SRS Labs SR785 User Manual
SRS
STANFORD RESEARCH SYSTEMS
SR785
Two Channel Dynamic
Signal Analyzer
SR785
Two Channel
Dynamic Signal
Analyzer
9" High Contrast CRT Display
800H x 600V resolution makes measurement
data easy to read.
$11,950
(U.S. list)
Features
●
FFT, Correlation and Order Tracking Measurements
●
ANSI Standard 1/1, 1/3, 1/12 Octave Analysis
●
Swept-Sine Mode (145 dB dynamic range)
●
20-pole/20-zero Curve Fit and Synthesis
●
Time/Histogram Mode
●
Windows95¨ DataViewer
●
Output to SDF¨, MAT¨, UFF, ASCII, PCX, GIF¨, PCL¨,
¨
Postscript
and HP-GL¨formats
Specifications
●
102.4 kHz frequency range on both channels
●
90 dB dynamic range (16 bit)
●
102.4 kHz real-time bandwidth
●
±0.2 dB accuracy
●
±0.05 dB channel match
●
100, 200, 400, 800 lines of frequency resolution
●
Source type: low distortion (-80 dBc) sine and
two-tone, swept-sine, white and pink noise,
burst noise, chirp, burst and arbitrary
3.5" DOS 1.44 Mbyte Disk Drive
Stores instrument setups, time capture data, waterfall data, trace data, data tables, limit tables, curve
fit/synthesis tables, math functions, arbitrary
source data and plotter/printer output data.
Standard Measurement Modes
• FFT
• Swept-Sine
• Octave
• TIme/Histogram
• Order Tracking
• Time Capture
Fast Responsive Marker
• Find Max/Min or track peaks
• THD, THD + N
• Band, sideband, harmonic power
• Waterfall
• Frequency and damping
• Peak find
• Absolute and relative
• Statistics
On-Line Help
Locate information on any
topic, browse specifications,
examine remote commands all from the front panel.
PC (XT) Keyboard Input
Enter text and annotations
quickly and easily.
User Math
Build powerful custom
measurements by directly
entering equations.
Input Channels
• Dual ADCs provide 102.4 kHz bandwidth on both
channels simultaneously.
• -50 dBV max full scale input sensitivity
• Built-in ICP power supply for accelerometers
• Switchable analog A-weighting filters
• Engineering units
SR785 Two Channel Dynamic
Signal Analyzer
FFT Spectrum Analysis
The SR785 Two Channel Dynamic Signal Analyzer is a
precision, full-featured signal analyzer that offers
state-of-the-art performance and a wide selection of features
at a price that's less than half that of competitive analyzers.
Building on its predecessor, the SR780, the SR785
incorporates new firmware and hardware that make it the
ideal instrument for analyzing both mechanical and electrical
systems. Whether your measurements involve modal analysis,
machinery diagnostics, vibration testing, servo systems,
control systems, or acoustics, the SR785 has the features and
specifications to get the job done. Standard measurement
groups include FFT, order tracking, octave, swept-sine,
correlation, time capture and time/histogram. The SR785
brings the power of several instruments to your application –
a spectrum analyzer, network analyzer, vibration analyzer,
octave analyzer and oscilloscope.
A unique measurement architecture allows the SR785 to
function as a typical dual channel analyzer with measurements like cross spectrum, frequency response, coherence,
etc. Alternatively, the instrument can be configured so that
each input channel functions as a single channel analyzer with
its own span, center frequency, resolution, and averaging.
This allows you to view a wideband spectrum and
simultaneously zoom in on spectral details.
The same advanced architecture provides storage of all
measurement building blocks and averaging modes. Vector
averaged, RMS averaged, unaveraged and peak hold versions
of all measurements are simultaneously acquired and can be
displayed without re-taking data.
Use the SR785 to monitor the fundamental and
harmonics of your signal. Total harmonic power
and THD are calculated in real-time for fast,
accurate analysis.
Bottom display shows a wideband FFT, while the
top display shows a narrowband FFT of the same
signal. The sideband marker has been selected for
calculation of the total sideband power.
Averaging
The SR785 comes equipped with a wide selection of
averaging techniques to improve your signal to noise ratio.
Choose RMS averaging to reduce signal fluctuations, vector
averaging to actually eliminate noise from synchronous
signals, or peak hold averaging. In the order-tracking
measurement group, time averaging is available. Both linear
and exponential averaging are provided for each mode.
The SR785 is so fast, there's no need for a separate "fast
averaging" mode. Averaging is always fast, and the display
update rate is never sacrificed to increase the averaging rate.
For instance, in a full span FFT measurement with a 4 ms
time record, 1000 averages take exactly 4 seconds, during
which the SR785 still operates at its maximum display rate.
For impact testing, the average preview feature allows each
time record or spectrum to be accepted or rejected before
adding it to the measurement.
View order maps or track individual orders with the
SR785.
The SR785 tracks up to 400 orders simultaneously.
You can display the amplitude profile of any two
orders in tracked order mode.
Order Tracking
Order tracking is used to evaluate the behavior of rotating
machinery. Measurement data is displayed as a function of
multiples of the shaft frequency (orders), rather than absolute
frequency. Combined with a waterfall plot, the SR785
provides a complete history or "order map" of your data as a
function of time or RPM. Using the slice feature, the amplitude profile of specific orders in the map can be analyzed.
In tracked order mode the intensity of individual orders vs.
RPM is measured. Unlike other analyzers, there’s no need to
track a limited number of orders to ensure full speed
measurements. The SR785’s speed allows simultaneous
tracking of up to 400 orders.
Run-up and run-down measurements are available in both
polar and magnitude/phase formats. RPM profiling is
Run-up and run-down measurements in both polar
and bode formats are available.
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