An Iterative Algorithm for Passive Detection with Direct-Path Interference

Passive radar detects and tracks targets of interest using non-cooperative illuminators of opportunity (IOs). This type of radar has become very popular nowadays since qualified IO sources are widely accessible. In this work, the target detection problem for passive multistatic radar is studied. The radar receivers observe not only noise-contaminated reflections of the IO signal but also non-negligible direct-path interference (DPI). We propose a generalized likelihood ratio test (GLRT) approach, where the estimation problem in the alternative hypothesis is solved by using an iterative method. The signal transmitted from the IO is treated as a deterministic but unknown process. A clairvoyant matched filtering detector is also provided to benchmark the detection performance by assuming the knowledge of the IO waveform. Numerical results show the effectiveness of our proposed detector when DPI is present.