Shaped spectrum multi-channel orthogonal satellite data transmission

In many applications of satellite data communications, particularly for small Earth stations, there is a need to provide flexible data capacity without the need for equipment such as the modem and multiplexer to be replaced from time to time as the capacity is upgraded. The system that is proposed consists of a programmable number of frequency division multiplexed phase shift modulated data channels, conventionally spectrally shaped with root raised cosine filters. If more capacity is required, an increased power/bandwidth space segment lease is negotiated from the satellite operator and additional channels are transmitted. The existing channels remain unchanged in terms of spectral shape and signal format. Another advantage is that differing error rate requirements may be accommodated by transmitting different power levels for the various channels. A typical system arrangement with modems and multiplexers is shown