CZT CORRECTION OF RANGE-DEPENDENT RESIDUAL-RCM FOR AIRBORNE SAR MOTION COMPENSATION

For the airborne SAR imaging, the motion compensation (MOCO) is required because of the phase error caused by the atmospheric turbulence. In the case of ultrahigh-resolution and wide-swath, the phase error may be range-dependent (RD), which may induce a RD residual-RCM after the correction of range cell migration (RCM) by using the range migration algorithm (RMA). Currently, phase gradient autofocus (PGA) is widely used to estimate the phase error from the raw data. However, the RD residual-RCM may degrade the accuracy of the PGA. To overcome such a problem, we present a CZT correction algorithm to correct the RD residual-RCM. Processing of airborne real data validates the effectiveness of the proposed algorithm.