SYSTEM, CIRCUIT AND METHOD FOR SIGNAL DETECTION, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To facilitate maintenance and monitoring as a system by reducing the output response time of a signal detection circuit, and hence detecting signals for each subscriber.

SOLUTION: The signal detection circuit comprises an AC coupling differential preamplifier 2 with the output of an avalanche photodiode 1 as input, and a first limiter circuit 3 for amplifying the output. The output of the first limiter circuit 3 is branched into two. One of them is outputted as a DATA signal from an identification circuit 4; and the other is inputted to a high-pass filter circuit 5 passing only signal components, is inputted to a comparator 8 via a logarithmic amplifier 6 and a peak detection circuit 7, and is compared with a signal identification reference voltage for outputting as a signal detection signal.

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