Patent ID: 6055021
Filing Date: 2000-04-25
Classification: H01Q,H03L,H03M,H04L,H04N

Abstract:
In a digital signal system in which digital signals are received in frames of M digital bits and in which each frame contains a specified sync code of N bits, a method for determining whether the system has synchronized to the framing of the digital signals comprising the steps of:(1) receiving a serial stream of digital bits;(2) converting said received stream into a parallel form having N bits;(3) for each received digital bit, comparing the parallel form of N bits for a match with the specified sync code;(4) if a match is not found in the comparison, go to step (3);(5) if a match is found in the most recent comparison,(a) setting a counter to locate the next expected occurrence of said sync code within the serial stream;(b) incrementing a confidence counter by 1;(c) if the confidence counter reaches a specified threshold, indicating that sync has been established;(d) at the next expected occurrence of said sync code within the serial stream, comparing the parallel form of the N bits at that time for a match with the specified sync code;(e) go to step (5);(6) if no match is found in the most recent comparison,(a) setting a counter to locate the next expected occurrence of said sync code within the serial stream;(b) decrementing the confidence counter by 1;(c) if the confidence counter falls to a second specified threshold, indicating that sync is not established and returning to step (3);(d) go to step (5).