An Interference-Tolerant Algorithm for Wide-Band Moving Source Passive Localization

A new technique for locating a moving source radiating a wide-band almost-cyclostationary signal is proposed. For this purpose, the signals received on two possibly moving sensors are modeled as jointly spectrally correlated, a new nonstationarity model that allows one to describe the Doppler effect accounting for a time-scale or time-stretch factor in the complex envelopes of the received signals. The proposed approach relaxes the narrow-band condition constraint under which the Doppler effect is modeled just as a frequency-shift of the carrier. The typical interference-tolerance property of cyclostationarity-based algorithms is shown to be valid under mild conditions also for (jointly) spectrally correlated signals. With respect to classical source location methods, removing the constraint of the narrow-band condition allows the adoption of larger signal bandwidths and data-record lengths, lower signal-to-noise and signal-to-interference ratios, and the capability to operate in scenarios with higher mobility. The new source location method, dubbed wide-band spectral coherence alignment (WB-SPECCOA), is exploited in a location problem involving low Earth orbit satellites.