Patent ID: 6310708
Filing Date: 2001-10-30
Classification: H04B,H04J

Abstract:
A supervisory signal transmitter for use with a WDM communications system comprising:a light source unit driven by an electrical signal, converting the electrical signal to a corresponding light signal;a supervisory signal generating unit generating an electrical signal having a predetermined frequency to be used for driving said light source unit to produce a supervisory signal;an idle signal generating unit generating an electrical signal having a frequency different from the predetermined frequency of the supervisory signal to be used for driving said light source unit to produce an idle signal; anda switching unit switching between the electrical signal generated by said supervisory signal generating unit and the electrical signal generated by said idle signal generating unit to selectively apply to said light source unit, whereby the supervisory signal is output from said light source unit while no idle signal is output from said light source unit and vice versa, and whereby the supervisory signal and the idle signal are alternately transmitted so that the alternately transmitted signals are constantly transmitted, and a receiver of the alternately transmitted signals extracts information about supervision of the WDM communications system by detecting a change of frequency between the supervisory signal and the idle signal.