ENHANCED QPSK OR DQPSK DATA DEMODULATION FOR DIRECT SEQUENCE SPREADING (DSS) SYSTEM WAVEFORMS USING ORTHOGONAL OR NEAR-ORTHOGONAL SPREADING SEQUENCES

摘要

A method of correcting phase error of a phase shift keyed (PSK) signal includes (a) receiving a signal modulated by a spreading sequence; (b) despreading the received signal using a receiver spreading sequence similar to the spreading sequence of step (a); (c) calculating a crosscorrelation profile between the receiver spreading sequence and the received signal; and (d) calculating an autocorrelation profile of the receiver spreading sequence to determine a spreading code property (SCP). The method also includes (e) estimating a timing error in alignment between the autocorrelation and the crosscorrelation profiles; and (f) correcting a phase error of the signal despread in step (c), by using the SCP and the estimated timing error.