Patent ID: 7133611

Claim:
A main signal controlling apparatus in a termination station of a WDM optical communications system, comprising: a repeater supervisory control unit executing a supervisory control for a repeater arranged on a transmission line of the WDM optical communications system; a pre-emphasis control unit making a pre-emphasis that adjusts a level difference among wavelengths of a WDM optical signal transmitted from the terminal station; a threshold value setting control unit setting and controlling a threshold value that an optical signal receiving device uses to detect a signal; a wavelength dispersion compensation control unit adjusting a wavelength dispersion compensation amount at a transmitting end or a receiving end; and a priority control unit preferentially executing a repeater supervisory control, a pre-emphasis control, a threshold value setting control, and a wavelength dispersion compensation control in this order, so that the controls are executed without exerting a bad influence on a quality of a main signal transmitted/received by the WDM optical communications system, when at least two of the controls occur simultaneously, including if a repeater supervisory control from an opposed terminal station and a repeater supervisory control from a local terminal station occur simultaneously, information is exchanged via a dedicated line which connects priority control units of both of the terminal stations, and an earlier started control is executed with a higher priority.