New time-domain clutter-lock algorithm

The authors present a new clutter-lock algorithm to estimate the Doppler spectrum centre frequency. The algorithm is based on the fact that the number of zero crossings in the in-phase and quadrature channels is minimum when the azimuth received signal is base-band converted by using the correct Doppler centroid. Although the problem of estimating the Doppler centre frequency is of interest in many fields, the authors investigated the performance of the proposed algorithm when used in the context of SAR data focussing. First, the authors briefly recall the problem of SAR signal processing, then they introduce the proposed algorithm. Its validity is demonstrated by applying it both to simulated and real data. Finally, the algorithm is compared to existing clutter-lock techniques in terms of both estimation accuracy and processing time