METHOD OF DETECTING PREDETERMINED PATTERN WHICH HAS PREDETERMINED REPEATING PERIOD IN SIGNAL RECEIVED WITH FIRST SPEED IN TRANSMISSION LINE

摘要

Method of detecting the INFO_1 signal pattern which avoids false activation of a data transmission line caused by noise on the line. An initial line sampling rate four times the nominal 192 kbs line rate is used to detect a HIGH mark to avoid the difficulties resulting from sampling right at the edge of a mark. Subsequent sampling is done at the nominal line rate to detect two opposite polarity marks out of every consecutive eight-bit time periods. If six consecutive eight-bit time periods are detected, each having its HIGH and LOW marks in the same relative positions, the line is activated. The method is readily implemented as a set of three "state machines" and consequently can be constructed from programmable logic arrays.