On-board compression of SAR data through range focusing

To reduce the bandwidth of the downlink channel in spaceborne SAR systems some form of data compression is required. Compressing the raw data is very inefficient because these data exhibit little or no correlation; on the other hand, data focusing is too demanding to be carried out on-board. The authors propose to carry out a partial, low-complexity focusing on-board, in order to recover part of the original dependencies, and then to compress the resulting data by means of a variable-rate adaptive vector quantization algorithm. Experiments show a performance improvement of 0.5-0.7 dB over comparable compression techniques.