MONITOR CONTROL SIGNAL TRANSMITTER AND ITS METHOD

摘要

PROBLEM TO BE SOLVED: To keep the transmission characteristic of an optical transmission system stable regardless of a simple and inexpensive circuit configuration. SOLUTION: While no monitor control signal (SV signal) is sent, an idle signal with a frequency different from that of the SV signal and the same maximum power is outputted. A duty ratio of the idle signal is set so that a mean power of the SV signal and a mean power of the idle signal are equal to each other. The circuit of the transmitter is provided with a changeover section 11 that selects a driving signal of an LD 12 having a prescribed frequency for generating the SV signal or a driving signal of the LD 12 with a frequency for generating the idle signal and different from that of the SV signal. A switch of the changeover section 11 is switched by a command signal for monitor control. The LD 12 gives the SV signal or the idle signal depending on the driving signal fed from the changeover section 11.