Adaptive Target Detection in Passive Bistatic Radars: A Theoretical Analysis

Abstract

This paper provides a theoretical analysis to consolidate the theory of “adaptive” target detection in the surveillance channel of passive bistatic radars where noise, strong returns of clutter and target returns are present. It is known in the literature that by generating the mixing product for each bistatic sample delay in the surveillance channel using the preprocessed and multipath-free reference channel signal, adaptivity can be realized. However, the theoretical background of this idea is not strong. In this paper, the statistical characteristics and the distribution of the mixing product are analyzed leading to the hypothesis test applicable to the “adaptive” detection problem. We investigate the iid requirements of secondary data, and a suitable scheme for secondary data generation in which these requirements are approximately satisfied is proposed. Several adaptive target detectors from active pulse radars’ literature based on the derived hypothesis test are generalized for use in passive radars and their performances are assessed by simulations and theoretical analysis. The simulation results indicate that these detectors are generally preferred compared to the conventional cross ambiguity function processing. It is also shown that the simulation-based and theoretical detection performances validate each other.