Efficient SAR raw data compression in frequency domain

SAR raw data compression is necessary to reduce the huge amount of data for downlink and the required memory on board. In view of interferometric and polarimetric applications for SAR data it becomes more and more important to pay attention to phase errors caused by data compression. Here, a detailed comparison of block adaptive quantization in time domain (BAQ) and in frequency domain (FFT-BAQ) is given. Inclusion of raw data compression in the processing chain allows an efficient use of the FFT-BAQ and makes implementation for on-board data compression feasible. The FFT-BAQ outperforms the BAQ in terms of signal-to-quantization noise ratio and phase error and allows a direct decimation of the oversampled data equivalent to FIR-filtering in time domain. Impacts on interferometric phase and coherency are also given.