Patent ID: 7068710

Claim:
A method for operation of a receiver of a spread spectrum system in which a signal received at the receiver has a received time and frequency and is transmitted from a transmitter in accordance with a predetermined modulation scheme and having a transmitted time and frequency, there being a time offset and a frequency offset between the received signal and the transmitted signal, and in which the receiver includes a predefined correlation surface in accordance with the predetermined modulation scheme, the method comprising: generating in the receiver an expected signal, the expected signal being a function of time and frequency comprising a frequency parameter shifted from the transmitter frequency and a time parameter shifted from the transmitter time, correlating the received time and frequency of the received signal with said time and frequency shifted parameters of the expected signal to provide respective correlation measures therebetween, deriving, using said correlation surface, a computational expression indicative of the value of the correlation at a point displaced in time by the time offset plus the time shift and displaced in frequency by the frequency offset plus the frequency shift, and comparing the correlation measure with the computational expression and determining the time offset and the frequency offset.