FFT Spectrum Analyzers SR785 — 100 kHz two-channel dynamic signal analyzer SR785 Dynamic Signal Analyzer · DC to 102.4 kHz bandwidth · 90 dB dynamic range · Low-distortion synthesized source · 145 dB dynamic range in swept-sine mode · Order tracking · 20-pole/20-zero curve fitting · Real-time octave analysis · Up to 32 Mbyte memory · GPIB and RS-232 interfaces The SR785 Two-Channel Dynamic Signal Analyzer is a precision, full-featured signal analyzer that offers state-ofthe-art performance 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. For measurements involving servo systems, control systems, acoustics, vibration testing, modal analysis, or machinery diagnostics, 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 wide-band 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. Stanford Research Systems

SR785 Dynamic Signal Analyzer Order map (top), tracked order (bottom) 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 Run-up...

SR785 Dynamic Signal Analyzer Swept-sine Bode plot of low-pass filter response each point in the measurement, producing up to 145 dB of dynamic range. A frequency resolution of up to 2000 points is also provided. Auto-ranging can be used with source auto- leveling to maintain a constant input or output level at the device under test (to test response at a specific amplitude, Auto-resolution ensures the fastest possible sweeps, and adjusts the frequency steps in the scan based on the DUT's response. Phase and amplitude changes that exceed user- defined thresholds are measured with high frequency...

SR785 Dynamic Signal Analyzer or frequency data, stored files, constants, or a rich array of supplied operations including arithmetic functions, FFT, inverse FFT, jco, d/dco, exp, In x and many others. All of the averaging modes are available as user-math operands. Unlike many other analyzers, the SR785's measurement rate is virtually unaffected when user math is selected. For instance, the function exp(ln(conj(FFT2/FFTl))) can be calculated with Waterfall plots are a convenient way of viewing a time history of your data. Each successive measurement record is plotted along the z-axis making it...

Instrument Modes FFT, Time/Histogram, Correlation, Octave, Swept-Sine, Order Tracking Frequency Domain Measurements Frequency Response, Linear Spectrum, Cross Spectrum, Power Spectrum, Coherence, Power Spectral Density Time Domain Measurements Time Record, Cross-Correlation, Auto-Correlation, Orbit Amplitude Domain Measurements Histogram, PDF, CDF FFT Resolution 100, 200, 400, 800 lines Views Linear Magnitude, Log Magnitude, dB Magnitude, Magnitude Squared, Real Part, Imaginary Part, Phase, Unwrapped Phase, Nichols, Nyquist, Polar Units V, V2, V2/Hz, V/√Hz, meters, meters/s, meters/s2, inches,...

Specifications apply after 30 minutes warm-up and within two hours of last auto-offset. Measured with 400-line resolution and anti-alias filters enabled unless stated otherwise. Measurement Groups Groups FFT, Correlation, Time Histogram, Swept-Sine, Order Tracking 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 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...

Two-Tone Source Transient Capture Mode Maximum rate Max. capture length Continuous data recording 262,144 samples/s for both inputs 2 Msamples (single input) 8 Msamples with optional memory Octave Analysis Standards Conforms to ANSI std. S1.11-1986 Order 3 Type 1-D and IEC 225-1966 Frequency range (Band centers) 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)...