Abstract: An improved modulator and demodulator for use in a spread spectrum system. The modulator can process two data channels (I and Q) at nominal data rate or one high speed channel demultiplexed into two nominal rate data channels. The modulator includes one pseudorandom noise (PN) sequence generator that generates two orthogonal PN sequences. The two PN sequences are provided to a switch. Each channel includes a demultiplexer, one output of which controls which PN sequence is provided by the switch. The other demultiplexer output is then modulo-2 added (exclusive-OR'd) with the chosen PN sequence, and the modulo-2 sum is provided to the rest of the transmitter. The demodulator processes the two I and Q channels and includes a PN sequence generator providing replicas of the two PN sequences. Each channel is divided into subchannels, each subchannel being multiplied by one of the PN sequences and the results integrated.

Abstract: 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.