Digital lock-in algorithm and parameter settings in multi-channel sensor signal detection

Abstract

In order to implement demodulation of multi-channel composite signal in sensor signal detection system with high accuracy and high speed, in this paper we present a demodulation algorithm and schemes on how to optimize performances in detail based on the idea of software radio. A multi-channel composite signal was demodulated by the algorithm combined with a high-speed digital lock-in algorithm based on oversampling. To further enhance the signal-to-noise ratio, we discussed how to cut down crosstalk between adjacent channels, and a cascade filter was proposed. The result is helpful to effectively set carrier frequencies, from which a method of choosing parameters in frequency division multiplexing is obtained. Theoretical analysis shows that the new method has advantages such as high accuracy, high speed, and wide application range. It is suitable for sensor signal detection with AC signal excitation, and it can also improve overall system performance.