| 摘要 |
<P>PROBLEM TO BE SOLVED: To highly accurately measure and compensate for wavelength dispersion in an optical transmission line, without affecting a main signal, during system introduction and in-services. <P>SOLUTION: A strength modulation signal such as a tone signal is superimposed for monitoring the wavelength dispersion of a transmission line. A transmitted tone-modulated signal is divided into bands and the band-divided signals are received. A baseband frequency component to be monitored is extracted and a phase difference is detected. In the band division, an optical frequency at which transmissivity of a band dividing means becomes maximum is matched to a frequency at which an optical frequency difference from central carrier frequencies of a DPSK signal and an FSK signal becomes equal. The divided bands have optical frequencies (wavelengths) different from each other, thereby being group-delayed differently for dispersion. By monitoring a delay (phase) difference Δτ between transmitted two tone signals, an absolute value and a code of the wavelength dispersion are monitored. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
