An optical transceiver includes processing circuitry to calculate, when test signals are sent to a transmission line from a transmitter and a receiver receives the test signals having passed through a wavelength filter, a bandwidth of the received test signals, the transmitter generating, as the test signals, a collection of narrowband signals, the narrowband signals having a narrower bandwidth than a bandwidth of the wavelength filter and having different frequencies, and the wavelength filter included in an optical splitter inserted in the transmission line, and the collection of narrowband signals including a narrowband signal having a higher frequency than a highest frequency in the bandwidth of the wavelength filter and a narrowband signal having a lower frequency than a lowest frequency in the bandwidth of the wavelength filter, and to determine a modulation rate and a modulation level of the transmission signal depending on the calculated bandwidth.

An optical transceiver includes processing circuitry to calculate, when test signals are sent to a transmission line from a transmitter and a receiver receives the test signals having passed through a wavelength filter, a bandwidth of the received test signals, the transmitter generating, as the test signals, a collection of narrowband signals, the narrowband signals having a narrower bandwidth than a bandwidth of the wavelength filter and having different frequencies, and the wavelength filter included in an optical splitter inserted in the transmission line, and the collection of narrowband signals including a narrowband signal having a higher frequency than a highest frequency in the bandwidth of the wavelength filter and a narrowband signal having a lower frequency than a lowest frequency in the bandwidth of the wavelength filter, and to determine a modulation rate and a modulation level of the transmission signal depending on the calculated bandwidth.

In an optical network having a terrestrial terminal and an open cable interface (OCI) connecting a submarine cable to a terrestrial cable, the OCI may include a filter positioned on an optical path between the terrestrial cable and the submarine cable and configured to pass first communication signals of a first frequency band, and filter out secondary signals of a second frequency band that does not overlap with the first frequency band. The secondary signals may be looped back to the terrestrial terminal. The terrestrial terminal may detect the looped back secondary signals, and in response, determine the presence of the OCI and that the supervisory signals were rerouted by the OCI.

A data communication network includes a network node and a processor. The network node includes an optical link and a reflectometry analyzer to provide a plurality of reflectometry results, each reflectometry result providing a characterization of physical and operational properties of the optical link at the time of the reflectometry result. The processor receives a first set of the reflectometry results, and calculates a federated fingerprint of the physical and operational properties of the optical link based on the plurality of fingerprints in first set of the reflectometry results. The federated fingerprint is a combination of fingerprints from every section of the optical link. The processor receives a second set of the reflectometry results, and compares each of a plurality of fingerprints in the second set of reflectometry results with a respective corresponding fingerprint in the federated fingerprint. The processor determines whether a physical tampering of the optical link has occurred based upon the comparison.

An information handling system includes a plurality of network nodes and a processor. Each network node includes an optical link and a reflectometry analyzer. The reflection analyzers provide a plurality of reflectometry results that each provide a characterization of physical properties of the optical link. The processor receives the reflectometry results, analyzes the reflectometry results to define a fingerprint of the physical properties of the optical link, and determines a status for each of the optical links based upon the associated fingerprints. The status for each of the optical links includes one of a plurality of graded statuses. Each graded status represents a qualitative measure of the physical properties of the associated optical link. A first graded status represents a better qualitative measure than a second graded status. The processor further receives a request to route a data flow from a first one of the network nodes to a second one of the network nodes. The data flow is associated with a service level agreement that defines that the data flow is to be routed on optical links that have the first graded status. The processor further determines a path between the first network node and the second network node where each of optical links in the path have the first graded status.

A performance monitor configured to unify at least two different signal-quality estimates into a single performance metric such that a systematic error associated with the performance metric can be approximately constant or smaller than a specified fixed limit over a significantly wider range of data-link conditions than that of a conventional performance metric of similar utility. In an example embodiment, the performance metric can be based on a weighted sum of two different SNR estimates, obtained from an error count of the receiver's FEC decoder and from a constellation scatter plot generated using the receiver's symbol decoder, respectively. Different weights for the weighted sum may be selected for different data-link conditions, e.g., using SNR thresholding, analytical formulas, or pre-computed look-up tables. The performance metric may be supplied to a control entity and considered thereby as a factor in a possible decision to trigger protective switching and/or a transponder-mode change.

First transmission device includes a first counter that generates counter value incremented in a specified cycle. Second transmission device includes a second counter that. generates counter value incremented in the specified cycle. Polarization variation monitoring device acquires a first counter value generated by the first counter and a second counter value extracted by the first transmission device from a received frame transmitted from the second transmission device when the first transmission device detects polarization variation, and a third counter value generated by the second counter and a fourth counter value extracted by the second transmission device from a frame transmitted from the first transmission. device when the second detector detects the polarization variation. The polarization variation monitoring device determines an occurrence position of the polarization variation based on the first counter value, the second counter value, the third counter value and the fourth counter value.

A transmission includes an input shaft and an output shaft, the input shaft selectively accepting a torque input from a prime mover, and the output shaft selectively providing torque output to a driveline. A controller determines a shaft displacement angle representing an angle value of rotational displacement difference between at least two shafts of the transmission, and performs a transmission operation responsive to the shaft displacement angle.

A communication apparatus includes a plurality of devices, each of the plurality of devices includes a monitoring unit configured to monitor at least one other device to detect an error that has occurred in the other device, and each of the plurality of devices is monitored by at least one other device.

An object is to provide a monitoring signal light output apparatus capable of transmitting a monitoring signal light with a simple configuration. An optical demultiplexer (11) is inserted into an optical fiber (F1) and demultiplexes a monitoring signal light (M1) transmitted through the optical fiber (F1). A SOA (13) amplifies and modulates the monitoring signal light (M1) separated by the optical demultiplexer (11). A control unit (15) outputs a signal (S1) indicating a state of a submarine apparatus. A SOA drive unit (14) outputs a drive signal (S2) to the SOA (13) in response to the signal (S1) to perform a modulation operation of the monitoring signal light (M1). An optical multiplexer (17) multiplexes the monitoring signal light (M1) amplified and modulated by the SOA (13) into the signal light transmitted by the optical fiber (F1). The monitoring signal light output apparatus is mounted on the submarine apparatus.