A moving-target imaging method for azimuth multi-channel HRWS SAR system based on spectrum energy distribution

Azimuth multi-channel (AMC) synthetic aperture radar (SAR) systems can achieve high-resolution and wide-swath (HRWS) imaging, widely used in marine monitoring. However, for the moving ship targets irradiated by the AMC HRWS SAR system, false targets and defocus will appear in HRWS images caused by their motion. The existing methods behave poorly in case of low signal-to-noise ratio and channel non-uniformity. To improve the quality of HRWS images, the letter proposes a moving ship target imaging method based on spectrum energy distribution. Firstly, radial velocity of ship target is estimated by energy distribution factor parameter constructed by spectrum energy distribution. Secondly, the azimuth velocity is calculated by the phase difference between adjacent channels. Meanwhile, the importance of channel phase error on imaging is demonstrated. Finally, echo compensation and imaging method are performed to get a clear and focused image. Simulation experiments on point targets and area targets verify the effectivity of the proposed method. The proposed method can effectively suppress the false ship target, whose maximum energy is reduced from about -20 dB to below -40 dB, providing clearer images for the various application of different users.