Design of Digital Lock-in Amplifier Based on Wiener Filter

Abstract

This paper introduced the design of a digital lock-in amplifier for weak crack detection. Due to the limitation of flicker noise and low pass filter performance, the error of the traditional lock-in amplifier in detecting weak signal will be large. In order to solve this problem, this paper designed an algorithm according to the source of noise. First, an orthogonal vector digital phase locked amplifier has been built. In addition, we have proposed and implemented a noise removal method based on Wiener filter, and optimized the anti-interference performance of the lockin amplifier by sliding mean algorithm. The simulation results show that the proposed design can effectively extract the weak crack signals submerged in noise, optimize the performance of the traditional lock-in amplifier, improve the accuracy and reduce the noise interference.