Low Probability Of Intercept Signal Detection And Estimation

The low intercept probability of intercept signal is used as the signal generated by the low intercept probability(LPI)radar.Its low power,frequency agility and large time-width-bandwidth feature make the intercept probability radar signal have excellent anti-interference and anti-interception performance,Intercepting the receiver puts higher demands on it.In this research,three typical low-intercept probability radar signals,including frequency hopping signals,linear frequency modulation(LFM)signals and nonlinear frequency modulation(NLFM)signals,are used to analyze the signal detection and parameter estimation.For the detection and parameter estimation of frequency hopping signals,the frequency hopping signal can be regarded as the characteristic of single-frequency signal,ie 1-sparse signal in a short time.The method of compressed sensing is used to detect and estimate the parameters,which effectively reduces the frequency hopping signal processing data amount.The method based on probability sliding window is proposed to process the frequency-hopping signal after compression sampling,which can effectively suppress the influence of white Gaussian noise,so that the signal parameters can be accurately estimated at a low SNR.For chirp signals,the LFM signal is mainly used in the fractional domain,and the fractional Fourier transform(FRFT)is linear,which is additive,so the fractional Fourier transform is used for multi-component LFM signals.The detection and parameter estimation are carried out,and the LFM signal component separation method based on kurtosis value is proposed,which can effectively reduce the masking effect of strong LFM signal components on weak signal components and improve the accuracy of multi-component LFM signal parameter estimation.For the nonlinear frequency modulation(NLFM)signal,due to the cross term of the Wigner-Ville distribution,the influence is relatively large,and the effects of several different improved time-frequency distributions are compared,and a short-time fractional Fourier transform is introduced for analysis.The NLFM signal describes the optimization principle in detail,and verifies its effect on the time-frequency analysis of multi-component NLFM signals.Finally,the instantaneous frequency of the single-component NLFM signal is estimated by using the short-time fractional Fourier transform.