A preFEC BER of a selected optical link is determined. A FEC Detected Degrade (FDD) threshold, FEC Excessive Degrade (FED) threshold, and FEC limit threshold are obtained for the selected optical link. The FDD threshold is less than the FED threshold and the FED threshold is less than the FEC limit. Based on the FDD threshold, FED threshold, the FEC limit, and a determination that a postFEC BER==0, it is determined whether a link down condition of the selected optical link can be asserted or de-asserted.

In a coherent optical receiver device, the dynamic range considerably decreases in the case of selectively receiving the optical multiplexed signals by means of the wavelength of the local oscillator light, therefore, a coherent optical receiver device according to an exemplary aspect of the invention includes a coherent optical receiver receiving optical multiplexed signals in a lump in which signal light is multiplexed; a variable optical attenuator; a local oscillator connected to the coherent optical receiver; and a first controller controlling the variable optical attenuator by means of a first control signal based on an output signal of the coherent optical receiver; wherein the coherent optical receiver includes a 90-degree hybrid circuit, a photoelectric converter, and an impedance conversion amplifier, and selectively detects the signal light interfering with local oscillation light output by the local oscillator out of the optical multiplexed signals; and the variable optical attenuator is disposed in the optical path of the optical multiplexed signals in a stage preceding the photoelectric converter, inputs the optical multiplexed signals, and outputs them to the coherent optical receiver controlling the intensity of the optical multiplexed signals based on the first control signal.

An optical signal detection apparatus. The apparatus includes an optical-to-electrical conversion module, a control module, a gain adjustment module, and an analog-to-digital conversion module. The optical-to-electrical conversion module is configured to receive an optical signal, and convert a received optical signal into an electrical signal; the control module is configured to obtain a first gain value corresponding to a first detection time period, the first detection time period is a detection time period in the detection cycle, different detection time periods in the detection cycle correspond to different gain values, and the first gain value is used for controlling the gain adjustment module to adjust an amplitude of the electrical signal; and the analog-to-digital conversion module is configured to perform sampling on an adjusted electrical signal, where the adjusted electrical signal is in a sampling range of the analog-to-digital conversion module.

Data transceiving electronic device (100), configured to permit the establishment of at least a communication with at least an electronic device (301; 302) remotely positioned with respect to the data transceiving electronic device (100), said data transceiving electronic device (100) comprises a radio frequency module (105) configured to receive and transmit electronic data on a wireless channel according to at least a predefined first wireless communication standard, and an optical transceiver module (108) in turn comprising at least an optical transmitter (109) and an optical receiver (110); said data transceiving electronic device (100) being configured to select said optical transceiver module (108) as the preferential priority module for the establishment of said communication with said at least one electronic device (301; 302).

In an alien wave system, one or more transponders connected to a line system may be owned and operated by a different entity from the entity that owns and operates the line system. In such a situation, diagnosing and correcting faults, and achieving good performance, may be challenging. As such, a system and methods for interoperability in an alien wave system are provided.

Systems and methods include determining which services in a single Optical Transport Unit Cn (OTUCn) that is transmitted in an optical network via a plurality of optical carriers are affected by failed one or more optical carriers of the plurality of optical carriers; continuing to operate the single OTUCn with unaffected one or more optical carriers of the plurality of optical carriers; and adjusting some or all of the services from the failed one or more optical carriers to the unaffected one or more optical carriers.

A test instrument for providing an optics troubleshooting technique of an optical transceiver is disclosed. The test instrument may comprise a processor and a memory, which when executed by the processor, performs the optics troubleshooting technique. The optics troubleshooting technique may include identifying a test signal from the optical transceiver. The optics troubleshooting technique may include determining signal power associated with the signal. The optics troubleshooting technique may further include applying one or more expert mode settings. In some examples, the one or more expert mode settings may be applied in a predefined order until an acceptable BER result is achieved over a predefined test period. In this way, test instrument may determine which of the one or more expert mode settings is responsible for the acceptable BER result.

[Problem] whether optical input interruption detected by an OXC device is due to an external failure from an upstream side or an internal failure of the OXC device in a transponder device connected to the OXC device using an optical transmission line, and this determination is implemented at low cost. [Solution] An optical transmission system (10A) is configured by connecting a plurality of OXC devices (14A) using optical fibers (16) between transponder devices (15A1) that relay optical signals transmitted to/from terminals (19a, 19b). The OXC device (14A) includes an OSC part (4d1) and a monitoring control part (4e1). The OSC part (4d1) outputs wavelength information on an optical signal in which optical input interruption has occurred and path information on a path of an optical fiber (16) in which the optical input interruption has occurred, at the time of detecting the optical input interruption from the optical fiber (16). In accordance with the wavelength information and the path information that have been output as above, the OXC device (14A) includes an AIS generation part (4j) that generates an AIS signal including both pieces of information on the wavelength and the path of the optical signal relating to the optical input interruption and alarm information relating to both the pieces of information.

[Problem] whether optical input interruption detected by an OXC device is due to an external failure from an upstream side or an internal failure of the OXC device in a transponder device connected to the OXC device using an optical transmission line, and this determination is implemented at low cost. [Solution] An optical transmission system (10A) is configured by connecting a plurality of OXC devices (14A) using optical fibers (16) between transponder devices (15A1) that relay optical signals transmitted to/from terminals (19a, 19b). The OXC device (14A) includes an OSC part (4d1) and a monitoring control part (4e1). The OSC part (4d1) outputs wavelength information on an optical signal in which optical input interruption has occurred and path information on a path of an optical fiber (16) in which the optical input interruption has occurred, at the time of detecting the optical input interruption from the optical fiber (16). In accordance with the wavelength information and the path information that have been output as above, the OXC device (14A) includes an AIS generation part (4j) that generates an AIS signal including both pieces of information on the wavelength and the path of the optical signal relating to the optical input interruption and alarm information relating to both the pieces of information.

[Problem] To determine a time difference between clocks which, for example, are placed far apart from each other with high accuracy at low cost. [Solution] In a time comparison system 20, an intermediate station 21 disperses a single optical signal 21c in the spatial region using the optical complex amplitude modulation to simultaneously transmit the optical signal 21c to a plurality of comparative stations 22 and 23 apart from each other. The intermediate station 21 transmits the optical signal 21c while changing the transmission angle using phase modulation, performs intensity scanning for the reflected light c1 of the optical signal 21c, and detects the peak intensity to determine the directions of the comparative stations 22 and 23. The reflected light c1 of the optical signal 21c transmitted to the comparative stations 22 and 23 of which the direction have been determined, is detected to determine a round-trip propagation delay time between the intermediate station 21 and each of the comparative stations 22 and 23. The difference calculation unit 25 calculates a sum of time difference between each of times to and tb associated with the comparative stations 22 and 23 and the time tc associated with the intermediate station 21, and the determined propagation delay time to determine time information of each of the comparative stations 22 and 23. Based on the result of subtracting, from the time information of the comparative stations 22, the time information of the comparative stations 23, the time difference between the comparative stations 22 and 23 is determined.