Time-chirp Distribution for Detection and Estimation of LPI Radar Signals

One of the primary challenges for an Electronic Support (ES) receiver is interception and analysis of low probability of intercept (LPI) radar signals, which for example are linear frequency-modulated (LFM) signals. In the paper detection and estimation of LFM waveform parameters based on the extended forms of the standard cubic phase function (CPF) is proposed. Originally the CPF function was introduced for instantaneous frequency rate (IFR) estimation. Extended forms are created by summation operations or multiplication operations, or integration operations of the time slices of the standard CPF function. The CPF function and its extended forms concentrate energy of LFM waveforms along a IFR line in the time-chirp domain just as the short time Fourier transform (STFT) and Wigner-Ville distribution (WVD) concentrates energy of LFM signals along an instantaneous frequency (IF) line in time-frequency domain. Based on the extended forms of the standard CPF function, test statistics have been proposed and intensively evaluated in Monte-Carlo simulations. Selected results of investigations on parameter estimation and high detection efficiency obtained by the proposed methods are presented.