A novel Doppler chirp rate and baseline estimation approach in time domain for multi-channel in azimuth HRWS SAR system

Similar to the conventional synthetic aperture radar (SAR) imaging processing, the estimation of Doppler chirp rate is one key problem for the multi-channel in azimuth high-resolution and wide-swath (HRWS) SAR system. At the same time, the accurate estimation of baseline in azimuth is also important for the reconstruction of ambiguity-free Doppler spectrum. In this paper, based on the Map Drift algorithm and correlation function approach, a novel Doppler chirp rate estimation approach in time domain is proposed for the multichannel in azimuth HRWS SAR system. Furthermore, a baseline length in azimuth estimation algorithm is developed from the proposed Doppler chirp rate method, which is based on the correlation function between the echoes of adjective channels. The proposed approaches are successfully applied to process the real five-channel HRWS SAR echo and the good performance is demonstrated.