Patent ID: 7778619
Filing Date: 2010-08-17
Classification: H03J

Abstract:
1. A method for automatically correcting a frequency error of a local oscillator in a receiver, the method comprising: receiving a signal which includes a sequence known to the receiver; generating samples from the signal; correlating the samples and the sequence with a plurality of block correlators to generate a plurality of correlation values, each of the block correlators correlating 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 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 sum over an accumulation time equal to N sequences, where N is a predetermined integer selected to ensure less than one quarter chip movement between frequency updates; computing an angle value of the accumulated conjugate product and sum; computing a frequency error estimate based on the angle value; correcting a frequency error of the local oscillator using the frequency error estimate; performing a plurality of correlations of the samples and the code sequence at each of a plurality of lags to generate a plurality of correlation values at each of the lags; computing a plurality of conjugate product and sums of the correlation values at the lags; combining the conjugate product and sums; and computing the angle value from the combined conjugate product and sums.