Atec Stanford-Research-Systems-SR785 - Manual (Page 6)

SR785 Specifications
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 25 ppm from 20 °C to 40 °C
Dynamic Range
Dynamic range 90 dB typical, 80 dB guaranteed
(FFT and Octave).
145 dB typical (Swept-Sine).
Includes spurs, harmonics,
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 − 100 dBfs typical (input grounded,
noise floor > − 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 window effects)
Cross channel ±0.05 dB, DC to 102.4 kHz
(frequency response 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, freq.
<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 center of time
record. For Uniform, Force and
Exponential windows, phase is
relative to a cosine wave at
beginning of the time record.
Cross channel ±0.5 deg. (DC to 51.2 kHz)
±1.0 deg. (DC to 102.4 kHz)
(frequency response meas., both
inputs on same range, vector avg.)
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), differential (A − B)
Input impedance 1 M Ω + 50 pF
Shield to chassis Floating mode: 1 M Ω + 0.01 µ F
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 M
Ω
Max. input: ±5 V
Min. trigger level: 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 100,000 samples after the trigger.
Pre-trigger Measurement record starts up to
8000 samples prior to the trigger.
Tachometer Input
Pulses per revolution 1 to 2048
RPM accuracy ±50 ppm (typ.)
Tach level range ±25 V, ±5 V, TTL
Tach level resolution 20 mV @ ±25 V, 4 mV @ ±5 V
Max. tach input level ±40 Vp
Stanford Research Systems phone: (408)744-9040
www.thinkSRS.com