FRAME SYNCHRONIZATION SYSTEM

摘要

A binary data transmission system employing a sending station and a receiving station with intermediate stations disposed therebetween in tandem. The binary data signal transmitted by such a system includes in a predetermined time division multiplex frame period M groups of time division multiplex channel data signals, each of the groups of channel signals having a normal sync signal. Each of the intermediate stations and the receiving station monitor the received and transmitted M groups of channel data signals on a time sequential basis. A frame synchronization system detects the lack of sync in any of the groups applied thereto on a time sequential basis and substitutes for the thusly detected erroneous group of channel signals dummy data signals including dummy sync signals. To prevent stations subsequent to the stations substituting the dummy data signals for erroneous normal data signals from providing an erroneous error indication and substitution of dummy data for error free normal data signal, the frame synchronization system detects, establishes and maintains sync of each monitored group of channel signals in response to either the normal sync signal or the dummy sync signal. The frame synchronization system provides a variable search time to establish the desired synchronization to either normal or dummy sync signals for each group of channel data signals coupled thereto.