This letter focuses on ship target localization using a multistatic passive radar system based on navigation satellites opportunistic illuminators. In such systems, the typical approach to localize the targets is taking peripheral decisions at each bistatic channel to detect the target followed by bistatic ranges intersection. In contrast, here we consider a centralized approach in order to jointly detect and localize the ship target of interest. The proposed approach entirely operates in a Cartesian plane representing the surveyed maritime area and it is able to combine the signals pertaining the different bistatic links despite the variation of the e.m. response of the targets, typically occurring in the framework under consideration as the target is illuminated by multiple (and possibly widely separated) transmitters viewing angles. Moreover, the hypothesis of point-like targets is here replaced with the more realistic case of extended targets (i.e., occupying more than one resolution cell). The ship localization effectiveness of the method is proved via both synthetic and experimental datasets.

No abstract

Target detection by means of space-based passive radar sensors generally requires the adoption of long integration time strategies to reinforce sufficiently the signal strength. These are usually based on the recovery of the target Doppler-rate to cope with the range and Doppler migration experienced over the long dwell considered. In this work, we put forward a Taylor-series approach that capitalizes on the set of bistatic Doppler-rates estimated in Global Navigation Satellite Systems (GNSS)-based multistatic radar configurations to estimate the velocity of ship targets with increased accuracy with respect to conventional Doppler-based procedures. Both the cases of single-element and array receiver configurations have been considered. Theoretical and numerical results under different use cases show as leveraging on the long integration times adopted at the detection stage could significantly increase the accuracy of the estimated ship velocity components. Few experimental results are also provided, verifying the potentialities of the proposed approach in operative scenarios of practical interest for this technology. The proposed approach is not limited at the GNSS case, but it could be potentially applied to any multistatic passive radar system.