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FFT Analyzer  SR760 & SR770 ... from $4950 
SR760 and SR770 — 100 kHz FFT analyzers 
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SR760 and SR770 FFT Analyzers

The SR760 and SR770 are singlechannel 100 kHz FFT spectrum analyzers with a dynamic range of 90 dB and a realtime bandwidth of 100 kHz. Additionally, the SR770 includes a lowdistortion source which allows you to measure the transfer functions of electronic and mechanical systems. 
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SR760 and SR770 FFT Analyzers
The SR760 and SR770 are singlechannel 100 kHz FFT spectrum analyzers with a dynamic range of 90 dB and a realtime bandwidth of 100 kHz. Additionally, the SR770 includes a lowdistortion source which allows you to measure the transfer functions of electronic and mechanical systems. The speed and dynamic range of these instruments, coupled with their flexibility and many analysis modes, makes them the ideal choice for a variety of applications including acoustics, vibration, noise measurement and general electronic use.
High Dynamic Range
The SR760 and SR770 have a dynamic range of 90 dB. This means that
for a fullscale input signal, the instruments have no spurious
responses larger than 90 dBc (1 part in 30,000). Even signals as
small as 114 dBc (1 part in 500,000) may be observed by using averaging.
The low frontend noise and low harmonic distortion of the SR760
and SR770 allow you to see signals that would be buried in the noise
of other analyzers.
Powerful Processing
The SR760 and SR770 use a pair of highspeed, 24bit digital signal processors (DSPs) to filter, heterodyne and transform sampled data from its 16bit analogtodigital converter. This computing capability allows the analyzers to operate at a realtime bandwidth of 100 kHz. In other words, the SR760 and SR770 process the input signal with no dead time. Your measurements will be done in as little as a tenth of the time of other analyzers, which typically have a realtime bandwidth of about 10 kHz.
Easy To Use
The SR760 and SR770 are easy to use. The simple, menuoriented interface logically groups related instrument functions. Contextsensitive help is available for all keys and menus, and entire instrument setups can be saved to disk and recalled with a single keystroke.
Spectrum Measurements
The spectrum, power spectral density, and input time record can
be displayed in a variety of convenient linear and logarithmic units
including Vp, Vrms, dBVp, dBVrms or userdefined engineering units
(EUs). The magnitude, phase and real and imaginary parts of complex
signals can all be displayed. Several window functions including
Hanning, FlatTop, Uniform and BlackmanHarris can be chosen to
optimize inband amplitude accuracy or minimize outofband side
lobes.
Octave Measurements
The SR760 and SR770 also compute both the 15 and 30 band 1/3 octave spectra, commonly used in acoustics and noise measurement applications. Aweighting compensation is available for octave measurements. Amplitudes are computed for band 2 (630 mHz) through band 49 (80 kHz).
Triggering and Averaging
Flexible triggering and averaging modes let you see signals as low as 114 dB below full scale. RMS averaging provides an excellent estimate of the true signal and noise levels in the input signal, while vector averaging can be used with a triggered input signal to actually reduce the measured noise level. Both rms and vector averaging can be performed exponentially, where the analyzer computes a running average (weighting new data more heavily than older data), or linearly, where the analyzer computes an equally weighted average of a specified number of records. Triggering can be used to capture transient events or to preserve spectral phase information. Both internal and external triggering are available with adjustable pretrigger and posttrigger delays.
Synthesized Source
The SR770 includes a lowdistortion (80 dB), synthesized source
which can be used to make frequency response measurements. It generates
single frequency sine waves, twotone signals for intermodulation
distortion (IMD) testing, pink and white noise for audio and electronic
applications, and frequency chirp for transfer function analysis.
This direct digital synthesis (DDS) source provides an output level
from 100 µV to 1 V, and delivers up to 50 mA of current.
Frequency Response Measurements
With its lowdistortion DDS source, the SR770 is capable of performing
accurate frequency response measurements. The source is synchronized
with the instrument's input allowing transfer functions to be measured
with 0.05 dB precision. The SR770 measures the magnitude and phase
response of control systems, amplifiers, and electromechanical
systems, and displays the resulting Bode plot.
Limit and Data Tables
Sometimes it is important to keep track of a few key portions of a spectrum. Data tables allow up to 200 selected frequencies to be displayed in tabular format. Automated entry makes it easy to set up data tables for harmonic or sideband analysis. Convenient limit tables allow the entry of up to 100 separate upper or lower limit segments for passfail testing. On exceeding a limit, the analyzers can be configured to generate a screen message, an audio alarm, or a GPIB service request.
Analysis Modes
Three builtin analysis modes simplify common measurements. Harmonic analysis computes both harmonic power and THD (Total Harmonic Distortion) relative to a specified fundamental. Sideband analysis lets you compute power in a set of sidebands relative to the carrier power. And band analysis lets you easily integrate the power in a selected frequency band. All three analysis modes provide clear, onscreen markers which make it easy to pick out frequencies of special interest, such as harmonics or sidebands.
Markers
The SR760 and SR770 have a marker that is designed to be fast, responsive and flexible. The marker can be configured to read the maximum, minimum or mean of a selected width of display, or can be set to tracking mode to lock on to a moving peak. Deltamode readouts let you easily view frequency or amplitude differences between two peaks. Automated peakfind lets you quickly move between the peaks in a spectrum. And the markers for the upper and lower displays can be linked to display similarities or differences in the two spectra.
Math Functions
Data taken with the SR760 and SR770 can be processed with the builtin trace calculator. Basic arithmetic functions such as addition, subtraction, multiplication, division, square roots and logarithms can be performed on traces. Traces can be combined with other onscreen traces, or with traces stored on disks. These calculator functions are quite useful for performing background subtraction or normalization of data.
Flexible Storage and Output
All traces, data tables and limit tables can be stored using the
3.5" disk drive for the SR760 and the USB drive for the SR770. Data can be saved in a spacesaving binary format,
or an easytoaccess ASCII format for offline analysis. A variety
of hardcopy options let you easily print data from the instruments.
The screen can be dumped to a dotmatrix printer or a LaserJet compatible
laser printer via the standard rearpanel Centronics printer interface.
Complete limit and data tables, as well as a summary of the instrument
settings, can be printed. Data can be plotted to any HPGL compatible
plotter with an RS232 or GPIB interface.
Easy to Interface
All functions of the analyzers can be queried and set via the standard RS232 and GPIB interfaces. A comprehensive set of commands allows complete control of your analyzer from a computer. Data can be quickly transferred in binary format, or more conveniently in ASCII format. The complete command list is available as a help screen in the instruments for convenient reference while programming.
SR760 and SR770 FFT Analyzers  
Frequency  
Measurement range  476 µHz to 100 kHz  
Spans  191 mHz to 100 kHz in a binary sequence  
Center frequency  Anywhere within the 0 to 100 kHz measurement range  
Accuracy  25 ppm from 20 °C to 40 °C  
Resolution  Span/400  
Window functions  BlackmanHarris, Hanning, FlatTop and Uniform  
Realtime bandwidth  100 kHz  
Signal Input  
Number of channels  1  
Input  Singleended or differential  
Input impedance  1 MΩ, 15 pF  
Coupling  AC or DC  
CMRR (at 1 kHz)  90 dB (input range <6 dBV) 80 dB (input range <14 dBV) 50 dB (input range ≥14 dBV) 

Noise  
Typ.  5 nVrms/√Hz at 1 kHz (166 dBVrms/√Hz)  
Max.  10 nVrms/√Hz (160 dBVrms/√Hz)  
Amplitude  
Fullscale input range  60 dBV (1.0 mVp) to +34 dBV (50 Vp) in 2 dB steps  
Dynamic range  90 dB (typ.)  
Harmonic distortion  No greater than 80 dB from DC to 100 kHz (input range 0 dBV)  
Spurious  No greater than 85 dB below full scale (<200 Hz). No greater than 90 dB below full scale to 100 kHz (50 dBV input range). 

Input sampling  16bit A/D at 256 kHz  
Accuracy  ±0.3 dB ± 0.02 % of full scale (excluding windowing effects)  
Averaging  RMS, Vector and Peak Hold. Linear and exponential averaging up to 64k scans.  
Trigger Input  
Modes  Continuous, internal, external, TTL  
Internal level  Adjustable to ±100 % of input scale. Positive or negative slope.  
Min. trigger amplitude  10 % of input range  
External level  ±5 V in 40 mV steps. Positive or negative slope. 10 kΩ Impedance  
Min. trigger amplitude  100 mV  
External TTL  Requires TTL level, (low <0.7 V, high >2 V)  
Posttrigger  Measurement record is delayed by 1 to 65,000 samples (1/512 to 127 time records) after the trigger. Delay resolution is 1 sample (1/512 of a record).  
Pretrigger  Measurement record starts up to 51.953 ms prior to the trigger. Delay resolution is 3.9062 ms.  
Phase indeterminacy  <2°  
Display Functions  
Display  Real, imaginary, magnitude or phase  
Measurements  Spectrum, power spectral density, time record and 1/3 octave  
Analysis  Band, sideband, total harmonic distortion and trace math  
Graphic expand  Display expand up to ×50 about any point  
Harmonic marker  Displays up to 400 harmonics  
Data tables  Lists Y values of up to 200 points  
Limit tables  Detects data exceeding up to 100 userdefined upper and lower limit trace segments.  
Source (SR770 only)  
Amplitude range  0.1 mVp to 1.0 Vp  
Amplitude resolution  1 mVp (output >100 mVp), 0.1 mVp (output <100 mVp)  
DC offset  <10.0 mV (typ.)  
Output impedance  <5 Ω, 50 mA peak output current  
Sine Source  
Frequency range  DC to 100 kHz  
Resolution  15.26 mHz  
Amplitude accuracy  ±1 % (0.09 dB) of setting  
Spectral purity  (Harmonics and subharmonics) 80 dBc, f <10 kHz 70 dBc, f >10 kHz (Spurious) <100 dB full scale 

TwoTone Source  
Frequency range  DC to 100 kHz  
Resolution  15.26 mHz  
Amplitude accuracy  ±1 % (0.09 dB) of setting  
Spectral purity  (Harmonics and subharmonics) 80 dBc, f <10 kHz 70 dBc, f >10 kHz (Spurious) 100 dB full scale 

White Noise Source  
Frequency range  DC to 100 kHz (all spans)  
Flatness  <1.0 dBpp (rms averaged spectra)  
Pink Noise Source  
Frequency range  DC to 100 kHz (all spans)  
Flatness  <4.0 dBpp (using 1/3 octave analysis)  
Chirp Source  
Output  Equal amplitude sine waves at each frequency bin of the current span  
Flatness  <0.05 dBpp (typ.), <0.2 dBpp (max.)  
Phase  AutoPhase function calibrates to current phase spectrum.  
General  
Monitor  Monochrome CRT. 640H by 480V resolution. Adjustable brightness and position.  
Interfaces  IEEE488.2, RS232 and Printer interfaces standard. An XT keyboard input is provided for additional flexibility.  
Hardcopy  Screen dumps and table and setting listings to dot matrix and LaserJet compatible printers. Data plots to HPGL compatible plotters (RS232 or IEEE488.2).  
Data storage  USB drive for SR770. Disk drive, 3.5" DOS compatible format, 720 kbyte for SR760 

Power  60 W, 100/120/220/240 VAC, 50/60 Hz  
Dimensions  17" × 6.25" × 18.5" (WHL)  
Weight  36 lbs.  
Warranty  One year parts and labor on defects in materials and workmanship  