A simple microcontroller based digital lock-in amplifier for the detection of low level optical signals
Dorrington, A. A. & Künnemeyer, R. (2002). A simple microcontroller based digital lock-in amplifier for the detection of low level optical signals. In Proceedings of the First IEEE International Workshop on Electronic Design, Test and Applications (DELTA ‘02), Christchurch, New Zealand, January 29-31 2002 (pp.486-488). Washington, DC, USA: IEEE computer society.
Permanent Research Commons link: https://hdl.handle.net/10289/3215
Traditionally digital lock-in amplifiers sample the input signal at a rate much higher than the lock-in reference frequency and perform the lock-in algorithm with high-speed processors. We present a small and simple digital lock-in amplifier that uses a 20 bit current integrating analogue-to-digital converter interfaced to a microcontroller. The sample rate is set to twice the reference frequency placing the sampled lock-in signal at the Niquest frequency allowing the lock-in procedure to be performed with one simple algorithm. This algorithm consists of a spectral inversion technique integrated into a highly optimised low-pass filter. We demonstrate a system with a dynamic range of 103dB recovering signals up to 85dB below the interference.
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