Multirate, constant envelope, constant bandwidth, modulation, channelization and detection system based on orthogonal bipolar spreading vectors

摘要

A modulation channelization and demodulation system based on orthogonal bipolar spreading vectors is provided that permits a variable information rate to be transmitted without inducing envelope fluctuations and permits multiple access without requiring the transmitter amplifiers to support the combined information rate of all users. The modulation system uses the vectors of a Hadamard matrix to form communication channels. The information rate on any channel may be doubled by using half the vector length to transmit information. The vector that is not non-orthogonal-in-the-half to the rate-doubled vector is preferably deactivated. In the same fashion, higher information rates may be provided through truncation of the transmission vector and the elimination of the resultant non-orthogonal vectors. A multi-channel receiver including a Fast Hadamard Transform structure comprised of controllable modified logic cells for performing the multi-rate communication of the present invention is illustrated. A multi-channel transmitter for performing the present invention is also shown.