Weak Signal Detection Based On Cross Correlation And Wavelet

Weak signal detection is widely used in scientific research and engineering applications,such as spectral analysis,chemical sample detection,geological exploration,air monitoring and so on.The theory and method of weak signal detection and the research of new instrument for weak signal detection have attracted widespread attention in the field of signal detection.There are many kinds of weak signal detection technology,and each detection method has its advantages and disadvantages,and the application situation is different.In the early stage of weak signal detection,a single detection method is often used.With the development and research in the research field of weak signal detection,the signal types are becoming more and more complex.It is difficult to obtain a good detection effect by using a single weak signal detection and detection method.In this paper,in view of the application of weak signal detection in GMR biosensor,a weak signal detection scheme based on cross correlation and wavelet transform is selected,and a weak signal detection circuit specially used for magnetic bead signal detection is made,and the actual effect of the circuit is tested.The main work of this paper is as follows:(1)Through literature retrieval,we understand the status of weak signal detection at home and abroad,learn the relevant theoretical knowledge of cross correlation detection and wavelet transform,and determine the weak signal detection scheme based on the combination of cross correlation detection and wavelet threshold filtering based on FFT.(2)On the basis of the demand analysis of the weak signal detection circuit,the selection of hardware is completed,and the hardware system scheme of the lower computer and the upper computer is determined,in which the lower computer is STM32 and the upper computer is PC.The front end signal conditioning circuit is made to complete the signal amplification,filtering and A/D conversion,and the specific circuits involved in each module are simulated.(3)The software is divided into two parts: the lower computer software and the upper computer software.On the lower computer STM32,the design and verification of the FIR bandpass filter are completed using the FIR function of the DSP library and the FIR bandpass filter is completed with the convolution theorem,and the cross correlation detection algorithm is completed by using Fourier transform function and complex function.The processing effect of the program is verified by MATLAB.On the upper computer PC,three modules of communication,wavelet threshold filtering and output display are designed by using Python's Pyserial,PyWavelet and Matplotlib libraries respectively.(4)The experimental verification system of the weak signal detection circuit is built.The experimental results show that the sensitivity of the weak signal detection circuit is 1.22818 uV/mV,and the weak signal of 11-100 uV can be detected.