Along-track motion compensation approach for airborne wide-beam SAR based on sub-aperture processing

Introduction: Motion compensation (MoCo) is one of the key steps to gather well-focused images for airborne synthetic aperture radar (SAR). For SAR systems operating at low frequencies, e.g. the VHF/ UHF band, wide-beam processing is needed in MoCo to deal with the angular dependent motion error. Therefore, a sub-aperture MoCo algorithm was proposed [1] to compensate for the motion error across the nominal flight track. However, the along-track MoCo, which may be done by adjusting the pulse repetition frequency (PRF) [2] or resampling the raw data in the azimuth direction [3], was not involved in [1]. This Letter presents a new along-track motion compensation approach for airborne wide-beam SAR on the basis of the sub-aperture MoCo algorithm. Unlike the PRF-adjusting method which needs extra hardware equipment and the time-consuming resample method, the proposed approach is an efficient improvement, which compensates for the along-track motion error in a sub-aperture processing procedure.