Modulating circuit, demodulating circuit and modulating and demodulating circuit system, using PPM method

摘要

A demodulating circuit demodulates a PPM signal obtained as a result of modulation performed in accordance with a PPM method. This circuit includes a detecting portion and a control portion. The detecting portion detects a predetermined carrier pulse provided within a symbol period of the PPM signal, using a clock signal having a frequency double or higher than double the transmission rate of the PPM signal. The controlling portion stops supply of the clock signal to the detecting circuit after the detecting portion detects the predetermined carrier pulse until the subsequent symbol period starts.