DESPREADING/DEMODULATING DIRECT SEQUENCE SPREAD SPECTRUM SIGNALS

摘要

A spread-spectrum system in which the receiver (501) may decode the spread-spectrum signal without any need for a locally generated copy of the chip sequence used by the transmitter to encode the signal, and without the need for synchronizing operation of the receiver with the transmitter. The system may comprise a receiver (501) in which the incoming spread-spectrum signal is delayed by a plurality of delay lines (503, 504) and in which the signal and its delayed versions are multiplied (505) and filtered (506) to recover the original data. The delay imposed by each delayline (503, 504) may be small compared with a single bit-transmission time. Alternatively, the data may be prepared by the transmitter to account for delays at the receiver which are not small compared with a single bit-transmission time. In such case, the receiver may impose delays which are not small compared with a single bit-transmission time, and may review the data which is recovered by multiplication and filtering to reverse the preparation step performed at the transmitter.