A Time Difference Estimation Algorithm Based On VMD And Generalized Extension Approximation

Time Difference of Arrival(TDOA)positioning is one of the most important methods in passive positioning system,which has the characteristics of simple positioning method,low system hardware equipment requirements,easy networking,and flexibility,and plays a great role in military and daily production life.There are many factors affecting the positioning accuracy of TDOA,and the accuracy of time difference estimation is the most important one,and its accuracy directly determines the positioning accuracy.Therefore,the research on high-precision time difference estimation technology has great significance and value.This study addresses the field of high-precision time difference estimation algorithm,and the main research contents are as follows.In order to solve the problem that the classical inter-correlation method and the quadratic correlation method have large errors and ±1 sampling period theoretical errors in the case of low signal-to-noise ratio,a time difference estimation algorithm of inter-correlation method combined with Short Time Fourier Transform(STFT)is proposed.First,the time difference between the two signals is roughly measured by using the classical correlation method,and one of the signals is delayed by the corresponding time;Then,the short time Fourier transform is performed on the other signal within a certain time difference range with one signal as the reference,and the relative delay between the sliding signal and the reference signal is judged to be zero by continuously comparing the frequency domain characteristics of the reference signal and the sliding signal.The experimental results show that the improved algorithm has higher accuracy of time difference estimation compared with the quadratic correlation method,and effectively solves the problem of theoretical error.A time difference estimation algorithm based on Variational Mode Decomposition(VMD)and generalized extended approximation is proposed.The algorithm is mainly optimized from the three aspects of signal receiving end,signal processing end and spectrum peak value of correlation function.At the receiving end,variational mode decomposition and wavelet threshold denoising are used respectively to denoise the received signals.At the signal processing end,the envelope of correlation function is obtained by the generalized quadratic correlation method.In order to improve the accuracy of spectral peak value,the generalized extended approximation method is used to interpolate spectral peak value of correlation function.Matlab simulation results show that when the signal-to-noise ratio is-10 d B,the accuracy of the time difference estimation algorithm based on VMD and generalized extended approximation is improved by more than 30% compared with the generalized quadratic correlation method.In the case of high signal-to-noise ratio,the accuracy of time difference estimation can be improved by more than 80%.