Enhanced Passive GNSSBased Radar Imaging Based on Coherent Integrated MultiSatellite Signals Weak reflected signal is one of the main problems in a recent developing remote sensing toolxe2x80x94passive GNSSbased radar (GNSS radar). To address this issue, an enhanced GNSS radar imaging scheme on the basis of coherently integrating multiple satellites is proposed. In the proposed scheme, to avoid direct signal interference at surveillance antenna, the satellites that used as transmission of opportunity are in backscattering geometry model. To coherently accumulate echo signal magnitudes of the scene center in the targeted sensing region illuminated by the selected satellites, after performing the paralleled range compressions, a coordinates alignment operator is performed to the respective range domains, in which, pseudorandom noise (PRN) code phases are aligned. Thereafter, the coordinates aligned range compressed signals of the selected satellites are coherently integrated along azimuth domain so that imaging gain is improved and azimuth processing can be accomplished in only one state operation. The theoretical analysis and field proofofconcept experimental results indicate that compared to both conventional bistatic imaging scheme and the stateoftheart multiimage fusion scheme, the proposed scheme can provide a higher imaging gain; compared to the stateoftheart multiimage fusion scheme, the proposed scheme has a less computational complexity and faster algorithm speed.

Experimental Demonstration of Ship Target Detection in GNSSBased Passive Radar Combining Target Motion Compensation and TrackbeforeDetect Strategies This work discusses methods and experimental results on passive radar detection of moving ships using navigation satellites as transmitters of opportunity. The reported study highlights as the adoption of proper strategies combining target motion compensation and trackbeforedetect methods to achieve long time integration can be fruitfully exploited in GNSSbased passive radar for the detection of maritime targets. The proposed detection strategy reduces the sensitivity of longtime integration methods to the adopted motion models and can save the computational complexity, making it appealing for realtime implementations. Experimental results obtained in three different scenarios (port operations, navigation in open area, and river shipping) comprising maritime targets belonging to different classes show as this combined approach can be employed with success in several operative scenarios of practical interest for this technology.