A DBTV System for Optimum Bandwidth Efficiency

A system for direct broadcasting by satellite is described which allows both a doubling of capacity without significant loss of quality compared with conventional broadcast TV and the option of trading the increased capacity in a compatible manner for enhanced definition and aspect ratio in the future. In order to achieve the necessary increase in bandwidth efficiency, two processes which exploit the redundancy in typical TV pictures are employed. Firstly, a relatively simple non-linear pre and post-filtering process is used to allow the time compression to be increased without significantly reducing the S/N. Secondly, subsampling and adaptive interpolation is used to limit the increase in time compression and the reduction in baseband bandwidth. One possible way of implementing compatible extension is described.