Radar image compression

In this paper an algorithm based on emerging data compression techniques and suitably adapted to the radar data of a VTS (Vessel Traffic Service) System is presented. The basic idea derives from the JPEG (Joint Photographic Experts Group) standard which converts image data to a spatial frequency representation using a 2-D discrete cosine transform (DCT). It quantizes the components with different degrees of granularity, reflecting the human visual system's spatial-frequency sensitivity then encoded using variable-length (entropy) coding. The algorithm has been analysed and implemented. An Alenia proprietary board is used for raw video data A/D conversion and to collect all data contained in user defined windows. Commercial hardware is used to run compression/decompression algorithms. The prototype collects radar data, compresses and transmits them via a telephone line to a remote console. Different tests have been performed in several European harbours and channels and some preliminary results are reported.