SYSTEM FOR DISCRETE DATA TRANSMISSION WITH NOISE-LIKE, BROADBAND SIGNALS

摘要

An improved system for transmitting and receiving spread spectrum signals includes a transmitter and a receiver, each with a data channel and a control channel. The transmitter uses two pseudorandom noise sequences (PNS), one whose period is equal to that of a coded data bit ("bit PNS"), the other whose period is equal to that of a codeword ("word PNS"). The data channel is modulated by a carrier signal and spread by the bit PNS. The control channel is modulated by a quadrature-phase version of the carrier signal and spread by the word PNS. The control channel sends instructions to the PNS generators to change the forms of the PN sequences in the transmitter. The receiver includes a control channel tracking and acquisition (T & A) and carrier restoration module and a data channel T & A module. The control channel T & A uses a stored version of the word PNS and outputs a word synchronization signal, a phased version of the word PNS, a quadrature-phase carrier signal, and an in-phase carrier signal. The receiver control channel recovers the control signals and uses them to change the forms of the PN sequences in the receiver. The data channel T & A uses a stored version of the bit PNS to despread received signal. The data channel T & A also outputs a bit synchronization signal used in decision-making and decoding the demodulated received signal.