Maximum‐likelihood‐based Doppler centroid estimation algorithm for MC‐HRWS SAR system

For the multi-channel in azimuth high-resolution and wide-swath (MC-HRWS) synthetic aperture radar (SAR), a novel maximum-likelihood-based Doppler centroid estimation algorithm is developed. During the estimation process, the Doppler centroid is estimated by using the maximum-likelihood approach to combine the range-frequency-variant Doppler characteristics in each channel, such as the cross-functions between neighbouring channels in the range-frequency domain. In addition, the channel mismatch in phase and along azimuth baseline position measurement error can also be estimated. Finally, the experimental results of some real squint mode MC-HRWS SAR data are utilised to validate the theoretical investigations and the proposed approach.