Simple synchronic detection at audio frequencies through a PC sound card

We present a simple personal computer based, synchronic detection system that emulates a lock-in amplifier at audio frequencies. The inputs of the sound card are used to acquire two sets of samples: the one to be measured, previously preamplified, and the reference. From the last one, two "quas...

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Bibliographic Details
Published in:Review of scientific instruments 2007-05, Vol.78 (5), p.055108-055108-4
Main Authors: González, Martín G., Santiago, Guillermo D., Slezak, Verónica B., Peuriot, Alejandro L.
Format: Article
Language:English
Subjects:
Acoustics - instrumentation
Computer Peripherals
Electronics - instrumentation
Equipment Design
Equipment Failure Analysis
Microcomputers
Reproducibility of Results
Sensitivity and Specificity
Signal Processing, Computer-Assisted - instrumentation
Sound Spectrography - instrumentation
Sound Spectrography - methods
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Summary:We present a simple personal computer based, synchronic detection system that emulates a lock-in amplifier at audio frequencies. The inputs of the sound card are used to acquire two sets of samples: the one to be measured, previously preamplified, and the reference. From the last one, two "quasiorthogonal" signals are derived to perform dual-phase detection. The procedure is fast and compares favorably with a benchtop lock-in amplifier. In the band from 100 Hz to 20 kHz we obtained average amplitude and phase errors below 1% and 0.1°, respectively.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.2740063