volume | PIER Journals

Abstract

The variable orbit altitude and platform velocity in high-eccentricity orbit synthetic aperture radar (HEO SAR) increase the difficulty in obtaining effective radar echoes. In this letter, a new stripmap imaging mode with multi-parameter joint agile variation in HEO-SAR is proposed. First, the range side-looking angle is adjusted during the whole raw data acquisition interval according to the time-varying side-looking geometric relationship, while the pulse repetition frequency (PRF) is continuously changed to obtain uniform azimuth sampling due to the satellite velocity variation. Besides simultaneously adjusting the side-looking angle and the operated PRF, echo sampling start time and range sampling points are also continuously changed to decrease the echo data rate. According to the echo characteristics in HEO SAR, its corresponding imaging algorithm is presented, which includes range samples adjustment, azimuth resampling, cubic filtering, nonuniform Fourier fast transform (NUFFT) for nonlinear range cell migration correction (RCMC) and modified azimuth compression. A system design example with multi-parameters joint agile variation for the desired resolution of 3 m and the swath width of 30 km is given, while an imaging simulation experiments on point targets are carried out. Both simulation results of multi-parameters variation design and point targets imaging validate the proposed stripmap imaging mode with multi-parameters joint agile variation in HEO SAR.

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Mr. Xuhang Lu

Dr. Wei Xu

Professor Pingping Huang

Professor Weixian Tan

Professor Yaolong Qi