An free of iteration array-error estimation method for multi-channel SAR systems*

Abstract

This paper considers the problem of estimating gain-phase and position errors for multi-channel synthetic aperture radar (SAR) systems. In multi-channel SAR systems, the clutter spectrum components within a Doppler bin can be used as calibration sources with known directions. Conventional eigen-structure methods, which iterates alternatively between the self-calibration method for gain-phase error estimation and the least squares method for estimating position errors, may converge to a local optimal solution. In this paper, it is observed that the steering vectors corresponding to a pair of Doppler bins within the same range bin have a rotational relationship. We obtain a new array-error estimation method based on this observation. The method, which obtain the position errors in terms of extracting the rotational matrix in a least square's framework, is proposed via combining the projection matrices corresponding to the paired Doppler bins. The validity of the proposed method is verified by the experimental results of measured four-channel SAR data.