Patent ID: 8625984

Claim:
A transmission device comprising: a transponder including an oscillator configured to oscillate a local optical laser, a wavelength controller configured to control setting of an oscillation wavelength of the local optical laser to receive an expected input signal light, a coherent receiver configured to combine the local optical laser and input signal light received and output a loss-of-light (LOL) signal when the coherent receiver is unable to receive the input signal light, and a controller configured to determine an erroneous connection of a signal line related to the input signal light by controlling the oscillation wavelength of the local optical laser using a detected wavelength of the input signal light by the coherent receiver, when the LOL signal is not detected by the coherent receiver and a loss-of-signal (LOS) is detected by a signal processing circuit; and a determination circuit configured to provide notification of the erroneous connection of the signal line related to the input signal light.