Patent ID: 8050572
Filing Date: 2011-11-01
Classification: H03F,H03K,H04B

Abstract:
1. A receiver which receives a transmitted optical signal as a digital signal constituted by a pulse train with a known pulse width, the receiver comprising abnormal pulse detection means for detecting, by comparing the received optical signal with a reference digital signal generated based on the optical signal, a variation in pulse width in the optical signal being transmitted, and stopping external output of the received optical signal for a predetermined period of time if the variation in the pulse width is detected in the optical signal, wherein, the optical signal is input as a negative-logic digital signal constituted by a low level indicating a signal “1” and a high level indicating a signal “0”, and the abnormal pulse detection means includes: incoming pulse edge detection means for detecting a moment of fall of the received optical signal and outputting a result of detection as an edge detection signal; reference pulse generation means for generating the reference digital signal as a positive-logic digital signal constituted by a low level indicating a signal “0” and a high level indicating a signal “1”, based on the edge detection signal output from the incoming pulse edge detection means; logic means for outputting a signal indicating a negative AND of the optical signal and the reference digital signal; muting signal generation means for generating, based on a signal generated by logically inverting the signal indicating the negative AND output from the logic means, a muting signal which disallows the external output of the received optical signal for the predetermined period of time; and output stop means for stopping the external output of the received optical signal for the predetermined period of time, if the muting signal is input.