Improved channel mismatch estimation for multi‐channel HRWS SAR based on azimuth cross‐correlation.

In multi‐channel high‐resolution and wide‐swath (HRWS) synthetic aperture radar (SAR) processing, range sampling time errors and phase mismatches severely degrade the reconstruction performance of unambiguous Doppler spectrum. To address this problem, an improved channel mismatch estimation algorithm for multi‐channel HRWS SAR is presented in this Letter. The technique of combining phase wrapping and weighted least‐squares fitting is capable of realising a robust estimation of range sampling time errors and constant phases between adjacent channels. Then, Doppler centroid as well as channel phase mismatches can be estimated from these constant phases based on the theory of spatial cross‐correlation coefficient (SCCC). Compared to the conventional algorithm, the improved performance can be achieved by using the proposed two‐step procedure. The effectiveness of the proposed algorithm is confirmed by experimental results based on airborne real data. [ABSTRACT FROM AUTHOR]