Target detection for passive radar with noisy reference channel

This paper considers the problem of target detection in a passive radar consisting of a reference channel (RC) and a surveillance channel (SC). The RC receives an unknown source signal directly transmitted by a non-cooperative illuminator of opportunity (IO), whereas the SC collects target echoes due to the illumination by the same IO. The conventional solution to this passive detection problem is a cross-correlation (CC) based detector that cross-correlates the reference signal from the RC and the surveillance signal from the SC. It is known that the CC detector is very sensitive to the noise level in the RC. In this paper, we develop four detection algorithms based on the generalized likelihood ratio test principle, by treating the unknown source signal from the IO to be deterministic or stochastic and under conditions whether the noise variance is known or unknown. Our results demonstrate that when the reference signal is noisy, three of the proposed detectors offer significant improvements in detection performance over the CC detector.