Unambiguous across‐track velocity estimation of moving targets for multichannel synthetic aperture radar‐ground moving target indication systems

Abstract

In this study, a method of estimating unambiguous across-track velocity of moving targets is presented. The method can be used for ground moving target indication mode of multichannel synthetic aperture radar (SAR) systems. The basic idea is to decompose the unambiguous velocity into the fractional and the integer parts, and to estimate them individually. As such, an integrated velocity estimation scheme is proposed. In the scheme, the idea of clutter suppression interferometry is adopted to estimate the fractional velocity part via the along-track interferometry technique. For estimating the integer velocity part, the ideas behind the multilook beat frequency are adapted and applied to coarsely estimate the unambiguous velocity first, and then the coarsely estimated unambiguous velocity is combined with the fractional velocity part to obtain an estimate of the ambiguity number. Finally, the ambiguity number and the fractional velocity part are combined to otain an accurate estimate of the unambiguous velocity. The proposed algorithm is tested with real SAR data. The results show that the integrated scheme represents an accurate solution to the unambiguous across-track velocity estimation problem.