Transmitting spread spectrum data with commercial radio

摘要

A transmitter prepares digits for transmission, e.g. as spread spectrum data accompanying commercial radio, using code sequences having exactly zero cross-correlation. The code sequences include phased versions of the maximal length sequence, with an additional "0" bit appended to the end of each phased version. Information signals (which may be analog signals, or digital signals encoded as two or more analog levels) are transmitted by multiplying each information signal by one of the code sequences, and adding the resulting sequences together to form an output sequence for transmission. A receiver that recovers the information signals correlates the received sequence with each of the code sequences, producing results which are directly proportional to the information signals.