Model SR785 Dynamic Signal Analyzer

1 Revision (March, 2017) Operating Manual and Programming Reference Model SR785 Dynamic Signal Analyzer 1290-D Reamwood Avenue Sunnyvale, CA 94089 Phone: (408) 744-9040 Fax: (408) 744-9049 Email: Copyright 1995, 1996, 1998, 2006, 2017 Stanford Research Systems, Inc. All Rights Reserved 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.

2 Contact Stanford Research Systems or an authorized representative before returning this product for repair. Information in this document is subject to change without notice. Copyright Stanford Research Systems, Inc., 1995, 1996, 1998, 2006, 2017. All rights reserved. Stanford Research Systems, Inc. 1290-D Reamwood Avenue Sunnyvale, California 94089 Printed in i SR785 Dynamic 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.

3 Line Voltage Selection The SR785 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.

4 Line Fuse Verify that the correct line fuse is installed before connecting the line cord. For 100V/120V, use a Amp fuse. For 220V/240V, use a 3/4 Amp fuse. Line Cord The SR785 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.

5 Fan The fans in the SR785 are required to maintain proper operation. Do not block the vents in the chassis or the unit may not operate properly. ii iii SR785 Dynamic 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 1-2 Front Panel Quick Start 1-3 Things To Watch Out For 1-5 Analyzing a Sine Wave 1-7 Measuring a Frequency Response Function 1-11 Linking (Advanced Operation) 1-15 Triggering and the Time Record 1-19 Octave Analysis 1-23 Capture 1-27 Waterfall Display 1-34 Swept Sine Measurement 1-41 Saving and Recalling 1-47 User Math Functions 1-52 Limit Testing 1-56 Exceedance Statistics 1-60 Chapter 2 Analyzer Basics Measurement Groups 2-4 What is an FFT?

6 2-6 FFT Frequency Spans 2-8 FFT Time Record 2-10 FFT Windowing 2-12 FFT Measurements 2-16 Views 2-21 FFT Averaging 2-24 Real Time Bandwidth and Overlap 2-27 Waterfall Display 2-30 Capture Buffer 2-33 The Source 2-36 Correlation Analysis 2-38 Octave Analysis 2-41 Swept Sine Measurements 2-47 Order Analysis 2-55 Time/Histogram Measurements 2-58 Trace Storage 2-60 User Math Functions 2-61 Signal Inputs 2-65 iv Contents Input Connections 2-68 Intrinsic Noise Sources 2-70 External Noise Sources 2-71 Curve Fitting and Synthesis 2-75 Chapter 3 Operation Overview 3-3 Front Panel Connectors 3-6 Rear Panel Connectors 3-8 Screen Display 3-11 Status Indicators 3-18 Keypad 3-23 Normal and Alternate Keys 3-23 Menu Keys 3-24 Entry Keys 3-25 Control Keys 3-28 Function Keys 3-34 Macros 3-38 Chapter 4 Menus Frequency Menus 4-7 FFT Frequency Menu 4-7 Octave Frequency Menu 4-12 Swept Sine Frequency Menu 4-15 Order Frequency Menu 4-19 Time/Histogram Frequency Menu 4-23 Display Setup Menu 4-25 Display Options Menu 4-46 Marker Menu 4-50 Normal Marker Menu 4-54 Harmonic Marker Menu 4-58 Sideband Marker Menu 4-61 Band Marker Menu 4-64 Frequency/Damping Marker Menu 4-66 Source Menus 4-67 Sine Source Menu 4-71 Chirp Source Menu 4-73 Noise Source Menu 4-75 Arbitrary Source Menu 4-78

7 Swept Sine Source Menu 4-83 Input Menu 4-87 Input Configuration Menu 4-89 Transducer Parameter Menu 4-92 Tachometer Input Menu 4-95 Playback Input Menu 4-97 Contents v Trigger Menu 4-100 Average Menus 4-107 FFT, Correlation, and Order Average Menu 4-107 Octave Average Menu 4-115 Swept Sine Average Menu 4-119 User Math Menu 4-122 Window Menu 4-131 Waterfall Menu 4-135 Capture Menu 4-143 Analysis Menu 4-147 Data Table Analysis Menu 4-150 Limit Testing Analysis Menu 4-152 Marker Statistics Analysis Menu 4-156 Exceedance Statistics Analysis Menu 4-159 Curve Fit Menu 4-161 Disk Menu 4-167 Nodal Degree-of-Freedom Menu 4-171 Recall Settings Menu 4-174 Disk Buffers Menu 4-177 Disk Upkeep Menu 4-182 Output Menu 4-184 System Menu 4-191 System Remote Menu 4-194 System Preferences Menu 4-196 System Date/Time Menu 4-199 System Diagnostics Menu 4-200 Edit Macro Menu 4-203

8 Chapter 5 Programming Index of Commands 5-2 Alphabetical List of Commands 5-12 Introduction 5-21 Command Syntax 5-25 Frequency Commands 5-28 Display Setup Commands 5-37 Display Options Commands 5-43 Marker Commands 5-45 Source Commands 5-53 Input Commands 5-60 Trigger Commands 5-66 Average Commands 5-68 User Math Commands 5-74 Window Commands 5-78 Waterfall Commands 5-80 Capture Commands 5-83 vi Contents Memory Allocation Commands 5-84 Data Table Commands 5-85 Limit Test Commands 5-87 Marker Statistics Commands 5-89 Exceedance Statistics Commands 5-90 Disk Commands 5-94 Output Commands 5-97 System Commands 5-100 Front Panel Commands 5-102 Data Transfer Commands 5-107 Interface Commands 5-117 Nodal Degree-of-Freedom Commands 5-118 Status Reporting Commands 5-120 Status Word Definitions 5-124 Example Program 5-129 Chapter 6 File Conversion Why File Conversion?

9 6-2 SR785 File Types 6-3 Supported External File Types 6-4 Using the File Conversion Utility 6-5 vii SR785 Dynamic Signal Analyzer Table of Figures Figure 2-1 Waterfall Display 2-30 Figure 2-2 Transfer Functions 2-48 Figure 2-3 Capacitive Coupling 2-71 Figure 2-4 Inductive Coupling 2-72 Figure 2-5 Resistive Coupling 2-73 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 Overlay 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 3-15 Figure 3-8 Marker Position Bar 3-15 Figure 3-9 Status Indicator Panel 3-18 Figure 3-10 Front Panel Keypad 3-23 viii ix SR785 Dynamic Signal Analyzer Features Measurements FFT Group FFT (Linear Spectrum)

10 Time Record Windowed Time Time Capture Frequency Response Power Spectrum Cross Spectrum Coherence Orbit User Math Functions Correlation Group Cross Correlation Autocorrelation Time Record Windowed Time Time Capture User Math Functions Octave Analysis Group 1/1, 1/3, 1/12 Octave Time Capture User Math Functions LEQ Impulse Swept Sine Group Spectrum Transfer Function Cross Spectrum Normalized Variance User Math Functions Time Histogram Group Histogram Probability Density Cumulative Density Unfiltered Time Record User Math Functions Time Capture Views Log Magnitude Linear Magnitude Magnitude Squared Real Part Imaginary Part Phase Unwrapped Phase Nichols Plot Nyquist Plot Displays Single Dual Upper/Lower Front/Back 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 Correlation Windows [- ] [- ] [ ]