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SR850 — DSP lock-in amplifier with graphical display

SR850 — DSP lock-in amplifier with graphical display
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SR850 — DSP lock-in amplifier with graphical display - 1

• 1 mHz to 102.4 kHz frequency range • >100 dB dynamic reserve • 0.001 degree phase resolution • Time constants from 10 ps to 30 ks (up to 24 dB/oct rolloff) • Auto-gain, -phase, -reserve and -offset • Data logging (up to 65k samples) • Smoothing, curve fitting & statistics • GPIB & RS-232 interfaces • SR850... $9500 (U.S. list) 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. Digital Precision 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. 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 SRS Stanford Research Systems

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SR850 — DSP lock-in amplifier with graphical display - 2

to 512 Hz, you are able to see exactly how your data changes in time—not just what the current output value is. After the data has been acquired, the SR850 offers a variety of data reduction options, such as Savitsky-Golay smoothing, curvefitting and statistical analysis. A built-in 3.5” disk drive, along with standard RS-232 and GPIB interfaces, makes it easy to transfer data to your computer. Because the SR850 uses a digital phase-shifting technique rather than analog phase-shifters, the reference phase can be adjusted with one millidegree resolution. In addition, the X and Y outputs are...

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SR850 — DSP lock-in amplifier with graphical display - 3

defining an appropriate trace. Trace values can be displayed as a bar graph with an associated large numerical display, or as a strip chart showing the trace values as a function of time. Additionally, you can display polar plots showing the phasor formed by the in-phase and quadrature components of the signal. All displays can be easily scaled from the front panel or over the computer interfaces, and an auto-scale feature is available to quickly optimize the display. The screen can be configured as a single large display, or as two horizontally-split displays. the SR850’s frequency scans....

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SR850 — DSP lock-in amplifier with graphical display - 4

Signal Channel Voltage inputs Sensitivity Current input Input impedance Voltage input Current input Gain accuracy Noise (typ.) Line filters CMRR Dynamic reserve Reference Channel Frequency range Reference input Input impedance Phase resolution Absolute phase error Relative phase error Orthogonality Phase noise Int. reference Ext. reference Phase drift Harmonic detection Acquisition time Single-ended or differential 2 nV to 1 V 106 or 108 V/A 10 MQ+25 pF, AC or DC coupled 1 kQ to virtual ground ±1 % (±0.2 % typ.) 6 nV/\Hz at 1 kHz 0.13 pA/VHz at 1 kHz (106 V/A) 0.013 pA/VHz at 100 Hz (108...

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