| 摘要 |
<P>PROBLEM TO BE SOLVED: To measure a dispersion value of a transmission path between a light transmitter and a light receiver during operation. <P>SOLUTION: A wavelength modulator 12 modulates wavelengths at a cycle f1 by the amount of wavelength modulation Δλ. Its output light is impressed with data modulation according to an input signal in a light modulator 11 and outputted as signal light. The signal light is converted into an electric signal in a photoelectric converting part 21 and converted into a clock signal and a reproduced and discriminated output signal by a clock extracting circuit 22. A reference timing signal creating circuit 23 creates a reference timing signal synchronous with the clock signal outside measuring time and holding a phase immediately before measurement within the measuring time. A phase detector 24 outputs a predetermined phase difference at all times outside the measuring time and outputs a phase difference which changes according to the modulation of the wavelength modulator 12 within the measuring time. The output of the phase detector 24 is inputted to a dispersion detector 25, and the dispersion value of the transmission path is outputted through the use of the amount of change in the phase difference in the phase detector 24. <P>COPYRIGHT: (C)2003,JPO |
