| 摘要 |
PURPOSE:To always allow a discriminating circuit to execute discrimination at the best discriminating point regardless of the polarizing state of input signal light by providing a single nonlinear circuit or more, which correct the demodulating signal of a demodulating circuit by means of nonlinear characteristic, and equalizing the relations between the voltage value of the respective synthesized demodulating signals and the input frequencies of the respective demodulating circuits. CONSTITUTION:A diode 1 is inserted between capacitors 2 and 2 to be inserted to a signal route, the cathode of the diode 1 is grounded through a coil 3, and an anode is grounded through the coil 3 and a bias power source 4. A voltage Vb of the bias power source 4 is set so as to be the nonlinear characteristic according to the characteristic of the demodulating circuit to correct the demodulating signal. Further the signal after the addition of an adder 10, which adds the demodulating signal after the correction outputted from demodulated waveform compensating circuits 9-1 and 9-2, is supplied to a discriminating circuit 11, and a compound processing is executed. Thus the optimal discrimination is attained by the optimal discriminating voltage regardless of the polarizing state of the input signal light. |
