Patent ID: 11929787
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Telecommunications (Electrical engineering)
Classification: CPC H | IPC H

Claim 1:
2. An optical transmission method for redundantly transmitting a multiplexed signal obtained by multiplexing N (N is an integer of 2 or greater) optical signals having different wavelengths, the optical transmission method comprising:
a first demultiplexing step of inputting a first multiplexed signal and demultiplexing the input first multiplexed signal into the N optical signals;
N first detection steps of inputting the N optical signals demultiplexed in the first demultiplexing step, each of the first N detection steps including detecting presence or absence of deterioration of a corresponding input optical signal of the input optical signals based on a signal level of the corresponding input optical signal;
a second demultiplexing step of inputting a second multiplexed signal and demultiplexing the input second multiplexed signal into the N optical signals;
N second detection steps of inputting the N optical signals demultiplexed in the second demultiplexing step, the N second detection steps including detecting presence or absence of deterioration of a corresponding input optical signal of the input optical signals based on a signal level of the corresponding input optical signal;
a selection step of selecting, based on detection result of presence or absence of deterioration of each of the optical signals in the first detection step and the second detection step, N optical signals having different wavelengths from either the optical signals demultiplexed in the first demultiplexing step or the optical signals demultiplexed in the second demultiplexing step, wherein for each selected optical signal, difference between signal level of the selected optical signal and signal level of another optical signal having a wavelength adjacent to the wavelength of the selected signal is less than a threshold; and
multiplexing the selected optical signals together.