Patent ID: 11942755
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Telecommunications (Electrical engineering)
Classification: CPC H | IPC H

Claim 1:
2. The optical transmission system according to claim 1, wherein
the transmission unit of the first transponder unit includes
an encoder unit, including one or more processors, configured to encode the electric signal from the communication apparatus into a multi-level signal,
a digital/analog conversion unit, including one or more processors, configured to convert the multi-level signal output from the encoder unit into a digital signal,
a quadrature modulation unit, including one or more processors, configured to output signal light obtained by performing quadrature modulation on the laser light with the multi-level signal being the converted digital signal, and
a phase control unit, including one or more processors, configured to perform variable phase control of causing phase of the multi-level signal from the encoder unit to be advanced or delayed, in accordance with the fed back BER.