Abstract: A method, apparatus, and program, for evaluating an optical network node. The method comprises providing at least one communication path of the node with a capability by which lasing can occur in the communication path, and detecting whether lasing has been established in the communication path to determine whether the optical node is operational. If no lasing is detected in the detecting, a fault exists in the communication path. The method further comprises determining an insertion loss in the communication path, and determining whether the insertion loss is comparable to a predetermined insertion loss, to confirm whether the node is configured correctly.

Abstract: An apparatus and a method for accurately detecting Loss of Optical Power (LOS) by noise power cancellation effect and optical power is measured at two output ports of an athermal periodic filter, wherein one output port in the optical frequency domain, is aligned with the signal channels of an input WDM signal (on-grid port), whereas the second output port is aligned complementary to the first output port (off-grid port). In a preferred embodiment, the apparatus computes the ratio of the measured optical powers at the two output ports of the periodic filter, and comparing them to a threshold value that is determined from the overall common-mode rejection ratio (CMRR) of the detection apparatus. In an alternative embodiment, the apparatus additionally compares the optical power measured at the on-grid port to a threshold power that is determined from system design parameters.

Abstract: A node device receives supervisory control information on a dedicated wavelength different from a wavelength of signal light, which is input from an input port together with the signal light, and extracts, from signal light to be output from an output port, information superposed on an optical main signal of the signal light. Then, it is confirmed whether or not the signal light to be output and the supervisory control information correspond by using the extracted information, and supervisory control information corresponding to the signal light to be output is transmitted on the dedicated wavelength from the output port.

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: A system for communication of signals between remote devices and monitoring and control devices via fiber. The system in accordance with one aspect of the invention includes a plurality of remote interface units each coupled to a corresponding one of the remote devices, a base unit coupled to one or more monitoring devices and one or more control devices, and a central hub coupled between the base unit and the plurality of remote interface units. The central hub is coupled to the base unit by a first fiber optic link, and is coupled to the remote interface units by additional fiber optic links.

Abstract: A communication network is provided for interconnecting a network of digital systems, such as multimedia devices. Each node of the communication network may include a receiver and a transmitter. The receiver and transmitter of each node can be an optical receiver and transmitter. The optical receiver is preferably powered by two power supply pins, each providing different supply amounts. An activity detector within the receiver can be powered from a first supply amount, and the signal path of the optical receiver can be supplied from a second supply amount greater than the first supply amount. The first supply amount is provided at all times, and the second supply amount is only provided if activity is detected. A voltage regulator which provides the first supply amount can be beneficially embodied on the same integrated circuit as a network interface to reduce the manufacturing cost of the network.

Abstract: An apparatus provides measurement of power of an optical signal transmitted in a wavelength multiplexing scheme, based on the optical spectrum and the information on the optical signal. A method provides measuring the power of an optical signal transmitted in a wavelength multiplexing scheme based on the optical spectrum of the optical signal and information acquired on the optical signal.

Abstract: Disclosed is an optical transmission system capable of transmitting optical signals of E-band and other bands through one optical fiber. The system includes a first thin film filter for receiving optical signals of E-band and other bands at both sides thereof respectively, and multiplexing the optical signals of both E-band and other bands by selectively transmitting wavelength ranges received at one side, reflecting wavelength ranges received at the other side, and then coupling the optical signals of both E-band and other bands; an optical fiber for transmitting the optical signals multiplexed by the first thin film filter to a receiving portion; and a second thin film filter for selectively separating and demultiplexing the E-band and other bands from the optical signals transmitted through the optical fiber.

Abstract: Monitoring an optical signal comprises sampling the optical signal from two or more distinct tap points to retrieve a sample set. Multiple such sample sets are obtained over time. A joint probability distribution or phase portrait of the sample sets is assessed for indications of optical signal quality. The tap distinction can be polarization, for example to determine OSNR, or frequency. The tap distinction can be a time delay, which can enable diagnostic differentiation between multiple impairments, such as OSNR, dispersion, PMD, jitter, Q, and the like. Machine learning algorithms are particularly suitable for such diagnosis, particularly when provided a two dimensional histogram of sample density in the phase portrait.

Abstract: The present invention provides an optical transmitter applicable to the WDM communication system. The optical transmitter includes a light-emitting device, an APC circuit and a processing unit. The processing unit, responding to a command TX_DISABL, which is sent from the control unit that communicates with the host controller, stops the optical output power of the transmitter by decreasing the reference to a preset value in step wise. Moreover, the processing unit, responding to a command ENABLE that is also sent from the control unit, starts the optical output by increasing the reference to another preset value in step wise.

Abstract: An optical transmission control circuit includes: an analog input section which receives optical transmission states as an analog values; an A/D conversion section which converts the analog values into digital values; a value storage section which stores maximum value of the digital values provided by the A/D conversion section; an output register which outputs a value to a host apparatus; and a control section which controls the maximum value storage section to store the maximum value of the digital values therein and controls the output register to output the maximum value to the host apparatus.

Abstract: A method for automatically implementing Tandem Concatenation Monitoring (TCM), includes: requesting a network management system for a required number of TCM levels; assigning an available TCM level to a pair of network nodes in a sub-network; performing TCM processing, mapping TCM use information into a corresponding overhead, transferring the TCM use information together with TCM overhead information downstream, and reporting TCM information to the network management system; and extracting TCM monitored information, determining transmission quality of each sub-network of a set of sub-networks, and locating a network failure. The invention also presents a device for automatically implementing TCM, including a controller, a TCM generator and a TCM terminator which cooperate with each other to automatically implementing a TCM function.

Abstract: According to one aspect of the invention, an optical network including multiple optical network devices, or nodes, is provided. At each node, an optical performance monitor analyzes dispersion while a dispersion compensation module reduces the amount of dispersion in the signals. Information about the dispersion and the amount of compensation performed by the dispersion compensation module is generated by the optical performance monitor and stored in a memory. If the bit error rate of a particular path between nodes becomes too high, a new path is used. A monitoring computer then accesses the information about the dispersion stored in at least one node of the old path. The information allows a user to determine where along the path the greatest amount of dispersion is occurring.

Abstract: A system and method for loading unutilized channels of a WDM system with noise to improve system performance. A transmitter amplifier may impart noise to unutilized channels by reducing amplifier input or providing feedback of the amplifier output. Noise signals may also be looped back to the transmitter from received signals.

Abstract: Methods and apparatuses are provided for performing jitter measurements in a transceiver module. Accordingly, there is no need to use expensive test equipment that must be inserted into and removed from the network in order to obtain these measurements. In addition, because the measurements can be obtained at any time without any interruption in communications over the network, jitter performance can be monitored more closely and more frequently to facilitate better and earlier diagnosis of problems that can lead to failures in the network.

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 method and apparatus is provided for obtaining status information from a given location along an optical transmission path. The method begins by generating a cw probe signal having a prescribed frequency that is swept over a prescribed frequency range. The cw probe signal is transmitted over the optical path and a returned COTDR signal in which status information concerning the optical path is embodied is received over the optical path. A receiving frequency within the prescribed frequency range of the returned COTDR signal is detected to obtain the status information. The detecting step includes the step of sweeping the receiving frequency at a rate equal to that of the prescribed frequency. A period associated with the receiving frequency is temporally offset from a period associated with the prescribed frequency.

Abstract: Differently designed measuring systems exist of which most contain a central signal processing unit and a number of electrical measuring components, and in which the measured values furnished by the measuring components are optically transmitted over optical wave guides. The aim of the invention is to provide a measuring system of this type, which has low power consumption and enables a reliable optical data transmission. To this end, an optical loop is provided between a central measuring unit (MG) and a sensor head (SK). Microprocessors (MP1, MP2), which are situated inside the central measuring unit (MG) and inside the sensor head (SK), carry out transmitting, measuring and monitoring tasks as a distributed controller with bi-directional data communication. A frame synchronization signal serves both for supplying power as well as for deriving a clock signal for block-oriented data transmission.

Abstract: An optical network unit (ONU) of an Ethernet passive optical network (EPON) and a control method thereof eliminates or substantially reduces instances of an ONU transmitting in time slots other than its allocated time slot. The ONU includes: a medium access controller for accessing a medium without temporal overlapping in order to transmit during one or more allocated TDM time slots without collision in upstream transmission to an optical line terminal; a burst-mode optical transceiver having a separately allocated wavelength before outputting the signal in the upstream transmission; and a complex programmable logic device for controlling an optical output of the burst-mode optical transceiver by monitoring an optical-output control signal from the medium access controller. An erroneous output from an ONU malfunction can be prevented from by cutting off the output once the duration of the allocated time slot has been reached.

Abstract: The invention relates to a compensator of attenuation drift in an optical multi-wavelength switch (MWS) which uses input signal amplitude dither and external VOA dither cancellation to determine relative position of MEMS micro mirror hence indirectly determining attenuation level.

Abstract: The optical transmitter and receiver of the invention includes: a variable dispersion compensator that performs wavelength dispersion compensation on an optical signal of a differential M-phase modulation format input from a transmission path; an optical amplifier that compensates an optical loss in the variable dispersion compensator; a delay interferometer that delays and interference processes the optical signal output from the optical amplifier; and a photoelectric conversion circuit that photoelectric converts the output light from the delay interferometer to generate a demodulated electric signal. The output level of the optical amplifier is decreased at the time of start up to deteriorate the OSNR of the optical signal input to the photoelectric conversion circuit, to thereby realize a state in which an error occurs more easily, and then optimization control of the variable dispersion compensator and the delay interferometer is started.

Abstract: An optoelectronic module for converting and coupling an information-containing electrical signal with an optical fiber including a housing having an electrical input for coupling with an external cable or information system device and for transmitting and receiving information-containing electrical signals over such input, and a fiber optic connector adapted for coupling with an external optical fiber for transmitting and receiving an optical signal; an electro-optic subassembly coupled to the information containing electrical signal and converting it to and/or from a modulated optical signal corresponding to the electrical signal; parametric data-collection means disposed in the housing acquiring environmental and/or operational data associated with the module; and a communication interface for wirelessly transferring the data to an external device, such as a portable terminal.

Abstract: The subassembly includes a laser for emitting signals towards fibers to be monitored, a passive alignment carrier, a photodetector for monitoring reflected laser signals from the fibers and for monitoring laser output power, and an optical fiber. The laser is disposed within the passive alignment carrier. The optical fiber is embedded in the passive alignment carrier, and has an angled fiber facet. The laser emits signals toward and through the angled fiber facet, whereby a portion of the laser signal illuminates the photodetector, and another portion illuminates the fibers that are being monitored and reflects back to the photodetector such that faults on the fibers can be detected.

Abstract: An optoelectronic module for converting and coupling an information-containing electrical signal with an optical fiber including a housing having an electrical input for detachably coupling with an external cable or information system device and for transmitting and receiving information-containing electrical signals over such input, and a fiber optic connector adapted for coupling with an external optical fiber for transmitting and receiving an optical signal; an electro-optic subassembly coupled to the information containing electrical signal and converting it to and/or from a modulated optical signal corresponding to the electrical signal; a memory disposed in said housing for storing an encrypted identifier; and a communication interface disposed in said housing for electrically transferring the data to an external device when the module is authenticated using the encrypted identifier, to enable operation of the module.

Abstract: A position in which an optical signal characteristic is compensated in an optical network can be chosen. An optical network equipment measures an optical signal characteristic for each wavelength, and notifies an optical network equipment on a communication path of an optical signal characteristic index and control necessity determination threshold. In an upstream portion of the communication path, the optical network equipment (a start point or the like of the communication path) that can compensate the optical signal characteristic for each wavelength determines the necessity to eliminate a deviation between wavelengths and the position to eliminate it, using the optical signal characteristic index and the control necessity determination threshold.

Abstract: A method for tracing a communication route through a network coupling a first device with a second device is provided. A first signal is transferred from the first device to the second device to cause a plurality of intermediate devices to report first information concerning the first signal. The first information is processed to identify the intermediate devices as defining the communication route. The intermediate devices are configured so that a second signal, when transferred from the first device toward the second device, causes a subset of the intermediate devices to report second information concerning the second signal. The second signal is transferred from the first device toward the second device. The second information is processed to identify the subset of the intermediate devices as a portion of a sequence of the intermediate devices defining the communication route.

Abstract: A method for detecting a failure network terminal in a Passive Optical Network includes: changing timeslots assigned to potential failure network terminals one by one; and determining the failure network terminal according to uplink data frames sent by the potential failure network terminals whose timeslots are changed. Embodiments of the present invention also disclose an apparatus and system for detecting a failure network terminal. The solution of the present invention may detect which Optical Network Unit/Terminal (ONU/ONT) fails and perform the corresponding processing in accordance with embodiments of the present invention, which recovers the system health and improves the network security, stability and self-healing ability.

Abstract: Systems and methods for sensing properties of a workpiece and embedding a photonic sensor in metal are disclosed herein. In some embodiments, systems for sensing properties of a workpiece include an optical input, a photonic device, an optical detector, and a digital processing device. The optical input provides an optical signal at an output of the optical input. The photonic device is coupled to the workpiece and to the output of the optical input. The photonic device generates an output signal in response to the optical signal, wherein at least one of an intensity of the output signal and a wavelength of the output signal depends on at least one of thermal characteristics and mechanical characteristics of the workpiece. The optical detector receives the output signal from the photonic device and is configured to generate a corresponding electronic signal.

Abstract: The present invention relates an optical waveform measuring apparatus designed to eliminate the polarization dependency of an intensity correlation signal without a polarization diversity arrangement. The apparatus comprises a sampling light outputting unit for outputting a sampling light pulse to sample light under measurement, a sampling result outputting unit for developing a nonlinear optical effect stemming from the light under measurement and the sampling light pulse from the sampling light outputting unit to output light corresponding to a result of the sampling of the light under measurement, and a polarization state control unit for, before the start of the measurement of the light under measurement, carrying out control on the basis of a power level of the light from the sampling result outputting unit so that a polarization state of the light under measurement, which is to be inputted to the sampling light output unit, is placed into a predetermined state.

Abstract: An arrangement in a fiber optic network device for analyzing a set of optical signals traversing the fiber optic network device is provided. The arrangement includes a set of ports for receiving and outputting the set of optical signals. The arrangement also includes a set of photodiodes, which is configured at least for receiving and forwarding the set of optical signals. The arrangement further includes a splitter, which is configured at least for receiving the set of optical signals from a first photodiode, splitting the set of optical signals into at least a first part and a second part, and forwarding the first part to a second photodiode and the second part to a third photodiode. The set of optical signals is configured to traverse the fiber optic network device irrespective whether power is provided to circuitry of the fiber optic network device.

Abstract: The Fibre Channel Credit Extender (FCCE) (600) is a network device that is disposed between and connected to an end node (210) and an optical repeater (220). The FCCE (600) contains as many buffer credits as necessary, to solve bandwidth problems in a network. In a situation where maximum bandwidth is required in both directions of a link, the FCCE (600) breaks a single logical link into three physically separated “linklets.” The short-distance linklets attain maximum bandwidth by use of the existing buffer credits of the end nodes. The long-distance linklet attains maximum bandwidth by use of very high receive buffer credits in the FCCEs (600). In this way, only those links that need maximum bandwidth over distances not covered by end-node credit counts need be attached to an FCCE (600). The FCCE (600) contains the optical repeater to gain distance on that link, and contains high credit count receive buffers to gain bandwidth on the link.

Abstract: In one embodiment, a control method, according to which a cascade of control messages is propagated between nodes of an optically transparent network, with each message being sent from a node to an adjacent downstream node to inform the latter about a control operation scheduled to be performed at the message-sending node and/or an upstream node that impacts an optical communication signal received at that downstream node. The cascade of control messages effectively creates an ad hoc control domain, in which control operations performed at various nodes of that domain can be coordinated to reduce unfavorable interactions between those control operations. By repeatedly propagating appropriate cascades of control messages through the network, control domains can be changed dynamically and adaptively to reflect any changes to the network topology, equipment, and/or traffic distribution.

Abstract: A system and method using differential loop gain for fault analysis in line monitoring equipment. Differential loop gain data is calculated from loop gain data, and fault analysis is conducted using differential loop gain data, e.g. by comparing the differential loop gain data to predefined fault signatures.

Abstract: The invention relates to a package starting control device determining a moment and a sequence of starting a package corresponding to an individual wavelength to be wavelength-division-multiplexed in a wavelength division multiplex transmission device. An object of the invention is to provide a package starting control device capable of effectively increasing or decreasing the number of wavelengths at low cost without changing a basic structure drastically.

Abstract: An automatic circulation collection type data system is constructed by connecting a monitoring device and data collecting modules disposed at respective places through optical cables. The monitoring device transmits a trigger pulse for data collection through the optical cable to each data collecting module. An identification code is given to each data collecting module, and each data collecting module has an automatic circulation mechanism comprising first and second optical switches, a data collecting unit, and a controller 6 for performing various kinds of control for data collection. When receiving the trigger pulse from the monitoring device, the automatic circulation mechanism turns on the third switch and transmits the collected data through the optical cable to the monitoring device together with the identification code, and also transmits a trigger pulse through the optical cable to a next data collecting module.

Abstract: The invention aims to provide an optical transmission system that specifies such a transmission condition so as to obtain high spectrum efficiency and a large transmission distance-capacity product at the same time, and uses low cost and small sized optical senders and optical receivers, to realize a high density wavelength multiplexing optical transmission. For this purpose, a WDM optical transmission system of the invention has a system structure that specifies by calculation the spectrum efficiency at which transmission distance-capacity product becomes a maximum value based on the determination of the type of signal light modulation and the assumption of an equation model expressing transmission characteristics of an optical multiplexer and an optical demultiplexer, and optimizes a bit rate and frequency spacing of signal light output from each optical sender, and the transmission characteristics of the optical multiplexer and the optical demultiplexer, so as to approach the spectrum efficiency.

Abstract: The invention relates to a method and a device for operating an optical transmitting device having a plurality of optical transmitters that can be driven independently. The method includes detecting the parameter values of the individual transmitters, comparing the parameter values determined with one another and/or with a prescribed comparison value, and selecting one of the transmitters for the communication operation of the transmitting device based on the comparison. The method further includes operating the transmitting device with the selected transmitter.

Abstract: An electro-optical transceiver module having at least one parallel optical transmit lane and at least one parallel optical receiver lane, the module comprising optical receiver lane signal detection circuitry to detect a loss of signal on one or more of the receive lanes, and optical transmit lane control circuitry to control a optical transmit lane corresponding to the receive lane, on which a loss of signal was detected to transmit a signaling mode optical signal indicating the loss of signal on the receive lane. In a multiple lane parallel optic embodiment, and by signaling a loss of a signal on a per lane basis, a break or fault in a sub-set of fibers of a parallel optical link will not result in the entire parallel optic link being lost.

Abstract: Identification of optical channels in wavelength division multiplex (WDM) optical networks may be confounded by unwanted noise tones interfering with pilot/dither tones used for identifying optical channels. The invention describes a method of selecting pilot/dither tones that are selectively restricted to avoid allocating dither/pilot tone frequencies that appear as noise tones along the path of an optical channel in the optical network.

Abstract: An optical repeater device of the present invention comprises: a preamble compensating circuit 53, for taking out a normal data signal from burst signals propagating through a communication transmission path, and for adding a preamble signal before and/or after the data signal. Furthermore, the preamble compensating circuit 53 comprises: a detector circuit 53a, for inputting the burst signal, and for outputting only the normal data signal; a buffer circuit 53b, for storing the data signal output from the detector circuit 53a, and for outputting thereof; a preamble signal generation circuit 53d, for outputting at least one type of the preamble signal; and an data output select circuit 53e, for outputting the data signal at the time of the data signal input from the buffer circuit 53b, and for outputting the preamble signal from the preamble signal generation circuit 53d at any other time thereof.

Abstract: A method for monitoring an optical transmission line in which digital optical signals are transmitted bidirectionally between a first and a second end point of the transmission line. At the first end point of the transmission line the digital optical signal to be transmitted to the second end point is amplitude-modulated with a preset frequency, with the modulation amplitude being small relative to the amplitude of the digital signal. At the second end point of the transmission line a small fraction of the power of the received digital signal is overcoupled passively on the optical transmission line in the direction towards the first end point and is transmitted to the first end point together with the digital signal to be transmitted from the second end point to the first end point of the optical transmission line. At the first end point the amplitude-modulated component of the received digital signal is detected.

Abstract: A system and method for detecting and correcting for thermal shifting of the passbands of an input filter of an optical receiver relative to the passbands of an output of an optical device, such as an optical router, where the router and the receiver are operating at remote locations and at different operating temperatures that cause thermal drifting of the passbands. In one implementation RF signals are impressed on optical signals transmitted by a transmitter to the optical router. Different frequency RF signals are impressed on each of the optical signals and the receiver uses the detected RF frequencies to cancel portions of optical signals that have drifted into adjacent passbands at the optical receiver. In another implementation a mechanically adjustable filter is employed at the receiver which is used to achieve a needed degree of shifting of the receiver passbands to compensate for passband misalignment between the router and the receiver.

Abstract: A method for processing fault dependency of different levels of tandem connection monitoring is provided. The method comprises obtaining monitored coverage scopes of the different levels of tandem connection monitoring (TCM); locating a fault section according to an overlapping relationship between monitored coverage scopes of the at least two different levels of TCM at which the warnings are reported and performance degradation degrees of the at least two different levels of TCM, the fault section being located when warnings are reported in at least two different levels of TCM; and outputting location-related information that includes information of the fault section to a user.

Abstract: During initial start-up of an optical communication system, an ASE reference span loss is calculated based on transmitting power and received power of ASE light generated by an optical amplifier, and an OSC reference span loss is calculated based on the transmitting power and the received power of OSC light. During normal operation of the optical communication system, a span loss is calculated using the OSC light, and an amount of change in the span loss representing a difference between the span loss and the OSC reference span loss is calculated. A current span loss between a transmitting station and a receiving station is calculated by adding the amount of change in the span loss to the ASE reference span loss.

Abstract: An optical signal connection apparatus comprising a first node and a second node connects first and second optical signal transmission lines to respective first and second routers. The first node includes a first port coupled to the first router via the first optical signal transmission line, and is configured to handle a first type of optical signals associated with the first router. The second node includes a second port coupled to the second router via the second optical signal transmission line, and is configured to handle a second type of optical signals associated with the second router. The information regarding the first type of optical signal is compared with information regarding the second type of optical signal to determine whether or not the first and second optical signal transmission lines are compatible to each other.

Abstract: A light-transmitting apparatus for demultiplexing an input signal completing waveform division multiplexing into wavelength components and transmitting the wavelength components through their respective transmission lines includes a wavelength-count-detecting unit for detecting the number of wavelengths of wavelength components included in the input signal and determining whether the number of wavelengths is normal or abnormal. The light-transmitting apparatus further includes a plurality of identifier-detecting units each associated with one of the wavelength components and used for determining whether or not an identifier set in one of the wavelength components that has the associated wavelength is normal, and a judgment unit for forming a judgment on existence of an error for each of the wavelength components on the basis of a detection result output by the wavelength-count-detecting unit and a detection result output by the identifier-detecting unit associated with the wavelength component.

Abstract: A method of optical communication includes providing a plurality of optical signals each associated with a distinct channel of a composite optical signal. A unique pilot tone signature is superimposed on each channel. The spectral composition of each signature includes a plurality of frequencies. In one embodiment, binary frequency shift keying at a frequency fm is used to shift between instantaneous frequencies f1 and f2 wherein f2+?f=f1??f=fc. Choosing ? ? ? f f m ? 1.1602 produces a spectrum having a plurality of dominant components at least some of which have substantially the same amplitude. A method of detecting the presence of a selected pilot tone signature having a plurality n of dominant spectral components F1 . . . Fn includes generating a power spectrum P0(f). Sk(f) is calculated as a product of a plurality of frequency shifted versions of P0(f), where k?{1 . . . n}. The existence of a dominant spectral component at Fk indicates the presence of the selected pilot tone signature.

Abstract: A method for monitoring an optical network includes communicating optical traffic along a working path of an optical network. The optical network comprises a protection path for the optical traffic to communicate the optical traffic upon a failure in the working path. The protection path comprises two or more network elements coupled together by optical lines. The method also includes monitoring an idle signal of the protection path to detect an error in the protection path comprising an error in a component of one or more of the network elements.

Abstract: Network elements are identified as being connected to optical nodes by instructing two network elements in a spectrum group of the CMTS to transmit at frequencies f1 and f2, respectively. Frequencies f1 and f2 are selected such that they produce intermodulation distortions (intermods) in the laser transmitter at f3 when combined. If intermods are produced which exceed a predetermined threshold, then the two network elements are determined to be on the same node. If the total power of the signal by the laser transmitter exceeds an impact threshold, then the test is stopped and new network elements are selected for testing.

Abstract: The control of the transmission of useful optical signals on different line paths of an optical transmission device is accomplished via at least one of the following features: using signal sources and signal sinks, the useful optical signals are coupled into the line paths, or are coupled out of them; at least one portion of the optical line paths is configured as normal line paths having coupling nodes via which a switchover to an alternative line path can be undertaken if a normal line path is disturbed; in addition to the useful optical signals, test signals, whose evaluation is used for the switchover between the line paths, are transmitted bidirectionally section-by-section; at least two types of test signals can be transmitted, of which a first type is used as an indicator for an intact line path and a second type as an indicator for a disturbed line path; and any switchover to an alternative line path is only undertaken if, before the detection of the disturbance, a test signal of the first type has be