Patent ID: 6278865
Filing Date: 2001-08-21
Classification: H03J

Abstract:
A method of measuring the frequency difference in a radio receiver generating for synchronization purposes a tuning frequency corresponding to a transmission frequency, and in which the strength and phase of a received signal is measured in relation to the tuning frequency, said method comprising:measuring the phase of a received signal at least two temporally successive times,comparing the measured phases with one another,generating a signal phase shift on the basis of the comparison, and forming a frequency difference between the transmission frequency and the tuning frequency on the basis of the phase shift,wherein the phase of the received signal is measured temporally N (N.gtoreq.2) successive times and C groups are formed of the phases measured, each group comprising M measured phases, where C is determined by the formula ##EQU9##M is M<N and C, M and N .epsilon.{1, 2, 3, . . . },the phases are grouped chronologically,successive phases are subtracted from one another to form phase deviations and the phase deviations are proportioned according to the temporal difference,a search is made for at least one group in which all relative phase deviations are substantially the same, andthe frequency difference between the transmission frequency and the tuning frequency is formed on the basis of the phase deviation of the group found,wherein 4 phase deviations, X.sub.1, X.sub.2, X.sub.3, and X.sub.4, are measured when N is N=4, four groups C.sub.4.sup.4-3 =4 are formed in the following manner:X.sub.1, X.sub.2, and X.sub.3,X.sub.1, X.sub.2, and X.sub.4,X.sub.1, X.sub.3, and X.sub.4, andX.sub.2, X.sub.3, and X.sub.4,temporally proportioned phase deviations are generated:phase differences X.sub.2 -X.sub.1 and X.sub.3 -X.sub.2,phase differences X.sub.2 -X.sub.1 and (X.sub.4 -X.sub.2)/2,phase differences (X.sub.3 -X.sub.1)/2 and X.sub.4 -X.sub.3, andphase differences X.sub.3 -X.sub.2 and X.sub.4 -X.sub.3,a search is made for at least one group where the proportioned phase deviations are substantially the same, and the frequency difference between the transmission frequency and the tuning frequency is formed on the basis of the phase deviation of the group found.