Compression of SAR data through range focusing and variable-rate vector quantization

In spaceborne SAR systems, some form of data compression is required to reduce the bandwidth of the downlink channel. Compressing the raw data is very inefficient because such data exhibit little or no correlation. Data focusing would restore the original dependencies of the image, but it is too complex to be implemented onboard. In this paper we propose to carry out a partial, low-complexity focusing onboard, and then compress the resulting data by means of a suitable algorithm based on variable-rate adaptive vector quantization. Experiments show a performance improvement of 0.5-0.7 dB over compression techniques proposed in the literature.