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 (2002)
Christchurch, New Zealand
Jan. 29, 2002 to Jan. 31, 2002
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.