PROBLEM TO BE SOLVED: To improve an identification characteristic for signals from light front-end parts of a plurality of systems.;SOLUTION: A differential four phase deviation modulated light reception circuit comprises: photoelectric conversion parts 3-1, 4-1, 3-2, 4-2, 5-1, and 5-2 outputting a plurality of electric signals of which phase modulation components are intensity-modulated from received optical signals; a clock oscillator 11 generating a clock signal having a frequency corresponding to a control signal input; a plurality of phase comparison circuits 12-1 and 12-2 outputting signals having values corresponding to phase differences between the clock signal and the plurality of electric signals, respectively; and an average calculation circuit 15 supplying the clock oscillator 11 with a signal as the control signal which is an average calculation result of the values of the signals corresponding to the phase differences. The clock oscillator 11 supplies the clock signal generated according to the control signal as a common clock signal. The differential four phase deviation modulated light reception circuit further comprises data reproduction parts 6b and 6c reproducing a plurality of data signals synchronized with the common clock signal from the plurality of electric signals respectively.;COPYRIGHT: (C)2012,JPO&INPIT
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