Abstract:

To solve the problems of a low parameter accuracy,noise-dependent prior knowledge and a limited scope of application in the parameter estimation method of Linear Frequency Modulation under impulse noise,a new parameter estimation method of Linear Frequency Modulation signal is proposed.First,the principle of LV’s Distribution is introduced,and it is pointed out that the performance of the algorithm will be seriously degraded under the impulse noise,and that the parameter estimation ability will fail completely under the strong impulse noise.Then,the property of the nonlinear function Sigmoid is quoted and derived,leading to the result that the phase information of the Linear Frequency Modulation signal before and after the nonlinear function transformation remains unchanged.By combining the LV’s Distribution and the properties of the nonlinear function,using the nonlinear function to process the original signal,and then being divided by its conjugate,the two-dimensional Fourier transform of its symmetric parameter instantaneous autocorrelation function is carried out according to the definition of LV’s Distribution,and the signal is transformed into the Centroid Frequency Chirp Rate domain.Finally,the parameter estimation of the Linear Frequency Modulation signal can be realized according to the peak coordinates.Simulation results show that for the single-component and two-component Linear Frequency Modulation signal,the proposed algorithm can effectively suppress impulse noise and does not depend on the prior knowledge of noise,and can accurately estimate the parameter of the Linear Frequency Modulation signals under strong impulse noise and an extremely low signal-to-noise ratio.The method is simple to implement and has good robustness.Moreover,the parameter estimation of complex signals can be realized,which is beneficial to the application in signal processing.

Key words: liner frequency modulation signal, nonlinear function, LV’s distribution, impulse noise, parameter estimation