A Study on the Weak Signal Detection System Applied to the High Field Research Based on the Digital Lock-In Technique and Wavelet Filter

An improved digital lock-in technique with a wavelet filter is developed for the weak signals detection. A simulated signal modulated with a frequency of 40 kHz and contaminated by white noise is constructed to estimate the performance of the system. In this study, the selection of the wavelet filter parameters, such as the decomposition level, the wavelet basis and the threshold strategy is discussed. Finally, the performance of the system in different conditions is presented.