Patent Number: 6,310,708

Title: Supervisory signal transmitter and method

Abstract: During a time interval when a supervisory signal is not transmitted, an idle signal which is different in frequency from but substantially equal in maximum power to the supervisory signal is output. The duty ratio of the idle signal is set so that the supervisory signal and the idle signal become substantially equal to each other in average power. A transmitter is equipped with a switcher for switching between the supervisory signal and the idle signal for selective application to a laser diode. The switcher is controlled by a command signal for supervisory and control. The laser diode is driven by an output of the switcher to transmit the supervisory signal and the idle signal.

Inventors: Ota; Kenji (Kawasaki, JP), Kitamura; Mitsuo (Kawasaki, JP)

Assignee: Fujitsu Limited

International Classification: H04J 14/02 (20060101); H04B 10/08 (20060101); H04B 010/04 ()

Expiration Date: 10/30/2018