A Novel Approach for the Characterization of FSK Low Probability of Intercept Radar Signals via Application of the Reassignment Method

A novel approach of employing the reassignment method as a signal analysis technique for use in digital intercept receivers for the analysis of frequency shift keying (FSK) low probability of intercept (LPI) radar signals is taken. Digital intercept receivers are currently moving away from Fourier analysis techniques using the FFT as the basic tool for detecting and extracting parameters of LPI radar signals, and are moving towards classical time-frequency analysis techniques (e.g. Spectrogram, Wigner-Ville distribution (WVD)). These classical techniques, though an improvement over Fourier analysis techniques, suffer from a lack of readability, due to poor time frequency localization and cross-term interference. This lack of readability can lead to inaccurate detection and parameter extraction of these signals, potentially threatening survivability of the intercept receiver environment in certain situations. The reassignment method, with its ´squeezing´ and ´smoothing´ qualities, is considered as an innovative and improved signal analysis technique for this scenario. The FSK signal is used for testing. Experimental modeling and simulation results are subjectively assessed and measured via seven different metrics (including time-frequency localization, a novel metric). Reassignment method results are compared to classical time frequency analysis results. The results confirm the improved readability of the reassignment method, and consequently, more accurate signal detection and parameter extraction metrics. These results have the potential of improving timeliness of signal characterization, and as a result, increasing aircraft survivability in particular situations.