Abstract: A node of an optical transport network system transmits optical wavelengths to an adjacent node through an operational line. An apparatus for protection switching of the optical transport network system transmits only an optical channel with a fault among a plurality of optical channels composed of flexible optical channel data units in an optical wavelength of the operational line, via a reserve line.

Abstract: Systems and method for monitoring an optical power of a dual-polarization signal are disclosed. The systems and methods may include measuring a first parameter set associated with a supervisory signal, the supervisory signal being communicated in-band with the dual-polarization signal; calculating a second parameter set from the first parameter set; calculating an intensity value from the second parameter set, the intensity value associated with one of the polarization states of the dual-polarization signal; and estimating a signal power associated with the supervisory signal from the intensity value.

Abstract: A universal optical receiver may include an optical channel monitor configured to acquire spectral data for an optical signal on at least one selected optical channel, a tunable local oscillator configured to be tuned to a center frequency of the optical signal on the at least one selected optical channel, a storage device configured to store data associated with the optical signal responsive to acquisition of the spectral data and tuning of the tunable local oscillator, and processing circuitry configured to execute an algorithm that employs a plurality of binary distinctions based on physical characteristics of the optical signal and employs at least one calculation of figure of merit associated with a series of parameter values of the optical signal to identify a format of the optical signal.

Abstract: An optical communication system comprises a network interface device (NID) having a media converter coupled to an optical fiber of a passive optical network (PON). The media converter converts optical signals from the PON into electrical signals for communication across at least one non-optical channel, such as a conductive or wireless connection, to customer premises equipment (CPE), such as a residential gateway or other customer premises (CP) device. Rather than implementing an optical media access control (optical MAC) layer in the NID, an optical MAC layer for handling PON protocols and management is implemented by the CPE, thereby effectively extending the customer end of the PON across at least one non-optical connection to the CPE. By implementing the optical MAC layer at the CPE, the complexity of the NID is reduced thereby lowering the cost of the NID.

Abstract: A method, an apparatus and a system for detecting a connection status of an optical fiber jumper are provided in the embodiments of the present invention. The method for detecting a connection status of an optical fiber jumper includes: judging a connection status of a second port and a first port according to whether an optical signal sent by the first port to the second port through a first optical fiber is received, wherein the first optical fiber is connected to two ends of an optical fiber jumper, and the two ends of the optical fiber jumper are connected to the first port and the second port respectively; and obtaining a port identification corresponding to the first port according to the optical signal if the optical signal is received.

Abstract: In accordance with the present disclosure, disadvantages and problems associated with polarization dependent effects of a polarization multiplexed optical signal may be reduced through polarization scrambling. In accordance with an embodiment of the present disclosure a method for detecting polarization scrambling of a polarization multiplexed optical signal comprises receiving a polarization multiplexed optical signal associated with an optical network. The polarization multiplexed optical signal including a scrambled polarization orientation, the polarization orientation scrambled according to a scrambling frequency. The method further comprising receiving a polarization signal indicating the polarization scrambling of the received optical signal. The method additionally comprises descrambling the optical signal according to the polarization scrambling as indicated by the polarization signal.

Abstract: An optical transmission system includes a first node and a second node, the first node includes a first optical amplifier which outputs a signal to the second node through a first transmission line and a first monitoring unit, the second node includes a monitor which monitors a signal from the first transmission line, a second optical amplifier which outputs a signal to the first node through a second transmission line and a second monitoring unit, upon detecting disconnection from the first transmission line, the second monitoring unit transmits a notification for making power of the first optical amplifier reduced, upon receipt of the notification, the first monitoring unit reduces power of the first optical amplifier, and transmits a completion notification to the second monitoring unit, and upon not receiving the completion notification even after expiration of an allowed time, the second monitoring unit reduces power of the second optical amplifier.

Abstract: The present disclosure provides to Optical Transport Network (OTN_ synchronization systems and methods that maintain proper sequential ordering of events at nodes which may be utilized in performing root cause analysis or diagnosing network performance. In an exemplary embodiment, the systems and methods utilize functionality incorporated into OTN providing a cost effective and standards-based approach to nodal synchronization. Once synchronized, network events are logged with an appropriate timestamp enabling a determination of a sequential order of network events can be determined. Further, the node timestamps may be synchronized, with microsecond or even sub-microsecond of precession which is critical in diagnosing network failures or slow traffic recovery.

Abstract: There are disclosed systems and methods for detecting whether an Optical Network Unit (ONU) in a network may be causing a communications interference due to laser overlap. In one embodiment, an Optical Line Terminal (OLT) selects a pair of ONUs suspected of possibly causing laser overlap. The OLT then grants a first window to a first ONU for transmitting a first message, and grants to another ONU different from the pair of ONUs a second window for transmitting a second message. If the first message is not received by the OLT, then the OLT indicates that the first ONU may be causing laser overlap. In another embodiment, the OLT grants to an ONU a window for transmitting a message to the OLT. If the message is not received by the OLT when expected, then the OLT indicates that the ONU may be causing laser overlap. Other embodiments are disclosed.

Abstract: Systems and methods for detecting component rotation within a communication assembly are provided. In certain embodiments, a system includes a module; an adapter block that includes multiple front ports and multiple rear ports configured to receive an optical connector; a managing entity configured to control port identification for the front and rear ports; and a circuit board mounted to the adapter block, wherein the circuit board comprises multiple front contact assemblies and multiple rear contact assemblies, wherein each front port is associated with a front contact assembly and each rear port is associated with a rear contact assembly, wherein when a rear contact assembly is electrically coupled to a connector, the connector generates an event that is sent to the managing entity, whereupon the managing entity remaps the port identification for the front and rear ports.

Abstract: A system and method for Passive Optical Networks (PON) providing integration (cross-correlation) of powersave and fiber protection, optionally with encryption, facilitating the successful operation and/or benefits that can be gained when operating a PON system with these features. A major problem with power save is the detection, since both the OLT and the ONUs rely on a valid signal in order to detect fiber failure. However, the OLT may not detect this for sleeping ONUs, and an ONU in Tx/Rx sleep-mode, may not detect a fiber failure, and may not be aware of the OLTs switchover. In addition to solving the problem of combined fiber protection and power savings, a solution is also needed for providing security for this combination. A current embodiment is a system and method for Passive Optical Networks (PON) providing integration (cross-correlation) of powersave and fiber protection, optionally with encryption.

Abstract: The path selection and wavelength assignment to a selected path are performed by mapping the wavelength reach to the demand distribution (agile reach) resulting in a 50-60% increase in the network reach. The network reach is further increased (about 2.2 times) when on-line measured performance data are used for path selection and wavelength assignment. The connections may be engineered/upgraded individually, by optimizing the parameters of the entire path or of a regenerator section of the respective path. The upgrades include changing the wavelength, adjusting the parameters of the regenerator section, controlling the launch powers, mapping a certain transmitter and/or receiver to the respective wavelength, selecting the wavelengths on a certain link so as to reduce cross-talk, increasing wavelength spacing, etc.

Abstract: Due to demand for more network bandwidth, a need for multi-user optical network topologies has, and will continue to, increase. A method or corresponding apparatus in embodiments of the present invention provide for an availability determination tool for determining and displaying wavelength and subrate availabilities within a network. Benefits of embodiments of a tool include allowing a user to identify the availability and capacity of any wavelength on any network, via an interactive graphical user interface, such as by using three-dimensional representations. In one embodiment, the disclosed availability determination tool allows users to locate and view any combination of available wavelengths between nodes in an optical network topology, and generate graphical and tabular reports of the availability in order to maintain an efficient and organized method or apparatus for determining and controlling wavelengths in a network.

Abstract: An optical transmission device according to the present invention comprises: a Raman amplification means; a main signal light sending means which sends first main signal light; a communication interruption detection light monitoring means which sends a first signal if it cannot detect communication interruption detection light; a main signal light monitoring means which sends a second signal if it cannot detect second main signal light; a light monitoring signal analysis means which sends a result of its analysis of a light monitoring signal as a third signal in a predetermined period of time; and a control means which makes the Raman amplification means suspend the generation of the excitation light, if it cannot receive the third signal even after the elapse of the predetermined period of time in the state it has received the first signal and has not received the second signal, and stops sending of the first main signal light from the main signal light sending means when receiving the second signal further.

Abstract: A system includes two optical modules that perform auto-setting of the optical links between the optical modules. One optical module sends an optical signal with a test pattern to the other optical module. If the receiving module determines that the test pattern is successfully received, it sends a pass indication to the transmitting module, and the transmitting module can configure its driver path in accordance with a transmit current setting used to transmit the test pattern. If the test pattern is not successfully received, the receiving module sends a fail indication, and the transmitting module can increase the transmit current setting and resend the test pattern. When the system includes multiple optical channels, one channel can be tested while feedback is provided on another channel. The system can iterate through all optical channels until they are all configured.

Abstract: An Ethernet adapter system may include a transmitter to insert a payload type identifier sequence in a generic frame procedure header to indicate that a network is a converged enhanced Ethernet network. The transmitter may insert idle sequences in a stream of data frames transmitted along a link. The system may include a receiver to recognize a condition and to force a loss of synchronization condition on the link that will be converted by the receiver into a loss of light condition. The receiver may scan the transmitted stream of data frames for invalid data frames and introduce a code into the stream of data frames whenever an invalid data frame is detected.

Abstract: An optical communication module in which the pin arrangement can be applied flexibly. An optical communication module has an outer shape formed based on normal standards and which is able to communicate with a host-side circuit board, etc. to which it is fitted, via a predetermined communication interface; wherein the optical communication module exchanges input/output I/F information with the circuit board, etc., and the communication interface can be switched to another communication interface based on these input/output I/F information.

Abstract: A system to provide carrier frequency control in an optical network includes a first network element monitoring performance information and a second network element coupled to the first network element by the optical network. The second network element receives performance information from the first network element using an administration channel bandwidth, and modifies a carrier frequency associated with the second network element based on the performance information such that the carrier frequency is aligned to a center of a signal channel bandwidth. A method of providing carrier frequency control includes transmitting performance information by the first network element to the second network element using an administration channel bandwidth, and modifying the carrier frequency by the second network element based on the performance information such that the carrier frequency is aligned to the center of the signal channel bandwidth.

Abstract: A method and a Reconfigurable Optical Add Drop Multiplexer (ROADM) where blocking of a first optical signal carried over a specific optical channel in the ROADM is performed by compensating the first optical signal by a second optical signal created for that purpose.

Abstract: In a first aspect, the method and apparatus of the present disclosure can be used to periodically and/or intermittently place one or more ONUs attached to a PON in a power savings mode so that an OTDR test can be performed. While in the power savings mode, the ONUs temporarily suspend their transmitter function and power down their upstream lasers. In a second aspect, the method and apparatus of the present disclosure can be used to coordinate the performance of OTDR during one or more periodic or intermittent discovery slots used to detect and register ONUs recently connected to the PON. Because new ONUs are infrequently connected to the PON and ONUs already registered are not permitted to transmit during the discovery windows, OTDR can be performed during these windows without impacting, to a great degree, the normal operation of the PON.

Abstract: A method and apparatus for suppressing pump-mode optical beat interference noise in a Raman amplified fiber link of an optical network, wherein a wavelength of a laser beam generated by a first pump laser and a wavelength of a laser beam generated by a second pump laser of a pair of polarization multiplexed pump lasers are detuned with respect to each other to suppress the optical beat interference, OBI, noise in the Raman amplified fiber link of said optical network.

Abstract: An optical add/drop multiplexer including one or more optical drop multiplexers connected in free space or fused by optical fiber pigtails, a wavelength blocker with an input port connected to an output port of the optical drop multiplexer through the fusion of the fiber pigtails, one or more optical add multiplexers connected in free space or fused by fiber pigtails, a digital signal processor, an analog-to-digital signal converter, a digital-to-analog converter, and a plurality of electronic control and feedback loops for tuning and scanning an optical wavelength.

Abstract: There is provided a method of determining transmission quality of a path in an optical communication network system obtained by connecting a plurality of networks, the method including: acquiring a value representing transmission performance corresponding to a network condition of each of spans in the path in the optical communication network system; and determining the transmission quality of the path on the basis of the acquired value representing transmission performance corresponding to the network condition of each of spans.

Abstract: A method of communicating data between a network device and a data network to which the device is connected via an optical fiber data link in which the device is connected to the optical fiber data link and the connection is monitored to detect data communication at a first standard. If data communication is detected at the first standard, data communication is established using the first standard. If not, the connection is monitored at the second standard. If data communication is detected at the second standard, data communication is established using the second standard.

Abstract: Disclosed is an optical line terminal for monitoring and controlling upstream and downstream optical signals, and more particularly, to an optical line terminal for monitoring and controlling upstream and downstream optical signals, which adds different low frequency monitoring signals to upstream and downstream wavelength division multiplexing optical signals in a bidirectional wavelength division multiplexing (WDM) optical network and senses and detects low frequency components of upstream and downstream optical signals to unite, monitor, and control optical outputs and wavelengths of the upstream and downstream wavelength division multiplexing optical signals into a single system.

Abstract: Compensation for in-phase (I) and quadrature (Q) timing skew and offset in an optical signal may be achieved based on the correlation between derivatives of I and Q samples in the optical signal. The magnitude of the correlation between derivatives is measured to determine the presence of skew. Correlation between derivatives may be coupled with frequency offset information and/or with trials having additional positive and negative skew to determine presence of skew. Correlations are determined according to pre-defined time periods to provide for continued tracking and compensation for timing skew that may result from, for example, thermal drift.

Abstract: Chip identification pads for identification of integrated circuits in an assembly. In one example embodiment, an integrated circuit (IC) assembly includes a controller, a plurality of ICs, a shared communication bus connecting the controller to the plurality of ICs and configured to enable communication between the controller and each of the plurality of ICs, and a set of one or more chip identification pads formed on each IC. Each set of chip identification pads has an electrical connection pattern. The electrical connection pattern of each set is distinct from the electrical connection pattern on every other set. Each distinct electrical connection pattern represents a unique identifier of the corresponding IC thereby enabling the controller to distinguish between the ICs.

Abstract: One embodiment provides a system for performance monitoring in a passive optic network (PON). The system includes an optical line terminal (OLT) and an optical network unit (ONU). The OLT includes an optical transceiver configured to transmit optical signals to and receive optical signals from the ONU, and a performance monitoring mechanism configured to monitor performance of the PON based on received optical signals.

Abstract: A method and apparatus for controlling traffic in an optical network having a plurality of OLTs for communicating with a plurality of PONs. A traffic controller receives traffic information concerning current traffic volume and, preferably with reference to a rules database, calculates the number of OLTs required to support the current traffic volume. A separate determination may be made whether a network reconfiguration is permitted at this time. If a reconfiguration is permitted, the traffic controller configures a traffic control switch to route the PON traffic to an from only the calculated number of OLTs. The traffic control switch may be implemented using a voltage-controlled optical fiber coupling or electronically, routing the traffic as electrical signals to and from electro-optical converters associated with each PON. The OLTs to be used may be selected by the traffic controller.

Abstract: Optical autodiscovery is provide between two optical modules to insure that when an optical signal is coupled between the two optical module, the optical signal from a first module does not interfere with operation of a second module. The autodiscovery is implemented by sending an optical identification signal from the first optical module via the coupling to the second optical module from which signal, the second optical module can verify and determined acceptance of the coupled first optical module. During this autodiscovery process, the optical identification signal from the first optical module may be attenuated or shifted in optical spectrum so as not to interfere with the operation of the second optical module. Autodiscovery may also be employed in cases where a first optical module is to receive an optical signal from a second module.

Abstract: A system and method is disclosed that allows for the monitoring, analyzing and reporting on performance, availability and quality of optical network paths. The correlation of PM parameter metrics to client connections, coupled with threshold-based alarm generation provides a proactive and predictive management, reporting and analyzing of the health and effectiveness of individual path connections to alert Operational Support (OS) staff and/or customers to signal degradation and impending Network Element (NE) failures. The system and method performs in real-time processing intervals required for alarm surveillance in a telecommunications network.

Abstract: To provide a technology of preventing an optical signal from being mistakenly recognized as an optical noise even when a surge occurs. A control device of a node that transfers signal light monitors inputted light, determines, when power of the inputted light reaches a saturation level of a monitor unit as a result of monitoring, that the inputted light is signal light, further determines based on a spectral line shape of the inputted light, when the power thereof does not reach the saturation level, whether the inputted light is the signal light or ASE light; and stops a transfer of the ASE light if determined to be the ASE light.

Abstract: Optical Transport Network (OTN) High Order (HO) mapping systems and methods utilize pointer processing to map one HO signal into another similarly sized HO signal. An OTN HO mapping method and circuit include receiving a first HO signal at a first rate, asynchronously mapping the first HO signal into a second HO signal at a second rate, wherein the first rate and the second rate are substantially similar, translating a portion of overhead from the first HO signal to overhead of the second HO signal, utilizing pointers in the overhead of the second HO signal for frame alignment of the first HO signal, and transmitting the second HO signal containing the first HO signal.

Abstract: A multi-channel optoelectronic device is configured to establish a redundant status link with a remote device. The optoelectronic device can transmit N transmit optical signals to the remote device over a plurality of transmit channels and receive N receive optical signals from the remote device over a plurality of receive channels. The optoelectronic device includes one or more spare transmit and receive channels. When used with a remote device having spare transmit and receive channels, each device can establish a status link with the other and use the status link to switch out transmit and/or receive channels to identify and permanently switch out the worst transmit and/or receive channels. Alternately, the device can interoperate with a non-status-link enabled remote device by determining that the remote device is not status-link enabled, transitioning to a low transmit power mode, and transmitting and receiving over a plurality of default transmit and receive channels.

Abstract: Portable apparatus for measuring parameters of optical signals propagating concurrently in opposite directions in an optical transmission path between two elements, at least one of the elements being operative to transmit a first optical signal (S1) only if it continues to receive a second optical signal (S2) from the other (10) of said elements, comprises first and second connectors for connecting the apparatus into the optical transmission path in series therewith, and a device connected between the first and second connectors for propagating at least the second optical signal (S2) towards the one of the elements, and measuring the parameters of the concurrently propagating optical signals (S1, S2). The measurement results may be displayed by a suitable display unit. Where one element transmits signals at two different wavelengths, the apparatus may separate parts of the corresponding optical signal portion according to wavelength and process them separately.

Abstract: A remotely controlled fiber testing method has the steps of: building a fiber network system including a local fiber station and a remote fiber station; sending a modulated signal to the remote fiber station by the local fiber station; demodulating the modulated signal to obtain a control command by the remote fiber station; executing the control command to obtain a testing result by the remote fiber station; modulating the testing result and sending the testing result back to the local fiber station; and demodulating the testing result by the local fiber station. Only one technician appointed to the local fiber station is sufficient to do the testing action. Therefore, the personnel cost is effectively reduced.

Abstract: A method and a device for monitoring a cable system in the field of communications are provided. An optical signal emitted by an optical source to a transmission link of the cable system is divided into two paths of optical signals, in which one path of optical signals serve as local coherent light, and the other path of optical signals are transformed by multipath frequency shift to multiple paths of detection optical signals of different frequencies. A monitoring result is obtained by performing coherent detection, with the local coherent light, on the returned optical signals of the multiple paths of detection optical signals of different frequencies. The device includes an optical source, a multipath frequency shift module, and a coherency module.

Abstract: Consistent with the present disclosure, an optical receiver is paired with an optical transmitter in a transceiver card or module, for example. During normal operation, the optical transmitter supplies optical signals for downstream transmission on a first optical communication path, and the optical receiver receives additional optical signals from a second optical communication path. During a transmitter monitoring mode (or “loopback”), however, when monitoring of transmitter parameters is desired, an optical switch directs the output or portion thereof from the transmitter to the receiver. The receiver may then supply monitoring data or information to a control or processor circuit, which, in turn, may supply control signals to the transmitter. In response to such control signals, the performance of the transmitter may be optimized, for example, by reducing BER and/or OSNR to a desired level.

Abstract: A method removes signal interference in a passive optical network. The passive optical network includes an optical line terminal, a splitting unit coupled with the optical line terminal, an optical network unit coupled with the splitting unit, and an identification signal uniquely associated with the optical network unit. The method includes the steps of sending a first signal, detecting the first signal, comparing the detected first signal with an identification signal and decoupling the optical network unit from the splitting unit if the comparing step results in a mismatch.

Abstract: Optical network protection devices and protection methods including: a working line; a protection line; a determination module configured to determine the protection type of optical network; a first judgment module configured to judge whether the working line is normal according to performance parameter values of service signal in the working line and switching conditions configured for multiplexing section protection when the protection type of optical network is the multiplexing section protection; a second judgment module, configured to judge whether the working line is normal according to performance parameter values of service signal in the working line and switching conditions configured for channel section protection when the protection type of optical network is the channel section protection; a switching module, configured to take the service signal in the protection line as an output signal when working line is abnormal.

Abstract: An apparatus comprising a Generic Status Portal (GSP) configured to grant access to a Managed Entity (ME) via an Optical Network Terminal (ONT) Management and Control Interface (OMCI), wherein the ME comprises status information about a non-OMCI management domain at the ONT. Also included is an apparatus comprising at least one processor configured to implement a method comprising initializing an ONT ME, adding status information associated with a managed function to the ONT ME, indicating a status information update of the ONT ME, and providing the status information via an OMCI. Included is a method comprising providing status and performance monitoring (PM) information from an ONT via an OMCI at the ONT, wherein the status and PM information is associated with at least one managed function instance of at least one non-OMCI domain.

Abstract: A wavelength sensing lighting system may include a light source, a sensor and a controller. One or more light sources and sensors may be included in an array. The light source may emit an illuminating light and the sensor may sense an environmental light. The illuminating light may include data light. The lighting system may include a plurality of nodes connected in a network. The nodes may communicate by emitting and receiving the data light, which may be analyzed by the controller. The light source and the sensor may be provided by a light emitting semiconductor device that is capable of emitting illuminating light and receiving environmental light. A conversion material may convert the wavelength of a source light into a converted light. The conversion material may increase the wavelength range of light emittable and detectable by the lighting system.

Abstract: A hub node in a wavelength division multiplexed optical network automatically discovers at least one of new client-side optical ports and new edge-side optical ports. The hub node comprises a wavelength switch network, port discovery equipment, and a controller. The wavelength switch network routes any wavelength channel that does not support a matching pair of client-side and edge-side ports to port discovery equipment at the hub node. The port discovery equipment searches for new ports, and, responsive to finding a new port, automatically discovers a predefined set of one or more attributes of the new port. The controller determines that a client-side port and an edge-side port are a matching pair of ports if discovered sets of attributes of those ports match according to one or more predefined rules. The controller then controls the wavelength switch network to re-route the wavelength channel supporting that matching pair between those ports.

Abstract: A method includes generating a test signal and modulating the test signal. The method may also include transmitting the test signal on an optical path, where the optical path may include a number of add-drop multiplexer devices and amplifiers. The method may also include receiving the test signal at a destination device and converting the received test signal into an electrical signal. The method may further include identifying a portion of the electrical signal that is associated with the modulated test signal.

Abstract: A wavelength-division multiplexing transmission device including: a dummy light source configured to emit and quench dummy light; a monitoring unit configured to monitor an optical level relating to the received wavelength-division multiplexed light; a dummy light controller configured to control the dummy light source to emit dummy light in case where the monitoring unit determines based on the monitored optical level that the wavelength-division multiplexed light is in a condition of input interruption; and a multiplexer configured to multiplex the light of the wavelength modulated based on the transmission data and the dummy light emitted by the dummy light source, wherein the transmitter transmits wavelength-division multiplexed light generated by the multiplexer.

Abstract: A passive optical network comprises a first node configured to transmit a downlink data signal over a communication channel of an optical link, the communication channel having a first wavelength, and a second node configured to transmit an uplink data signal over the optical link using the communication channel having the first wavelength. The first node and/or the second node is adapted to perform at least one monitoring measurement on the communication channel having the first wavelength, and provide monitoring information, comprising the at least one monitoring measurement, in a monitoring channel. Common public radio interface (CPRI) traffic can therefore be transported over an optical transport network (OTN), by using a frequency reuse technique to provide a symmetrical bi-directional communication link between a first node and a second node, and using a frame structure of the optical transport network to provide a monitoring channel.

Abstract: A method of determining a power correction factor for an optical power of an optical channel of a wavelength division multiplexed communications network. The method comprises configuring an optical source of the communications network to generate an unmodulated optical carrier signal for the optical channel. The method further comprises determining the optical power of the unmodulated optical carrier signal (PHIGH). The method further comprises configuring the optical source to apply a test modulation pattern to the optical carrier signal, to generate a modulated optical carrier signal. The method further comprises determining the optical power of the modulated optical carrier signal (PMOD). The method further comprises determining a power correction factor for the optical channel by determining the difference between the optical powers of the unmodulated optical carrier signal and the modulated optical carrier signal.

Abstract: In a communication line switching method for an optical communications system in which a station-side line terminal apparatus and user-side line terminal apparatuses are connected via a plurality of redundant physical lines, the discovery of the station-side optical line terminal registering the user-side line terminal apparatuses, wherein the registered user-side line terminal apparatuses monitoring a time stamp drift error that is generated when a difference between a time stamp included in a received signal and a local time measured by the own apparatus is larger than a value set in advance and, when the time stamp drift error occurs, shifting to a deregistered state and waiting for registration by the discovery. The station-side line terminal apparatus switches a physical line from a working physical line to a backup physical line of the physical lines.

Abstract: Control and monitoring of airfield lighting from a control tower and other maintenance/supervisory locations uses double loop self healing fiber optic communications circuits to enhances speed of operation even with large and complex airfield lighting system requirements, and significantly increased reliability and operating lifetime thereof. A plurality of local light control and monitoring groups are used, wherein each group has at least one fiber optic communications concentrator that independently communicates with light controllers within the group and the remote supervisory control and monitoring systems in the control tower and other locations. This allows faster control response of the lamps in each of the airfield light fixtures, and monitoring concentration of operational data within each group.

Abstract: The invention refers a method and an arrangement for in service Raman gain measurements and monitoring of a wavelength division multiplex system. By measuring the power level values of a transmitted WDM signal (WMS_TX) and an optical supervisory signal (OSS_TX) at the transmitter and the power level values of the received signals (WMS_RX; OSS_RX) the Raman gain can be calculated for the different channels.