JPS6423636A - Signal protecting circuit - Google Patents

Abstract

PURPOSE:To send stored latest normal signals so as to protect signals when a signal error occurs, by storing signals when no signal error occurs. CONSTITUTION:The frame synchronism of input signals is detected by means of a frame synchronism detecting means 1 and the error of the input signals is detected by means of an error detecting means 2 at every prescribed number (<1) of frames of the input signals. On the other hand, while the input signals are inputted to and stored in a storing means 3 at every prescribed number of frames, the storing data are outputted to a selecting means 4 after they are delayed in accordance with the output of the error detecting means 2. At the selecting means 4, the input signals are also stored temporarily at every prescribed number of frames and either one is selected from the stored input signals and the output signal of the storing means 3 at the same timing by means of the output of the error detecting means 2. Thus normal signals are always sent from the selecting means 4. Therefore, even when an error occurs in the code of a transmission line, the latest normal data before the occurrence of the code error can be sent.