A high frequency transmitter comprises a large number of narrowband channels spaced over a broad bandwidth transmission. In one arrangement input data to be transmitted is demultiplexed (1101) so that sections of data are transmitted in groups of channels at 50 baud (say), each 50 baud channel produces...http://www.google.com/patents/US5422913?utm_source=gb-gplus-sharePatent US5422913 - High frequency multichannel diversity differential phase shift (DPSK) communications system
