Patent ID: 7634199

Claim:
An optical communication system comprising: an optical transmission apparatus comprising: an input port to receive an electric signal with a frequency band; a noise generator to generate noise; a transmission filter configured to receive the noise and filter a noise portion from the noise, wherein the noise portion is of a frequency band that is lower than the frequency band of the electric signal, and wherein the noise portion includes a center frequency of 50 MHz; a transmission signal generator comprising a multiplexer to multiplex the noise portion with the electric signal to generate a transmission signal; an electric/optical converter to convert the transmission signal into an optical signal and send out the optical signal to an optical transmission path; and an optical receiving apparatus connected to the optical transmission apparatus via the optical transmission path and receiving the optical signal through the optical transmission path, the optical receiving apparatus comprising: an optical/electric converter to convert the optical signal received through the optical transmission path into a receive electric signal; and a receiving filter to remove the noise from the received electric signal.