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Dynamic Signal Analyzer SR780 ... from $9950
SR780 100 kHz 2-ch. FFT analyzer
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SR780 Dynamic Signal Analyzer
  • DC to 102.4 kHz bandwidth
  • 90 dB dynamic range
  • Low-distortion synthesized source
  • 145 dB dynamic range (swept-sine)
  • Real-time octave analysis
  • Up to 32 Mbyte memory
  • GPIB and RS-232 interfaces
The SR780 Dynamic Signal Analyzer combines high performance and low cost in a full-featured package. It offers 102.4 kHz dual-channel FFTs with 90 dB dynamic range, swept-sine measurements, ANSI standard octave analysis, waterfall displays and transient capture for less than half the cost of other similarly equipped analyzers.
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User's Manual

SR780 Dynamic Signal Analyzer

The SR780 Dynamic Signal Analyzer combines high performance and low cost in a full-featured package. It offers 102.4 kHz dual-channel FFTs with 90 dB dynamic range, swept-sine measurements, ANSI standard octave analysis, waterfall displays and transient capture for less than half the cost of other similarly equipped analyzers.

Spectrum Analysis

The SR780 delivers true two-channel, 102.4 kHz FFT performance. Its fast 32-bit floating-point DSP processor gives the SR780 a 102.4 kHz real-time rate with both channels selected. Two precision 16-bit ADCs provide a 90 dB dynamic range in FFT mode. Selectable 100 to 800 line analysis optimizes time and frequency resolution, and you can zoom in on any portion of the 102.4 kHz range with a frequency span down to 191 mHz.

The SR780’s unique architecture lets the two displays function independently. You can choose separate frequency spans, starting frequencies, number of FFT lines, or averaging modes for each display. So it’s easy look at a wideband display and zoom in on a specific feature simultaneously. The SR780 lets you select from two sampling rates: 256 kHz or 262 kHz, so frequency spans come out in either a binary (102.4 kHz, 51.2 kHz,...) or decimal (100 kHz, 50 kHz, 25 kHz,...) sequence depending on your requirements.

Flexible Averaging

Several averaging choices are provided. RMS averaging reduces signal fluctuations, while vector averaging minimizes noise from synchronous signals. You can choose linear averaging (stable averaging) for fixed signals, or exponential averaging to track drifting features. Because the SR780’s 102.4 kHz real-time bandwidth lets it take data seamlessly, vector averaging can be selected for any signal that’s repetitive within the time record—no trigger is necessary.

Transducer Units

Automatic unit conversion makes translating accelerometer data easy. You can enter accelerometer conversions directly in V/EU, EU/V or dB (1 V/EU). The SR780 will display results in units of meters, inches, mil, g, kg, lbs., N, dynes, pascals, bars, or dBSPL. Accelerometer data is automatically converted to velocity or displacement units. Built-in ICP power means you won’t need an external power supply for your accelerometer.

Octave Analysis

Real-time octave analysis at frequencies up to 40 kHz (single channel) or 20 kHz (two-channel), is standard in the SR780. Octave analysis is fully compliant with ANSI and IEC standards. Full octave, 1/3 octave and 1/12 octave analysis are all available. Switchable analog A-weighting filters as well as built-in user math weighting functions (A,B and C) are included. Octave averaging choices include exponential time averaging, linear time averaging, peak hold, and equal confidence averaging. IEC compliant peak hold, impulse, fast and slow sound level measurements are all calculated.

Swept-Sine Analysis

Swept-sine analysis is used for measurements involving high dynamic range or wide frequency intervals, and is also a standard feature of the SR780. Selectable auto-ranging optimizes the input range at each point in the measurement, providing up to 145 dB of dynamic range. Auto-ranging can be used with source auto-leveling to maintain a constant input or output level at the device under test. To ensure the fastest sweeps possible, auto-resolution can also be selected, providing a variable scan speed tailored precisely to the signal being measured.

User Math

User-defined math functions are available in all measurement groups. Equations are created from time or frequency data, stored files, constants, or a rich array of supplied operations including the arithmetic functions, FFT, inverse FFT, jΩ, d/dΩ, exp, ln x and many others. Unlike many analyzers, the SR780's measurement rate isn't reduced when user math is selected. For instance, the function exp(ln(conj(Average(FFT2/FFT1))) can be calculated with a 50 kHz real-time bandwidth.


Six source types are available: low distortion (-80 dBc) single or two-tone sine waves, chirp, white noise, pink noise, and arbitrary waveforms. The chirp and noise sources can both be bursted to provide a source that’s active only over a selected portion of the time record for FFT measurements, or to provide an impulsive noise source for acoustic measurements. The digitally synthesized source provides output levels from 0.1 mV to 5 V, and delivers up to 100 mA of current.

Arbitrary waveform capability is standard on the SR780. The arbitrary source can be used to playback a section of a captured waveform, play a selected FFT time record or upload a custom waveform.


The SR780 comes standard with 2 Msamples of standard capture memory. Waveforms can be captured at 262 kHz or any sub-multiple of 262 kHz, allowing you to select the sample rate and capture length that’s right for your data. Once captured, any portion of the signal can be played back in FFT or Octave mode. The convenient AutoPan feature lets you display the measurement results synchronously with the corresponding portion of the capture buffer to easily identify important features. An optional memory expansion module lets you extend the SR780’s capture depth to 8 Msamples—that’s almost 30 seconds of capture at the maximum sampling rate.


All Octave and FFT Measurements can be stored in the SR780’s 2k-deep waterfall buffers. Waterfall storage is selectable as every nth time record for FFT measurements, or you can select a storage interval in seconds (down to 4 ms) for octave measurements. While displaying waterfalls, you can adjust the skew angle to reveal important features, or change the baseline threshold to eliminate low-level clutter. Any z-axis slice or x-axis record can be saved to disk or displayed separately for individual analysis.


The SR780 includes a wide variety of built-in analysis features. Marker analysis lets you use the marker to easily measure the power contained in the harmonics, sidebands, or within a given band of frequencies. THD, THD+N, sideband power relative to carrier, and total integrated power are calculated in real time and displayed on the screen. Marker statistics quickly calculate the maximum, minimum, mean and standard deviation of data at any point in the display.

A data table feature lets you display up to 100 selected data points in tabular format. Limit tables allow you to define up to 100 upper and lower limit segments in each display for GO/NO-GO testing.


The SR780's built-in USB drive, computer interfaces (GPIB and RS-232) and printer port provide flexibility when saving, printing and exporting data. Data can be saved in binary or ASCII formats and displays can be printed/plotted to any of the ports or the disk drive. Supported formats include PCL, GIF, PCL (LaserJet/ DeskJet), dot-matrix, postscript and HP-GL, PCX or GIF. Utilities are included to translate your HP SDF files into SR780 format.

Measurements - FFT Group
FFT, Time Record, Windowed Time, Time Capture,
Transfer Function, Cross Spectrum, Coherence, Cross-Correlation, Auto-Correlation, Orbit, User Math

Measurements - Octave Analysis Group
1/1, 1/3, 1/12 Octave, Time Capture, User Math, Leq, Impulse, Total Power

Measurements - Swept-Sine Group
Spectrum, Transfer Function, Cross Spectrum, User Math

FFT Resolution
100, 200, 400, 800 lines

Linear Magnitude, Log Magnitude, Magnitude Squared, Real Part, Imaginary Part, Phase, Unwrapped Phase, Nichols, Nyquist

V, V2, V2/Hz, V/√Hz, meters, inches, mils, g, kg, lbs., N, dynes, pascals, bars, SPL, user-defined engineering units (EUs)

Single, Dual, Waterfall with Skew, Zoom and Pan

RMS, Vector, Peak Hold, Linear, Exponential, Equal Confidence (Octave), Preview Time Record

Continuous, Internal, External (Analog or TTL), Source, Auto/Manual Arming

Source Outputs
Sine, Two-Tone, Swept-Sine, White/Pink Noise, Burst Noise, Chirp, Burst Chirp, and Arbitrary

Hanning, Blackman-Harris, Flat-Top, Kaiser, Force/Exponential, User-Defined, +/-T/2, +/-T/4, T/2, Uniform

User Math
+, -, ×, /, Conjugate, Magnitude/Phase, Real/Imaginary, Sqrt, FFT, Inverse FFT, jΩ, Log, Exp, d/dx, Group Delay, A-, B-, C-Weighting, x/x-1

Harmonic, Band, Sideband, THD, THD + N, Limit Test with Pass/Fail, Data Table, Exceedance, Statistics

Time Capture
Captures time data for later analysis (FFT or Octave). Up to 2 Msamples (8 Msamples optional) of data can be saved.

3.5", 1.44 Mbyte, DOS formatted disk. Save data and setups.

Hard Copy and Interfaces
Print to dot matrix or PCL (LaserJet and DeskJet) printers. Plot to HP-GL or postscript plotters. Print/plot on-line (RS-232 serial, Centronics parallel or IEEE-488.2) or to disk file. EPS, GIF, PCX graphic formats also available for disk storage.




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

SR780 Dynamic Signal Analyzer
Specifications apply after 30 minutes warm-up and within 2 hours of last auto-offset. Measured with 400 line resolution and anti-alias filters enabled unless stated otherwise.
Measurement Groups
Groups FFT, Octave Analysis, Swept-Sine
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 two 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)
Accuracy 25 ppm from 20 °C to 40 °C
Dynamic Range
Dynamic range  
     FFT and Octave
90 dB typical, 80 dB guaranteed.
145 dB
Includes spurs, harmonic and intermodulation distortion and alias products. Excludes alias responses at extremes of span.
Harmonic distortion <-80 dB (single tone in band)
Intermod. distortion <-80 dB (two tones in band, each less than -6.02 dBfs)
Spurious <-80 dBfs
Alias responses <-80 dBfs (single tone outside of span, <0 dBfs, less than 1 MHz)
Full-span FFT noise floor -100 dBfs typ. (input grounded, >-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)
Cross channel ±0.05 dB (DC to 102.4 kHz)
(transfer function measurement, both inputs on the same range, rms averaged)
Phase Accuracy
Single channel ±3.0 deg. relative to external TTL trigger (-50 dBfs to 0 dBfs, frequency <10.24 kHz, center of frequency bin, DC coupled).
For Blackman-Harris, Hanning, Flat-Top and Kaiser windows, phase is relative to a cosine wave at the center of the time record. For Uniform, 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)
Signal Inputs
Number of inputs 2
Full-scale input range -50 dBV (3.16 mVp) to +34 dBV (50 Vp) in 2 dB steps
Maximum input level 57 Vp
Input configuration Single-ended (A) or differential (A-B)
Input impedance 1 MΩ + 50 pF
Shield to chassis Floating mode: 1 MΩ + 0.01 µF. Grounded mode: 50 Ω. Shields grounded in (A-B) mode
Max. shield voltage 4 Vp
AC coupling 0.16 Hz cutoff frequency
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 Type 0 tolerance, ANSI standard S1.4-1983 (10 Hz to 25.6 kHz)
Crosstalk <-145 dB below signal (input to input and source to inputs, 50 Ω receiving input source impedance)
Input noise <10 nVrms/√Hz above 200 Hz (<-160 dBVrms/√Hz)
Trigger Input
Modes Free run, Internal, External, or External TTL
Internal Level adjustable to ±100 % of input scale, positive or negative slope. Min. trigger level: 5 % of input range
External Level adjustable to ±5 V in 40 mV steps, positive or negative slope.
Input impedance: 1 MΩ
Max. input: ±5 V
Min. trigger amplitude: 100 mV
External TTL Requires TTL level to trigger (low <0.7 V, high >3.0 V)
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.
Transient Capture
Mode Continuous data recording
Maximum rate 262,144 samples/s for both inputs
Maximum capture Length 2 Msamples (single input)
8 Msamples with optional memory
Octave Analysis
Standards Conforms to ANSI standard S1.11- 1986, Order 3, Type 1-D and IEC 225-1966
Frequency range Single channel
1/1 Octave     0.125 Hz to 32 kHz
1/3 Octave     0.100 Hz to 40 kHz
1/12 Octave   0.091 Hz to 12.3 kHz
Two channels
1/1 Octave     0.125 Hz to 16 kHz
1/3 Octave     0.100 Hz to 20 kHz
1/12 Octave   0.091 Hz to 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 Impulse, Peak, Fast, Slow and Leq per ANSI S1.4-1983 Type 0 and IEC 651-1979 Type 0
Source Output
Amplitude range 0.1 mVp to 5 Vp
Amplitude resolution 0.1 mVp (output >500 mVp)
DC offset <10.0 mV (typ.)
Offset adjust ±5 VDC (sine, two-tone)
Output impedance <5 Ω, ±100 mA peak output current
Sine Source
Amplitude accuracy ±1 % of setting, 0 Hz to 102.4 kHz
0.1 Vp to 5.0 Vp, High-Z load
Harmonics, sub-harm. & spurious 0.1 Vp to 5 Vp
<-80 dBc (fundamental <30 kHz)
<-75 dBc (fundamental <102 kHz)
Two-Tone Source
Amplitude accuracy ±1 % of setting, 0 Hz to 102.4 kHz
0.1 Vp to 5 Vp, High-Z load
Harmonics, sub-harm. <-80 dBc, 0.1 Vp to 2.5 Vp
White Noise Source
Time record Continuous or burst
Bandwidth DC to 102.4 kHz or limited to span
Flatness <0.25 dBpp (typ.), <1.0 dBpp (max.), 5000 rms averages
Pink Noise Source
Bandwidth DC to 102.4 kHz
Flatness <2.0 dBpp, 20 Hz to 20 kHz (using averaged 1/3 Octave Analysis)
Chirp Source
Time record Continuous or Burst
Output Sine sweep across the FFT span
Flatness ±0.25 dB (amplitude: 1.0 Vp)
Swept-Sine Source
Auto functions Source level, input range and frequency resolution
Dynamic range 145 dB
Arbitrary Source
Amplitude range ±5 V
Record length 2 Msamples (playback from arbitrary waveform memory or capture buffer). Variable output sample rate.
CRT monitor Monochrome, 800H by 600V resolution
Interfaces IEEE-488.2, RS-232 and printer interfaces standard. All instrument functions can be controlled through computer interfaces. A PC (XT) keyboard input is provided for additional flexibility.
Hardcopy Print to dot matrix and PCL compatible printers. Plot to HP-GL or postscript plotters. Print/plot to RS-232 or IEEE-488.2 interfaces or to disk file. Additional file formats include GIF, PCX and EPS.
Data storage USB drive
Preamp power Power connector for SRS preamps
Power 70 W, 100/120/220/240 VAC, 50/60 Hz
Dimensions 17" × 8.25" × 24" (WHL)
Weight 56 lbs.
Warranty One year parts and labor on defects in materials and workmanship
Phone: (408)744-9040 • Fax: (408)744-9049 • email: