Patent ID: 7509108

Claim:
A method for automatically correcting a frequency error of a local oscillator in a receiver, the method comprising: receiving signals from a transmitter, each signal including a sequence known to the receiver; sampling the signals to generate multiple sets of samples; performing a correlation of each set of the samples and the sequence with a plurality of block correlators to generate a plurality of correlation values, each of the block correlators performing a correlation of a portion of the samples and a corresponding portion of the code sequence; generating a conjugate product and sum of the plurality of correlation values for each set of samples by multiplying correlation values generated by consecutive block correlators in a conjugate sense to generate a plurality of conjugate products and summing the conjugate products; accumulating the conjugate product and sums; computing an angle value of the accumulated conjugate product and sum; computing a frequency error estimate based on the angle value; generating a correction signal based on the frequency error estimate; and applying the correction signal to the local oscillator to correct a frequency error, wherein the conjugate product and sum is accumulated over N sets of samples and the number N is adjusted in accordance with the frequency error estimate.