Patent ID: 6418116
Filing Date: 2002-07-09
Classification: H04J

Abstract:
A transmission system having an uninterruptible switchover function and comprising:a transmitting side including: a frame pulse insertion circuit inserting a frame pulse for phase synchronization at the top of each frame signal, and a distribution circuit branching said frame signal having the frame pulse to transmit to a plurality of lines; and a receiving side including: detection circuits provided correspondingly to the plurality of lines, each detecting alarm and error of the frame pulse transmitted through corresponding one of the plurality of lines, first and second line selection circuits, each receiving the frame signals transmitted from the plurality of lines and selecting one of the plurality of lines to output the frame signal transmitted from the selected line, first and second delay circuits each receiving outputs from the first and second line selection circuits, first and second fixed-amount delay circuits respectively receiving the frame signals delayed by said first and second delay circuits and giving an identical amount of delay to the frame signals, a third line selection circuit receiving outputs from said first and second fixed-amount delay circuits and selecting and outputting either one of the outputs, which is transmitted from a normally operational line, and a control circuit adjusting the amount of delay produced by said first and second delay circuits so that phases of the outputs from said first and second fixed-amount delay circuits mutually coincide, and controlling said third line selection circuit to select either one of the outputs, which is transmitted from said normally operational line in the event of an alarm or error detected by the detection circuits on an active line.