An Approach to FM LPI Radar Detection

Abstract

FM (Frequency Modulated) LPI (Low Probability of Intercept) radars, unlike conventional radars, transmit a long-duration or continuous signal, with low power, using causal modulation. These characteristics of the LPI radar make it virtually invisible to conventional RWR (Radar Warning Receivers) and MAGE (Electronic Warfare Support Measures) receivers. Many studies in the field of Electronic Warfare (EW) are being developed in order to deal with this advantage of the LPI radar. A promising approach is the use of MAGE equipment with Time-Frequency Transform methods to find causality in the noise spectrum. This article applies the Wavelet Packets Transform (WPT) to the problem of electromagnetic spectrum characterization, aiming at the development of a methodology for automatic classification. The time-frequency characterization of FM LPI radar signals obtained through the WPT is compared to that obtained through the Choi-Williams Distribution (Choi-Williams Distribution - CWD) and the Short-Time Fourier Transform - STFT.