SR850 DSP Lock-In Amplifier0 pages

Digital Lock-In Amplifiers
SR850 — DSP lock-in amplifier with graphical display

SR850 DSP Lock-In Amplifier
The SR850 is a digital lock-in amplifier based on an
innovative DSP (Digital Signal Processing) architecture. The
SR850 boasts a number of significant performance advantages
over traditional lock-in amplifiers—higher dynamic reserve,
lower drift, lower distortion, and dramatically higher phase
resolution. In addition, the CRT display and 65,536 point
memory make it possible to display and process data in a
variety of formats unavailable with conventional lock-ins.

· 1 mHz to 102.4 kHz frequency range
· >100 dB dynamic reserve
· 0.001 degree phase resolution
· Time constants from 10 µs to 30 ks
(up to 24 dB/oct rolloff)

Digital Precision

· Auto-gain, -phase, -reserve and -offset

At the input of the SR850 is a precision 18-bit A/D converter
which digitizes the input signal at 256 kHz. The A/D converter,
together with a high-speed DSP chip, replace the analog
demodulator (mixer), low-pass filters and DC amplifiers
found in conventional lock-ins. Instead of using analog
components, the SR850 is implemented by a series of precise
mathematical calculations which eliminate the drift, offset,
non-linearity and aging inherent in analog components. The
same DSP chip digitally synthesizes the reference oscillator,
providing a source with less than –80 dBc distortion, 100 mHz
frequency resolution, and 2 mV of amplitude resolution.

· Data logging (up to 65k samples)
· Smoothing, curve fitting & statistics
· GPIB & RS-232 interfaces

Digital Flexibility
The SR850 has a 7" CRT display which supports a large
selection of display options. Data can be viewed numerically
or graphically in bar graph, polar plot and strip chart formats.
With 65,536 points of memory and data acquisition rates up

· SR850 ... $7950 (U.S. list)

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