A Radial Velocity Estimation Method of Moving Ships for Spaceborne MC-ScanSAR Systems

Multichannel synthetic aperture radar (MC-SAR) systems in azimuth combined with scanning mode can realize the requirements of high-resolution and ultrawide-swath SAR imaging. Since the Doppler spectrums of targets in ScanSAR are incomplete and the range of the Doppler spectrum occupied by different targets is inconsistent, the radial velocity estimation of ship targets in multichannel ScanSAR (MC-ScanSAR) systems cannot be performed based on the traditional Doppler spectrum analysis method, which poses a challenge of the application for the MC-ScanSAR ship images. However, the velocity of moving ships introduces additional ambiguous targets in focused MC-ScanSAR images, which inevitably affects the interpretation and localization of ships, but enables the estimation of its radial velocity. This article proposed a radial velocity estimation method of ship for MC-ScanSAR single-look complex data. Based on the reconstruction mismatch generated by conventional reconstruction filters in the imaging process for moving target signals, a high-accuracy radial velocity estimation algorithm for ships was proposed to utilize the ambiguous-signal and main-signal correlation of the moving targets. The proposed method is validated by simulation results on point targets and maritime ships, and the results show that the high estimation accuracy can still be maintained under high sea conditions.