

TRIG/SWEEP OUT.............................................................................................. 10

RS232 and GPIB Interface Connectors................................................................ 10

Using the Instrument...................................................................................................... 11

Starting up................................................................................................................. 11

Generating Continuous Signals ................................................................................ 12

Generating Swept Signals......................................................................................... 16

Generating a Triggered Burst.................................................................................... 18

Special Waveforms................................................................................................... 19

Saving and Recalling Settings .................................................................................. 23

Arbitrary Waveforms ................................................................................................. 23

Other Functions and Waveforms .............................................................................. 24

viii

Getting Started

Introduction

This Getting Started Manual for the model 271

Programmable 10 MHz DDS Function Generator is

designed to provide an initial understanding of the way

the instrument is operated. The manual is set out in the

form of a tutorial, guiding you through a series of basic

front panel operations in order to familiarize you with the

controls and the modes of operation.

The Users Manual contains detailed specifications and

descriptions of all the functions and operations accessible

both from the front panel and by means of the remote

interfaces.

Before You Start

Mains Supply Voltage

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 of the Users Manu al .

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Getting Started Manual

Externally Applied Voltages

Caution - Front Panel Sockets

To avoid risk of damage to the instrument:

Do not apply external voltages to the MAIN

OUT or AUX OUT sockets.

Do not apply external voltages exceeding ±10

V to the TRIG IN socket.

Caution - Rear Panel Sockets

To avoid risk of damage to the instrument:

Do not apply external voltages to the

SYNC OUT or TRIG/SWEEP OUT sockets.

Do not apply external voltages exc eeding

±10 V to the VCA IN socket.

Do not apply external voltages exc eeding

+7.5 V or -2.5 V to the CLOCK IN/OUT socket.

Getting Started

Controls and Connections

shx0001f.gif

Figure 1. Model 271 Fron t Panel

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Getting Started Manual

The Liquid Crystal Display

The 4-line x 20-character LCD panel is used to display

and edit all the parameter values. The paradigm used for

selecting fields and editing values is described below.

If necessary (because of temperature variations etc.), you

can adjust the display contrast using a small screwdriver

or trimmer tool inserted in the hole marked LCD.

At power-up the instrument goes through a self-test cycle

and the display shows the firmware revision number for a

few seconds. If any tests fail, the display will show a

message indicating the nature of the fault; if this happens,

refer to the Users Manual.

The display shown above is called the "main menu" and

shows the frequency (or period), amplitude, dc offset and

symmetry of the waveform. Other menus, called "edit

menus", are called when you press the EDIT key followed

by a MODE key.

If the main menu display is not as shown in figure 1 above

then you should reset all settings to their factory defaults.

Do this by pressing RECALL, then the numeric 0 key,

then ENTER.

Controls

Function Keys

These three keys are used

to choose between the

basic waveforms: sine,

square and triangular

waves, and pulses and

ramps of either polarity.

shx0008f.gif

Repeated presses of a key will cycle the selection through

the two or three choices offered. The associated LED will

light.

Getting Started

Controls and Connections

FIELD and DIGIT Keys and the Rotary Control

The FIELD keys move the

display cursor between

fields.

The fields in the display

shown in figure 1 above

are "FREQ=", "10.00000",

"kHz", "VhiZ=" and so on.

shx0004f.gif

Each field is one of three types: a parameter name, a

parameter value or a unit name.

The DIGIT keys work in different ways depending on

selected field type.

When the field contains a numeric parameter value the

DIGIT keys move the cursor right (less significant) or left

(more significant). The rotary control will then increment

or decrement the digit indicated.

When the field contains a unit name, the DIGIT keys have

the effect of multiplying or dividing the value by 10; they

simultaneously set the display of the value and its unit in

the most convenient engineering format. The rotary

control has the same effect.

Thus, for example, if you select kHz with the FIELD key,

successive presses of the right DIGIT key (or rotating the

knob clockwise) change the value and the units as follows:

10.00000kHz

100.0000kHz

1.000000MHz

10.00000MHz

When the field contains a parameter name, successive

presses of the DIGIT keys allow you to make a selection

from all the possible choices for that parameter. Again, the

rotary control has the same effect.

For example, with VhiZ selected in the start-up screen

above, successive presses of the right DIGIT key (or

rotating the knob clockwise) change the amplitude

displayed as follows:

VhiZ=+20.0 Vpp

VhiZ=+7.07 Vrms

V =+10.0 Vpp

V =+3.54 Vrms

OUT =+24.0dBm

All of these are equivalent representations of the output

amplitude, for a sine wave. If the waveform is not

sinusoidal then you can still display the rms values but the

dBm representation is excluded from the list.

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Getting Started Manual

Numeric, Units and SET Keys

You can use these keys to

enter parameter values

directly. For example, to

set the period to 125 µs,

select the first field (FREQ),

change it to period (PER)

by pressing a DIGIT key,

then enter 1, 2, 5, us on

the keypad.

shx0009f.gif

If the numeric value is dimensionless, for example a

BURST COUNT, the ENTER key terminates the entry;

otherwise it is terminated by the units key.

If you are editing one of the

parameters in the main

menu (frequency/period,

amplitude, dc offset or

symmetry) you can use one

of the SET keys to navigate

to the appropriate field

directly.

shx0007f.gif

The CE key clears the entry, one key press at a time.

The ESCAPE key abandons the current editing action.

In addition, if the display is of any menu other than the

main menu, the ESCAPE key will return you to the main

menu.

Getting Started

Controls and Connections

MODE Keys

Alternate presses of a MODE key will turn the mode

(TRIG, GATE, AM, etc.) on or off, and when the function is

on the associated lamp is lit.

If you press the EDIT key then press a MODE key you will

see the edit menu for that mode. The associated lamp

flashes when the edit menu is displayed.

Some of the modes share

keys with the numeric

keypad. For example, to

see the edit screens for

HOP mode, press EDIT

then the numeric 5 key.

To return to the main menu

from any edit menu, press

the ESCAPE key.

shx0010f.gif

UTILITIES Keys

The UTILITIES keys give

access to the STORE,

RECALL and REMOTE

edit menus. The instrument

can store up to nine set-ups

(numbered 1 to 9), and can

recall any of those plus

set-up 0 which is the factory

default set-up and is not

editable.

shx0011f.gif

The MAN/SYNC key is used for manual triggering and

synchronizing two or more generators when suitably

connected together. Further information on synchronizing

two generators is given in the Users Manual.

OUTPUT Key

The OUTPUT key turns the

MAIN OUT on and off.

When the output is on the

LED next to the key is lit.

The default state at power-

up is with the output off.

shx0018f.gif

271

Getting Started Manual

Front Panel Inputs and Outputs

MAIN OUT

MAIN OUT is the 50  or

600  output from the main

generator. It will provide up

to 20 V p-p into a high-

impedance load or 10 V p-p

into a matched 50  or

600  load. It can tolerate a

short circuit for 60 seconds.

shx0005f.gif

AUX OUT

The AUX OUT socket

provides a two-level TTL

and CMOS compatible

signal, synchronous with

the signal from the

MAIN OUT socket.

shx0006f.gif

The symmetry of the AU X OUT signal is the same as that

set for the main output but you can adjust the phase

relationship between MAIN OUT and AUX OU T using the

PHASE setting in the TRIG menu.

AUX OUT logic levels are nominally 0 V and 5 V from

typically 50 . AUX OUT will withstand a short-circuit.

EXT TRIG

EXT TRIG is the external

trigger input for the non-

continuous modes (trigger,

gate, sweep, FSK and hop)

and for synchronizing the

generator as a slave to an

external master generator.

shx0012f.gif

Getting Started

Controls and Connections

Rear Panel Connectors

CLOCK IN/OUT

This socket operates both

as an input and as an

output, depending on the

mode in which the

instrument is being used.

shx0013f.gif

As an input it can be used either to run the instrument

from an external master clock or as a synchronization

input when slaved to another instrument as the master.

As an output it provides the internal master clock or the

master synchronization output for another instrument as

the slave.

In both modes the levels are TTL and CMOS compatible.

VCA IN

This is the modulation input

for voltage controlled

amplitude (VCA). +2.5 V

will drive the amplitude to

100 % of its programmed

value. The input

impedance is approximately

6 k.

shx0013f.gif

Modulation is beyond the scope of this Getting Started

Manual but is covered in detail in chapter 8 of the Users

Manual.

SYNC OUT

This socket is used when

the instrument is the master

in a master-slave set-up. It

provides a signal to drive

the EXT TRIG front panel

input of the slaved

instrument.

shx0014f.gif

Master-slave operation is beyond the scope of this Getting

Started Manual but is covered in chapters 12 and 13 of the

Users Manual.

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Getting Started Manual

TRIG/SWEEP OUT

The TRIG/SWEEP output

socket provides both trigger

and marker signals,

depending on the

instrument's mode of

operation.

shx0016f.gif

Its primary use is for triggering an oscilloscope or other

recording device, but it can also provide z-axis bright-up

markers during sweep and frequency-hopping modes.

RS232 and GPIB Interface Connectors

These sockets are for

controlling the instrument

remotely, using a PC or

other controller device.

Remote control is beyond

the scope of this Getting

Started Manual, but is

covered in detail in chapter

16 of the Users Manual.

shx0017f.gif

Getting Started

Using the Instrument

While familiarizing yourself with the instrument you will find

it useful to observe the outputs on an oscilloscope. For

most purposes it is sufficient to connect the MAIN OUT

front panel socket to the oscilloscope's Y input, and the

AUX OUT front panel socket to the oscilloscope's trigger

input.

If no oscilloscope is available you can still learn a great

deal about the instrument settings, since the effect of

front-panel operations is visible in the LCD display in the

form of text messages, parameter information, menus and

status information.

Starting up

The ac supply on/off switch is located at the bottom left

side of the front panel.

Caution

Before connecting to the ac supply, check

that the supply voltage setting is correct for

the region. Please refer to the Users Manual

if it needs to be changed.

Plug in and switch on the instrument

On power-up the LCD panel illuminates and the

instrument performs a series of self tests. In the event

that an error message is displayed please refer to the

Users Manual.

Check the LCD Display

It should look similar to the main menu shown in figure 1.

If not, press RECALL, 0, ENTER to bring up the factory

default main menu.

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Getting Started Manual

Generating Continuous Signals

Select SINE on the function keys, if it is not already

selected.

If there is no signal at the oscilloscope input it will almost

certainly be because the generator's output is switched off.

If the lamp next to the MAIN OUT socket is not lit, press

the OUTPUT key. The AUX O U T socket is always on.

Press the right FIELD key to put the cursor in the numeric

part of the top line and move the cursor a couple of digits

to the right with the right DIGIT key. You can experiment

with the rotary control to adjust the frequency setting.

You can also experiment with entering frequencies using

the numeric keypad, and with using the DIGIT key to

adjust the frequency in decades; to do this, put the cursor

under the rightmost (units) field.

Set a frequency, for example 12.5 kHz

You can do this by either of the methods above.

The easiest is probably to key

FREQ/PER, 1, 2, ., 5, kHz, ENTER.

The display should look like this:

FREQ=12.50000kHz

VhiZ=+20.0 Vpp 50Ω

DC=+0.00mV (+0.00mV)

SYM=50.0% (50.0%)

You can also view and edit in terms of period.

Move the cursor into the first field and press one of the

DIGIT keys.

The display should change to:

PER =80.00000us

VhiZ=+20.0 Vpp 50Ω

DC=+0.00mV (+0.00mV)

SYM=50.0% (50.0%)

Getting Started

Using the Instrument

Set the amplitude to +10 dBm

You can do this by keying AMP L, 1, 0, dBm.

The display will now look like this:

PER =80.00000us

OUT =+10.0dBm 50Ω

DC=+0.00mV (+0.00mV)

SYM=50.0% (50.0%)

If you switch the amplitude display back to VhiZ you

should see:

PER =80.00000us

VhiZ=+4.00 Vpp 50Ω

DC=+0.00mV (+0.00mV)

SYM=50.0% (50.0%)

If you are using a 50  termination on the oscilloscope

input then the signal amplitude will be half the displayed

value, 2 V p-p.

Have a look at some other waveforms

Using the function keys you can select any of the

waveforms and observe them on the oscilloscope display.

Change the dc offset

If the output is still set to 4 V p-p then with the dc offset in

the fractional millivolts range you will not be able to see

changes on the oscilloscope, so the first thing to do is to

force a range change.

Do this by pressing the DC OFFSET key and entering

(say) 1.5 V.

You can then use the rotary control to adjust the waveform

offset in steps which depend on the cursor position. For

smoother control press the right DIGIT key.

PER =80.00000us

VhiZ=+4.00 Vpp 50Ω

DC=+1.50 V (+1.50 V)

SYM=50.0% (50.0%)

Note that with the cursor placed as shown, pressing the

+/- key will change the polarity of the offset voltage.

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Getting Started Manual

Effect of the output attenuator

The instrument has an output attenuator with fixed steps

of 20 dB. The attenuator follows the output stages so any

dc offset added to the waveform is subject to the

attenuator.

With the waveform amplitude set to 4 V p-p the attenuator

is switched out; however if you adjust the output to (say)

0.4 V p-p, 20 dB of attenuation is switched in. When this

happens you will be warned that the dc offset has been

changed.

Try it. Set the amplitude to 4 V p-p and the dc offset to

+1.5 V.

Now change the amplitude by pressing AMPL, 0.4, V. The

instrument will beep and you should see something like

this for a few seconds:

**** WARNING 07 ****

* DC OFFSET CHANGE *

* BY OUTPUT LEVEL *

********************

Then this:

PER =80.00000us

VhiZ=+4.00 Vpp 50Ω

DC=+1.50 V (+151.mV)

SYM=50.0% (50.0%)

The figure in brackets to the right of the programmed dc

offset is the value which results from the application of

20 dB of attenuation. It may differ slightly from the

calculated value (150 mV) because of the attenuator's

saved calibration factors.

Getting Started

Using the Instrument

Asymmetric waveforms

Symmetry adjustments work in much the same way as dc

offset adjustments. However, because of the lengthy

calculations which the instrument makes following a

change to the symmetry setting, you may find it easier to

use direct numeric entry rather than the rotary control.

Again, the symmetry of the output is displayed in brackets

at the right of the programmed value and in certain

circumstances the programmed and actual values may

differ. For example, at high output frequencies the

specification limits for symmetry are 20 to 80 % for a

square wave but 1 to 99 % for a sine wave. Full details are

given in the Specifications section in chapter 1 of the

Users Manual.

Adjusting the phase

The AUX O U T socket supplies a TTL and CMOS-

compatible (0/+4 V) reference signal against which you

can adjust the phase of the signal at the MAIN OUT

socket.

Return to the factory default settings by pressing

RECALL, 0, ENTER, then press the EDIT key followed by

TRIG.

The lamp next to the TRIG key will flash and you should

see a screen like this:

SOURCE=EXT

TGEN=1.00ms 1.000kHz

BURST COUNT= 0001

PHASE=+000° (+000°)

The instrument is still operating in continuous, not

triggered mode, so the settings for the trigger source, the

internal trigger generator and the burst count are not

relevant here. The only item on this menu which affects

continuous modes as well as triggered and gated modes

is the PHASE setting.

Move the cursor to the last digit of the phase numeric

value field and use the rotary control to move the phase of

the AUX O U T relative to that of the MAIN OUT.

SOURCE=EXT

TGEN=1.00ms 1.000kHz

BURST COUNT= 0001

PHASE=+116° (+116°)

You may want to trigger the oscilloscope from the

271

Getting Started Manual

instrument's AUX OUT socket in order to see the phase

effects more clearly.

There are some limitations on using the phase control at

frequencies above 30 kHz - chapter 5 of the Users Manual

explains these in detail.

Generating Swept Signals

The instrument has an independently-controlled internal

trigger generator which produces a square wave with a

period from 20 µs to 200 s (in 20 µs steps), corresponding

to a repetition frequency from 0.005 Hz to 50 kHz. In most

modes the signal is made available at the rear panel

TRIG/SWEEP OUT socket.

In sweep mode, the sweep begins on the negative edge of

the signal (the transition from +4 to 0 V; if you include

markers in the sweep set-up then each marker produces

an additional narrow +1 V pulse on the

TRIG/SWEEP OUT signal.

For this tutorial we will generate a logarithmic sine wave

sweep from 261.6 to 1108.7 Hz. This 2-octave range is

well within the limits of audibility, so you can listen on

headphones if you wish. Set the amplitude to about -

10 dBm or you may be surprised by the intensity.

The description "logarithmic" means that the sweep

spends an equal period at each note of the scale (and is a

misnomer because the rate of frequency increase with

time is in fact exponential).

The set up process is as follows:

Press RECALL, 0, ENTER to reset to the factory defaults.

Then press EDIT and SWEEP.

Getting Started

Using the Instrument

At this point the lamp next to the SWEEP key should be

flashing and the display should look like this:

MODE=BEG-END LAW=LOG

RAMP TIME=0.05 s

TRIG SRC=CONTINUOUS

MORE->>>

All these settings are fine except for the sweep time, which

is too short if you are listening to the signal.

Change the sweep time to, say, 5 seconds. When you

press the ENTER key the display will return to the main

menu, so press EDIT and SWEEP again and use the

FIELD key to move to the next screen.

MODE=BEG-END LAW=LOG

RAMP TIME=5.00 s

TRIG SRC=CONTINUOUS

MORE->>>

Now set the beginning and end frequencies. The

frequencies shown here correspond to a sweep of 2

octaves starting at middle C, with a marker in the middle of

the sweep.

BEG FRQ=261.6000 Hz

END FRQ=1.108700kHz

MARK FRQ=523.3000 Hz

MORE->>>

Now press the SWEEP key.

The sweep is generated continuously. You can reverse

the direction on the first sweep edit menu by changing

MODE=BEG-END to MODE=END-BEG.

You can also set up to initiate the sweep manually - do

this by changing TRIG SRC=CONTINUOUS to

TRIG SRC=MAN/REMOTE. Single sweeps are now

initiated by pressing the MAN/SYNC key.

Note that the settings for the internal trigger generator

have no bearing on the sweep in this instance.

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Generating a Triggered Burst

In this exercise you will use the internal trigger generator

to initiate a burst of 500 cycles of a 2 kHz tone twice every

second. The period of the internal trigger generator is thus

500 ms.

Press RECALL, 0, ENTER to reset to the factory defaults.

Then press EDIT and TRIG. The lamp next to the TRIG

key should flash and the display should show:

SOURCE=EXT

TGEN=1.00ms 1.000kHz

BURST COUNT=0001

PHASE=+000° (+000°)

Change the settings to:

SOURCE=TGEN [FREE]

TGEN=500.ms 2.000 Hz

BURST COUNT=0500

PHASE=+000° (+000°)

The word FREE against the SOURCE parameter

indicates that the internal trigger generator has not already

been assigned to some other function. If it had been, that

function would be shown in place of the word FREE.

Press ENTER, turn the output on and set the frequency on

the main menu to 2 kHz, which at that point will be a

continuous tone.

FREQ=2.000000kHz

VhiZ=+20.0 Vpp 50Ω

DC=+0.00mV (+0.00mV)

SYM=50.0% (50.0%)

Press TRIG to initiate the triggered burst mode.

To synchronize an oscilloscope to the trigger generator

(rather than to the burst waveform itself), connect the rear

panel TRIG/SWEEP OUT socket to the oscilloscope's

trigger input.

Again, by changing the trigger source to

TRIG SRC=MAN/REMOTE, you can initiate tone bursts by

pressing the MAN/SYNC key.

There are similar modes which use the internal trigger

generator as the source of trigger signals, and there are

gated (i.e. level-sensitive) modes which correspond to the

edge-sensitive triggered modes. The Users Manual

contains detailed information on these modes.

Getting Started

Using the Instrument

FSK Mode

The FSK (frequency shift keying) mode can also be driven

from the internal trigger generator. Setting up is very

straightforward; the following settings give a continuous

waveform which switches between 800 Hz and 1.2 kHz

twice every second.

The edit menu for the FSK mode includes the basic

settings for the trigger generator, so there is no need to

visit the trigger generator set-up screen itself. First, free

the internal trigger generator. This is most easily done by

returning to the factory default settings.

Press EDIT then FSK and enter the settings shown here:

FREQ A=800.0000 Hz

FREQ B=1.200000kHz

SOURCE=TGEN [FREE]

TGEN=250.ms 4.000 Hz

Then press FSK again to start the generator with the new

settings and turn the output on.

Special Waveforms

Staircases

The instrument can generate a staircase waveform with up

to 16 steps. To demonstrate the set-up process we will

create a signal that approximates a 625-line PAL TV line

signal. This is the signal applied to the Z-axis of the TV's

CRT to modulate the brightness of the spot.

The refresh rate in PAL TV is 25 Hz (40 ms), and the

screen is rasterized into 625 lines. Thus each line takes

64 µs and the line frequency is the inverse of this,

15.625 kHz.

By definition, the black level (called the "blanking level"

because it cuts off the electron beam completely) is 30 %

of peak amplitude and the white level is 100 %. These

levels usually correspond to +0.3 V and 1.0 V respectively.

The line sync pulse is negative-going and takes the level

down to 0 %. It is nominally 4.7 µs wide and it occurs in

the first few microseconds of the cycle, just before a

region called the "back porch" which precedes the scan.

The horizontal scan runs from 12.05 to 63.70 µs; outside

this period the CRT is blanked.

To produce an image on the TV screen we will divide the

scan period into five approximately equal segments and

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Getting Started Manual

set the levels to produce five monochrome stripes from left

to right: grey, white, grey, black and grey again.

Our line signal thus looks like the drawing below:

shx0019f.gif

Figure 2. 625-line PAL TV Signal

In the instrument the number of horizontal points which

make up the complete waveform is 1024, so the horizontal

steps must be scaled to the range 0-1023.

Similarly, the full-scale signal amplitude is defined by

values up to +511, so the vertical amplitudes must be

scaled to to the range 0-511.

We can produce a table of all nine steps of the waveform

(numbered 0 to 8), as follows:

Getting Started

Using the Instrument

step name start (µs)

amplitude

start

scaled to 0-1024 step

length amplitude

scaled to 0-511

0 0 30% 0 29 153

1 sync pulse 1.8 0% 29 75 0

2 back porch 6.5 30% 104 90 153

3 50% grey 12.1 65% 194 165 332

4 white 22.4 100% 358 165 511

5 50% grey 32.8 65% 525 165 332

6 black 43.1 30% 690 165 153

7 50% grey 53.4 65% 854 165 332

8 front porch 63.7 30% 1019 5 153

These values can now be entered in the staircase set-up

screens. Press EDIT then the STAIR key. You should

see this screen:

VALS=ABS AUTO=YES

STEP=00 ACTIVE

LENGTH=0256

LEVEL=+511

Change the length for the first step (00) to 29 and the level

to +153. If you use the numeric and ENTER keys to make

the change, the step number automatically increments

after the level has been entered.

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Getting Started Manual

The second screen appears:

VALS=ABS AUTO=YES

STEP=01 ACTIVE

LENGTH=0256

LEVEL=+000

Continue entering the pairs of length and level values in

the table until the last step (08).

This is the final screen in which the length and level have

been keyed in, immediately before the final press of the

ENTER key:

VALS=ABS AUTO=YES

STEP=08 ACTIVE

LENGTH=0005

LEVEL=+153

The remaining steps (9 to 15 inclusive) are all inactive.

Press ESCAPE to complete this part of the set-up. You

should see a brief display indicating that the instrument is

making some calculations on the new waveform.

When the calculations are complete the display will return

to the main menu, on which you can complete the set-up

by changing the amplitude to 1.0 V peak into 50  and the

frequency to 15.625 kHz (or the period to 64 µs).

To initiate the signal, turn the output on and press the

STAIR key.

Getting Started

Using the Instrument

Saving and Recalling Settings

Having done all this work it would be wise to save the

settings for future use. You can do this simply by pressing

the STORE key, followed by a number in the range 1 to 9

and the ENTER key. Store 0 is reserved for the factory

default settings. You can recall the set-up at any time

using the RECALL key.

Arbitrary Waveforms

Arbitrary waveforms are best defined on a PC and

downloaded to the instrument via the RS232 or GPIB

interface. Each is identified by a name with up to 16

characters.

Several commonly-used waveforms are available from the

internal read-only memory (ROM) and can be recalled by

pressing the EDIT then the ARB keys.

The display will look something like this:

RECALL ARB No: 14

SINX/X

ENTER TO EXECUTE

Or possibly like this:

RECALL ARB No: 03

ARB 03 IS EMPTY

ENTER TO EXECUTE

The ROM is used for the factory-preset waveforms 06 to

21 inclusive, and the internal non-volatile RAM is used for

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Getting Started Manual

arbitrary waveforms 01 to 05. These first five store

locations are available for waveforms downloaded from a

PC.

When you press the ENTER key the output switches to

the selected waveform but the display does not change;

press ESCAPE to return to the main menu, then press

ARB and switch the output on to initiate the signal.

Note that there are no facilities for storing waveforms

edited using the instrument itself. However, certain

waveforms, for example waveforms which emulate the

effect of passing sharp edges through low-pass filters, can

be generated without the aid of a computer. There are

some examples described in chapter 15, Application

Examples, of the Users Manual.

Other Functions and Waveforms

The instrument offers a number of additional capabilities

and features which are beyond the scope of this Getting

Started Manual. These include:

• Amplitude modulation

• Frequency hopping

• Phase locking

• Noise generation

• Synchronizing two or more generators in master-slave

mode

• Remote operation through the RS232 and GPIB

interfaces.

These are all covered in detail in the Users Manual.