ALARM INDICATE SIGNAL DETECTOR IN DATA TRANSMISSION SYSTEM

摘要

The circuit detects the alarm indicate signal (AIS) from the transmitting data in the multiplexing equipment or the optical transmission equipment by using a counter. The circuit comprises: a pattern detector (12) including three flip-flops (FF1-FF3) for delaying and outputitng the input data in response to the clock signal (CK) and an exclusive NOR gate (EXN); an overhead processor (14) including three flip-flops (FF4-FF6) for delaying and outputting the subframe signal (RCO1) in response to the clock signal (CK) and two AND gates (AN1,AN2) for eliminating the overhead bit from the subframe and producing the confirming signal and the reset signal; an AIS confirming section (16) for transmitting the AIS pattern detection signal according to the confirming signal; and an AIS state maintaing/restoring circuit (18) including a multiplexer (MUX), a counter (CNT) and a flip-flop (FF10).