Patent ID: 7586820

Claim:
A method of detecting sync signals having different patterns respectively, the method comprising the steps of: a) comparing a pattern of an input sync signal with sub patterns in a first sync pattern to determine whether or not the pattern of the input sync signal agrees with one of the sub patterns in the first sync pattern, wherein the sub patterns in the first sync pattern are equal to the patterns of the sync signals respectively; b) in a case where the step a) determines that the pattern of the input sync signal agrees with none of the sub patterns in the first sync pattern, comparing the pattern of the input sync signal with sub patterns in a second sync pattern to determine whether or not the pattern of the input sync signal agrees with one of the sub patterns in the second sync pattern, wherein the sub patterns in the second sync pattern have temporal fluctuations with respect to the patterns of the sync signals, and each of the sub patterns in the second sync pattern is assigned to only one of the sync signals; c) determining that a sync signal is detected in one of (1) a case where the step a) determines that the pattern of the input sync signal agrees with one of the sub patterns in the first sync pattern and (2) a case where the step b) determines that the pattern of the input sync signal agrees with one of the sub patterns in the second sync pattern; d) determining whether synchronization is in a locked state or an unlocked state in response to a result of the determining by the step c); e) performing the step a) when the step d) determines that the synchronization is in the locked state; f) determining whether or not a sync signal has been detected when the step d) determines that the synchronization is in the unlocked state; g) in a case where the step f) determines that a sync signal has not been detected, comparing the pattern of the input sync signal with the sub patterns in the first sync pattern to determine whether or not the pattern of the input sync signal agrees with one of the sub patterns in the first sync pattern; h) determining that a sync signal is detected in a case where the step g) determines that the pattern of the input sync signal agrees with one of the sub patterns in the first sync pattern; and i) determining that a sync signal is not detected in a case where the step g) determines that the pattern of the input sync signal agrees with none of the sub patterns in the first sync pattern.