REAL-TIME SYNTHETIC APERTURE RADAR (SAR) PROCESSING WITH A NEW SUBAPERTURE APPROACH

A time domain subaperture approach has been developed at DLR which is suitable for real-time synthetic aperture radar (SAR) processing and produces high quality, full resolution images. The real-time subaperture algorithm is based on an approximation of the phase history correction in each subaperture with a simple linear correction, which can be carried out by an up/down-conversion of the received signal followed by a moving average operation. The characteristics of the impulse response function are improved considerably by means of a frequency overlap of the subapertures and become comparable to a conventional matched filter response. Special algorithms for high quality SAR processing, such as auto-focus, Doppler centroid estimation, and range migration correction, can be efficiently implemented. High flexibility is achieved for multilook processing and no secondary range compression is needed, even for high squint angles. Dedicated hardware is under development for the DLR airborne SAR (E-SAR) System.