Doppler centroid block estimation for multi-channel in azimuth SAR

The multichannel in azimuth synthetic aperture radar (MC-SAR) system is very promising for high-resolution and wide-swath (HRWS) imaging, whereas Doppler centroid block estimation related to the channel phase calibration has a great influence on image quality. In order to solve the problem of the Doppler centroid block estimation, this paper proposes an effective way to improve its precision. This paper analyses the reason of the Doppler ambiguity hop when estimating the Doppler centroid in block. According to the position of the reference baseband Doppler centroid and the block estimate of baseband Doppler centroid, the Doppler ambiguity is adjusted differently. Finally, the effectiveness of the proposed method is demonstrated by real airborne data.