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Electronic Design, Test and Applications, IEEE International Workshop on (2002)
Christchurch, New Zealand
Jan. 29, 2002 to Jan. 31, 2002
ISBN: 0-7695-1453-7
pp: 486
Adrian A. Dorrington , University of Waikato
Rainer Künnemeyer , University of Waikato
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.
digital lock-in amplifier; integrating input; optimised digital filter

R. Künnemeyer and A. A. Dorrington, "A Simple Microcontroller Based Digital Lock-in Amplifier for the Detection of Low Level Optical Signals," Electronic Design, Test and Applications, IEEE International Workshop on(DELTA), Christchurch, New Zealand, 2002, pp. 486.
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