Stanford Research Systems DS360 Operations Guide

Download

Operating Manual and Programming Reference

Model DS360 Ultra Low Distortion Function Generator

1290-D Reamwood Avenue

Sunnyvale, CA 94089 U.S.A.

Phone: (408) 744-9040, Fax: (408) 744-9049

email: infor@thinkSRS.com • www.thinkSRS.com

Revision 1.5 (June, 2001)

DS360 Ultra Low Distortion Function Generator Revision 1.5 (6/01)

Certification

Stanford Research Systems certifies that this product met its published specifications at the time of shipment. Stanford Research Systems further certifies that its calibration measurements are traceable to the United States National Institute of Standards and Technology (NIST).

Warranty

This Stanford Research Systems product is warranted against defects in materials and workmanship for a period of one (1) year from the date of shipment.

Service

For warranty service or repair, this product must be returned to a Stanford Research Systems authorized service facility. Contact Stanford Research Systems or an authorized representative before returning this product for repair.

Information in this document is subject to change without notice.

Stanford Research Systems, Inc. 1290-D Reamwood Avenue Sunnyvale, California 94089

Printed in USA

DS360 Ultra Low Distortion Function Generator

Safety and Preparation for Use

WARNING!

Dangerous voltages, capable of causing injury or death, are present in this instrument. Use extreme caution whenever the instrument is cover is removed. Do not remove the cover while the unit is plugged in to a live outlet.

Caution

This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set for the wrong AC line voltage, or if the wrong fuse is installed.

Line Voltage Selection

The DS360 operates from a 100, 120, 220 or 240 Vrms AC power source having a line frequency of 50 or 60 Hz. Before connecting the power cord to a power source, verify that the LINE VOLTAGE SELECTOR, located in the rear panel fuse holder, is set so that the correct AC input voltage is visible.

Line Fuse

Line Cord

Power Switch

Conversion to other AC input voltages requires a change in the fuse holder voltage card position and fuse value. Disconnect the power cord, open the fuse holder cover door and rotate the fuse-pull lever to remove the fuse. Remove the small printed circuit board and select the appropriate operating voltage by orienting the printed circuit board so that the desired voltage is visible when pushed firmly into its slot. Rotate the fuse-pull lever back into its normal position and insert the correct fuse into the fuse holder.

Verify that the correct fuse is installed before connecting the line cord. For 100/120 VAC, use a 1 Amp fuse and for 220/240 VAC use a 1/2 Amp fuse.

The DS360 has a detachable, three-wire power cord for connection to the power source and to a protective ground. The exposed metal parts of the instrument are connected to the outlet ground to protect against electrical shock. Always use an outlet which has a properly connected protective ground.

The power switch is located on the front panel of the unit, in the lower right hand corner. Turn on the unit by pressing the switch in.

Fan

The fan in the DS360 is required to maintain proper operation. Do not block the vents in the chassis or the unit may not operate properly.

DS360 Ultra Low Distortion Function Generator

Contents

Safety and Preparation For Use i Contents iii Table of Figures v Specifications vii Abridged Command List xi

Chapter 1 Getting Started

General Installation 1-3 Front Panel Operation 1-4 Continuous Waveforms 1-5 Frequency Sweeps 1-6 Tone Bursts 1-7

Chapter 2 Basics

Introduction 2-3 Front Panel Features 2-5 Rear Panel Features 2-12

iii

Chapter 3 Operation

Power On 3-3 Setting Functions 3-4 Output Configuration 3-9 Modify Functions 3-11 Instrument Setup 3-19 Troubleshooting 3-23

Chapter 4 Programming

Index of Commands 4-2 Introduction 4-5 Command Syntax 4-8 Function Output Commands 4-9 Digital Output Commands 4-12 Modify Function Commands 4-14 Setup and Control Commands 4-17 Status Reporting Commands 4-18 Hardware Test and Calibration Commands 4-19 Status Byte Definition 4-21 Example Programs 4-23

Chapter 5 Digital Output

Overview 5-3 DS360 Functions 5-4 Setting the Digital Output 5-7 Inactive Functions and Parameters 5-9 Default Settings 5-10

DS360 Ultra Low Distortion Function Generator

iv Contents

Chapter 6 Testing

Preparation for Testing 6-3 Front Panel Test 6-7 Self Test 6-8 Frequency Test 6-9 Amplitude Test 6-10 Harmonic Distortion 6-13 Waveform Test 6-15 Sweep Test 6-17 Burst Test 6-18 DC Offset Test 6-19 Output Impedance Test 6-21 DS360 Performance Test Record 6-23

Chapter 7 Circuitry

Overview 7-3 Digital Board Description 7-3 Analog Board Description 7-6 Front Panel Description 7-9 Programmable Resistor Board Description 7-9 Digital Board Parts List 7-11 Analog Board Parts List 7-16 Front Panel Parts List 7-29 Distortion Filter Parts List 7-33 Miscellaneous and Chassis Parts List 7-34 Digital Board Schematics DIG-1 to DIG-7 Analog Board Schematics ANA-1 to ANA-7 Front Panel Schematics FP-1 to FP-2 Programmable Resistor Board Schematics PROGR1

DS360 Ultra Low Distortion Function Generator

Table of Figures

Figure 2-1 Block Diagram 2-4 Figure 2-2 Front Panel 2-5 Figure 2-3 Keypad 2-6 Figure 2-4 Outputs 2-8 Figure 2-5 Indicators 2-9 Figure 2-6 Display 2-10 Figure 2-7 Rear Panel 2-12 Figure 2-8 Rear Outputs 2-13

Figure 6-1 Distortion Filter 6-5

DS360 Ultra Low Distortion Function Generator

Specifications

Waveforms

Sine Frequency 0.001 Hz to 200.000 kHz

vii

THD 1 V

Frequency

Unbalanced, 2 V

RMS

Typical Maximum

Balanced

RMS

0.001 Hz - 5.0 kHz < -110 dB -106 dB

5.0 kHz - 20.0 kHz < -104 dB -100 dB

20.0 kHz - 40.0 kHz < -100 dB -96 dB

40.0 kHz - 100.0 kHz < -90 dB -85 dB

100.0 kHz - 200.0 kHz < -76 dB -68 dB

THD 10 V

Frequency

Unbalanced, 20 V

RMS

Typical Maximum

Balanced

RMS

0.001 Hz - 5.0 kHz < -109 dB -105 dB

5.0 kHz - 20.0 kHz < -103 dB -99 dB

20.0 kHz - 40.0 kHz < -98 dB -93 dB

40.0 kHz - 100.0 kHz < -88 dB -83 dB

100.0 kHz - 200.0 kHz < -76 dB -68 dB

Square Frequency 0.001 Hz to 200 kHz

Rise Time 1.3 µs Even Harmonics <-60dBc (to 20 kHz)

White Noise Bandwidth DC to 200 kHz

Flatness < 1.0 dB pk-pk, 1 Hz to 100 kHz Crest Factor 11 dB

Pink Noise Bandwidth 10 Hz to 200 kHz

Flatness < 3.0 dB pk-pk, 20 Hz - 20 kHz

(measured using 1/3 octave analysis)

Crest Factor 12 dB

Bandwidth Limited Noise Bandwidth 100 Hz, 200 Hz, 400 Hz, 800 Hz,

1.6 kHz, 3.2 kHz, 6.4 kHz, 12.8 kHz,

25.6 kHz, 51.2 kHz, 102.4 kHz Center Frequency 0 Hz to 200.0 kHz, 200 Hz increments Flatness (in band) < 1.0 dB pk-pk Crest Factor Base Band (0 Hz Center Freq) 12 dB

Non Base Band 15 dB

DS360 Ultra Low Distortion Function Generator

viii

Two-Tone Type Sine-Sine, Sine-Square

Sine Frequency 0.001 Hz to 200.000 kHz Square Frequency 0.1 Hz to 5.0 kHz Square Resolution 2 digits SFDR >90 dB

Sine or Square Burst ON Cycles 1/2, 1 to 65534 cycles

Repetition Rate 1 to 65535 cycles Triggering Internal, External, Single, Externally Gated OFF Level 0.0 % - 100.0 % (of ON Level) OFF Resolution 0.1 % Max OFF Attenuation 1 kHz -90 dBc

10 kHz -70 dBc 100 kHz -58 dBc

White or Pink Noise Bursts ON Time 10µs - 599.9s

Repetition Time 20µs - 600s Triggering Internal, External, Single, Externally Gated OFF Level 0.0% - 100.0% (of ON Level) Resolution 0.1%

Sine or Square Sweeps Type Linear or Logarithmic

Range 0.001 Hz to 200.000 kHz Rate 0.01 Hz to 3.1 kHz Resolution 2 digits Flatness +/- 0.1 dB (1%)

Frequency

Resolution (unless otherwise specified) 6 digits or 1 mHz, whichever is larger Accuracy 25 ppm (0.0025%) + 4 mHz

from 20° to 40° C

Amplitude

Unbalanced Outputs

50Ω Load 5.0 µVpp - 14.4 Vpp 600Ω Load 5.0 µVpp - 20.0 Vpp Hi-Z Load 10.0 µVpp - 40.0 Vpp

Balanced Outputs

50 Ω Load 10 µVpp - 28.8 Vpp 150 Ω Load 10 µVpp - 28.8 Vpp 600Ω Load 10 µVpp - 40.0 Vpp Hi-Z Load 20 µVpp - 80.0 Vpp

Resolution V

or V

RMS

4 digits or 1µV, whichever is greater

dBm or dBV 0.1dB

Accuracy +/- 0.1 dB (1%)

DS360 Ultra Low Distortion Function Generator

Noise

Broadband Noise (for a 1 kHz sine wave into a high impedance).

40 Vpp - 1.26 Vpp <150 nV√Hz

1.26 Vpp - 126 mVpp <15 nV√Hz 126 mVpp - 12.6 mVpp <7.5 nV√Hz <12.6 mVpp <4 nV√Hz (Note: 4 nV√Hz is the measurement floor.)

Offset

Unbalanced Output 50Ω Load 0 - +/- 7.4 V

600Ω Load 0 - +/-10.0 V Hi-Z Load 0 - +/-20.0 V

Balanced Output Not Active Resolution 3 digits

Accuracy

(for all except pink noise) 1% +/- 25 mV for Vpp/2+Offset > 0.63V

1% +/- 2.5 mV for 0.63V > Vpp/2+Offset > 0.063V 1% +/- 250 µV for 63 mV > Vpp/2+Offset > 6.3 mV 1% +/- 25 µV for Vpp/2+Offset < 6.3 mV

Specifications ix

DC DC

(for pink noise) 1% +/- 200 mV for Vpp/2+Offset > 0.63V

1% +/- 20 mV for 0.63V > Vpp/2+Offset > 0.063V 1% +/- 2 mV for 63 mV > Vpp/2+Offset > 6.3 mV 1% +/- 200 µV for Vpp/2+Offset < 6.3 mV

Outputs

Configuration Balanced and Unbalanced Connectors Floating BNCs, banana plugs and XLR Jack

Source Impedance Balanced 50 Ω ± 3%

150 Ω ± 2% 600 Ω ± 1% Hi-Z (50 Ω ± 3%)

Unbalanced 50 Ω ± 3%

600 Ω ± 1% Hi-Z (25 Ω ± 1 Ω)

Maximum Floating Voltage +/- 40 V

Digital Output

Output Types Professional (AES-EBU) balanced XLR

Consumer (S/PDIF) RCA phone jack and optical

Sample Rate 32.0 kHz, 44.1 kHz and 48.0 kHz

Accuracy ±100ppm

Output Waveforms Sine and two sine 2-Tones Output Frequency 32.0 kHz Sample Rate: 0.001 Hz to 14.5 kHz

44.1 kHz Sample Rate: 0.001 Hz to 20.0 kHz

48.0 kHz Sample Rate: 0.001 Hz to 20.0 kHz

DS360 Ultra Low Distortion Function Generator

Frequency Resolution 6 digits or 1 mHz, which ever is greater Output Amplitude Range 0 % to 100 %,

Resolution 0.00001%

Number of bits per word AES-EBU 16 - 20

S/PDIF 16 only

Other Outputs

Sync TTL squarewave (same frequency and phase as output) Burst Out TTL pulse marks burst (TTL high for ON time) Trigger/Gate In TTL pulse starts sweep or burst. TTL hi activates gated burst. Sweep TTL pulse marks beginning of sweep

General

Computer Interface GPIB and RS-232 standard. All instrument functions can be

controlled over the interfaces. Size 17”W x 3.5”H x 16.25”D Weight 17 lbs. Warranty One year parts and labor on any defects in material or

workmanship.

DS360 Ultra Low Distortion Function Generator

Abridged Command List

Syntax

Commands which have a question mark in parentheses (?) after the mnemonic may be queried. Commands that have a question mark without parentheses ‘? ‘ may only be queried. Commands without a question mark may not be queried. Optional parameters are enclosed by {}.

Variables

i, j, k, n integers x real numbers

Function Output Control Commands

FUNC (?) i 4-9 0=sin, 1=sqr, 2=wht noise, 3=pink noise, 4=2Tone. FREQ (?) x 4-9 Sets Output Freq to x. AMPL (?) x 4-9 Sets Ampl to x; must include VP, VR, dB, dV or dm. OFFS (?) x 4-9 Sets Output Offset to x. OUTE (?) i 4-9 Output Enable (i=1), Disable (i=0). OUTM (?) i 4-9 Output Mode 0=unbal, 1=bal. TERM (?) i 4-10 RELA (?) i 4-10 Sets Relative Amplitude Mode ON (i=1) or OFF (i=0). STPE (?) i 4-10 Freq Step Enable (i=1) Disable (i=0). FSTP (?) x 4-10 Sets Freq Step to x. TTAA (?) x 4-10 Sets Tone A amp to x; must include VP, VR, dB, dV or dm. TTBA (?) x 4-11 Sets Tone B amp to x; must include VP, VR, dB, dV or dm. TTAF (?) x 4-11 Sets Tone A frequency to x. TTBF (?) x 4-11 Sets Tone B frequency to x. TTMD (?) i 4-11 Sets 2-Tone Mode to sine (i=0) or square (i=1).

Source Impedance 0=50Ω, 1=150Ω, 2=600Ω, 3=HiZ.

Digital Output Control Commands

FUNC (?) i 4-12 0=sin, 4=2Tone (1, 2, 3 not allowed in digital mode). DFRQ (?) x 4-12 Sets Digital Output Freq to x. DAMP (?) x 4-12 Sets Digital Ampl to x (in %). OUTD (?) i 4-12 Digital Output Enabled (i=1) or Disabled (i=0). DIGM (?) i 4-12 Digital Output Mode 0=Professional, 1=Consumer. DIGF (?) i 4-12 Digital Sampling Frequency 0=48 kHz, 1=44.1 kHz, 2=32 kHz. STPE (?) i 4-13 Freq Step Enable (i=1) Disable (i=0). FSTP (?) x 4-13 Sets Freq Step to x. DTAA (?) x 4-13 Sets Digital Tone A amp to x (in %). DTBA (?) x 4-13 Sets Digital Tone B amp to x (in %). DTAF (?) x 4-13 Sets Digital Tone A frequency to x. DTBF (?) x 4-13 Sets Digital Tone B frequency to x. DIGB (?) i 4-13

Modify Function Commands

*TRG 4-14 Triggers a single sweep or burst. MENA (?) i 4-14 Modify Function Enable (i=1) or Disable (i=0). MTYP (?) i 4-14 Sets the modify function type to Lin Swp, Log Swp, Burst, BWNoise

Sets Digital Number of Bits (16 ≤ i ≤ 20).

for i=0,1,2,3.

DS360 Ultra Low Distortion Function Generator

xii Abridged Command List

TSRC (?) i 4-14 Sets the trigger source to Int, Ext, Single or Gate for i=0,1,2,3. STFR (?) x 4-14 Sets Sweep Start Frequency to x. SPFR (?) x 4-14 Sets Sweep Stop Frequency to x. RATE (?) x 4-14 Sets Sweep Rate to x. BCNT (?) x 4-15 Sets Burst Count to x (i=.5, 1-65534). RCNT (?) i 4-15 Sets Burst Rate to i (i=1-65535). DPTH (?) x 4-15 Sets Burst Depth to x; must include DB or PR (%). NBCT (?) x 4-15 Sets Noise Burst Count to x. NRCT (?) x 4-15 Sets Noise Rate Count to x. BNDW (?) x 4-16 Sets Noise BW to 100, 200, 400, 1.6k, 3.2k, 6.4k, 12.8k, 25.6k, 51.2k,

102.4k.

CENF (?) i 4-16 Sets BW Noise Center Frequency to i.

Setup Control Commands

*IDN? 4-17 Returns the DS360 device identification string. *RCL i 4-17 Recalls stored setting number i (0 to 9). *SAV i 4-17 Saves the current instrument setting as setting number i (1 to 9). KEYS (?) i 4-17 Simulates the pressing of a front panel key.

Status Reporting Commands

*CLS 4-18 Clears all status registers. *ESE (?) i 4-18 Sets/Reads the Standard Event Status Byte Enable register. *ESR? {i} 4-18 Reads the value of the Standard Event Status register {or bit i only}. *PSC (?) i 4-18 Sets the value of the power on status clear bit. *SRE (?) i 4-18 Sets/Reads the Serial Poll Enable register. *STB? {i} 4-18 Reads the value of the Serial Poll Byte {or bit i only}. DENA (?) i 4-18 Sets/Reads the value of the DDS enable register. STAT? {i} 4-18 Reads the value of the DDS register {or bit i only}.

Hardware Test and Calibration Commands

*TST? 4-19 Starts self test and returns status when done. $FCL 4-19 Recalls the factory calibration bytes. $FIL (?) n 4-19 Sets the State variable Filter to the n-th filter. $NOF (?) n 4-19 Sets the filter mode to n (0,1 or 2). $PRE (?) n 4-19 Sets the DS360 pre-amplifier attenuators to range n (0 to 31). $PST (?) n 4-20 Sets the DS360 post-amplifier attenuators to range n (0 to3). $WRD (?) j,k 4-20 Sets the value of calibration word j to k.

DS360 Ultra Low Distortion Function Generator

Chapter 1

Getting Started

These examples are designed to acquaint the first time user with the DS360 Ultra Low Distortion Function Generator. The DS360 is a flexible generator, capable of producing continuous and modified waveforms of exceptionally low noise and distortion, and high frequency accuracy and resolution. The DS360 is also relatively easy to use; the following examples will lead you step-by-step through some typical uses.

These examples require an oscilloscope to observe the output waveforms.

In this Chapter

1-1

General Installation 1-3

Caution 1-3 Line Voltage Selection 1-3 Line Fuse 1-3 Line Cord 1-3 Power Switch 1-3 Fan 1-3

Front Panel Operation 1-4

Keypad 1-4 Knob 1-4

Continuous Waveforms 1-5

Frequency Sweeps 1-6

Tone Bursts 1-7

DS360 Ultra Low Distortion Function Generator

1-2 Getting Started

DS360 Ultra Low Distortion Function Generator

General Installation

Caution

This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set for the wrong AC line voltage or if the wrong fuse is installed.

Line Voltage Selection

Getting Started 1-3

Line Fuse

Line Cord

Power Switch

Fan

Verify that the correct fuse is installed before connecting the line cord. For 100/120 VAC, use a 1 Amp fuse and for 220/240 VAC use a 1/2 Amp fuse.

The power switch is located on the front panel of the unit, in the lower right hand corner. Turn on the unit by pressing the switch in.

The fan in the DS360 is required to maintain proper operation. Do not block the vents in the chassis or the unit may not operate properly.

DS360 Ultra Low Distortion Function Generator

1-4 Getting Started

Front Panel Operation

Parameters are set in the DS360 using the front panel keypad or the spin knob. Most parameters can be set directly from the keypad, although it is often more convenient to use the spin knob. Keys are referenced by brackets like this: [Key].

Keypad

Use the up and down arrow keys [∧], [∨] to change between functions. To set a parameter, press the key with the desired parameter on it, ([FREQ] for example, to set the frequency). The current value will be displayed. Most parameters are labeled on the key itself; other parameters are labeled above the key in gray. To display these values, first press the [SHIFT] key, then the desired key ([SHIFT] [TRIG SRC] to set the trigger source). To change the value, press the appropriate numeric keys, followed by the correct units key. If the value has no particular units, any of the units keys may be used. If an error is made, press the [CLR] key to return to the current value. If the value entered is outside the allowable limits the DS360 will beep and display an error message.

Knob

The spin knob can be used to modify most parameters. Display the current value as described for the keypad and turn the knob to increment or decrement the parameter. The decade that is being incremented (or decremented) will flash. To change the decade that is being modified, use the left and right cursor keys [< ], [ >].

DS360 Ultra Low Distortion Function Generator

Continuous W aveforms

This section discribes how to set up different continuous waveforms, like sinewaves, squarewave or noise. Connect the PLUS (+) output to an oscilloscope to observe the waveforms.

1-5

1. Turn the unit on while holding down [CLR].

Wait until the power-on tests are completed.

2. Press the [AMPL] key. Press [1][Vpp]. Press the [FREQ] key. Press [2][kHz].

(Or turn the spin knob until the frequency reads

2.00 kHz)

3. Press the left cursor [<] key several times until

the kHz position is flashing. Turn the spin knob until the frequency reads 10.0000 kHz.

Press the function down [∨] key once. Press the [OFFSET] key. Press [1][VDC].

4. Press the function down [∨] key once. Press the [OFFSET] key. Press [0][VDC]. Press the [AMPL] key. Press [1][Vrms].

When the power is turned on with the [CLR] key depressed, the unit returns to its default settings. This places the unit in a known state. Set the DS360 for a 1 Vpp, 2 kHz sinewave.

The oscilloscope should show a 2 kHz sinewave with a 1 Vpp amplitude.

Set the DS360 for a 1 Vpp, 10 kHz, squarewave.

The oscilloscope should show a 10 kHz, 1 Vpp squarewave.

A 1 VDC offset should be added to the waveform.

Set the DS360 for 1 Vrms white noise with no offset.

The oscilloscope should show a noisy waveform of about 7 Vpp.

DS360 Ultra Low Distortion Function Generator

1-6

Frequency Sweeps

This section discribes how to set up a linear or logarithmic frequency sweep. The DS360 can sweep the output frequency of sine and square waves over any range of allowable frequencies. There are no restrictions on minimum or maximum sweep span. The sweep rate may range from 0.01Hz (100 s) to

3.1kHz (0.32 ms). Sweeps can be triggered from the internal rate generator, an external rate, the front panel or over the computer interface. The DS360 has a TTL sweep signal BNC on the rear panel that marks the beginning of a sweep. Connect the SWEEP OUT BNC on the rear panel of the DS360 to the second channel of the oscilloscope and set it to 2 V/div. The oscilloscope should be set to 0.2 ms/div and to trigger on the rising edge of this signal.

1. Press [RCL][0].

2. Press the modify function down [∨] key once. Press the [ON/OFF] key in the MODIFY FUNC

area.

3. Press the modify function up [∧] key once. Press the [RATE][2][kHz] keys. Press the [START][1][0][0][Hz] keys.

Press the [STOP][1][0][kHz] keys.

4. Press the function down [∨] key.

This places the DS360 in its default state.

Set DS360 for a logarithmic, 1kHz sweep of a sinewave.

The oscilloscope should show two periods of a 1 ms long log sweep.

Set the DS360 for a 2kHz linear sweep, with a start frequency of 100 Hz and a stop frequency of 10 kHz.

The oscilloscope should show 4 periods of a 0.5 ms long linear sweep.

Change the output wave form to a square wave.

The oscilloscope should show the same frequency sweep of a squarewave.

DS360 Ultra Low Distortion Function Generator

Tone Bursts

This section discribes how to set up tone bursts. The DS360 can produce a tone burst of between 1 and 65534 cycles of sine or square waves with a repetition rate of between 1 and 65535 cycles. It can also produce bursts of noise. Bursts are generated by synchronously gating the output at zero crossings. The “on” level of a burst may be any allowable output voltage; the “off” level can be set between 0 and 100% of the “on” level in 0.1% increments. Bursts can be triggered from the internal rate generator, an external rate, the front panel or over the computer interface. They can also be gated from an external source. The DS360 has a TTL burst signal BNC on the rear panel that is high for the duration of the on level of a burst and low otherwise. Connect the BURST OUT BNC on the rear panel of the DS360 to the second channel of the oscilloscope and set it to 2 V/div. The oscilloscope should be set to 1 ms/div and to trigger on the rising edge of this signal.

1-7

1. Press [RCL][0].

2. Press the modify function down [∨] key twice.

Press the [RATE] key, then [8][units key]. Press the [SHIFT][RATE] keys, then [3][units key] Press the [SHIFT][DEPTH] keys, then [1][0][%].

3. Press the modify function [ON/OFF] key. The oscilloscope should show an 8 cycle burst,

4. Press the [SHIFT][DEPTH] keys, then [0][%]. Set the DS360 to 0% “off” level.

5. Press the [RATE] key, then [1][2][units key]. Observe that repetition rate is 12 cycles.

6. Press the [SHIFT][RATE] keys, then [5]

[units key].

This places the DS360 in its default state.

Set the DS360 to generate a 3 cycle burst, repeating every 8 cycles, with a 10% off level.

Any of the 4 units keys can be used.

with 3 on cycles and 5 off cycles at 10% of the “on” level.

Observe that the “off” level is now totally flat.

Observe that the “on” time is now 5 cycles.

7. Press the [FREQ] key, then [4][kHz] key. Observe that the frequency changed, however the

relative “on” and “off” times haven’t changed.

DS360 Ultra Low Distortion Function Generator

1-8

DS360 Ultra Low Distortion Function Generator

2-1

Chapter 2

Basics

In this Chapter

Introduction 2-3

Traditional Function Generators 2-3 DS360 Function Generator 2-3

Front Panel Features 2-5

Power Switch 2-5 Reset 2-5 Spin Knob 2-5 Keypad 2-6 Function Output 2-8 Auxiliary Outputs 2-8 Indicators 2-9 Display 2-11

Rear Panel Features 2-12

Power Entry Module 2-12 Auxiliary Outputs 2-13 Computer Interfaces 2-13

DS360 Ultra Low Distortion Function Generator

2-2 Basics

DS360 Ultra Low Distortion Function Generator

2-3

Introduction to Precision W aveform Synthesis

The DS360 uses Direct Digital Synthesis and analog signal processing to generate an extremely pure sinewave with extraordinary frequency resolution and stability. Traditional function generators typically use one of several methods to generate sinewaves, each having one or more major limitations.

Traditional Generators

Frequency synthesized function generators typically use a phase-locked loop (PLL) to lock to a stable reference, and use wave shaping circuits to produce the desired function. This solution often has limited frequency resolution. Typically frequency resolution is limited to about 1:10 Distortion performance is limited due to the wave shaping circuits, often to as low as

-40dB.

Arbitrary function generators eliminate the need for wave-shaping circuitry. Normally a PLL is used to create a variable clock that increments an address counter. This counter addresses memory location in a waveform RAM that produces data for a DAC. This waveform RAM can be filled with any data, to create “arbitrary” waveforms, as well as sines, squares or other common waveforms. Since this is a sampled data system, it requires an anti-imaging filter to create an accurate waveform. Sampling theory states that a waveform can be accurately reproduced, as long as it is sampled more than twice as fast as its highest frequency component. Since arbitrary function generators vary their clock frequency, they must also modify their output anti-imaging filter.

(some advanced PLL circuits have much higher resolution).

Direct digital synthesis, a relatively new technique, overcomes many of these problems. DDS works by generating addresses to a waveform RAM to produce data for a DAC. Unlike PLL based techniques, the clock is a fixed frequency reference. Instead of using a counter to generate addresses, an adder is used. On each clock cycle, the contents of a Phase Increment Register is added to the contents of the Phase Accumulator. The output of the Phase Accumulator is the address to the waveform RAM. By changing the value of the Phase Increment, the number of cycles required to step through the entire waveform RAM changes, thus changing the output frequency. Since a fixed frequency clock is used, only one anti-imaging filter is required. This technique features excellent frequency resolution, as good as 1:10

-70dB.

Low distortion oscillators normally use some variety of R-C circuit in a Wein Bridge configuration to generate a pure, low distortion sinewave. This solution suffers from poor frequency accuracy, resolution and stability, due to component aging and drift. Frequency stability and accuracy for these oscillators is normally measured in 100’s to 1000’s of PPM. Frequency resolution is typically between 0.1% to 1%. This technique features excellent distortion performance, as low as -100 dB or better.

and reasonable distortion performance, down to

DS360 Ultra Low Distortion Function Generator

2-4 Introduction

DDS with Advanced Signal Processing

A block diagram for the DS360 is shown in Figure 1. The DS360 utilizes direct digital synthesis to generate its basic waveform. A Motorola DSP56002 advanced 24 bit digital signal processor (DSP) acts as the phase accumulator and contains the internal waveform RAM. The DSP chip gives the DS360 exceptional flexibility for generation of different waveforms. A 32.333 MHz, 25 PPM crystal provides all clocking information for the DS360, giving it exceptional frequency stability.

The DSP waveform RAM feeds an ultra low distortion 20 bit DAC, which is followed by

a 7

order Cauer anti-imaging filter to accurately reconstruct the sampled waveforms. For sinewave generation, this is followed by a distortion reduction filter, that removes nearly all of the remaining distortion components of the waveform. The output of this filter passes through the fine amplitude control and to the low distortion balanced / unbalanced power amplifier. The power amplifier is capable of generating a 40 Vpp sinewave, with about -100dB of distortion in the unbalanced configuration and superior performance at lower amplitudes. Finally the signal passes through output attenuators, capable of 0, -20, -40 or -60 dB of attenuation.

Other waveforms follow slightly different paths. White noise skips the distortion reduction filters, while pink noise adds the pink noise filter. Squarewaves and the waveform sync signal are generated by discriminating the function with a high speed comparitor. Burst signals are generated by passing any of the waveforms through the burst DACs.

Main CPU

Display

Keys

Interfaces

56002

DSP Chip

20 bit D/A

Anti

Imaging

Filter

Distortion

Reduction

Filters

Comparator

Sine

Square

Burst Control

Logic

Burst Level

Fine Amplitude

Control

Figure 2-1 DS360 Block Diagram

DS360 Ultra Low Distortion Function Generator

Burst

Normal

Power

Amplifier

Course

Attenuators

Attenuator

Source

Resistors

Sync

Front Panel Features

OUTPUT

IMPEDANCE

SRS

STANFORD RESEARCH SYSTEMS

MODEL DS360 ULTRA LOW DISTORTION FUNCTION GENERATOR

BNC OUTPUT

40V max.

XLR OUTPUT

–

JACK OUTPUT

–

Power Switch

The power for the DS360 is turned on by depressing the power button. After turning the power on the LED display will display the units serial number for about 2 seconds, perform the internal self tests and begin operation.

40 VDC MAX.

COMMON

GROUND

STATUS REM SRQ ACT ERR

TRIG'D

SYNC OUT

TRIGGER/GATE IN

TRIGGER

OFF

EXT

150 600

SINGLE

HI Z

GATE

WHT NOISE

TTL

PINK NOISE

2-TONE

TTL

OFFSET

AMPL

INT

FREQ

STP/BWSTR/C

REL

TONE 2TONE1

DEPTH

TRIGRCOUNT

FUNCTION

RATE

OUTPUT

SECONDARY MODIFYENTRY

SWP/BURST

LIN SWP

UNBAL

FREQ

AMPL

OFFST

ON/OFF

LOG SWP

BURST

BAL

TRIG SRC

BW NOISE

START

DIGITAL

CENTER

DEPTH

STOP

BURST CNT

TRIGR

RATE

Figure 2-2 Front Panel

SHIFT

50 150 600 SHIFT STO RCL CLR F STEP F STEP ENA DIG FREQ # BITS

+/-

GPIB RS232

T2 MODE

CAL SRQ

T1/T2

DIG 1 DIG 2 DIG 3

2-5

Hz dB

Vp-p

kHz dBV

VDC

% dBm

Vrms

LOCAL

HI Z Vrms

DIG MODE

Vpp/DC

DIG 0

DISP REL

dBm

REL

kHz

dBV

POWER

ON/STBY

Reset

Spin Knob

Caution

This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set for the wrong AC line voltage or if the wrong fuse is installed.

Turn on the power while holding down the clear [CLR] key and continue to hold it for at least 2 seconds to reset the unit. The unit will perform power on tests and assume the default settings. Any stored settings will be lost.

The spin knob is used to modify the parameter currently displayed on the DS360 display. The flashing digit indicates which digit is being incremented. The knob will modify all numeric parameters, as well as parameters which have a list of choices.

DS360 Ultra Low Distortion Function Generator

2-6 Front Panel Features

Keypad

FUNCTION

WHT NOISE PINK NOISE

2-TONE

FREQ

AMPL

OFFST

ON/OFF

OUTPUT

UNBAL

BAL

DIGITAL

(SHIFT)

TRIGR

Function Keys

These keys control the main function output. The [∧] up and [∨] down function keys select between the main output functions. [FREQ], [AMPL] and [OFFST] select the output frequency, amplitude and DC offset voltage. [ON/OFF] turns the output on and off.

Output Selection Key

SECONDARY MODIFYENTRY

LIN SWP

LOG SWP

BURST

BW NOISE

SWP/BURST

ON/OFF

TRIG SRC

START

CENTER

DEPTH

STOP

BURST CNT

RATE

SHIFT

SHIFT STO RCL CLR

F STEP F STEP ENA DIG FREQ # BITS

+/-

GPIB RS232 CAL SRQ

T2 MODE

50 150 600

T1/T2

Figure 2-3 Keypad

HI Z

Vrms

DIG MODE

DIG 1 DIG 2 DIG 3

Vpp/DC

DIG 0

dBm

kHz

dBV

LOCAL

DISP REL

REL

The [∨] key changes the output configuration from one of the three choices: unbalanced, balanced and digital. Pressing the [∨] once moves one entry down the list; pressing the [SHIFT](∧) moves one entry up the list.

Trigger Key

The [TRIGR] key begins singly triggered modified functions, like single sweeps or bursts.

Modify Function Keys

These keys control the function output modification commands for sweeps, bursts or bandwidth limited noise. The [∧] up arrow and [∨] down arrow keys select the modification type. The [SWP/BURST] key turns the modification function on and off. The other keys select different function modification parameters (start frequency, burst depth).

Only modify functions that are allowable for the current function type (sine, square, noise...) can be selected (i.e. sweep can be selected for sine or square, but not white noise). Only modify parameters (START FREQ, STOP FREQ ...) that are valid for the selected modify function can be changed. If a currently invalid modify parameter is selected, the unit will beep and display “not APPL” (not applicable). If a function type

DS360 Ultra Low Distortion Function Generator

Shift Key

Numeric Keys

Front Panel Features 2-7

change causes the currently displayed modify function to become invalid, the display will revert to the frequency [FREQ] display.

The [SHIFT] key is used to select functions printed above the keys. Press the [SHIFT] followed by the [function] key to select the desired function. When the shift key is pressed, the shift LED will light. This indicates that the keypad is in “shifted” mode. Pressing [SHIFT] a second time will deactivate shift mode. Note that in the manual,

whenever [SHIFT] is indicated, the desired function is printed above the key, not on the key itself.

The numeric keypad allows for direct entry of the DS360’s parameters. To change a parameter value, type the new value, followed by one of the [units] keys. A typing error may be corrected by pressing the [CLR] key, which recalls the old value. The [+/-] key may be selected at any time during numeric entry.

Units Keys

Cursor Keys

Rel Key

The units are used to terminate numeric entries. Press the key with the desired units to enter the typed value. Some parameters have no particular units and any of the units keys may be used. When the amplitude is displayed, pressing one of the units keys will cause the display to change the units to the type pressed. This means that the amplitude display can changed from Vpp, Vrms, dBm and dBV without entering a new value.

The [>] cursor right and [<] cursor left keys move the flashing digit to the right and left of the display. They also switch between parameters which have a list of choices.

The [REL] key changes the amplitude display to the relative display mode. The amplitude is displayed in dB relative to the value when [REL] was pressed. Pressing [REL] a second time changes the amplitude display back to normal. Pressing [SHIFT][REL] shows the Vpp amplitude that the display is rel’d to.

DS360 Ultra Low Distortion Function Generator

2-8 Front Panel Features

Outputs

BNC OUTPUT

XLR OUTPUT

JACK OUTPUT

–

40V max.

Function Output

The three output types are connected in parallel. There are three separate sets of output connectors: BNC, XLR and banana plugs. The different output signals are the positive output, negative output, common and chassis ground. The connectors are configured as listed below.

Function Output Connections

Output Signal BNC Connection XLR Connection Banana Plug

Positive Output

Negative Output

Common Both BNC Shields Pin 1 Common (black) jack

Ground Pin 4 Ground (green) jack

+ BNC Center contact

- BNC Center contact

–

Figure 2-4 Outputs

Pin 2 + (red) jack Pin 3 - (white) jack

COMMON

40 VDC MAX.

GROUND

TRIGGER/GATE IN

SYNC OUT

TTL

The positive and negative outputs are both referenced to the common, which may be floated +/-40 V selectable. If the output is terminated into an incorrect impedance the output amplitude will be incorrect and may exhibit increased distortion.

from the chassis ground. The output impedance of the outputs is

Sync Output BNC

This output is a squarewave synchronized to the main function output. Its shield is connected to chassis ground and cannot be floated.

Trigger / Gate In BNC

A low to high TTL signal on this input begins externally triggered bursts and sweeps. For gated output, a TTL high gates the output on and a TTL low gates the output off. The BNC shield is connected to chassis ground and cannot be floated.

DS360 Ultra Low Distortion Function Generator

Indicators

Front Panel Features 2-9

STATUS

REM SRQ

ACT ERR

OUTPUT

OFF

TRIG'D

IMPEDANCE

50 150 600

HI Z

Figure 2-5 Indicator LED’s

Status LEDs

These 4 LEDs indicate the DS360’s status.

Status LEDs

Name Function

REM

The DS360 is in GPIB remote status. The [>] cursor right key returns local control.

SRQ The DS360 has requested service on the GPIB.

ACT Flashes for RS232 or GPIB activity. ERR Flashes on error in a command.

Configuration LEDs

These LEDs indicate the output configuration, source impedance and triggering mode of the DS360.

TRIGGER

INT

EXT

SINGLE

GATE

FREQ

AMPL

STP/BWSTR/C

TONE 2TONE1

TRIGRCOUNT

OFFSET

REL

DEPTH

RATE

Configuration LEDs

Heading Display LED Parameter

OUTPUT ON

OFF TRIG’D

IMPEDANCE 50

150 600 Hi-Z

TRIGGER INT

EXT SINGLE GATE

Output On Output Off

Sweep or Burst Triggered 50 Ω Output Impedance 150 Ω Output Impedance 600 Ω Output Impedance

Hi-Z Output Impedance Internal Trigger for Sweeps or bursts External Trigger for Sweeps or Bursts Single Trigger for Sweeps or Bursts External Gate for Bursts only

DS360 Ultra Low Distortion Function Generator

2-10 Front Panel Features

Parameter LEDs

These LEDs indicate which parameter is currently displayed in the parameter display.

Parameter LEDs

Display LED Parameter

FREQ Output Frequency AMPL Output Amplitude OFFSET Output Offset STARTF Start Frequency for Sweeps

Center Frequency for Bandwidth Limited Noise

STOPF Stop Frequency for Sweeps

Cutoff Frequency for Bandwidth Limited Noise

REL Indicates that the amplitude display is in REL mode. Does not indicate a specific

display.

TONE1 Indicates that Amplitude and Frequency Displays refer to TONE 1. Does not

indicate a specific display.

TONE2 Indicates that Amplitude and Frequency Displays refer to TONE 2. Does not

indicate a specific display.

DEPTH Off Level Depth for Bursts COUNT Burst Count for Bursts TRIGR Trigger Source for Sweeps and Bursts RATE Burst Rate for Bursts

DS360 Ultra Low Distortion Function Generator

Display

Front Panel Features 2-11

Parameter Display

This 8 digit display shows the value of the currently displayed parameter. Error, status messages and configuration information may also appear on the display.

Units LEDs

These LEDs indicate the units of the displayed value. If no LED is lit the number displayed has no units or is seconds (for noise bursts).

Display LED Meaning

Vrms V

Figure 2-6 Display

Units LEDs

Hz Hertz dB dB relative to preset value

P-P

kHz Kilohertz

dBV dB relative to 1 V

% % (used with BURST DEPTH)

dBm dB relative to 1mW into selected source impedance

Volts Peak-to-Peak

Volts DC

RMS

into selected source impedance

RMS

Hz dB

kHz dBV

%dBm

Vp-p VDC Vrms

DS360 Ultra Low Distortion Function Generator

2-12

Rear Panel Features

Power Entry Module

The power entry module is used to fuse the AC line, select the line voltage and block high frequency noise from entering or exiting the instrument. The DS360 uses a detachable three wire power cord for connection to the power source and the protective ground. All exposed metal parts of the unit are tied to the outlet ground to protect against electrical shock. Always use an outlet which has a properly connected protective ground.

Caution

CHASSIS GROUND

AES/EBU

COAX OPTICAL

SPDIF

DIGITAL OUTPUT

FUSE

PULL

LINE : 48-66 Hz FUSE : 1/2 A @ 100/120V 1/4 A @ 220/240V

STANFORD RESEARCH SYSTEMS MODEL DS360 ULTRA LOW DISTORTION

SRS

FUNCTION GENERATOR. MADE IN U.S.A.

Verify that the LINE VOLTAGE SELECTOR card is set so the correct AC input voltage value is visible. For continued protection against fire hazard

SWEEP OUT BURST TRIG OUT

WARNING

USE CORRECT FUSE.

WARNING

No user serviceable parts inside. Refer to user manual for safety notice. Service by qualified personnel only.

IEEE-488 STD PORT

RS232 (DCE)

Figure 2-7 Rear Panel

This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set to the wrong AC line voltage, or if the wrong fuse is installed.

Do not attempt to service or adjust this instrument while it is plugged into a live outlet.

Line Voltage Selection

The DS360 operates from a 100, 120, 220 or 240 V having a line frequency of 50 or 60 Hz. Before connecting the power cord to a power source, verify that the LINE VOLTAGE SELECTOR card, located in the rear panel fuse holder, is set so the correct AC input voltage is visible.

Conversion to other AC sources requires a change in the fuseholder voltage card position and fuse value. Disconnect the power cord, open the fuse holder and rotate the fuse lever to remove the fuse. Remove the small printed circuit board and select the operating voltage by orienting it so the correct voltage is visible when pushed back into its slot. Rotate the fuse-pull lever back to its normal position and insert the correct fuse into the holder.

nominal AC power source

RMS

Line Fuse

Verify that the correct fuse is installed before connecting the line cord. For 100/120 V

use a 1 amp fuse. For 220/240 V

RMS

use a 1/2 amp fuse.

RMS

DS360 Ultra Low Distortion Function Generator

Outputs and Computer Interface

WARNING

Verify that the LINE VOLTAGE SELECTOR card is set so the correct AC input voltage value is visible. For continued protection against fire hazard

USE CORRECT FUSE.

Rear Panel Features 2-13

AES/EBU

COAX OPTICAL

DIGITAL OUTPUT

AES-EBU

The AES-EBU (XLR) interface supports the professional digital audio interface format (IEC-958) and can transmit 16-20 bit wide data at data rates of 32, 44.1 and 48 kHz.

S/PDIF

The SPDIF/EIAJ coax and fiber optic outputs support the Sony-Philips Digital Interface and EIAJ digital audio data formats. The transmitter sends 16 bit wide data at 32, 44.1 and 48 kHz.

IEEE-488 Connector

SWEEP OUT BURST TRIG OUT

SPDIF

Figure 2-8 Digital Outputs & Computer Interfaces

The 24 pin IEEE-488 connector allows a host computer to control the DS360 via the IEEE-488 (GPIB) instrument bus. The GPIB address of the unit is accessed by pressing [SHIFT][GPIB]. The [>] cursor right key is the instrument “local” key.

Serial RS232 Connector

The RS232 interface connector is configured as a DCE (transmit on pin 3, receive on pin

2). The Baud Rate is accessed by pressing [SHIFT][RS232]. The interface parameters are: word length 8 bits, no parity and 2 stop bits.

Sweep Out

This output generates a short TTL pulse at the beginning of each sweep. It can be used to synchronize an external device to a sweep. Its shield is connected to chassis ground and cannot be floated.

DS360 Ultra Low Distortion Function Generator

2-14 Rear Panel Features

Burst Out

This TTL output goes high for the “ON” portion of a burst and low for the “OFF” portion. It can be used to synchronize an external device to a burst. Its shield is connected to chassis ground and cannot be floated.

DS360 Ultra Low Distortion Function Generator

3-1

Chapter 3

Operation

The following sections describe the operation of the DS360. The first section describes the basics of setting a function, including setting the function type, amplitude, frequency and offset. The second section explains setting the output configuration, including the output type and source impedance. The third section explains sweeps, bursts and bandwidth limited noise. The final section explains storing and recalling setups, running self tests and setting up the computer interfaces.

In this Chapter

Power On 3-3

Caution 1-3 Reset 1-3

Setting Functions 3-4

Function Type 3-4 Frequency 3-4 Amplitude 3-5 Unbalanced Amplitude Ranges 3-6 Balanced Amplitude Ranges 3-7 Offset 3-8 Function On/Off 3-8

Output Configuration

3-9

Output Type 3-9 Source Impedance 3-10

Modify Function 3-11

Modify Function Type 3-11 Modify Function On/Off 3-11 Modify Function Parameters 3-11 Sweeps 3-11 Bursts 3-13 Bandwidth Limited Noise 3-16

Instrument Setup 3-19

Default Settings 3-19 Storing and Recalling Settings 3-19 GPIB Setup 3-20 SRQ 3-20 RS-232 Setup 3-20 Self Tests 3-21

DS360 Ultra Low Distortion Function Generator

3-2 Operation

Troubleshooting 3-23

GPIB Problems 3-23 RS232 Problems 3-23 Error Messages 3-24 Operational Messages 3-25

DS360 Ultra Low Distortion Function Generator

Power On

When power is first applied to the DS360 the unit will display its serial number and ROM version. Next the DS360 will initiate a series of self-tests of the internal circuitry and stored data. The test should take about 3 seconds and end with the message “TEST PASS”. If the self-test fails the DS360 will display an error message indicating the nature of the fault (see the TROUBLESHOOTING section at the end of this chapter for more details). The unit will attempt to operate normally after a self test failure; press any key to clear the error message.

Caution

This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set for the wrong AC line voltage or if the wrong fuse is installed.

Reset

3-3

Turn the power on while holding down the [CLR] key and continue to hold it down for at least 1 second to reset the unit. The unit will perform its self-tests and assume its default settings.

Attention

The DS360 has two distinct modes: analog and digital. These are selected as described in the output configuration section. When the unit is in one mode (digital or analog), parameters of the other mode cannot be selected or quarried from either the front panel or the computer interface. This chapter describes the operation of the analog mode; for information on the digital mode, see Chapter 5.

DS360 Ultra Low Distortion Function Generator

3-4

Setting Functions

The following section describes how to set the parameters for the basic functions of the DS360, including function type, frequency, amplitude, offset and function on/off.

Function Type

The DS360 output function type is selected using the [∧] up and [∨] down function arrow keys. Press the appropriate key until the desired function LED is lit. The peak-topeak amplitude will remain the same between different functions. If the amplitude is displayed in any other units, they will be adjusted to reflect a constant peak-to-peak voltage. If the modify function is enabled and the type is incompatible with the new function, the modify function will be changed to a legal value (the parameters will remain unchanged).

The available functions are sinewaves, squarewaves, white noise, pink noise and twotones. Sinewaves and squarewaves are self explanatory. White Noise is a Gaussian weighted distribution, filtered to 200 kHz and is flat in amplitude over that region. Pink Noise extends from 10 Hz to 200 kHz with a -3 dB/octave amplitude response. There are two types of 2-Tones; sine-sine 2-tones and sine-square 2-tones. To display the current mode, press [SHIFT][T2 MODE]. To change modes, press the [>] right or [<] cursor key, or turn the spin knob. When in 2-Tone, only one set of parameters (amplitude, frequency) are available at a time. To toggle between displaying Tone 1 and Tone 2 parameters, press [SHIFT][T1/T2].

Frequency

The frequency ranges and resolution are shown in the table below.

Frequency Range of Functions

Function Frequency Range Frequency Resolution

Sinewaves 0.001 Hz - 200.000 kHz 0.001 Hz or 6 digits Squarewaves 0.001 Hz - 200.000 kHz 0.001 Hz or 6 digits White Noise 200 kHz White Noise (fixed) Pink Noise 200 kHz Pink Noise (fixed) Sine-Sine Two-Tone

Tone1 & Tone2 0.001 Hz - 200.000 kHz 0.001 Hz or 6 digits Sine-Square Two-Tone

Tone1 (Sine) Tone2 (Square)

0.001 Hz - 200.000 kHz

0.1 Hz - 5.0 kHz

0.001 Hz or 6 digits 2 digits

DS360 Ultra Low Distortion Function Generator

Setting Functions

If the function is set to White Noise or Pink Noise the character of the noise is fixed, unless a modification function is active. The frequency is not adjustable and displays

“noise”.

The frequency of both Tone1 and Tone 2 may be set. For Sine-Sine 2-Tones, both frequencies are set the same as for normal sines, as is Tone1 for Sine-Square 2-Tones. The squarewave in sine-square two-tones has limited frequency range and resolution. It can be set from 0.1 Hz to 5.0 kHz with 2 digits of resolution (i.e. 4.9 kHz or 110 Hz, not 104 Hz).

To set the frequency of a function, type the new value on the keypad and complete the entry with the appropriate units (Hz, kHz). Or change the frequency by using the spin knob. If too high a value is entered, the DS360 will beep and display “Range Err”. If a value less than 0.001 Hz is entered, the frequency is set to 0.001 Hz.

For output frequency settings only, the spin knob increment can set to a value other than the normal single digit increment (set by the [>] right and [<] left cursor keys). To display the step size mode, press [SHIFT][FSTEP ENA]. To toggle between the normal and the special step size mode, turn the spin knob or press either of the cursor keys. To display the current special step size, press the [SHIFT] [F STEP] keys. To set the special step size, type a new value and complete the entry with the appropriate units (Hz, kHz). The spin knob cannot be used to enter the step size.

3-5

Amplitude

To display the current amplitude, press the [AMPL] key. The amplitude may be set and displayed in Vpp, Vrms, dBm, dBV and dB from a relative value. The current units are indicated by the LEDs at the right of the display. dBm is defined as dB relative to 1 mW of power into the selected source impedance. dBV is defined as dB relative to 1 Vrms into the selected source impedance. (See the section on setting impedance and output configuration for more detail).The amplitude resolution is 4 digits or 1 µV, whichever is greater for Vpp and Vrms. For dBm, dB and dBV it is 3 digits or 0.1 dB, whichever is greater.

The units of the amplitude display may be changed between Vpp, Vrms, dBm and dBV without changing the amplitude by pressing the corresponding units key. When the DS360 is switched from one function to another, the peak-to-peak amplitude remains the same, but the values for other units will change to reflect the new function. To change the amplitude, type a new value on the keypad, followed by the appropriate units (Vrms, Vpp, dBm, dBV) key. Or use the spin knob to modify the current value. If the DS360s attenuator setting changes, the output will briefly go to zero as the amplitude is changed.

2-Tone Amplitude

The amplitudes of Tone1 and Tone2 are maintained separately from the other function amplitudes (i.e. when changing from another function to 2-Tone, the amplitudes will be the last 2-Tone amplitudes set, not the value of the previous function). In addition to the amplitude limits shown below, the amplitudes of Tone1 and Tone2 cannot differ by more than 1:1000 or:

DS360 Ultra Low Distortion Function Generator

3-6

Setting Functions

If the amplitude of either Tone1 or Tone 2 is set outside of these limits, the unit will beep, display the message “Adj 2tA” (adjusting 2Tone Amplitude) and modify the other Tone amplitude so it is within the allowable range.

Relative Amplitude

Amplitude may be set in dB relative to a user defined value for all functions except 2Tone. To make the currently displayed value the relative value, press [REL]. To set the value in dB (relative to the previously entered rel’d value), type the new value, followed by the [dB] key. The “rel’d” value can be displayed in Vrms, dBm or dBV, without changing the amplitude, by pressing the appropriate key. To display the “rel’d” value in Vpp, press [SHIFT][REL] which will display the Vpp value briefly. Pressing the [REL] key a second time takes the amplitude out of relative mode, as does entering a value in Vrms, dBm or dBV.

Unbalanced Output Amplitude

The amplitude range is limited by the DC offset, since (V For a DC offset of zero, the amplitude range for each function is shown in the tables

below for different source impedance’s.

) + |VDC| ≤ 20 V |VDC| ≤ (200 * V

AC PEAK

 

$PS7RQH



 ≤≤



AC PEAK

)

Unbalanced Hi-Z Output Amplitude Ranges

Function Vpp Vrms dBm dBV

Sine Square White Noise # 10 µV - 40.00 V 1µV - 5.714 V Pink Noise # 10 µV - 40.00 V 2µV - 5.000 V 2-Tone *

10 µV - 40.00 V 4 µV - 14.14 V 10 µV - 40.00 V 5 µV - 20.00 V

10 µV - 40.00 V 3 µV - 14.14 V

Unbalanced 50 ΩΩΩΩ Output Amplitude Ranges

Function Vpp Vrms dBm dBV

Sine Square White Noise # 5 µV - 14.40 V 1 µV - 2.057 V Pink Noise # 5 µV - 14.40 V 1 µV - 1.800 V 2-Tone *

5 µV - 14.40 V 2 µV - 5.091 V 5 µV - 14.40 V 3 µV - 7.200 V

5 µV - 14.40 V 2 µV - 5.091 V

-102 - 27.1 -115 - 14.1

-102 - 27.1 -112 - 17.1

-102 - 27.1 -125 - 4.2

-102 - 27.1 -126 - 2.7

-102 - 27.1 -115 - 14.1

-108 - 23.0

-106 - 26.0

-119 - 13.1

-120 - 11.5

-108 - 23.0

DS360 Ultra Low Distortion Function Generator

Unbalanced 600 ΩΩΩΩ Output Amplitude Ranges

Function Vpp Vrms dBm dBV

Sine Square White Noise # 5 µV - 20.00 V 1 µV - 2.857 V Pink Noise # 5 µV - 20.00 V 1 µV - 2.500 V 2-Tone *

5 µV - 20.00 V 2 µV - 7.071 V 5 µV - 20.00 V 3 µV - 10.00 V

5 µV - 20.00 V 2 µV - 7.071 V

Balanced Output Amplitude

Since there is no offset allowed for balanced output, the amplitude is only limited:

Setting Functions

-112 - 19.2 -115 - 17.0

-112 - 19.2 -112 - 20.0

-112 - 19.2 -125 - 7.0

-112 - 19.2 -126 - 5.5

-112 -19.2 -115 - 17.0

3-7

AC PEAK

The amplitude range for each function is shown in the tables below for different source impedance’s.

≤ 40 V

Balanced Hi-Z Output Amplitude Ranges

Function Vpp Vrms dBm dBV

Sine Square White Noise # 20 µV - 80.00 V 3 µV - 11.43 V Pink Noise # 20 µV - 80.00 V 3 µV - 10.00 V 2-Tone *

20 µV - 80.00 V 8 µV - 28.28 V 20 µV - 80.00 V 10 µV - 40.00 V

20 µV - 80.00 V 8 µV - 28.28 V

Balanced 50 ΩΩΩΩ and 150 ΩΩΩΩ Output Amplitude Ranges

Function Vpp Vrms dBm dBV

Sine Square White Noise # 10 µV - 28.80 V 2 µV - 4.114 V Pink Noise # 10 µV - 28.80 V 2 µV - 3.600 V 2-Tone *

10 µV - 28.80 V 4 µV - 10.18 V 10 µV - 28.80 V 6 µV - 14.40 V

10 µV - 28.80 V 4 µV - 10.18 V

-96 - 33.2 -109 - 20.2

-96 - 33.2 -106 - 23.2

-96 - 33.2 -119 - 10.2

-96 - 33.2 -120 - 8.70

-96 - 33.2 -109 - 20.2

-103 - 29.0

-100 - 32.0

-113 - 19.1

-114 - 17.6

-103 - 29.0

Balanced 600 ΩΩΩΩ Output Amplitude Ranges

Function Vpp Vrms dBm dBV

Sine Square White Noise # 10 µV - 40.00 V 2 µV - 5.714 V Pink Noise # 10 µV - 40.00 V 2 µV - 5.000 V 2-Tone *

* The maximum amplitude for 2-Tones is based on the sum of the two signals. Additionally the difference between the two signals is limited to 1000:1 (i.e. the smaller of the two can be no smaller than 1000x less than the larger).

10 µV - 40.00 V 4 µV - 14.14 V 10 µV - 40.00 V 6 µV - 20.00 V

10 µV - 40.00 V 4 µV - 14.14 V

-106 - 25.2 -109 - 23.0

-106 - 25.2 -106 - 26.0

-106 - 25.2 -119 - 13.1

-106 - 25.2 -120 - 11.5

-106 - 25.2 -109 - 23.0

DS360 Ultra Low Distortion Function Generator

3-8

Setting Functions

# The rms, dBm and dBV values for White & Pink Noise are based on the total power in the output bandwidth (200 kHz) at a given peak-to-peak setting.

Offset

Press the [OFFST] key to display the DC offset. The DC offset range is limited by the amplitude, since

AC PEAK

| + |VDC| ≤ 20 V |V

| ≤ (200 * V

offset

AC PEAK

The offset has three digits of resolution, however the smallest increment is determined by the sum of the peak AC amplitude and the DC offset. The tables below show the offset range and resolution for given amplitude settings. Offset is not active for balanced outputs and is the same polarity for both unbalanced outputs (a +2 V

offset sets both

the positive and negative offsets to +2 V) for unbalanced outputs.

Unbalanced Hi-Z

AC PEAK

0 to 12.59 mV

12.60 mV to 125.9 mV

126.0 mV to 1.259 V 1 mV

1.260 V to 20.00 V 10 mV

| + |VDC| Offset Resolution (VDC)

10 µV

100 µV

Unbalanced 50 ΩΩΩΩ

AC PEAK

0 to 6.319 mV

6.320 mV to 63.19 mV

63.2 mV to 0.6319 V 1 mV

0.6320 V to 7.200 V 10 mV

| + |VDC| Offset Resolution (VDC)

10 µV

100 µV

Unbalanced 600 ΩΩΩΩ

AC PEAK

6.320 mV to 63.19 mV

63.20 mV to 0.6319 V 1 mV

0.6320 V to 10.00 V 10 mV

To set a new offset, type the desired value on the keypad, followed by the [V use the spin knob to modify the currently displayed offset value.

| + |VDC| Offset Resolution (VDC)

0 to 6.319 mV

Function On / Off

The output may be switched on or off by pressing the [ON/OFF] key. The output status is indicated on the main display under the OUTPUT heading. When the output is off, the output connectors are terminated into the select source impedance.

DS360 Ultra Low Distortion Function Generator

10 µV

100 µV

] key. Or

Output Configuration

This section describes how to configure the output type and source impedance of the DS360.

Output Type

The DS360 has two different output types: unbalanced and balanced. The currently selected output type is indicated by the LED in the OUTPUT section. To change to the other output selection, press [∨] output down key. The significance of the different output types is listed below.

Unbalanced Output

An unbalanced output signal refers to a signal that is referenced to a common DC potential. Peak-to-peak or RMS voltages are measured to that common level. Most normal function generators use this configuration. Both the positive and negative outputs of the DS360 have the selected source impedance and output voltage amplitude present. The two signals are equivalent, the only difference being that the positive signal is 180° out of phase with the negative signal.

3-9

Digital Output

When the unbalanced output is selected, the amplitude limits are set to the unbalanced output values. The offset function is available. Offsets are the same polarity for both outputs (a +2 V

offset will offset both the positive and negative outputs by 2 volts).

Balanced Output

A balanced output signal refers to a signal that is measured to another signal, not a common DC potential, although one may be present. Peak-to-Peak or RMS voltages are measured from signal to signal instead of signal to common. This configuration is used for many audio applications. Typically the measured voltage will be twice the voltage (or +6 dB) from each signal to a common signal. The output voltage and source impedance is measured between the positive and negative outputs on the DS360. The signals are the same as for the unbalanced case (albeit a different amplitude), however their amplitude is measured differently.

When the balanced output is selected, the amplitude limits are set to the balanced output values. The offset function is not active, since offset has no meaning for a balanced output.

Pressing [SHIFT] the front panel analog output and enables the rear panel digital output, indicated by the OUTPUT LED’s. Pressing [SHIFT analog output mode. See Chapter 5 for information on configuring and operating the digital output.

[∨] output down key selects the DS360’s digital output. This disables

]

[∨] output down key again returns the unit to the

DS360 Ultra Low Distortion Function Generator

3-10

Output Configuration

Source Impedance

The source impedance of the DS360 can be set to different values. When the output of the DS360 is terminated into the selected source impedance, the amplitude set on the front panel will be the amplitude seen by the load. If the output is not terminated into the selected load, the amplitude set on the front panel will be incorrect. If one of the source impedance’s is selected (not Hi-Z), and the unit is terminated into a high impedance, the amplitude will be double the set value. The Hi-Z should be used when the output is terminated into a high impedance. The Hi-Z amplitude will be correct (<1% error) for all load impedance’s larger than 5 kΩ.

The output impedance changes for unbalanced and balanced. Each output (positive and negative) has the selected source impedance for unbalanced outputs. For balanced outputs, each output has 1/2 the selected source impedance.

Source Impedance Unbalanced Balanced

Source Impedance for + or - Output

50Ω 50Ω 25Ω 150Ω 75Ω 600Ω 600Ω 300Ω

Hi-Z

25Ω 25Ω

The selected source impedance is displayed under the IMPEDANCE heading to the left of the display. To change the impedance, press [SHIFT][impedance], where impedance is either 50Ω, 150Ω, 600Ω or Hi-Z. It is not necessary to press an entry key to select source impedance’s.

If changing the source impedance from Hi-Z or 600Ω to 50Ω or 150Ω would cause an out of range amplitude or offset, the following will occur. The DS360 will beep, display the message Adj volt and adjust the amplitude to 14.4V

and the offset to 0 VDC..

DS360 Ultra Low Distortion Function Generator

Modify Function

This section describes how to set the modify functions on the DS360, including sweeps, bursts and bandwidth limited noise.

Modify Function Type

Modify functions are associated with the different output functions. Only the options available for the currently selected function type are accessible in the MODIFY FUNC list. Sweeps are available for sine and square waves; bursts are available for sines, squares, white and pink noise; bandwidth limited noise is available for white noise only. No modify functions are active for 2-Tones. Press the [∧] up or [∨] down keys in the MODIFY FUNC area until the desired selection is lit. If you cannot select the desired type of modify function, verify that the selected function type allows that modify function type.

Modify Function On/Off

To activate or deactivate the currently selected modification, press the [ON/OFF] key in the MODIFY FUNC area. The SWP/BURST LED is lit to indicate that the modification function is active.

3-11

Modify Function Parameters

The parameters for modify functions can be entered whether the function is currently active or not. Only modify parameters (START FREQ, STOP FREQ ...) that are valid for the selected modify function can be changed. If a currently invalid modify parameter is selected, the unit will beep and display “not APPL” (not applicable). If a function type change causes the currently displayed modify function to become invalid, the display will revert to the frequency display.

Sweeps

Frequency sweeps are active for sine and square waves. Sweeps are increasing in frequency and can be linear or logarithmic in nature. Frequency changes during the sweep are phase continuous, including the wrap around from stop to start frequency. The rate can be set from 0.01 Hz to 3.1 kHz, with 2 digits of resolution. Sweeps can be continuous, externally triggered or singly triggered. The DS360 has a Sweep output on the rear panel that can be used to synchronize an oscilloscope or other external device to the DS360 sweep output. Use the MODIFY FUNC [ON/OFF] key to begin or end sweeping.

Note

Sweeps have an amplitude rise at the wrap around point (stop frequency to start frequency transition) due to ringing in the reconstruction filter. The effect is minimal for stop frequencies below about 130 kHz. If high stop frequencies and large output amplitudes (>30 Vpp, unbalanced) are used, it is possible to cause the output to clip. To

DS360 Ultra Low Distortion Function Generator

3-12

Modify Function

minimize this, keep stop frequencies below 130 kHz when sweeping at maximum amplitude.

Sweep Type

Press the [∧] up or [∨] down key in the MODIFY FUNC area until the LIN SWP or LOG SWP LED is lit. The output frequency of a linear sweep changes linearly during

the sweep time. The output frequency of a log sweep changes exponentially during the sweep time, spending equal time in each decade of frequency (for example, in a log sweep from 1 kHz to 100 kHz, the sweep will spend half of the time in the 1 kHz to 10 kHz range and the other half in the 10 kHz to 100 kHz range).

Sweep Trigger Source

Sweeps can be continuously triggered, externally triggered or singly triggered. Internally triggered sweeps use an internal sweep rate generator (see the SWEEP RATE described below) to set the sweep repetition rate. Externally triggered sweeps begin on the rising edge of a TTL signal supplied by the user to the TRIGGER/GATE IN BNC on the front panel. Singly triggered sweeps begin by pressing the front panel [TRIGR] key or from one of the computer interfaces.

The current trigger source is indicated by an LED under the TRIGGER heading next to the frequency display. To view the current trigger source for modification, press the [SHIFT][TRIG SRC] keys. To change the trigger source, use the spin knob or [>] right or [<] left cursor keys.

While the DS360 is sweeping, the TRIG’D (triggered) LED is lit. It should be lit continuously for internally triggered sweeps. For external or single triggered sweeps, it will be lit for the duration of the sweep only. If a new trigger is received during an external or single triggered sweep including the specified dead time (see SWEEP RATE for details on dead time), the ERR LED will flash and any triggers will be ignored.

Sweep Rate

The sweep rate can be set continuously from 0.01 Hz (100 s) to 3.1 kHz ( 0.32 ms) with 2 digits of resolution (for example, you can set 1.1 kHz, but not 101 Hz). The period of a sweep is simply 1/Sweep Rate.

To display the current sweep rate, press the [RATE] key. To change the sweep rate, type a new value on the numeric keypad, followed by the appropriate units (Hz or kHz). Or use the spin knob to modify the current value. If a non-valid rate is entered, (1.001 kHz for example) the DS360 will round the value down to the nearest legal value. If an out of range value is entered, the DS360 will beep, display “Rate Err” and flash the ERR LED.

Internal Trigger

There are no additional restrictions on internal sweep rates.

External or Single Trigger

The DS360 synchronizes the external (or single) trigger signal to its internal clock. Because of this, there is an uncertainty of between 0 and 0.317 ms from the start signal

DS360 Ultra Low Distortion Function Generator

Modify Function

(from the TRIGGER IN, computer interface or front panel) and the actual beginning of the sweep. The SWEEP OUT BNC signal, which goes high at the beginning of the sweep, should be used if it is necessary to synchronize the DS360 with an external device, instead of the triggering signal. In addition, there is a dead time of between 0 and

0.317 ms between successive sweeps. If a trigger comes during a sweep or during the dead time following a sweep, it will be treated as an error and ignored. These factors limit the maximum rate that a sweep can be triggered externally (or singly) to somewhat less than for internally triggered sweeps. To never miss a trigger, the maximum external (or single) trigger rate is given by: 1/(Ext Sweep Freq) = 1/(Sweep Rate) + 0.634 ms. Sweeps can be triggered somewhat faster than this if it is permissible to skip triggers. Trigger errors simply indicate that a trigger has been ignored, but do not effect the output signal in any way.

3-13

Start and Stop Frequencies

The DS360 can sweep over any portion of its frequency range, from 0.001 Hz to 200.000 kHz. To display the current start or stop frequency, press the [START] or [STOP] key. To change the start or stop frequency, type a new value using the numeric keypad, followed by the appropriate units (Hz or kHz). If an out of range frequency is entered, the DS360 will beep, display “FREQ Err” and flash the ERR LED.

Bursts

Bursts are active for sinewaves, squarewaves, white noise and pink noise. A burst of sines or squares consists of a certain number of complete cycles at a particular level (the “ON” level), followed by another number of cycles at a reduced level (the “OFF” level). Time intervals (instead of number of cycles) are used for noise signals. This pattern can be triggered, either internally, externally, or on a single-shot basis. Additionally the output can be gated on and off by an external signal.

Bursts are programmed in # of counts for sine and square waves and in seconds for noise signals. The “ON” time is entered as the Burst Count. The Burst Rate is the combination of both the “ON” and “OFF” times as shown below.

BURST RATE = BURST COUNT + OFF CYCLES

The burst “OFF” level is set in percent or dB relative to the “ON” level and can range from 0 to 100% in 0.1% increments or from 0dB to -60dB in 0.1dB increments. The DS360 has a BURST output on the rear panel that can be used to synchronize an oscilloscope or other external device to the DS360 burst output. This signal remains a TTL high for the duration of the “ON” time and a TTL low for the “OFF” time. Use the MODIFY FUNC [ON/OFF] key to begin or end bursting.

Burst Trigger Source

Bursts can be continuously triggered, externally triggered or singly triggered. Internally triggered bursts use an internal burst rate generator (see the BURST RATE described below) to set the repetition rate. Externally triggered bursts begin on the rising edge of a TTL signal supplied by the user to the TRIGGER/GATE IN BNC on the front panel. Singly triggered bursts begin by pressing the front panel [TRIGR] key or from one of the

DS360 Ultra Low Distortion Function Generator

3-14

Modify Function

computer interfaces. In addition, the output can be gated on and off from the TRIGGER/GATE IN BNC, with TTL high setting the “ON” level and TTL low setting the “OFF” level.

The current trigger source is indicated by an LED under the TRIGGER heading next to the display. To view the current trigger source for modification, press the [SHIFT][TRIG SRC] keys. To change the trigger source, use the spin knob or [>] right or [<] left cursor keys.

During the “ON” time for bursts the TRIG’D (triggered) LED is lit. If a new trigger is received during an external or single triggered burst the ERR LED will flash. Any triggers received during an external or single triggered burst will be ignored. Trigger errors only indicate that a trigger occurred during a burst; there is no effect on the output waveform.

Sine and Square Wave Bursts

Internal Burst Rate

The burst rate is the total number of cycles in a burst, both the “ON” and “OFF” cycles, when generating internally triggered bursts. It is set in integer number of cycles and can range from 2 to 65535 (1 for the 1/2 cycle output. See below). In addition, it must be at least one count greater than the Burst Count. To display the current burst rate, press the [RATE] key. To modify the rate, type the new value in number of counts and press any of the entry keys. Or use the spin knob to modify the displayed value. If an illegal value is entered, the unit will beep, display “Range Er” and flash the ERR LED. If a value that is less than the current burst count is entered, the unit will beep, flash the ERR LED, display “AdjBur” (adjust burst), and adjust the Burst Count to one less than the Burst Rate.

External Burst Rate

External or single triggered sine or square bursts are synchronized to the output zero crossings. Because of this, there is an uncertainty of 0 to one cycle from the start signal (from the TRIGGER IN, computer interface or front panel) and the actual beginning of the burst. The BURST OUT BNC signal, which goes high at the beginning of the burst should be used if it is necessary to synchronize the DS360 with an external device, instead of the triggering signal. This limits the maximum rate that a burst can be triggered externally (or singly) to somewhat less than for internally triggered bursts. To never miss a trigger, the maximum external (or single) trigger rate is given by:

2XWSXW)UHT

([W7ULJ)UHT

Bursts can be triggered somewhat faster than this if it is permissible to skip triggers.

Burst Count

The burst count is the number of “ON” cycles (or high level) in a burst. It is set in integer number of cycles and can range from 1 to 65534. In addition it must be at least one count less than the Count Rate. To display the current Burst Count, press the [SHIFT][BURST CNT]. To modify the count, type the new value in number of counts and press any of the entry keys. Or use the spin knob to modify the displayed value. If an illegal value is entered, the unit will beep, display “Range Er” and flash the ERR LED.

%XUVW&RXQW

+

DS360 Ultra Low Distortion Function Generator

Modify Function

If a value that is greater than or equal to the current burst rate is entered the unit will beep, display “BurRatEr” ( burst rate error) and flash the ERR LED.

3-15

Noise Bursts

Internal Burst Rate

The burst rate for noise is set in seconds. Any entry key may be used and no units are displayed. The rate can vary between 20 µs to 600.0 s, with 4 digits of resolution. In addition, the rate must be greater than and within 4 digits of the Burst Count. To display the current burst rate, press [RATE]. To modify the rate, type the new value (in seconds) and press any entry key. Or use the spin knob to modify the displayed value. If an illegal value is entered, the unit will beep, display “Range ER” and flash the ERR LED. If a value less than the current burst count is entered, the unit will beep, flash the ERR LED, display “AdjBur” and adjust the Burst Count to 1/10 of the current Burst Rate. If the Burst Rate is adjusted to a value more than 4 digits above the current Burst Count, the Burst Rate is adjusted to the lowest allowable value (i.e. if the initial Burst Count is

0.001s, setting the Burst Rate to 600s will adjust the Burst Count to 0.1s).

External Bursts Rate

External noise bursts are not synchronized to anything, so there isn’t the uncertainty from the TRIGGER IN signal and the start of bursts that there is for sine or square waves. To never miss a trigger, the maximum external (or single) trigger rate is given by:



([W7ULJ)UHT

%XUVW&RXQW

when the burst count is expressed in seconds.

Burst Count

The burst count for noise is the “ON” time in a noise burst. Any entry key can be used and no units are displayed. The burst count can vary between 10 µs to 599.9 s, with 4 digits of resolution. In addition, the burst count must be less than and within 4 orders of magnitude of the Burst Rate. To display the current burst count, press [SHIFT][BURST CNT]. To modify the count, type the new value (in seconds) and press any entry key. Or use the spin knob to modify the displayed value. If an illegal value or a value greater than or equal the current burst rate is entered, the unit will beep, display “Range Er” and flash the ERR LED.

Burst Depth

The burst depth is the attenuation of the “OFF” level compared to the “ON” level. To enter a specific “OFF” level it is necessary to enter an “ON” level and calculate the required attenuation to generate the desired “OFF” level. The burst depth on the DS360 can vary from 0 to 100%, with a 0.1% resolution. It can also be displayed or entered in dB, ranging from -60.0 dB to 0 dB with 0.1 dB resolution. 0% depth (no output) can only be set in percent. If 0% is set and the units are changed to dB, the display will show “-999” as an overflow value since it cannot be displayed in dB.

To view the current depth, press [SHIFT][DEPTH]. To change the depth, type the new value followed by the appropriate units key (% or dB). Or use the spin knob to modify

DS360 Ultra Low Distortion Function Generator

3-16

Modify Function

the current value. If an out of range value is entered, the unit will beep, display “Depth Err” and flash the ERR LED.

Gated Output

When the DS360 is set to gated output mode (see Burst Trigger Source) the output is gated on and off from the TRIGGER/GATE IN BNC. A TTL high level outputs the “ON” level and TTL low the “OFF” level. For sine and square waves, level changing occurs at zero crossings. Because of this there is an uncertainty of between 0 and one cycle from the rising edge of the TRIGGER/GATE IN BNC and the actual level change of the output. Similarly there is an uncertainty at the falling edge. The BURST OUT BNC signal, which is high while the “ON” level is active should be used if it is necessary to synchronize the DS360 with an external device instead of the external gating signal. This is not a problem for gated noise signals, since it isn’t synchronized to anything.

1/2 Cycle Burst

The DS360 has a special mode where it can output a 1/2 cycle burst of a sine or square waves. The polarity is fixed (positive for the positive output; negative for the negative output). To use the 1/2 cycle burst count, type .5, followed by an entry key. The spin knob cannot be used to enter this value. The burst rate can be set to any legal value and all triggering modes are valid.

Bandwidth Limited Noise

Bandwidth limited noise is active for white noise only. The purpose of bandwidth limited noise is to maximize the noise power in the frequency of interest. The bandwidth limited white noise in the DS360 maintains a constant RMS voltage over nearly all bandwidths and center frequencies (see information in the CENTER FREQUENCY section below for more information). The bandwidth limiting is accomplished using a 3-Pole Butterworth Filter, for both the high and low pass filters. Use the MODIFY FUNC [ON/OFF] key to begin or end bandwidth limited noise.

Bandwidth

The Bandwidth of the bandwidth limited noise can be set to any of the following values: 100 Hz, 200 Hz, 400 Hz, 800 Hz, 1.60 kHz, 3.20 kHz, 6.40 kHz, 12.8 kHz, 25.6 kHz,

51.2 kHz or 102.4 kHz. These correspond to 1/2 bandwidth frequency spans, starting from the full bandwidth of the white noise.

To display the current bandwidth, press the [BW] key. To enter a new value, type the value followed by the appropriate units key (Hz or kHz). Or use spin knob to modify the current value. If the bandwidth is not entered exactly, the DS360 will round down to the next legal value for all values above 100 Hz; below 100 Hz will round to 100 Hz. If an out of range value is entered, the DS360 will beep, display “Freq Err” and flash the ERR LED.

DS360 Ultra Low Distortion Function Generator

Modify Function

3-17

Center Frequency

The center frequency can vary from 0 Hz to 200.000 kHz in 200 Hz increments. To display the current center frequency, press the [CENTER] key. To change the center frequency, type a new value using the numeric keypad, followed by the appropriate units (Hz or kHz). If an out of range frequency is entered, the DS360 will beep, display “Freq Err” and flash the ERR LED.

For bandwidth limited noise with high center frequencies and/or wide bandwidths there can potentially be a reduction in noise power. When

CENTER FREQUENCY + 1/2 BANDWIDTH > 200 kHz

the amplitude will be slightly reduced. This is due to the fact that the white noise generator has a bandwidth of 200 kHz, so any part of the noise bandwidth above 200 kHz will be filtered.

DS360 Ultra Low Distortion Function Generator

3-18

Modify Function

DS360 Ultra Low Distortion Function Generator

Instrument Setup

3-19

Instrument Setup

This section describes the DS360’s default settings, storing and recalling settings, setting the computer interfaces and running the self-tests.

Default Settings

Press [RCL][0] to recall the DS360’s default settings. This is a good place to begin whenever you wish to start the instrument from a known state. The default settings are listed below. See Chapter 5 for information on the default settings for the digital output.

Default Settings

Setting Default Value

Function Sine Frequency 1.00000 kHz Amplitude 1.000 Vrms

Offset 0.00 V

Output On/Off On

Output Type Unbalanced

Output Mode Analog

Output Impedance Hi-Z

Modify Function Linear Sweep

Modify Function On/Off Off

Start Frequency 1.000 Hz Stop Frequency 100.000 kHz

Sweep Rate 1.0 kHz

Trigger Source Internal

Burst Depth 50% Burst Count 1

Burst Rate 10

2-Tone Tone 1 Frequency 1.00000 kHz 2-Tone Tone 2 Frequency 10.0000 kHz

2-Tone Tone 1 Amplitude 1 Vrms

2-Tone Tone2 Amplitude 1 Vrms

2-Tone Mode Sine-Sine

Bandwidth Limited Noise Center Frequency 0 Hz

Bandwidth Limited Noise Bandwidth 3.2 kHz

GPIB Address 8

RS-232 Baud Rate 9600

Storing and Recalling Settings

Storing Settings

The DS360 can store up to 9 independent instrument setups in non-volatile RAM, separate from the default settings ([RCL][0]). To store the current instrument setup, press [STO] followed by a location number (1-9). After any of the units keys are pressed, the message “Store Done” will be displayed to indicate that the settings have been stored.

DS360 Ultra Low Distortion Function Generator

3-20 Instrument Setup

Memory location 0 is the location of the defaults and cannot be stored to. Storing to it will generate a range error.

Recalling Settings

To recall a stored setting, press [RCL] followed by a location number (0-9). After pressing any of the units keys to enter the location, the message “Rcl Done” will be displayed to indicate that the settings have been recalled. If nothing had been stored in the selected location or if the stored settings had been corrupted, the message “Rcl Err” will be displayed. Note that [RCL][0] recalls the default settings.

GPIB Setup

Press [SHIFT][GPIB] to display the current GPIB address. Use the spin knob to modify the address or enter the number directly from the keypad and one of the entry keys. The GPIB address can be set from 0 to 30.

Pressing [SHIFT][GPIB] a second time will display the last 256 characters of data that has been received by the DS360. This display is a scrollable 3 character window into the DS360’s input data queue. The data is displayed in ASCII hex format, where each character is represented by 2 hexadecimal digits. The most recently received character is indicated by the decimal point to the right of the digit. Turning the spin knob to the left moves the window earlier into the data queue; turning it to the right moves later into the queue. The display window cannot be moved later than the last character received.

SRQ

RS-232 Setup

The user may issue an user SRQ (service request) over the GPIB. Only one SRQ (user or otherwise) can be active at a time; the host computer must acknowledge any pending SRQ’s before a new one is sent. Note that the user SRQ is in addition to the usual service requests based on the unit’s status.

To issue an user SRQ, press [SHIFT][SRQ], followed by any of the entry keys. The message “Send SRQ” will appear prior to pressing the entry key. After the entry key is pressed (assuming that no other SRQ is pending), the message” “Sent SRQ” will appear, and the SRQ LED will appear. The SRQ LED will go off after the host computer does a serial poll of the DS360.

See Chapter 4 on programming for additional information on the GPIB.

Press [SHIFT][RS232] to display the RS-232 baud rate setting. Use the spin knob to modify the baud rate. The baud rate cannot be entered directly from the keypad. Baud rates supported are 300, 600, 1200, 2400, 4800, 9600 and 19.2 k.

Pressing [SHIFT][RS232] a second time will display the last 256 characters of data that has been received by the DS360. This display is a scrollable 3 character window into the DS360’s input data queue. The data is displayed in ASCII hex format, where each

DS360 Ultra Low Distortion Function Generator

Self-Tests

Instrument Setup

character is represented by 2 hexadecimal digits. The most recently received character is indicated by the decimal point to the right of the digit. Turning the spin knob to the left moves the window earlier into the data queue; turning it to the right moves later into the queue. The display window cannot be moved later than the last character received.

See Chapter 4 on programming for additional information on the RS-232.

The self tests check out much of the internal circuitry, including the CPU, data memory, ROM program memory, calibration constants integrity, stored settings integrity, DSP and DSP memory. The self tests are executed on power-up and take about 3 seconds to run. If all the self tests pass, the unit will display “tESt PASS” and operate normally. If they fail, the unit will stop and display an error message. Pressing any key will cause the unit to attempt to operate normally. Typically the user should power cycle the instrument to attempt to clear the error. Some errors are transient in nature and will disappear. If the problems continue, contact Stanford Research Systems for service information.

See the TROUBLESHOOTING section later in this chapter for a list and explanation of error messages.

3-21

DS360 Ultra Low Distortion Function Generator

3-22 Instrument Setup

DS360 Ultra Low Distortion Function Generator

Troubleshooting

Nothing Happens on Power On

Make sure that the power entry module on the rear panel is set for the correct line voltage, that the correct fuse is installed and that the line cord is inserted all the way into the power entry module. The selected line voltage should be visible through the clear window in the power entry module, just below the fuse, when the power cord is removed.

Reset

If the unit becomes “hung” or inoperative, or displays no sensible message, a full reset may fix the problem. To perform a full reset, hold down the [CLR] key while turning the power on. This procedure initializes the RAM and recalls all factory calibration values. It also distroys any stored settings. If you only want to return the instrument to it’s default state, press [RCL][0], which doesn’t clear all stored data.

3-23

Unable to Set Parameters

Be certain that the unit is set for the correct mode (analog or digital) for the parameters being adjusted (i.e. number of bits cannot be set in analog mode). This is true for both front panel and computer operation. The output mode is indicated by the LED’s in the OUTPUT section.

GPIB Problems

Make certain that the GPIB address of the DS360 matches what the controller expects. The address can set to any address from 0 to 30, however the default address is 8. If possible it is a good idea to use this address, unless you are otherwise constrained. To display the address, press [GPIB], and use the keypad or spin knob to modify it.

The DS360 will ignore its front panel keypad when Remote Enable (REN) is asserted by the GPIB. This “REMOTE” state is indicated by the REM LED. To return to LOCAL operation (ie to return control to the front panel) press the [LOCAL] key. Controlling programs may inhibit the ability to return to LOCAL operation by asserting the LocalLockout state (LLO). The only way to return from this state is to release it over the GPIB or by performing a total reset.

A linefeed character is sent with an End Or Identify (EOI), to terminate strings from the DS360. Be certain that your controller has been configured to accept this sequence.

DS360 Ultra Low Distortion Function Generator

3-24

Troubleshooting

RS-232 Problems

Make certain that the baud rate of the controller and the DS360 agree. The baud rate can be set from 300 to 19.2 k; the default is 9600. If it is practical, it is a good idea to use this value. To display the baud rate press [RS232], and use the keypad or knob to modify the value.The DS360 is configured to send or receive: 2 stop bits, 8 data bits and no parity bits.When data is being recieved by the DS360, the ACT LED will flash. If this LED is not flashing there is no data being recieved by the DS360.

When connecting the DS360 to a PC use a standard PC serial cable, not a “null modem” cable. The DS360 is a DCE (Data Communications Equipment) device, and should be connected with a straight cable to a DTE device (Data Terminal Equipment). The “minimum” cable needs pins 2, 3 and 7. For hardware handshaking, pins 5 and 20 (CTS and DTR) should also be passed. Occasionally pins 6 and 8 (DSR and CD) will be needed; these lines are always asserted by the DS360.

Error Messages

The DS360 has two types of error messages, operational error messages and self test error messages. Operational errors include entering out of range values or incorrect units. Self test error messages only occur when the unit is running its internal self tests.

Operational Errors

Message Meaning

AC-DC ER The Vac+|Vdc| value exceeded the limit for the current setting.

AC ERR The amplitude entered is out of the allowable range.

BUR.RAT.ER Burst Rate Error. Burst Count > Rate Count.

NO.Cal.JPR No Cal jumper. Calbyte cannot be written without setting the calibration jumper.

NOT APPL The parameter is not applicable to the current instrument setting.

OFF ERR The offset entered is out of the allowable range.

OUTQ ERR Output queue error. The output queue is full.

RANGE ER The value entered is out of the allowed range for the current parameter.

RCL ERR Memory error found on power up or when recalling a stored setting. (Also

occurs when recalling a setting that hasn’t been previously stored)

SYN ERR The command syntax is invalid.

TOUT ERR Time out error when writing DSP memory.

UNITS ER The units set with AMPL, T1AA, T2BA or DPTH commands are not allowable

or nonexistent.

DS360 Ultra Low Distortion Function Generator

Troubleshooting

3-25

Self-Test Errors

Message Meaning

CPU ERR The DS360 detected a problem with the CPU. CODE ERR XX The DS360 detected a ROM checksum error. XX is the expected checksum

value.

SYSD ERR The DS360 failed its RAM read / write test. CALD ERR The calibration data in RAM is corrupted. The factory calibration data will be

reloaded from PROM.

DSP 0 DSP not responding. The instrument must be power cycled. DSP 1

followed by: xxxxxx DSP 2

followed by: xxxxxx

TST n This message displays an encoded version of the bits 0-3 of the test register (see

DSP data bus error. The message is followed by a six digit (hex) code, corresonding to each data line (of 24) that is in error.

DSP address bus and memory cell error. The message is followed by a six digit (hex) code, made up of three words. Bits 0-15 are DSP address lines 0-15. Bits 16-18 are set if there is an error on the X, Y or P memory spaces. Bits 19-21 are set if there is an error in the low (D0-7), middle (D8-15) or high (D16-23) bytes of the memory space.

the *TST command).

Other Messages

The DS360 displays a number of messages to inform the user of its operational status or of actions the unit has taken. All possible messages are listed below.

Operational Messages

Message Meaning

ADDR xx GPIB address. The value xx is the current GPIB address. ADJ BUR The Burst count has been adjusted to be lower then the current Rate count. ADJ DFR The digital output frequency has been adjusted to an allowable range after

changing the sampling frequency.

ADJ VOLT The amplitude and offset has been adjusted to an allowable value after changing

the source impedance.

ADJ 2TA The non-selected 2Tone amplitude has been adjusted to within a 1:1000 range of

the currently selected tone.

ADJ 2TAll Tone 1 and Tone 2 amplitudes and offset have been adjusted to an allowable

value after changing the source impedance.

ADJ 2TFR Tone 2 Frequency has been adjusted after the Tone 2 mode was changed to

squarewave.

BAUD xxxx RS232 baud rate. The value xxxx is the current baud rate. CLEAR Second selection of the CAL menu. If the calibration jumper is set correctly,

pressing any unit key will recall the default calbytes from PROM.

DS360 Ultra Low Distortion Function Generator

3-26

LD DONE This message occurs after succesfully loading the DSP memory. RECALL Recall menu. It should be followed by a number between 0-9. RCL DONE This message will be displayed for about 1 second after a succesfull recall. STORE Store menu. Should be followed by a number between 1-9. (Store 0 will generate

STO DONE This message will be displayed for about 1 second after a succesfull store. SEND SRQ SRQ menu. Pressing any units key will generate a GPIB SRQ, assuming no other

SRQ SENT This message is displayed for about 1 second after a SRQ is successfully sent. SRC.INT

SRC.ETN SRC.SNGL SRC.GATE STEP OFF (/ON) Frequency Step Enable. (Valid for FREQ and 2Tone FREQ).

Troubleshooting

a Range Error).

SRQ is pending.

The Trigger Source for sweeps (int, ext, single) or bursts (int, ext, single, gate).

DS360 Ultra Low Distortion Function Generator

Chapter 4

Remote Programming

In this Chapter

Index of Commands 4-2 Introduction 4-5

Communication with GPIB 4-5 Communication with RS-232 4-5 Status Indicators and Queues 4-5 Command Format 4-6 Interface Ready and Status 4-6 GET (Group Execute Trigger) 4-7

4-1

Command Syntax 4-8 Function Output Control Commands 4-9

Function 4-9 Frequency 4-9 Amplitude 4-9 Offset 4-9 Output Commands 4-9 Relative Mode 4-10 Frequency Step 4-10 2-Tone Commands 4-10

Digital Output Control Commands 4-12

Function 4-12 Frequency 4-12 Amplitude 4-12 Output Mode 4-12 Digital Output Configuration 4-12 Frequency Step 4-13 2-Tone Commands 4-13 Number of Bits 4-13

Modify Function Commands 4-14

Trigger 4-14 Modify Function 4-14 Trigger Source 4-14 Sweep Commands 4-14 Burst Commands 4-15

DS360 Ultra Low Distortion Function Generator

4-2 Index of Commands

Bandwidth Limited Noise Commands 4-16

Setup Control Commands 4-17

System Commands 4-17 Front Panel Commands 4-17

Status Reporting Commands 4-18 Hardware Test & Calibration Commands 4-19 Status Byte Definition 4-21 Example Programs 4-23

GPIB Communications in C 4-24 RS-232 Communications in BASIC 4-25

DS360 Ultra Low Distortion Function Generator

Index of Commands 4-3

Index of Commands

Variables

i, j, k, n integers x real numbers

Function Output Control Commands

Source Impedance 0=50Ω, 1=150Ω, 2=600Ω, 3=HiZ.

Digital Output Control Commands

Modify Function Commands

*TRG 4-14 Triggers a single sweep or burst. MENA (?) i 4-14 Modify Function Enable (i=1) or Disable (i=0). MTYP (?) i 4-14 Sets the modify function type to Lin Swp, Log Swp, Burst, BWNoise

TSRC (?) i 4-14 Sets the trigger source to Int, Ext, Single or Gate for i=0,1,2,3. STFR (?) x 4-14 Sets Sweep Start Frequency to x. SPFR (?) x 4-14 Sets Sweep Stop Frequency to x.

Sets Digital Number of Bits (16 ≤ i ≤ 20).

for i=0,1,2,3.

DS360 Ultra Low Distortion Function Generator

4-4 Index of Commands

RATE (?) x 4-14 Sets Sweep Rate to x. BCNT (?) x 4-15 Sets Burst Count to x (i=.5, 1-65534). RCNT (?) i 4-15 Sets Burst Rate to x (i=1-65535). DPTH (?) x 4-15 Sets Burst Depth to x; must include DB or PR (%). NBCT (?) x 4-15 Sets Noise Burst Count to x. NRCT (?) x 4-15 Sets Noise Rate Count to x. BNDW (?) x 4-16 Sets Noise BW to 100, 200, 400, 1.6k, 3.2k, 6.4k, 12.8k, 25.6k, 51.2k,

102.4k.

CENF (?) i 4-16 Sets BW Noise Center Frequency to x.

Setup Control Commands

Status Reporting Commands

Hardware Test and Calibration Commands

DS360 Ultra Low Distortion Function Generator

Introduction

The DS360 Ultra Low Distortion Function Generator may be remotely programmed via either the RS232 or GPIB (IEEE-488) interfaces. Any computer supporting these interfaces may be used to program the DS360. Both interfaces are receiving at all times; the DS360 will respond to the interface that sent the query.

Communicating with GPIB

The DS360 supports the IEEE-488.1 (1978) interface standard. It also supports the required common commands of the IEEE-488.2 (1987) standard. Before attempting to communicate with the DS360 over the GPIB interface, the DS360’s device address must be set. To display the present address, press [SHIFT][GPIB]. The new address can be modified by using the keypad, followed by an entry key, or by using the spin knob.

Communicating with RS232

Remote Programming 4-5

The DS360 is configured as a DCE (transmit on pin 3, receive on pin 2) device and supports CTS/DTR hardware handshaking. The CTS signal (pin 5) is an output indicating that the DS360 is ready, while the DTR signal (pin 20) is an input that is used to control the DS360’s data transmission. If desired, the handshaking pins can be ignored and a simple 3 wire interface (pins 2, 3 and 7) may be used. The RS232 baud rate is displayed by pressing [SHIFT][RS232]. A new baud rate can be entered using the spin knob only; the baud rate cannot be entered using the numeric keys. The word length, parity and number of stop bits are fixed and cannot be modified. They are configured as follows: 2 stop bits, 8 data bits and no parity.

Status Indicators and Queues

To assist in programming, the DS360 has 4 interface status indicators which are located at the left side of the display. The REM LED is on when the DS360 is in a remote state (front panel locked out). The ACT LED is on whenever data is being received by the DS360. The ERR LED flashes when an error, such as an illegal command or out of range parameter, has been detected. The SRQ LED is on when the DS360 generates a service request. SRQ remains on until a GPIB serial poll is completed.

To help find programming errors, the DS360 can display the interface buffers on the display. The GPIB queue is accessed by pressing [SHIFT][GPIB] twice in succession. The RS232 queue is accessed by pressing [SHIFT][RS232] twice in succession. The last 256 characters received by each interface can be displayed in a scrollable 3 character window. The data is displayed in ASCII hex format, where each character is represented by 2 hexadecimal digits. The most recently received character is indicated by a decimal point to the right of the digit. Turning the knob counterclockwise moves the data window earlier into the data queue; turning the knob clockwise moves the data window later into the queue. The window cannot be moved later than the last character received.

DS360 Ultra Low Distortion Function Generator

4-6 Remote Programming

Command Format

Communication with the DS360 uses ASCII characters. Commands may be in either UPPER or lower case. A command to the DS360 consists of a four character command mnemonic with an optional ?, arguments if necessary and a command terminator. The terminator must be a linefeed <lf> or carriage return <cr> on RS232, or a linefeed <lf> or EOI on GPIB. No command processing occurs until a terminator is received. Commands function identically on RS232 and GPIB whenever possible. Command mnemonics beginning with an asterisk (*) are IEEE-488.2 (1987) defined common commands. These also function identically on RS232. Commands may require one or more parameters. Multiple parameters are separated by a comma (,). Multiple commands may be sent on the same line by separating them with semicolons (;).

There is no need to wait between commands. The DS360 has a 256 character buffer and processes commands in the order received. If the buffer fills, the DS360 will hold off handshaking on the GPIB and attempt to hold off handshaking on RS232. Similarly the DS360 has a 256 character output buffer to store output until the host computer is ready to receive it. If either buffer overflows, both buffers are cleared and an error is reported.

The present value of a particular parameter may be determined by querying the DS360 for its value. A query is formed by spending a question mark (?) with the command mnemonic and omitting the desired parameter from the command. Values returned from the DS360 are sent as a string of ASCII characters terminated with a carriage return <cr> on RS232 and by a linefeed <lf> on GPIB. If multiple query commands are sent on one command line (separated by semicolons), the answers will be sent individually, each with a terminator.

Examples of Commands:

FREQ 1000 <lf > Set the Output Frequency to 1.0 kHz *TRG <lf> Trigger a sweep or burst FUNC? <lf> Query the output function.

Interface Ready and Status

The No Command bit in the Serial Poll Status Byte signals that the DS360 is ready to receive and execute commands. When a command is received, this bit is cleared, indicating that command execution is in process. No other commands will be processed until this command is complete. Commands received during this time are stored in the buffer to be processed later. Only GPIB serial polling will generate a response while a command is in progress. When all pending commands have executed, the No Command bit is set again. By checking the No Command bit, a host computer can ensure that all previously sent commands have finished before sending a new command.

Since most commands execute very quickly, the host computer does not need to continually check the No Command bit. Commands can be sent one after another and they will processed immediately. However some commands, such as self tests, may require a long time to execute. In addition, the host computer may need to check that these commands executed without error. In these cases, the status should be queried.

DS360 Ultra Low Distortion Function Generator

SRQ

Remote Programming 4-7

When using the GPIB interface, serial polling may be used to check the No Command bit while operation is in progress. After the bit becomes set, the ERR bit may be checked to verify successful completion of the command.

If the RS232 interface is used, or serial polling is not available, then the *STB ? and *ESR ? status query commands may be used to query the Status Bytes. Since the DS360 processes one command at a time, the status query will not be processed until the previous command is complete. Thus a response to the status query itself signals that the previous operation is finished. The query response may then be checked for various errors.

GET (Group Execute Trigger)

The GPIB command GET will have the same effect as a *TRG command. If the DS360 is configured for a single triggered sweep or burst, then the GET bus command will trigger a sweep or burst. If the DS360 is not configured for one these, the command will be ignored.

DS360 Ultra Low Distortion Function Generator

4-8 Remote Programming

Command Syntax

The four letter mnemonic in each command sequence specifies the command. The rest of the sequence consists of parameters. Parameters shown in { } are not always required. Generally, parameters in { } are required to set a value in the DS360. Multiple parameters are separated by commas. Multiple commands may be sent on one command line by separating them with semicolons (;).

The present value of a parameter may be determined by sending a query command. Commands that may be queried have a question mark in parentheses (?) after the mnemonic. Commands that may ONLY be queried have a ? after the mnemonic. Commands that MAY NOT be queried have no ?. A query is formed by including the question mark ? after the command mnemonic and omitting the queried parameter from the command. The query parameters shown in { } are NOT sent with a query. The query returns the value of these parameters. Values are returned as a string of ASCII characters.

NOTE: Do NOT send ( ) or { } as part of the command.

Variables are defined as follows:

i, j, k, n integers x real numbers

All numeric variables may be expressed in integer, floating point or exponential formats (i.e. the number five can be either 5, 5.0 or 05E1). Strings are sent as a sequence of ASCII characters.

DS360 Ultra Low Distortion Function Generator

Remote Programming 4-9

Function Output Control Commands

Note: The analog output control commands may be selected only when the analog output type is selected.

If these commands are sent when the unit is in digital mode a “Not Appl” (not applicable) message will be displayed on the screen and syntax error will occur. The command OUTD0 (analog output) should be sent at the beginning of any program that uses the analog output. Also be aware that a couple of commands share common mnemonics and values with the digital output (FUNC, STPE, FSTP).

FUNC (?) i

The FUNC command sets the output function type to i as shown below. The FUNC? query returns the current function.

i Function

0 Sine 1 Square 2 White Noise 3 Pink Noise 4 2 Tone

FREQ (?) x

AMPL (?) x

The FREQ command sets the frequency to x Hertz. The FREQ? query returns the current output frequency. The frequency is set and returned with 1mHz resolution. If the current waveform is NOISE , an error will be generated and the frequency will not be affected. This command doesn’t set the frequencies for 2Tones. See TTAF and TTBF commands for 2-Tone frequencies.

The AMPL command sets the output amplitude to x. The value x must consist of the numerical value and a units indicator. The units may be VP (Vpp), VR (V

), DB (dB in relative mode only, see RELA command below), DM (dBm)

RMS

or DV (dBV). For example, the command AMPL1.0DM will set the output to 1.0 dBm. Setting the amplitude to 0 Volts will produce DC only, (no AC component), with the output controlled by the OFFS command. For amplitude- offset limits, see chapter 3.

The AMPL? query will return the amplitude in the currently displayed units. For example, if the display shows 10.0 V

, the AMPL? query will return 10VR. If

RMS

the units indicator is sent along with the command (such as AMPL?VP), the returned units will match the units indicator and the amplitude will be returned in those units.

This command doesn’t set the amplitude for 2-Tones. See TTAA and TTBA commands for 2-Tone amplitudes.

DS360 Ultra Low Distortion Function Generator

4-10 Remote Programming

OFFS (?) x

The OFFS command sets the output DC offset to x volts. The OFFS? query returns the current value of the DC offset. For amplitude-offset limits see chapter 3.

OUTE (?) i

The OUTE command disables the output for i=0 and enables the output for i=1. The OUTE? query returns the current status of the output.

OUTM (?) i

The OUTM command selects the output mode of the instrument. For i=0 the output is unbalanced and for i=1 it is balanced. The OUTM? query returns the current output mode.

TERM (?) i

The TERM command sets the output source impedence as indicated in the table below. The TERM? query returns the current source impedance setting. An error will be generated if the output impedance selected is not valid for the current output mode.

RELA (?) i

STPE (?) i

FSTP (?) x

i Source

Impedance

50 Ω

150 Ω

600 Ω

3 Hi-Z

The RELA command sets (queries) the relative mode for the output amplitude. For i=1, the relative mode is active, with the current amplitude setting as the relative amplitude. New values are set using dB relative to this value. For i=0 (or when setting a value in units other than dB) the relative mode is inactive. This command has no effect when 2Tone is selected.

The STPE command enables (i=1) or disables (i=0) the usage of the frequency step, which is set by the FSTP command. The STPE? query returns the current step enable mode.

The FSTP command sets the frequency step to x Hertz. The FSTP? query returns the current step frequency. The step is active only for the main frequency (FREQ) and STPE (step enable) = 1. The value x may range between 1mHz and 200kHz.

When the frequency step is enabled, it becomes the knob increment value.

DS360 Ultra Low Distortion Function Generator

TTAA (?) x

TTBA (?) x

Remote Programming 4-11

The TTAA command sets the Tone 1 amplitude to x. The value x must consist of the numerical value and a units indicator. The units may be VP (Vpp), VR (V DM (dBm) or DV (dBV). For example, the command TTAA1.0VP will set the Tone 1 to 1.0Vpp. The maximum value for the sum of Tone 1 and Tone 2 amplitude, as well as the ratio of the two, is limited as described in chapter 3. If the DS360 must modify the amplitude of either Tone 1 or 2, due to under or over ranging, a message is sent on the front panel and bit 3 in the DDS register is set.

The TTAA? query will return the amplitude in the currently displayed units. For example, if the display shows 10.0 V

, the TTAA? query will return 10VR. If

RMS

the units indicator is sent along with the command (such as TTAA?VP), the returned units will match the units indicator and the amplitude will be returned in those units.

The TTBA command sets the Tone 2 amplitude to x. The value x must consist of the numerical value and a units indicator. The units may be VP (Vpp), VR (V DM (dBm) or DV (dBV). For example, the command TTBA1.0VP will set the Tone 2 to 1.0Vpp. The maximum value for the sum of Tone 1 and Tone 2 amplitude, as well as the ratio of the two, is limited as described in chapter 3. If the DS360 must modify the amplitude of either Tone 1 or 2, due to under or over ranging, a message is sent on the front panel and bit 3 in the DDS register is set.

RMS

)

TTAF (?) x

TTBF(?) x

TTMD (?) i

The TTBA? query will return the amplitude in the currently displayed units. For example, if the display shows 10.0 V

, the TTBA? query will return 10VR. If

RMS

the units indicator is sent along with the command (such as TTBA?VP), the returned units will match the units indicator and the amplitude will be returned in those units.

The TTAF command sets the Tone1 frequency to x Hertz. The TTAF? query returns the current Tone1 frequency. The frequency is set and returned with 1mHz resolution.

The TTBF command sets the Tone 2 frequency to x Hertz. The TTBF? query returns the current Tone 2 frequency. The Tone 2 frequency must be a legal value for the 2-Tone type selected (see TTMD). If Tone 2 is a sinewave, the frequency is set and returned with 1mHz resolution. If Tone 2 is a squarewave, the frequency is set and returned with 2 digits of resolution (ie. 4.8kHz or 110Hz, but not 101Hz).

The TTMD command sets the Tone 2 mode to either sine (i=0) or square (i=1).The TTMD? query returns the current Tone 2 mode.

DS360 Ultra Low Distortion Function Generator

4-12 Remote Programming

Digital Output Control Commands

Note: The digital output control commands may be selected only when the digital output type is selected. If

these commands are sent when the unit is in analog mode a “Not Appl” (not applicable) message will be displayed on the screen and syntax error will occur. The command OUTD1 (digital output) should be sent at the beginning of any program that uses the digital output. Also be aware that a couple of commands share common mnemonics and values with the normal analog output (FUNC, STPE, FSTP).

FUNC (?) i

The FUNC command sets the output function type to i as shown below. The FUNC? query returns the current function. Note that square, white noise and pink noise (i=1,2,3) are not valid when the instrument is in digital mode. If the instrument mode is changed from analog to digital while the function is set to square, white or pink noise, the function will revert to sine.

i Function

0 Sine 4 2 Tone

DFRQ (?) x

DAMP (?) x

OUTD (?) i

DIGM (?) i

The DFRQ command sets the digital frequency to x Hertz. The DFRQ? query returns the current digital output frequency. The frequency is set and returned with 1mHz resolution. This command doesn’t set the frequencies for 2-Tones. See DTAF and DTBF commands for 2-Tone frequencies.

The DAMP command sets the digital output amplitude to x percent (%). The DAMP? query will return the digital amplitude in percent. The amplitude is sent and returned with 0.00001% resolution. This command doesn’t set the amplitude for 2-Tones. See DTAA and DTBA commands for 2-Tone amplitudes.

The OUTD command selects the output mode of the instrument. For i=0 the output is analog, for i=1 it is digital.The OUTD? query returns the current output mode.

The DIGM command selects the digital output format of the instrument. For i=0 the format is professional and for i=1 it is consumer.The DIGM? query returns the current digital output format.

DS360 Ultra Low Distortion Function Generator

DIGF (?) i

STPE (?) i

FSTP (?) x

Remote Programming 4-13

The DIGF command sets (queries) the digital sampling frequency for the digital output, based on the table below.

i Frequency

0 48.0 kHz 1 44.1 kHz 2 32.0 kHz

The STPE command enables (i=1) or disables (i=0) the usage of the frequency step, which is set by the FSTP command. The STPE? query returns the current step enable mode.

DTAA (?) x

DTBA (?) x

DTAF (?) x

DTBF(?) x

When the frequency step is enabled, it becomes the knob increment value.

The DTAA command sets the Tone 1 digital amplitude to x percent (%). The maximum value for the sum of Tone 1 and Tone 2 amplitude is limited as described in chapter 5. The DTAA? query will return the amplitude in percent (%).

The DTBA command sets the Tone 2 digital amplitude to x percent (%). The maximum value for the sum of Tone 1 and Tone 2 amplitude is limited as described in chapter 5. The DTBA? query will return the amplitude in percent (%).

The DTAF command sets the Tone1 digital frequency to x Hertz. The DTAF? query returns the current Tone1 frequency. The frequency is set and returned with 1mHz resolution.

The DTBF command sets the Tone 2 digital frequency to x Hertz. The DTBF? query returns the current Tone 2 frequency. The frequency is set and returned with 1mHz resolution.

DS360 Ultra Low Distortion Function Generator

4-14 Remote Programming

Modify Function Commands

Note: Most of the modify function parameters may be selected at any time that the unit is in analog mode. To observe the changes effecting the output, be sure that the appropriate modifying type is selected and the modify function is on. Some of the parameters cannot be modified for all settings. These are indicated below. When this occurs, a “Not Appl” (not applicable) message will be displayed on the screen and syntax error will occur.

*TRG

The *TRG command triggers a burst or a single sweep.The trigger source must be set to SINGLE.

MENA (?) i

The MENA command enables the modify function for i=1 and disables it if i=0. The MENA? query returns the current modify function status.

MTYP (?) i

TSRC (?) i

The MTYP command sets the modify function type to i as described in the table below. The MTYP? query returns the current type.

i Modify Function

0 LIN SWEEP 1 LOG SWEEP 2 BURST 3 BW NOISE

If the modify function is changed to a type which is incompatable with the currently selected output waveform, a range error will be sent and the command will be ignored.

If the parameter currently being displayed is undefined for the new MTYP (for example: start freq and burst), the “Not Appl” message will appear, a range error will be returned and the display will be changed to FREQ, regardless of what was displayed previously.

The TSRC command sets the trigger source for bursts and sweeps to i as described in the table below. The TSRC? query returns the current trigger source.

DS360 Ultra Low Distortion Function Generator

STFR (?) x

SPFR (?) x

RATE (?) x

Remote Programming 4-15

i Source

0 INTERNAL 1 EXTERNAL 2 SINGLE 3 GATE (burst only)

If the trigger source is set to gate when the unit is in burst mode and the unit is changed to sweep mode, the trigger source will change to internal.

The STFR (?) command sets (queries) the sweep start frequency to x Hertz. An error will be generated if the start frequency is higher than the current stop frequency.

The SPFR (?) command sets (queries) the sweep stop frequency to x Hertz. An error will be generated if the stop frequency is lower than the current start frequency.

The RATE command sets the sweep rate to x Hz. The value x is rounded to 2 significant digits and may range from 0.01 Hz to 3.1 kHz. The RATE? query returns the sweep rate in Hertz.

BCNT (?) x

RCNT (?) i

DPTH (?) x

NBCT (?) x

The BCNT command sets the burst count to x (1 to 65534). The BCNT? query returns the current burst count. The maximum value of x is limited to 1 less than the value of RCNT (see below). If this is exceeded a range error will occur. The burst count can also be set to .5, for a 1/2 cycle burst. The string “.5” must be sent without a leading zero (do not send “0.5”!).

The RCNT command sets the burst rate count to i (1 to 65535). The RCNT? query returns the current burst rate count. Setting RCNT less than or equal to the current BCNT will adjust BCNT to RCNT-1 (to .5 if RCNT is 1). An “ADJ BUR” message will be displayed and bit 3 (parameter adjust) will be set in the DDS status byte.

The DPTH command sets the burst depth to x. The value x must consist of the numerical value and a units indicator. The units must be DB (dB) or PR (%). If a 0% value is set, a query of DB will return -999 as an overflow value. The range for x is 0% to 100% or 0dB to -60dB. A query must be followed by one of the units indicators, for example DPTH?DB.

The NBCT command sets the Noise Burst Count to x. The NBCT? query the Noise Burst Count. The minimum value of x must be within 4 digits of NRCT; the

DS360 Ultra Low Distortion Function Generator

4-16 Remote Programming

maximum must be less than NRCT (i.e. for NRCT=3s, NBCT ranges from 1ms to 2.999s).

NRCT (?) x

The NRCT command sets the Noise Rate Count to x. The NRCT? query returns the current value of this parameter. x may range from 2 µs to 600 s.

If NRCT is set to a value lower than NBCT, NBCT is adjusted to NRCT/10; if NRCT is set to a value more than 4 digits above NBCT, NBCT is adjusted to the lowest allowable in that range (i.e. if NBCT=1ms, setting NRCT to 600s will adjust NBCT to 100ms). An “ADJ BUR” message is displayed and bit 3 in the DDS Status Byte is set in this case.

BNDW (?) i

The BNDW command sets the white noise bandwidth to one of the following frequencies:100 Hz, 200 Hz, 400 Hz, 800 Hz, 1.6 kHz, 3.2 kHz, 6.4 kHz, 12.8 kHz, 25.6 kHz, 51.2 kHz, 102.4 kHz. The value i is always expressed in Hz. Values lower then 100 Hz will set BNDW to 100 Hz; all other values will be rounded down.

CENF (?) i

The CENF command sets the white noise center frequency to i , which ranges from 0 to 200kHz. The resolution of i is 200 Hz; all settings will be adjusted to i modulo 200. CENF? query returns the currently set value.

DS360 Ultra Low Distortion Function Generator

Setup Control commands

Key Name

Key Code

Key Name

Key Code

FUNCTION UP

1021

FUNCTION DOWN

2122

OUTPUT UP

3223

TRIGGER

4324

MODIFY FUNC UP

5425

FREQ

6526

AMPL

7627

OFFS

8728

FUNCTION ON/OFF

9829

MODIFY FNC DOWN

10930

SWP BURST ON/OFF

Vrms / %

START/CENTER

Vpp / Vdc / dB

STOP/BW

kHz / dBm

RATE

Hz / dBV

SHIFT

not used

STO16right arrow

RCL17left arrow

CLR18REL38+/-19not used

(.)20not used

*IDN?

The *IDN? common query returns the DS360 device identification string. This string is in the format: “StanfordResearchSystems,DS360,sn,vn” where sn is the five digit serial number of the particular unit and vn is a 3 digit firmware version number.

*RCL i

The *RCL command recalls stored setting number i, where i may range from 0 to

9. If the stored setting is corrupt or has never had anything stored in it, an execution error will be generated. RCL0 recalls the default setting of the instrument (see Chapter 3 for the default settings).

*RST

The *RST common command resets the DS360 to its default configuration, initializes the unit and runs the self tests. It behaves the same as cycling the power off and on. The communication setup is not changed. All other modes and settings are set to the default conditions and values. This command takes some time to complete.

Remote Programming 4-17

*SAV i

KEYS (?) i

The *SAV command saves the current instrument settings as setting number i, where i ranges from 1 to 9 (setting number 0 is the default setting). An error will be generated if data is saved to setting 0.

The KEYS command simulates the pressing of a front panel key. The KEYS? query returns the keycode of the most recently pressed key. Keycodes are assigned as follows:

DS360 Ultra Low Distortion Function Generator

4-18 Remote Programming

Status Reporting Commands

Note: See tables at the end of the programming section for Status Byte definitions.

*CLS

The *CLS common command clears all status registers. This command does not affect the status registers.

*ESE (?) i

The *ESE command sets the standard event status byte enable register to decimal value i.

*ESR? {i}

The *ESR common command reads the value of the Standard Event Status Register. If the parameter i is present, the value of bit i is returned (0 or 1). Reading this register will clear it, while reading bit i will clear just bit i.

*PSC (?) i

The *PSC common command sets the value of the power-on status clear bit. If i=1, the power-on status clear bit is set and all status registers and enabled registers are cleared at power on. If i=0, the bit is cleared and the registers maintain their values at power on.

*SRE (?) i

*STB? {i}

DENA (?) i

STAT? {i}

The *SRE common command sets the serial poll enable register to the decimal value of parameter i.

The *STB common query reads the value of the serial poll byte. If i is present, the value of bit i is returned (0 or 1). Reading this register has no effect on its value as it is a summary of other status registers.

The DENA command sets the status enable register to the decimal value of parameter i.

The STAT? query reads the value of the DDS status byte. If i is present, the value of bit i is returned (0 or 1). Reading this register will clear it while reading bit i will clear just bit i.

DS360 Ultra Low Distortion Function Generator

Remote Programming 4-19

Hardware Test and Calibration Commands

*TST?

The *TST? common query runs the DS360 internal self tests. After the tests are complete, the test status is returned as a one byte decimal value. If the value is 0, no errors have been detected, otherwise the returned value is the encoded value of the status of the test register described below.

bit Meaning

0 CPU error detected 1 ROM checksum error 2 RAM error detected 3 CALD calibration data chksum err 4 DSP error detected 5 unused 6 unused 7 reserved

Note: The following commands are primarily intended for factory calibration of the DS360 and should never be needed during normal operation. Incorrect use of some of these commands can alter the calibration of the DS360. If this happens, perform a full reset, as described in chapter

$FCL

The $FCL command recalls the factory calibration bytes. This command will generate an error if the calibration jumper is not in the correct position.

$FIL (?) i

The $FIL command sets the State Variable Filter to the i-th filter, when a previous $NOF1 or $NOF2 command has been sent. In the $NOF0 mode this command is disabled and the filter number is selected as a function of frequency. The $FIL? query returns the currently selected filter number. The range for i is 0 to 36, where 0 means no filter is selected.

$NOF (?) i

The $NOF command sets the filter mode to 0, 1 or 2. Mode 0 is normal, the Z80 sets the appropriate filter function of frequency and tells the DSP which filter is set. In mode 1, the Z80 sets the filter function of $FIL command and tells the DSP that filter 0 is set. In mode 2, the Z80 sets the filter function of $FIL command and tells the DSP which filter is set. The $NOF query returns the current mode.

$PRE (?) i

The $PRE command sets the DS360 pre-amplifier attenuators to range i. The integer i is the attenuation range which takes values from 0 to 31. Each range sets the pre-attenuators to -1.25*i dB. Setting the amplitude will return the attenuators to their normal position. The $PRE? query returns the current attenuator position.

DS360 Ultra Low Distortion Function Generator

4-20 Remote Programming

$PST (?) i

The $PST command sets the DS360 post-amplifier attenuators to range i. The integer i is the attenuation range, which takes values from 0 to 3. Each range sets the post-attenuators to -20*i dB. Setting the amplitude will return the attenuators to their normal position. The $PST? query returns the current attenuator position.

$WRD (?) j, {k}

The $WRDj,k command sets the value of calibration word j to k. Parameter j may have a value from 0 to 950, while k may range from - 3270 to 65535 (see chapter 6 for calibration information). This command will generate an error if the calibration jumper is not enabled. NOTE: This command will alter the calibration of the DS360. To recall the factory calibration, use the $FCL command (Factory Calibration Calbytes). Calibration bytes cannot be altered unless the warm-up bit has been set.

DS360 Ultra Low Distortion Function Generator

Status Byte Definitions

The DS360 reports on its status by means of three status bytes: the Serial Poll Byte, the Standard Status Byte and the DDS Status Byte.

Upon power on, the DS360 may either clear all of its status enable registers or maintain them in the state they were in on power down . The *PSC command determines which action will be taken.

The status bits are set to 1 when the event or state described in the tables below has occured or is present.

Serial Poll Status Byte

Bit Name Set When

0 Mod Done No modify function in progress 1 Mod Enable Modify function enabled 2 User SRQ User sends a front panel SRQ 3 DDS An unmasked bit in DDS is set 4 MAV The gpib output queue non-empty 5 ESB An unmasked bit in ESB is set 6 RQS/MSS SRQ (service request) has occured 7 No Command No unexecuted commands in the input queue

Remote Programming 4-21

The DDS and ESB bits are set whenever any unmasked bit (a bit with the corresponding bit in the byte enable register set) in their respective status registers are set. Use DENA and *ESE commands to set the enable register bits. The DDS and ESB bits are not cleared until ALL enabled status bits in DDS and ESB status bytes are cleared (by reading the status bytes or using *CLS).

Using *STB? to Read the Serial Poll Status Byte

A bit in the Serial Poll Status Byte is NOT cleared by using *STB?. The bit stays set as long as the status condition exists. This is true even for RQS. RQS will be set whenever the same bit in the Serial Poll Status Byte AND Serial Poll enable registers are set. This is independent of whether a serial poll has occured to clear the service request.

Using Serial Poll

Except for SRQ, a bit in the Serial Poll Status Byte is NOT cleared by polling the status byte.When reading the status byte using a serial poll, the RQS bit signals that the DS360 is requesting service.The RQS bit will be set to 1 the first time the DS360 is polled following the service request. The serial poll automatically clears the service request. Subsequent serial polls will return RQS cleared (0) until another service request occurs. Polling the status byte and reading it with *STB? can return different values for RQS. When serial polled, RQS indicates a service request has occured. When read with *STB?, RQS indicates that an enabled status bit is set.

DS360 Ultra Low Distortion Function Generator

4-22 Remote Programming

Standard Event Status Byte

Bit Name Set When

0 Unused 1 Unused 2 Query Error Set on output queue overflow 3 Unused 4 Execution Error A command cannot be executed (Range Error)

5 Command Error Command Syntax Error or unrecognized

6 URQ Set by any keypress 7 PON Set by Power ON

This status byte is defined by IEEE-488.2 (1987) and is used primarily to report errors in commands received over the communications interface. The bits in this register stay set and are cleared by reading them using the *ESR command or by the *CLS command.

(Parameter out of range, command not valid, etc.)

command

DDS Status Byte

Bit Name Set When 0 Trig’d A burst or sweep is triggered 1 Trig Err A trigger rate error occurs 2 unused 3 Adjust Msg A 2-Tone or Burst parameter is adjusted 4 Warmup Warm-up period expired 5 Test Error A self test error occurs 6 Cal Enabled 1 = calibration enabled 7 Mem Error The stored settings where corrupt

The Warm-up bit will be set and remain set after the warm up period has expired. The rest of the bits in this register are set when the corresponding event occurs and remain set until cleared by reading this status byte (*ESR) or by the *CLS command.

DS360 Ultra Low Distortion Function Generator

Example Programs

Using Microsoft C with the National Instruments GPIB card on a PC

To succesfully interface the DS360 to a PC via the GPIB interface, the instrument, interface card and interface drivers must all be configured properly. To configure the DS360, the GPIB address must be set in the [SHIFT][GPIB] menu.The default address is 8; use this address unless a conflict occurs with other instruments in your system. The DS360 will be set to GPIB address 8 whenever a reset is performed (power on with the CLR key pressed).

Make sure that you follow all of the instructions for installing the GPIB card. The National Instruments card cannot be simply unpacked and put into your computer. To configure the card , you may need to set jumpers and switches on the card to set the I/O address and the interrupt levels. You must run the program “IBCONF” to configure the resident GPIB driver for your GPIB card. Please refer to the National Instruments manual for more information. In these examples, the following options must be set with IBCONF:

4-23

Device Name: DS360 Device Address: 8 EOS Character: 0Ah (linefeed) Terminate Read on EOS: Yes

Once all the hardware and GPIB drivers are configured, use “IBIC”. This terminal emulation program allows you to send commands to the DS360 directly from the computer keyboard. If you cannot talk to the DS360 via “IBIC”, then your programs will not run.

Use the simple commands provided by National Instruments. Use “IBWRT” and “IBRD” to send and receive from the DS360. After you are familiar with these simple commands, you can explore more complex programming commands.

DS360 Ultra Low Distortion Function Generator

4-24 Programming Examples

Example1: GPIB Communication in C language

/* C program to demonstrate communication with the DS360 via GPIB. Written in Microsoft C and uses National Instruments GPIB card. Assumes DS360 is installed as device name DS360. Refer to National Instruments for Device Name setup. */

#include <stdio.h> #include <string.h> #include <stdlib.h> #include <dos.h> #include <decl.h> /* National Instruments header files */

void main(void); int ds360;

void main() {

char cmd[40]; char start[20];

char stop[20];

if ((ds360 = ibfind(“DS360”)) < 0) /* open National driver */ {

printf (“Cannot find DS360\n”); exit(1);

}

/* Now that the driver is located, reset the DS360 */

sprintf (cmd,“*RST\n”); ibwrt(ds360,cmd,strlen(cmd)); /* send command */

/* Setup the DS360 as follows:

50kHz,square wave,1.5Vpp, -1.0Volt offset,display offset */

sprintf (cmd, “FREQ50000”;FUNC1;AMPL1.5VP;OFFS-1.5;KEYS8\n”); ibwrt(ds360,cmd,strlen(cmd)_; /* send command */

/* Now, query the DS360 for the sweep start and stop frequencies */

sprintf(cmd, “STFR?\n”); /* ask for start freq */ ibwrt(ds360,cmd,strlen(cm)); /* send query */ ibrd(ds360,start,20); /* read back start freq*/ sprintf(cmd, “SPFR?\n”); /* ask for stop freq */ ibwrt(ds360,cmd,strlen(cm)); /* send query */ ibrd(ds360,stop,20); /* read back start freq*/

printf(“\n\n\n\n **** DS360 Setup Demo ****”); printf(“\n\nDS360 Sweep Start Frequency = %eHz\n\n”,atof(start)); printf(“\n\nDS360 Sweep Stop Frequency = %eHz\n\n”,atof(stop));

}

DS360 Ultra Low Distortion Function Generator

Programming Examples 4-25

Example 2: RS232 communication in BASIC language

BASIC program to demonstrate communication with the DS360 via RS232. Program assumes the DS360 BAUD rate is set to 9600.

10 OPEN “com2:9600,n,8,2,cs,ds,cd” FOR RANDOM AS #1 ‘ Setup com2’ 20 PRINT #1, “ ” 30 PRINT #1, “*RST” ‘ Reset the DS360’ 40 GOSUB 190 ‘ Query DS360 and display result’ 50 PRINT #1, “FREQ123456” ‘ Set new frequency to 123.456kHz’ 60 GOSUB 190 ‘ Query DS360 and display result’ 70 PRINT #1, “*RST” ‘ Reset the DS360’ 80 FOR I=0 TO 4 ‘ Step through all functions ‘ 90 PRINT #1, “FUNC”,I 100 GOSUB 190 ‘ Query DS360 and display result’ 110 NEXT I 120 PRINT #1, “*RST” ‘ Reset the DS360’ 130 PRINT #1, “AMPL0VP” ‘ Set amplitude to 0 volts’ 140 FOR I=-5 TO 5 ‘ Set offset from -5V to 5v’ 150 PRINT #1, “OFFS”,I ‘ and query each time’ 160 GOSUB 190 ‘ Query DS360 and display result’ 170 NEXT I 180 END

‘ Routine to query the DS360 frequency,’ 190 PRINT #1, “FREQ?” ‘ amplitude and offset and display them’ 200 INPUT #1, F 210 PRINT #1, “AMPL?VP” 220 INPUT #1, A 230 PRINT #1, “OFFS?” 240 INPUT #1, O 250 PRINT “Freq=“ ;F; “ Ampl=“; A; “ Offs=“; O 260 RETURN

DS360 Ultra Low Distortion Function Generator

4-26 Programming Examples

DS360 Ultra Low Distortion Function Generator

5-1

Chapter 5

Digital Output

The following sections describe the operation of the digital output of the DS360. The first section describes the general specifics of the two common digital audio formats, the professional mode (AES-EBU) and the consumer mode (S/PDIF). This is a very basic description of the standards; for further detail the user should obtain the revelant standards. The second section how to set the various parameters for the digital output.

In this Chapter

Overview 5-3

Digital Audio Encoding 5-3 Channel Status Bytes 5-3 AES-EBU 5-3 S/PDIF 5-3 DS360 Functions 5-4

Setting the Digital Output 5-7

Output Type 5-7 Function Type 5-7 Frequency 5-7 Amplitude 5-8 Sampling Frequency 5-8 Number of Bits 5-9 Digital Mode 5-9 Inactive Functions and Parameters 5-9 Storing and Recalling Settings 5-9 Default Settings 5-10

DS360 Ultra Low Distortion Function Generator

5-2

Digital Output

DS360 Ultra Low Distortion Function Generator

Digital Output 5-3

Overview

The DS360 is capable of generating digital domain waveforms in two different digital audio formats. The two formats are AES-EBU, the professional digital audio format and S/PDIF, the consumer digital audio format.

The following description is provided to help user understand the operation of the DS360’s digital output. It by no means completely describes any of the specifications. For complete information, the user should obtain copies of the relevant standards (AES-EBU 1992, IEC 958, ANSI S4.40-1992 and EIAJ CP-340).

Digital Audio Data Encoding

The two formats of digital audio communication are very similar in terms of data format and encoding. Both formats support data rate of 32 kHz, 44.1 kHz and 48 kHz. Each audio sample is transmitted in a sub-frame. Each sub-frame consists of a preamble, 4 bits of auxiliary data, 20 bits of audio data and one bit each of validity, user, channel and parity. Two sub frames are combined to make a frame, 192 of which make up a block.

The channel bits of each sub-frame are combined to make up 24 eight bit bytes that convey status information. The first four bytes contain most of the important status information. The significance of the first four bytes of channel status bits of each interface are indicated below.

Professional Mode Channel Status Bytes

byte bit 0 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7

0 Pro=1 Audio Emphasis Lock Sampling Frequency 1 Channel Mode User Management 2 AUX Use Word Length Reserved 3 Reserved

Consumer Mode Channel Status Bytes

byte bit 0 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7

0 Pro=0 Audio Copy Emphasis Mode 1 Category Code Gen Stat 2 Source Number Channel Number 3 Sampling Frequency Clock Accuracy Reserved

DS360 Ultra Low Distortion Function Generator

5-4 Digital Output

AES-EBU

The AES-EBU digital audio interface format is described in AES3-1992 (also ANSI S4.40-1992). It is a means of serially transmitting two channels of periodically sampled audio signals on a single shielded twisted wire pair. The transmission rate is such that both audio channels can be transmitted in one sample period. Error detection is provided and there is a format for transmitting channel status (control) and user specific information. The control and user specific data is transmitted at the rate of one bit per sample.

The electrical specifications of the AES-EBU interface require that the data is transmitted as a differential signal over a shielded twisted pair of wire and are compatible with RS-

422. The signal level are specified for a 110Ω source impedance at 2-7 VPP into a load impedance of 110Ω. The connector provided on the DS360 is an XLR connector (male pins, female shell) with the signal on pins 2 and 3 and pin 1 grounded. Any high quality XLR cable can connect the DS360 to the device under test.

The major difference between the professional format (AES-EBU) and the consumer format (S/PDIF) is in the definition of the channel status bytes and the number of bits per word of data. The professional format can support between 16 and 24 bits per word of data (although the DS360 only supports 16-20 bits). The consumer format only supports 16 bits of data per word.

S/PDIF

The S/PDIF, or Sony-Phillips Digital Interface Format is described in IEC 958 (also EIAJ CP-340). It is a means of serially transmitting two channels of periodically sampled audio signals on a single shielded wire or over a fiber-optic link. The transmission rate is such that both audio channels can be transmitted in one sample period. Error detection is limited to parity checking and there is a format for transmitting channel status (control) and user specific information. The control and user specific data is transmitted at the rate of one bit per sample.

The electrical specifications of the S/PDIF require that the data is transmitted in an unbalanced configuration with an output impedance of 75Ω and a voltage of 0.5 V

±20% into a 75Ω load, with no cable. The connector provided on the DS360 is an RCA phono socket. In addition there is an fiber optic connector (Sharp GP1F32T), compatible with most consumer digital audio fiber optic cables (Sharp GP1C321 type or equivalent).

The major difference between the professional format (AES-EBU) and the consumer format (S/PDIF) is in the definition of the channel status bytes and the number of bits per word of data. The professional format can support between 16 and 24 bits per word of data (the DS360 supports 16-20 bits). The consumer format only supports 16 bits of data per word.

DS360 Ultra Low Distortion Function Generator

DS360 Digital Functions

The DS360 is capable of generating sine waves and two sine 2 Tones at sampling rates of 32 kHz, 44.1 kHz and 48 kHz. The frequency, amplitude, number of bits and sampling rate can be set. The following tables show the values that are set for the different status bits in each format. These cannot be changed.

Bit Name Meaning Value

Validity Sample Valid (0) 0 (Sample always valid) User User Data 0 (No user data) Channel Byte 0, bit 0 Pro 1 (Professional mode) Channel Byte 0, bit 1 Audio 0 (Audio) Channel Byte 0, bit 2 - 4 Emphasis 000 (No emphasis) Channel Byte 0, bit 5 Locked 0 (Locked) Channel Byte 0, bit 6 - 7 Sample Frequency 01 = 44.1 kHz, 10 = 48 kHz,

Channel Bytes 1 thru 22 Other channel status Always 0 Channel Byte 23 CRCC Depends on data

Professional Format Status Bits

11 = 32 kHz (bit 7,6)

Digital Output

5-5

Consumer Format Status Bits

Bit Name Meaning Value

Validity Sample Valid (0) 0 (Sample always valid) User User Data 0 (No user data) Channel Byte 0, bit 0 Pro 0 (Consumer Mode) Channel Byte 0, bit 1 Audio 0 (Audio) Channel Byte 0, bit 2 Copy Protect 1 (Copy permitted) Channel Byte 0, bit 3 - 5 Emphasis 000 (No emphasis) Channel Byte 0, bit 6, 7 Mode 00 Always Channel Byte 1 Category Code 0 Always Channel Byte 2 Source Number 0 Always Channel Byte 3, bits 0 - 3 Sample Frequency 0000 = 44.1 kHz,

0010 = 48 kHz,

0011 = 32 kHz (bits 3210) Channel Byte 3, bits 4 - 7 Clock Accuracy 0000 Always Channel Bytes 4 thru 23 Reserved 0 always

DS360 Ultra Low Distortion Function Generator

5-6 Digital Output

DS360 Ultra Low Distortion Function Generator

Digital Output 5-7

Setting the Digital Output

The following section describes how to set the parameters for the digital output functions of the DS360, including function type, frequency, amplitude, mode, number of bits and digital sampling frequency. Please note that in digital mode several analog mode functions are disabled and cannot be selected.

All parameters for the digital output are independent from their analog counterparts. When the digital mode is entered, the last digital output frequency used will be recalled, not the one previously used for the analog outputs. There are separate computer interface commands to set the various parameters as well.

Output Mode

The DS360 has two different output modes: analog and digital. The currently selected output is indicated by the LED in the OUTPUT section (balanced / unbalanced or digital). Pressing [SHIFT] [∨] output down key toggles between the two different modes.

The operation for the balanced and unbalanced outputs is described in Chapter 3.

When the digital mode is selected, the front panel analog output is disabled and the rear panel digital output is enabled. Note that in digital mode several functions are disabled and cannot be selected.

Function Type

The DS360 output function type is selected using the [∧] up and [∨] down function arrow keys. Press the appropriate key until the desired function LED is lit. In digital mode only sine waves and two sine 2 tone functions are available. Other functions cannot be selected. When in 2-Tone, only one set of parameters (amplitude, frequency) are available at a time. To toggle between displaying Tone 1 and Tone 2 parameters, press [SHIFT][T1/T2].

Frequency

To display the current output frequency, press the [FREQ] key. The frequency is displayed in Hz or kHz, depending on which unit LED is lit. The DS360 has 6 digits of frequency resolution or 1 mHz, whichever is greater. Any non displayed digits are zeroed to avoid having slightly different output frequencies for a given display value. The output frequency for the digital output is maintained separately from that of the analog output functions, so that when changing between digital and analog modes, the previous digital frequency will be recalled.

The frequency ranges are shown in the table below. Frequency resolution is 6 digits or

0.001 Hz, whichever is larger.

DS360 Ultra Low Distortion Function Generator

5-8 Digital Output

Frequency Range of Functions vs Sampling Frequency

Function 48 kHz 44.1 kHz 32 kHz

Sinewaves 0.001 Hz - 20.0 kHz 0.001 Hz - 20.0 kHz 0.001 Hz - 14.5 kHz Two-Tones (Tone1 & Tone2)

Amplitude

0.001 Hz - 20.0 kHz 0.001 Hz - 20.0 kHz 0.001 Hz - 14.5 kHz

The frequency of both Tone1 and Tone 2 may be set in the same manner as for normal sines. To toggle between displaying Tone 1 and Tone 2 parameters, press [SHIFT][T1/T2].

To display the current amplitude, press the [AMPL] key. The amplitude may be set and displayed only in % (percent) of full scale, since volts or other units have no meaning in the digital format. The current units (%) will be indicated by the LED at the right of the display. The amplitude resolution is 0.00001%, with a range of 0 to 100.00000%. To change the amplitude, type a new value on the keypad, followed by [%]. Or use the spin knob to modify the current value. The amplitude for the digital output is maintained separately from those of the analog output functions, so that when changing between digital and analog modes, the previous digital amplitude values will be recalled.

2-Tone Amplitude

The amplitudes of Tone1 and Tone2 are maintained separately from the sine amplitude (i.e. when changing from another function to 2-Tone, the amplitudes will be the last 2Tone amplitudes set, not the amplitude value of the sine). The amplitude limits for 2 tone are a function of the sum of the two amplitudes. {i.e. 0 ≤ (Amp1 + Amp2) ≤ 100 %}

Digital Sampling Frequency

The digital sampling frequency can be set to three values: 48.0 kHz, 44.1 kHz and 32.0 kHz. These correspond to frequencies commonly used for digital audio tape, compact disks and computer digital audio applications.

DS360 Ultra Low Distortion Function Generator

To display the current sampling frequency, press [SHIFT] [DIG FREQ]. The message “digF” will be displayed, followed by the sampling frequency in kHz. To change sampling

frequency, turn the spin knob to the left or right.

Number of Bits

The number of bits (of resolution) per word can be set from 16 to 20 for the professional mode. For the consumer mode the number of bits should always be set to 16.

To display the current number of bits, press [SHIFT] [# BITS]. The message “bitS” will be displayed, followed by the current number of bits. To change the number of bits, turn the spin knob to the left or right.

Digital Mode

The digital mode can be set to either professional or consumer modes. See the overview at the beginning of the chapter for more information about the two different formats.

To display the current digital mode, press [SHIFT] [DIG MODE]. The message “conS” or “ProF” (for consumer and professional modes, respectively) will be. To change the mode, turn the spin knob to the left or right.

Digital Output

5-9

Inactive Functions and Parameters

The following functions are inactive for digital mode. Pressing the keys of inactive functions will cause the unit to beep and display “not Appl” (not applicable). All modify functions are inactive and cannot be selected.

Inactive functions are: Offset,

Output ON/OFF, All Modify Function (cannot be selected), All Modify Function Parameters, All Source Impedance’s, Trigger, T2 Mode, REL

Storing and Recalling Settings

Digital output settings are stored and recalled at the time as the analog output settings. Settings can be stored in locations 1 through 9 and recalled in settings 0 through 9 with location 0 being the default settings. Remember that the digital parameters (amplitude, frequency) are independent of the analog parameters (i.e. different values are saved for digital and analog output frequencies). The output mode (digital, balanced or unbalanced) recalled will be the one the unit was in when the setting was saved.

DS360 Ultra Low Distortion Function Generator

5-10 Digital Output

Default Settings

Press [RCL][0] to recall the DS360’s default settings. This is a good place to begin whenever you wish to start the instrument from a known state. The default settings for the digital output are listed below. For information on the default settings for the analog output, refer to Chapter 3.

2-Tone Tone 1 Frequency 1.00000 kHz 2-Tone Tone 2 Frequency 2.00000 kHz

2-Tone Tone 1 Amplitude 50.0 %

2-Tone Tone2 Amplitude 50.0 %

Digital Output Default Settings

Setting Default Value

Function Sine

Frequency 1.00000 kHz

Amplitude 100.0 %

Output Mode Analog

Digital Mode Consumer

Sampling Frequency 44.1 kHz

Number of Bits 16

GPIB Address 8

RS-232 Baud Rate 9600

DS360 Ultra Low Distortion Function Generator

Chapter 6

Performance Tests

The performance tests described in this section are designed to verify with a high degree of confidence that the unit is performing within the specifications.

The results of each test should be recorded on a copy of the test sheet located at the end of this section.

In this Chapter

Getting Ready 6-3

Keypad 6-3 Knob 6-3 Reset 6-3 Serial Number 6-3 Firmware Revision 6-3 Necessary Equipment 6-4 Warm-up 6-4 Test Record 6-4 Distortion Measurements 6-5

6-1

1. Front Panel Test 6-7

2. Self Tests 6-8

3. Frequency Test 6-9

4. Amplitude Test 6-10

5. Harmonic Distortion 6-13

6. Waveform Test 6-15

7. Sweep Test 6-17

8. Burst Test 6-18

9. DC Offset Test 6-19

10. Output Impedance 6-21 Performance Record 6-23

DS360 Ultra Low Distortion Function Generator

6-2 Performance Tests

DS360 Ultra Low Distortion Function Generator

Stanford Research Systems DS360 Operations Guide

Specifications and Main Features

Frequently Asked Questions

User Manual