| 摘要 |
PROBLEM TO BE SOLVED: To avoid signal quality degradation due to the optical beat noise of an optical transmission line with a simple and inexpensive constitution by connecting respective terminal station equipment and a center unit by multi-drop topology. SOLUTION: The respective terminal station equipment 30 and the center unit 20 are connected through the multi-drop topology. Thus, the number of optical fibers as the optical transmission line 40 and the number of photodetectors 21 inside the center unit 20 are minimized, and the optical transmission line 40 and the inside of the center unit 20 are turned into the inexpensive constitution. Also, since a DFB laser diode 33, for which the light-emitting wavelength of respective laser diodes is selected so as to not to generate the optical beat noise in the band of FM video signals even if it is generated is adopted as the laser diode, the degradation of the signal quality due to the optical beat noise of the optical transmission line 40 can be surely prevented. That is, the degradation in the signal quantity due to the optical beat noise of the optical transmission line 40 is avoided with a simple and inexpensive constitution. |
