SRS SR780 Owner's manual

Revision 2.4. (0DUFK 201)

Operating Manual and

Programming Reference

Model SR780

Network Signal Analyzer

1290-D Reamwood Avenue

Sunnyvale, CA 94089 U.S.A.

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

Email: info@thinkSRS.com • www.thinkSRS.com

Stanford Research Systems, Inc.

SR780 Network Signal Analyzer

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 U.S.A.

i

SR780 Network Signal Analyzer

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 cover is removed. Do not remove the cover while

the unit is plugged into 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 SR780 operates from a 100V, 120V, 220V, or 240V nominal 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 card, located in the rear panel fuse

holder, is set so that the correct AC input voltage value is visible.

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 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.

Line Fuse

Verify that the correct line fuse is installed before connecting the line cord. For

100V/120V, use a 1.5 Amp fuse. For 220V/240V, use a 3/4 Amp fuse.

Line Cord

The SR780 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.

Service

Do not attempt to service or adjust this instrument unless another person, capable of

providing first aid or resuscitation, is present.

Do not install substitute parts or perform any unauthorized modifications to this

instrument. Contact the factory for instructions on how to return the instrument for

authorized service and adjustment.

Fan

The fans in the SR780 are required to maintain proper operation. Do not block the vents

in the chassis or the unit may not operate properly.

ii

SR780 Network Signal Analyzer

iii

SR780 Network Signal Analyzer

Contents

Safety and Preparation For Use i

Contents iii

Table of Figures vii

Features ix

Specifications xi

Chapter 1 Getting Started

General Installation 1-3

Front Panel Quick Start 1-4

Things To Watch Out For 1-5

Analyzing a Sine Wave 1-7

Measuring a Transfer Function 1-11

Linking (Advanced Operation) 1-15

Triggering and the Time Record 1-19

Octave Analysis 1-25

Capture 1-29

Waterfall Display 1-35

Swept Sine Measurement 1-43

Saving and Recalling 1-49

User Math Functions 1-55

Limit Testing 1-59

Exceedance Statistics 1-63

Chapter 2 Analyzer Basics

Measurement Groups 2-3

What is an FFT? 2-4

FFT Frequency Spans 2-6

FFT Time Record 2-8

FFT Windowing 2-10

FFT Measurements 2-14

Views 2-20

FFT Averaging 2-23

Real Time Bandwidth and Overlap 2-25

Waterfall Display 2-28

Capture Buffer 2-30

The Source 2-33

Octave Analysis 2-35

Swept Sine Measurements 2-41

Trace Storage 2-48

User Math Functions 2-49

Signal Inputs 2-55

Input Connections 2-58

Intrinsic Noise Sources 2-60

External Noise Sources 2-61

Chapter 3 Operation

Overview 3-3

iv Contents

SR780 Network Signal Analyzer

Front Panel Connectors 3-6

Rear Panel Connectors 3-8

Screen Display 3-11

Status Indicators 3-17

Keypad 3-22

Normal and Alternate Keys 3-22

Menu Keys 3-23

Entry Keys 3-24

Control Keys 3-26

Function Keys 3-32

Macros 3-36

Chapter 4 Menus

Frequency Menus 4-7

FFT Frequency Menu 4-7

Octave Frequency Menu 4-12

Swept Sine Frequency Menu 4-15

Display Setup Menu 4-19

Display Options Menu 4-33

Marker Menu 4-37

Normal Marker Menu 4-40

Harmonic Marker Menu 4-43

Sideband Marker Menu 4-46

Band Marker Menu 4-49

Source Menus 4-51

Sine Source Menu 4-55

Chirp Source Menu 4-57

Noise Source Menu 4-59

Arbitrary Source Menu 4-62

Swept Sine Source Menu 4-67

Input Menu 4-71

Analog Input Menu 4-71

Playback Input Menu 4-81

Trigger Menu 4-85

Average Menus 4-91

FFT Average Menu 4-91

Octave Average Menu 4-99

Swept Sine Average Menu 4-103

User Math Menu 4-107

Window Menu 4-115

Waterfall Menu 4-119

Capture Menu 4-127

Analysis Menu 4-131

Data Table Analysis Menu 4-133

Contents v

SR780 Network Signal Analyzer

Limit Testing Analysis Menu 4-135

Marker Statistics Analysis Menu 4-139

Exceedance Statistics Analysis Menu 4-142

Disk Menu 4-145

Recall Settings Menu 4-149

Disk Buffers Menu 4-152

Disk Upkeep Menu 4-158

Output Menu 4-161

System Menu 4-169

System Remote Menu 4-172

System Preferences Menu 4-174

System Date/Time Menu 4-176

System Diagnostics Menu 4-177

Edit Macro Menu 4-180

Chapter 5 Programming

Index of Commands 5-2

Alphabetical List of Commands 5-11

Introduction 5-19

Command Syntax 5-23

Frequency Commands 5-25

Display Setup Commands 5-31

Display Options Commands 5-35

Marker Commands 5-37

Source Commands 5-44

Input Commands 5-51

Trigger Commands 5-55

Average Commands 5-56

User Math Commands 5-61

Window Commands 5-63

Waterfall Commands 5-65

Capture Commands 5-68

Memory Allocation Commands 5-69

Data Table Commands 5-70

Limit Test Commands 5-72

Marker Statistics Commands 5-74

Exceedance Statistics Commands 5-75

Disk Commands 5-76

Output Commands 5-79

System Commands 5-82

Front Panel Commands 5-84

Data Transfer Commands 5-89

Interface Commands 5-101

Nodal Degree-of-Freedom Commands 5-102

Status Reporting Commands 5-104

Status Word Definitions 5-108

Example Program 5-113

vi Contents

SR780 Network Signal Analyzer

Chapter 6 File Conversion

Why File Conversion 6-2

Supported External File Types 6-3

SR780 File Types 6-4

Using the File Conversion Utility 6-5

vii

SR780 Network Signal Analyzer

Table of Figures

Figure 2-1 Waterfall Display 2-28

Figure 2-2 Transfer Functions 2-42

Figure 2-3 Capacitive Coupling 2-61

Figure 2-4 Inductive Coupling 2-62

Figure 2-5 Resistive Coupling 2-63

Figure 3-1 Front Panel 3-3

Figure 3-2 Rear Panel 3-8

Figure 3-3 Dual Display Screen 3-11

Figure 3-4 Single Display Screen 3-12

Figure 3-5 Vertical Scale Bar 3-13

Figure 3-6 Horizontal Scale Bar 3-14

Figure 3-7 Marker Region 3-14

Figure 3-8 Marker Position Bar 3-15

Figure 3-9 Status Indicator Panel 3-17

Figure 3-10 Front Panel Keypad 3-22

viii

SR780 Network Signal Analyzer

ix

SR780 Network Signal Analyzer

Features

Measurements FFT Group

FFT Time Record Windowed Time

Time Capture Transfer Function Cross Spectrum

Coherence Cross Correlation Autocorrelation

Orbit User Math Functions

Octave Analysis Group

1/1, 1/3, 1/12 Octave Time Capture User Math Functions

LEQ Impulse Reverberation

Swept Sine Group

Spectrum Transfer Function Cross Spectrum

User Math Functions

Views Log Magnitude Linear Magnitude Magnitude Squared

Real Part Imaginary Part Phase

Unwrapped Phase Nichols Plot Nyquist Plot

Displays Single Dual Upper/Lower Waterfall with Skew

Zoom and Pan

FFT Resolution 100, 200, 400 or 800 FFT lines

FFT Windows Hanning Blackman-Harris Flattop

Kaiser Uniform Force/Exponential

User defined [-T/2..T/2] [-T/4..T/4]

[0..T/2]

Averaging RMS Vector Peak Hold

Linear or Exponential Preview Time Records Equal Confidence

Analysis Harmonic Sideband Band

THD/THD+N Limit Testing Data Table

Exceedance (LN) Statistics Waterfall Slice

User Math +, -, *, / Conjugate Magnitude/Phase

Real/Imaginary Sqrt FFT/Inverse FFT

jω Log/Exp d/dx

Group Delay A, B, C Wt

Source Outputs Sine Two Tone Swept Sine

White/Pink Noise Burst Noise Chirp

Burst Chirp Arbitrary

Trigger Free Run External (Analog and TTL)

Internal Source Auto/Manual Arming

Time Capture Capture time data for later analysis (FFT or Octave). Up to 2M samples

of data can be saved.

x Features

SR780 Network Signal Analyzer

Storage 3.5”, 1.44 Mbytes, DOS formatted disk. Save data, setups and hardcopy.

Hard Copy Print to dot matrix or LaserJet/InkJet printers. Plot to HPGL or Postscript

plotters. Print/Plot on-line (serial, parallel or IEEE-488) or to disk file.

GIF, EPS and PCX graphic formats available for disk output.

Interfaces RS232 serial, Centronics parallel and IEEE-488.

Help On screen help system provides Operating Manual and Programming

Reference on-line.

xi

SR780 Network Signal Analyzer

Specifications

Specifications apply after 30 minutes of warm-up and within 2

hours of last auto-offset. All specifications are with 400 line

FFT resolution and anti-alias filters enabled unless stated

otherwise.

Frequency

Range 102.4 kHz or 100 kHz (both displays have the same range).

FFT Spans 195.3 mHz to 102.4 kHz or 191 mHz to 100 kHz.

The 2 displays can have different spans and start frequencies.

FFT Resolution 100, 200, 400 or 800 lines

Real Time Bandwidth 102.4 kHz (highest FFT span with continuous data

acquisition and averaging on both inputs).

Accuracy 25 ppm from 20°to 40°C

FFT Dynamic Range

Dynamic Range -90 dBfs typical, -80 dBfs guaranteed (FFT and Octave),

145 dB (Swept Sine).

Includes spurs, harmonic and intermodulation distortion and

alias products. Excludes alias responses at extremes of span.

Harmonic Distortion <-80 dB (Single tone in band).

Intermodulation Distortion <-80 dB (Two tones in band, each <- 6.02 dBfs).

Spurious <-80 dBfs

Alias Responses <-80 dBfs (Single tone outside of span, < 0 dBfs, < 1 Mhz).

Full Span FFT Noise Floor -100 dBfs typical (Input grounded, Input Range > -30 dBV,

Hanning window, 64 RMS averages).

Residual DC Response < -30 dBfs (FFT with Auto Cal On).

Amplitude Accuracy

Single Channel ± 0.2 dB (excluding windowing effects).

Cross Channel ± 0.05 dB (dc to 102.4 kHz)

(Transfer Function measurement, both inputs on the same

Input Range, RMS averaged).

Phase Accuracy

Single Channel ± 3.0 deg relative to External TTL trigger.

(-50 dBfs to 0 dBfs, freq < 10.24 kHz)

(Center of frequency bin, DC coupled)

For Uniform, Blackman-Harris, Hanning, Flattop

and Kaiser windows, phase is relative to a cosine

wave at the center of the time record.

For Force and Exponential windows, phase is relative

to a cosine wave at the beginning of the time record.

Cross Channel ± 0.5 deg (dc to 51.2 kHz)

± 1.0 deg (dc to 102.4 kHz)

(Transfer Function measurement, both inputs on the same

Input Range, Vector averaged.)

xii Specifications

SR780 Network Signal Analyzer

Signal Inputs

Number of Inputs 2

Full Scale Input Range -50 dBV (3.16 mVpk) to +34 dBV (50 Vpk) in 2 dB steps.

Maximum Input Level 57 Vpk

Input Configuration Single-ended (A) or True Differential (A-B).

Input Impedance 1 MΩ + 50 pF

Shield to Chassis Floating Mode: 1 MΩ + 0.01 µF

Grounded Mode: 50

Ω

Shields are always grounded in differential input (A-B).

Maximum Shield Voltage 4 Vpk

AC Coupling -3 dB rolloff at 0.16 Hz.

CMRR 90 dB at 1 kHz (Input Range < 0 dBV).

80 dB at 1 kHz (Input Range <10 dBV).

50 dB at 1 kHz (Input Range ≥10 dBV).

ICP Signal Conditioning Current Source: 4.8 mA

Open Circuit Voltage +26 V

A-weight Filter ANSI Standard S1.4-1983; 10 Hz to 25.6 kHz,

Type 0 Tolerance.

Crosstalk <-145 dB below signal,

(Input to Input and Source to Inputs, 50 Ω receiving input

source impedance).

Input Noise <10 nVrms/√Hz (< -160 dBVrms/√Hz) above 200 Hz.

Trigger Input

Modes Continuous, Internal, External, or External TTL.

Internal Level adjustable to ±100% of input scale.

Positive or Negative slope.

Minimum Trigger Amplitude: 5% of input range

External Level adjustable to ±5V in 40 mV steps.

Positive or Negative slope.

Input Impedance: 1 MΩ

Max Input: ±5V

Minimum Trigger Amplitude: 100 mV

External TTL Requires TTL level to trigger (low<0.7V, high>3.0V).

Post-Trigger Measurement record is delayed up to 8192 samples after the

trigger.

Pre-Trigger Measurement record starts up to 8192 samples prior to the

trigger.

Time Capture

Mode Continuous real time data recording to memory.

Maximum Rate 262,144 samples/sec for both inputs.

Lower rates may be used for longer capture.

Maximum Capture Length 2M samples standard,

4M and 8M samples optional.

Octave Analysis

Standards Conforms to ANSI S1.11-1986, Order 3, Type 1-D.

Frequency Range Band centers:

Single Channel

Specifications xiii

SR780 Network Signal Analyzer

1/1 Octave 0.125 Hz - 32 kHz

1/3 Octaves 0.100 Hz - 40 kHz

1/12 Octaves 0.091 Hz - 12.34 kHz

Two Channels

1/1 Octave 0.125 Hz - 16 kHz

1/3 Octaves 0.100 Hz - 20 kHz

1/12 Octaves 0.091 Hz - 6.17 kHz

Accuracy < 0.2 dB (1 second stable average, single tone at band center).

Dynamic Range 80 dB (1/3 Octave, 2 second stable average),

per ANSI S1.11-1986.

Sound Level Exponential time averaged broadband power (L),

per ANSI S1.4-1983, Type 0.

Broadband Impulse and Peak power, per

IEC 651-1979, Type 0.

Sum of octave bands total power.

Source Output

Amplitude Range 0.1 mVpk to 5 Vpk

Amplitude Resolution 0.1 mVpk

DC Offset <10.0 mV (typical)

Output Impedance < 5 Ω; ±100 mA peak output current.

Sine

Amplitude Accuracy ±1% of setting, 0 Hz to 102.4 kHz

0.1 Vpk to 5.0 Vpk, high impedance load.

Offset 0 V to ±5 V, max output ±5 V (ac+dc).

Harmonics, Sub-Harmonics 0.1 Vpk to 5 Vpk, 0 V offset,

and Spurious Signals <-80 dBc (fundamental < 30 kHz),

<-74 dBc (fundamental > 30 kHz).

Two Tone

Amplitude Accuracy ±1% of setting, 0 Hz to 102.4 kHz

0.1 Vpk to 5 Vpk, high impedance load.

Offset 0 V to ±5 V, max output ±5 V (ac+dc).

Harmonics, Sub-Harmonics 0.1 Vpk to 2.5 Vpk, 0 V offset,

and Spurious Signals < -80 dBc (fundamental < 30 kHz),

<-74 dBc (fundamental > 30 kHz).

White Noise

Time Record Continuous or Burst

Bandwidth DC to 102.4 kHz or limited to analysis span.

Flatness <0.25 dB pk-pk (typical), <1.0 dB pk-pk (max),

(5000 rms averages).

Pink Noise

Time Record Continuous or Burst

Bandwidth DC to 102.4 kHz

Flatness <2.0 dB pk-pk, 20 Hz - 20 kHz,

(measured using averaged 1/3 Octave Analysis).

xiv Specifications

SR780 Network Signal Analyzer

Chirp

Time Record Continuous or Burst

Output Sine sweep across the FFT span.

Flatness ±0.25 dB pk-pk, Amplitude = 1.0 Vpk.

Crest Factor 1.94 (5.77 dB)

Swept Sine

Auto Functions Source Level, Input Range and Frequency Resolution.

Dynamic Range 145 dB

Arbitrary

Amplitude Range ± 5V

Record Length 2M samples (playback from Arbitrary Waveform memory or

a Capture buffer),

4M and 8M samples optional.

Variable output sample rate.

General

Monitor Monochrome CRT, 800H by 600V resolution.

Interfaces IEEE-488, RS232 and Printer interfaces standard.

All instrument functions can be controlled through the

IEEE-488 and RS232 interfaces. A PC (XT) keyboard input is

provided for additional flexibility.

Hardcopy Print to dot matrix and HP LaserJet/InkJet compatible printers.

Plot to HPGL or Postscript plotters. Print/Plot to RS232 or

IEEE-488 interfaces or to disk file. Additional file formats

include GIF, PCX and EPS.

Disk 3.5 inch DOS compatible format, 1.44 Mbytes capacity.

Storage of data, setups and hardcopy.

Preamp Power Power connector for SRS preamplifiers.

Power 70 Watts, 100/120/220/240 VAC, 50/60 Hz.

Dimensions 17"W x 8"H x 22"D

Weight 56 lb.

Warranty One year parts and labor on materials and workmanship.

1-1

SR780 Network Signal Analyzer

Chapter 1

Getting Started

These example measurements are designed to acquaint the first time user with the SR780 Network

Analyzer. They provide a foundation for understanding how to use the SR780. For a more complete

overview of the instrument and its capabilities, refer to the ‘Analyzer Basics’ and ‘Operation’ sections of

this manual.

Many of the examples use the test filter enclosed with this manual. The filter is a simple twin-tee 1 kHz

passive notch filter. This filter provides an interesting transfer function for these measurements.

In This Chapter

General Installation 1-3

Caution 1-3

Line Voltage Selection 1-3

Line Fuse 1-3

Line Cord 1-3

Power Switch 1-3

Screen Brightness 1-3

Fan 1-3

Front Panel Quick Start 1-4

[Hardkeys] 1-4

<Softkeys> 1-4

Knob 1-4

Help 1-4

Things To Watch Out For 1-5

Start 1-5

Live Display 1-5

Narrow Span 1-5

Low Detection Frequency 1-5

Averaging 1-5

Triggering 1-5

Scaling and Ranging 1-6

Local 1-6

Reset 1-6

Analyzing a Sine Wave 1-7

Measuring a Transfer Function 1-11

Linking (Advanced Operation) 1-15

Triggering and the Time Record 1-19

Octave Analysis 1-25

Capture 1-29

Waterfall Display 1-35

Swept Sine Measurement 1-43

Saving and Recalling 1-49

User Math Functions 1-55

Limit Testing 1-59

Exceedance Statistics 1-63

1-2 Getting Started

SR780 Network Signal Analyzer

Getting Started 1-3

SR780 Network Signal Analyzer

General Installation