METHOD OF CORRECTING THE FREQUENCY OF A LOCAL CARRIER IN A RECEIVER OF A DATA TRANSMISSION SYSTEM AND RECEIVER USING THIS METHOD

摘要

47 This frequency correction method is used in the receiver of a data transmission system in which a synchronizing word is transmitted before the data. It comprises several steps during each of which there are calculated at least one pair of in-phase partial correlations Cr(k-l), Cr(k) and at least one pair of quadrature partial correlations Ci(k-l), Ci(k). The partial correlations of the order (k-l) and (k) in each step relate to two consecutive portions of the same length of a local synchronizing word and the samples of the received demodulated signal; the portions of a step p are greater than the portions of step p - l, the partial correlations of a step p are phase-corrected by taking account of the frequency correction calculated in step p - l. A frequency deviation is calculated from the partial correlations of each step. The final frequency correction to be retained is the sum of the frequency deviations calculated at the end of each step.