The Stanford Research System SR830 Lock-In Amplifier simultaneously
displays the magnitude and phase of a signal. The Lock-In Amplifier use Digital Signal Processing (DSP) to replace
the demodulators, output filters, and amplifiers found in conventional lock-ins. The SR830 multiplies the signal
by a pure sine wave at the reference frequency. All components of the input signal are multiplied by the reference
simultaneously. The amplifier provides uncompromised performance with an operating range of 1 mHz to 102 kHz
and 100 dB of drift-free dynamic reserve. The SR830 Amplifier has two 16,000 point buffers to simultaneously
record two measurements. Data is transferred from the buffers using the computer interfaces. A trigger input
is also provided to externally synchronize data recording.
The DSP Lock-In Amplifier SRS SR830 have differential inputs
with 6 nV/√Hz input noise. The input impedance is 10 MΩ, and minimum full-scale input voltage sensitivity is
2 nV. The input can also be configured for current measurements with selectable current gains of 106 and 108
V/A. A line filter (50 Hz or 60 Hz) and a 2× line filter (100 Hz or 120 Hz) are provided to eliminate line related
interference. However, unlike conventional lock-in amplifiers, no tracking band-pass filter is needed at the
input. This filter is used by conventional lock-ins to increase dynamic reserve. Unfortunately, band pass filters
also introduce noise, amplitude and phase error, and drift. The DSP based design of these lock-ins has such
inherently large dynamic reserve that no tracking band-pass filter is needed.
SRS SR830 quotation today.
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The digital signal processor also handles the task of output filtering, allowing time constants from 10 µsec
to 30,000 s, with a choice of 6, 12, 18 and 24 dB/oct rolloff. For low frequency measurements (below 200 Hz),
synchronous filters can be engaged to notch out multiples of the reference frequency. Since the harmonics of
the reference have been eliminated (notably 2F), effective output filtering can be achieved with much shorter
The built-in direct digital synthesis (DDS) source generates a very low distortion (-80 dBc) reference signal.
Single frequency sine waves can be generated from 1 mHz to 102 kHz with 4˝ digits of resolution. Both frequency
and amplitude can be set from the front panel or from a computer. When using an external reference, the synthesized
source is phase locked to the reference signal.
The Dual Phase Lock-In Amplifier SR830 is simple to use. All instrument functions are set from the front-panel
keypad, and a spin knob is provided to quickly adjust parameters. Up to nine different instrument configurations
can be stored in non-volatile RAM for fast and easy instrument setup. Standard RS-232 and GPIB (IEEE-488.2)
interfaces allow communication with computers. All functions can be controlled and read through the interfaces.
SRS SR830 Features
- Frequency : 1 mHz to 102.4 kHz
- >100 dB dynamic reserve
- Phase Resolution : 0.01 degree
- 5 ppm/°C stability
- Auto-gain, -phase, -reserve and -offset
- GPIB and RS-232 interfaces
Ask for SRS SR830 detailed specification.