A new technique for locating a moving source radiating a wide-band almost-cyclostationary signal is proposed in [J42]. 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.
A new signal-selective wide-band cross-ambiguity function is introduced in [C57]. It performs a sinusoidally weighted correlation of a signal with a time-scaled and delayed version of a reference signal. If the reference signal is almost cyclostationary and the frequency of the weighting sinusoid is one of its cycle frequencies properly scaled, the new function, referred to as the wide-band cyclic cross-correlation function, exhibits the signal selectivity properties that are typical of cyclostationarity-based techniques. The new function is exploited for the localization and speed estimation of a wide-band moving source whose signal impinges on two sensors in a severe noise and interference environment.