Abstract: Several systems and method for remotely monitoring a communication system are disclosed. An RF signal received at a remote facility is analyzed at the remote facility and an ancillary data signal including information relation to at least one characteristic of the RF signal is generated. The ancillary data signal is modulated and combined with the RF signal. The combined RF signal is transmitted to a local facility in an optical form, where the ancillary data signal is recovered. An ancillary data signal block provides control signal in response to the local ancillary data signal. The control signals may be local control signals for controlling local devices or remote control signals for controlling devices at the remote facility. The ancillary data may include a power level of the RF signal and a version of the RF signal may be generated at the local facility with a power level approximately equal to the power level of the original RF signal.

Abstract: A communication network access device is adapted for duplex communication and provides transmit and receive signal paths. A controllable socket is coupled to the transmit and receive signal paths and linked to a control interface for activating/deactivating the control interface. A pluggable module is coupled to the transmit and receive signal paths via the controllable socket in an activated status and to a transmission path carrying uni-directional signals. The module includes a first optical device and a splitter in the transmission path and is coupled to a second optical device via the splitter. The second optical device responds to a portion of uni-directional signals provided by the splitter for placing the communication access device in a link up condition for uni-directional signals provided by the first optical device to the transmission path serving an optical local area network.

Abstract: A system to communicate optical data signals in parallel includes an optical splitter to split the data signals into two polarization multiplexed (PM) signals; and two reception channels coupled to the optical splitter, where each reception channel tracks and isolates a PM signal independently.

Abstract: In one embodiment, the invention provides an optical interconnect comprising a transmitter for generating and transmitting an optical signal, a receiver for receiving the optical signal from the transmitter and for converting the received optical signal to an electrical signal, and a pre-transmitter distort circuit for applying a pre-transmitter distort signal to the transmitter to adjust the shape of the optical signal generated by the transmitter. Distortions are introduced into the optical signal when the optical signal is generated, transmitted to the receiver, and converted to the electrical signal. As a result of the signal applied to the transmitter by the pre-transmitter distort circuit, the optical signal generated by the transmitter has distortions to compensate for the distortions introduced into the optical signal, wherein the electrical signal, into which the optical signal is converted, has a desired shape.

Abstract: Current approaches for determining and identifying whether a correct length of fiber cable is installed between network elements configured to communicate using specific lengths of cable require manual inspection. Such manual inspection may include the use of markers used for visual inspection of cables matching corresponding network elements. An embodiment of the present invention utilizes identifiers unique to cables of various lengths to determine whether a correct length of cable has been installed. Further, embodiments of the present invention determine whether the unique identifier is received by a network device according to a channel mapping corresponding to a unique physical mapping associated with cables of various lengths. The use of the identifiers and channel mappings enable automatic discovery of lengths of cable that are installed between network devices.

Abstract: Described herein are systems and methods for a field-configurable optical network terminal (ONT) device at a subscriber to provide one or more communication services to the subscriber. The field-configurable ONT device is of a modular design operable for the insertion of additional communication modules or removal of existing communication modules from the ONT device for scaling the device to increased or decreased communication capacity as desired.

Abstract: A method of collecting data from an optical channel monitor for monitoring the power of a wavelength-division multiplexed light signal at each wavelength is disclosed. The total light power is analog-to-digital converted by an A/D converter. The data of the total light power which has been analog-to-digital converted is compared with a reference light power by a comparator for each conversion, and when the difference between the total light power and the reference light power exceeds a predetermined threshold, a power fluctuation flag is turned ON. After the comparison, the above process of the analog-to-digital conversion and the comparison is iterated until the optical channel monitor completes the data collection for each wavelength. Thereafter, the processor determines whether the power fluctuation flag is ON or not. When the power fluctuation flag is ON, the processor discards the currently collected data and maintains the data which were collected immediately before.

Abstract: A router comprising an interface module (IM), having an optical path and an electrical path and a speed sensor coupled between an input of the router and an input of the IM. The speed sensor is adapted to receive a packet and detect a speed of the IM connection and in response to the speed of the IM connection being above a threshold value, the speed sensor provides the packet to the optical path of the IM and in response to the relative speed being below the threshold value, the speed sensor provides the packet to the electrical path of the IM.

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: A GPON module comprises a housing and a circuit board disposed in the housing. The circuit board further includes ground lines that substantially isolate regions of the circuit board, an electro-optical interface for converting an inbound optical signal to an electrical signal and processing circuitry that is arranged to provide an electrical RF signal to an RF interface. The RF interface comprises a three-pin RF connector exposed from the housing, wherein the RF connector is coupled directly to the circuit board, and two of the three pins are coupled to ground.

Abstract: A system and method for monitoring an optical communication system. The system may include trunk terminals coupled through a trunk path and a branch terminal coupled the trunk path. A monitoring signal routing device within the branch terminal routes a monitoring signal from a branch-drop path to a branch-add path.

Abstract: The present disclosure provides a system, apparatus and method to provide for monitoring of characteristics of optical signals, as part of wavelength division multiplexed signals for example, transmitted over a network infrastructure. The characteristics of each optical signal may be monitored and maintained at desired values in order to optimize system performance. A system including a coherent detector, as part of a coherent receiver for example, may be employed to associate each transmitted optical signal with a modulated source. Control signals generated by the system can then be provided to elements of the modulated source to control characteristics, such as optical power, optical frequency, and optical phase, for example, of the transmitted optical signal.

Abstract: In a controlling circuit, a photo coupler is used for isolating noises, and a general purpose amplifier is used for adjusting a gain, so that a logic tester may test analog signals in cooperation with relays having different specifications and operating voltage level differences in an analog measurement module. A shift register of each controlling circuit of a controlling module also transmits a test data signal to a next stage controlling circuit, so that a logic tester may simultaneously output a plurality of bits to multiple controlling circuits and multiple analog measurement modules by using merely one I/O port.

Abstract: A method of transmitting an Operations, Administration and Maintenance (OAM) message and of processing an error in a Passive Optical Network (PON) system is provided. Using an OAM packet format that may be used in common in the PON system, a process of transmitting or receiving an OAM message may be simplified, an efficiency of the process may be increased, and an Optical Network Unit (ONU) may be managed at a high speed.

Abstract: A method of controlling communication between transceivers includes transmitting payload data from a transmitter of a first transceiver in a data channel of a physical link to a receiver of a second transceiver, the second transceiver further including an equalizer, varying equalizer settings in the equalizer, analyzing effects of varying equalizer settings to determine transmitter diagnostic settings for the first transceiver, and transmitting the transmitter diagnostic settings from a transmitter of the second transceiver in an out-of-band channel of a physical link to a receiver of the first transceiver a second transceiver in a data channel.

Abstract: An optical transmission system includes transmitter 100 and receiver 200. Transmitter 100 adds state information for identifying a state of transmitter 100, to a signal and transmits the signal to receiver 200. Receiver 200 obtains the state information added to the signal transmitted from transmitter 100 and identifies a state of transmitter 100 based on the obtained state information.

Abstract: A method, bus controller, and computer program product for arbitrating use of a communication bus for a certain one of a plurality of interconnected nodes that share the bus. The method includes the steps of: presenting a data frame on the transmitter and receiver side of the bus, where the certain node presents at the transmitter side, where the data frame has a embedded clock of a predetermined timing and a header field, synchronizing, by the certain node, with the embedded clock in the data frame at the receiving side of the bus, successively presenting, by the certain node, an idle pattern on the bus determined by a preassigned node ID, emitting light, by the certain node, on the bus at a predetermined timing preassigned to the certain node, and monitoring light emission on the bus that indicates a bus access request from another one of the nodes.

Abstract: Optical fiber-based wireless systems and related components and methods are disclosed. The systems support radio frequency (RF) communications with clients over optical fiber, including Radio-over-Fiber (RoF) communications. The systems may be provided as part of an indoor distributed antenna system (IDAS) to provide wireless communication services to clients inside a building or other facility. The communications can be distributed between a head end unit (HEU) that receives carrier signals from one or more service or carrier providers and converts the signals to RoF signals for distribution over optical fibers to end points, which may be remote antenna units (RAUs). A microprocessor-based control system or systems may also be employed.

Abstract: A testing input module for testing an in-service WDM system is provided. The testing input module includes a first light source configured to emit a first light signal to one or more empty channels of the in-service WDM system; and a tunable second light source configured to emit a second light signal to test the one or more empty channels. The testing input module also includes a first switch module configured to: receive from the first light source and output the first light signal during a first time interval; and receive from the second light source and output the second light signal during a second time interval. The second time interval is a duration wherein a channel power monitoring function of the in-service WDM system is not triggered.

Abstract: An optical transmission apparatus includes a network, a plurality of transponders, a monitor, a multiplexer, and demultiplexer. The plurality of transponders connected with the network, each of the plurality of transponders having a response transfer processing unit for communicating between the other transponders via the network, the plurality of transponders categorized a first transponder and a second transponder; The monitor connected with each of the transponder units, respectively, the monitor monitoring the plurality of transponders and sending a first request and a second request to the plurality of transponders. The first transponder responds an answer to the monitor via the network when the first transponder receives the first request. The second transponder responds an answer to the monitor instead of the first transponder via the network when the first transponder receives the second request.

Abstract: A method for allocating and configuring TCM in an embodiment of the present invention includes: configuring the domain that needs TCM in a network and the scope of the domain; determining the ODU service that needs TCM; and allocating TCM automatically according to the ODU service trail and the configured domain; and enabling or disabling the TCM of each level. The present invention enables the system to allocate TCM automatically. The TCM levels can be allocated easily in a centralized way, or for each node in a distributed way. The present invention ensures that the TCM level allocated for the service in the forward direction corresponds to that in the reverse direction. The method is perfectly applicable to the networks of more than six operators. The TCM levels are handled according to the allocated order, thus ensuring correct insertion of AIS and BDI and unique result of insertion.

Abstract: An optical switching device includes plural wavelength selective switches that respectively have a first port and a plurality of second ports; and an optical coupler that has a plurality of third ports on an input-side or an output-side, respectively optically coupled to the first ports of the wavelength selective switches.

Abstract: Exemplary embodiments of the invention relate to an analyzer device configured to interface with an optical transceiver module having a diagnostic communications port, wherein the port is configured to access diagnostic and other data contained within the transceiver controller via a backdoor interface. Controller data, including operational parameter values and module setup values, is accessible while the transceiver operates in conjunction with an external host and may be retrieved, and sometimes modified, in real time without interrupting normal transceiver operation or suspending the transmission of data over optical fibers. The analyzer device accesses the data via the diagnostic communications port on the outside of the transceiver module.

Abstract: An optical wireless communication device having a PhotoDiode (PD) for photosensitive detection means, receives a guide message from a specific optical wireless communication device, determines any one optical wireless communication scheme among different optical wireless communication schemes which are included in the guide message and supportable by the specific optical wireless communication device, as a content delivery scheme to be used during content reception, sends a response message including the content delivery scheme, and receives the content that is delivered based on the content delivery scheme.

Abstract: The present invention relates to communications technologies, and discloses a method for monitoring the state of a fiber line, a repeater, and a submarine cable system. The repeater includes a first optical amplifier (OA), a second optical amplifier, a first gating unit, a second gating unit, a first coupler, a second coupler, a third coupler, and a fourth coupler. The first coupler, the fourth coupler, and the first gating unit form an in-to-in loopback path between the input end of the first OA and the input end of the second OA; and the second coupler, the third coupler, and the second gating unit form an out-to-out loopback path between the output end of the first OA and the output end of the second OA.

Abstract: Apparatus, systems and methods for separating a selected optical signal wavelength component from a plurality of optical signal wavelength components of an aggregate optical signal, and for passing the selected optical signal wavelength component while suppressing the remaining wavelength components are provided. Generally, the apparatus provides an optical signal wavelength selective element enabling output of a selectable optical signal wavelength component. The system contains a fiber optic cable carrying an optical signal, an optical signal measurement apparatus to measure optical signal characteristics, and an optical wavelength selector to pass the selected optical signal wavelength component to the optical signal measurement apparatus.

Abstract: A power-saving mode flag generating unit 101e sets a power-saving mode flag to active (non power-saving mode, turning on the power-source) when it receives a reset signal from a MAC unit 102. Furthermore, the power-saving mode flag generating unit 101e sets the power-saving mode flag to sleep (power-saving mode, turning off the power source) in accordance with a signal-interrupt detection signal obtained by the signal-interrupt detecting unit 101f1 of the packet monitoring unit 101f. Depending on the state of a packet, the power-saving mode flag generating unit 101e changes the power-saving mode flag to active or sleep for the data communication area of the packet; however, for the ranging area of the packet, the power-saving mode flag generating unit 101e always sets the power-saving mode flag to active. A pattern discriminating unit 101g discriminates between the data communication area and the ranging area of the packet.

Abstract: An optical transmission apparatus including a cooler includes: a platform having a transmission line patterned to have an angle of 90°; a light source mounted on the platform such that it is connected to the transmission line of the platform and generating light; a cooler positioned under the platform and uniformly maintaining the temperature of the light source; and a transistor outline (TO) stem package allowing the platform to be mounted thereon and having a lead pin connected to the transmission line of the platform through a bonding wire. Temperature control characteristics are provided, high frequency characteristics are improved, and a lens, or the like, can be mounted in a passive alignment manner.

Abstract: A transponder and system for monitoring the status of equipment, such as an optical node, on a network are described. The transponder has an external fiber optic input connection element, an external fiber optic output connection element, an internal receiver connected to the input connection element for converting incoming optical signals to electrical RF signals for use internally within the transponder, and an internal transmitter connected to the output connection element for converting outgoing electrical RF signals to optical signals to be transmitted from the transponder. The transponder also includes status monitoring circuitry interfacing with equipment being monitored and a cable modem communicating with the status monitoring circuitry for receiving information therefrom and for generating an outgoing signal. A method of monitoring the status of an optical node on a network is also disclosed.

Abstract: An optical signal quality monitor includes a splitter splitting an input optical signal into two signals; a low-frequency converter converting one split optical signal to a low frequency signal by modulating the optical signal with a frequency offset signal; and an intensity ratio calculator calculating an intensity ratio between the low frequency signal and the other split optical signal, thereby appropriately confirming the quality of a high-bit rate optical signal. The monitor includes plural processing lines, each line including the splitter, the low-frequency converter, and the intensity ratio calculator. At least one line includes an optical noise superimposer superimposing optical noise on the one split signal before inputted to the converter or an optical band-pass filter transmitting the one split signal before inputted to the converter. The monitor includes a polarization state changer changing the polarization state of the input signal before inputted to the splitter.

Abstract: A non-intrusive monitoring optical connection between two fiber optic lines including a sending fiber optic end that emits light to a first lens that collimates the light to a larger diameter parallel beam of light that enters a tunnel, a second lens that focuses the light from the tunnel to an end of a receiving fiber optic line, a mirror disposed in the tunnel between the first and second lenses, which reflects and diverts part of the parallel beam of light to a diverting tunnel, and a second diverting mirror, disposed at a non-zero angle to a longitudinal axis of the diverting tunnel, which directs the beam from the diverting tunnel into a second diverting tunnel wherein it is collimated by a third lens, disposed in the second diverting tunnel, to an end of a monitoring fiber optic line.

Abstract: An apparatus for performing an optical line analysis of continuous data signals. The apparatus comprise a phase position processor for computing a phase early/late indicator; a phase control code processor for computing a difference phase indicator; a frequency extractor for computing a low frequency jitter indicator; and a statistical calculator for computing a plurality of statistical measures regarding frequency and amplitude components of a jitter of an input continuous data signal, wherein the statistical measures are computed based on one of the phase early/late information indicator, the difference phase indicator, or the low frequency jitter indicator.

Abstract: A method and apparatus for buffering an encoded signal having a plurality of codewords for a turbo decoder is provided. The method comprises de-interleaving each sub-block of the codeword received at the turbo-decoder; and storing LLRs of the de-interleaved codeword LLRs into an input buffer. Thereafter, each of punctured locations, if any, in the de-interleaved codeword is indicated to a read logic for enabling the latter to fill in each of those locations with a pre-determined LLR value as and when a read request corresponding to one of those locations arrives. This method obviates the need for storing the pre-determined LLRs at the punctured locations into the input buffer and thereby cuts down the input latency of turbo decoder significantly for higher code rates.

Abstract: A method of sampling a radio frequency signal comprises: receiving the radio frequency signal; modulating an optical signal with the radio frequency signal and an oscillator signal to generate a modulated signal; applying a filter to the modulated signal to generate an intermediate frequency signal, the filter having an intermediate pass band and an intermediate roll-off, the intermediate pass band and the intermediate roll-off in combination defining a intermediate frequency band having a first bandwidth; and sampling the intermediate frequency signal at a sampling frequency using a number of optically interleaved analogue-to-digital converters. The oscillator signal and the sampling frequency in combination are arranged such that the intermediate frequency band is defined between consecutive multiples of half of the sampling frequency. Corresponding apparatus for sampling a radio frequency signal is also disclosed.

Abstract: The invention relates to a method and an optical receiver implementing this method suitable for robustly receiving unencoded optical data. The method set the threshold for the receiver using values relating to the high and low values of a binary signal. However, for some data patterns these values may not be accurately determined, such as for extended periods of constant high or low values being transmitted. In this case the method, in one embodiment, assumes that the extinction ratio of the signal is substantially constant and is thereby able to track the threshold for the signal.

Abstract: An optical device includes a light source, a controller that supplies control information to the light source and controls an output level of the light source, a monitor that outputs an operation state of the optical output as a monitor output, and an auxiliary controller that records the monitor output and the control information. When the controller stops supplying the control information, the auxiliary controller outputs the control information to the light source in accordance with the relation between the recorded monitor output and the recorded control information.

Abstract: A system and method is described for determining a condition of a communication line, such as the absence of a filter device on a digital subscriber line (DSL). A first signal characterized by a high upstream power is activated over the line, and a first set of parameters associated with the communication line is obtained. A second signal characterized by a low upstream power is activated, and a second set of parameters associated with the communication line is obtained. Comparison of first and second sets of parameters is indicative of a condition of the connection and presences or absence of a DSL filter on the communication line.

Abstract: A data transmission system and method are provided. The data transmission system includes a first link partner and an optical transceiver unit. The first link partner includes a controller. When the first link partner is in an abnormal operation mode, the controller controls the first link partner to exit from the abnormal operation mode. The optical transceiver unit is coupled between the first link partner and a second link partner and performs data transmission between the first link partner and the second link partner. According to the data transmission system and method, one link partner can accurately detect whether another link partner is coupled to the one link partner through an optical transceiver unit. Accordingly, data transmission between the two link partners can be stably performed through the optical transceiver unit.

Abstract: A network design apparatus designs arrangement of various types of optical transmission devices in stations within a linear section in a network. An acquisition unit acquires information concerning the type of optical transmission device to be provided in the stations, and information concerning cost and transmission degradation for the optical transmission devices. The designing unit designs, based on the information acquired by the acquisition unit, an arrangement for which transmission degradation between stations respectively including an optical transmission device applicable as an optical regenerative repeater, is less than or equal to a threshold, and also has the least cost. An output unit outputs information concerning the arrangement designed by the design unit.

Abstract: This G-PON network testing apparatus composes a network by connecting between an OLT, ONU or ONT by a optical fiber. This testing apparatus stores testing items and code numbers in a storing section by correlating them from each other. It obtains data receiving time and transmits the data to a delay buffer A when no test is implemented and generates testing data in which a code number is added to the data when a test is implemented. Then, this testing apparatus extracts the code number from the generated testing data to implement the testing item and obtains time when the testing item is finished. Then, it calculates a test time necessary for implementing the test from this time and the data receiving time and reads the data transmitted to the delay buffer A after an elapsed of the calculated test time.

Abstract: A method is provided including the steps of monitoring at least one performance metric of at least one network component in an optical network system, determining whether the at least one network component is a rogue network component using the at least one performance metric, saving environment data to a non-volatile storage medium, and modifying the operation of the rogue network component to reduce interference of the rogue network component with the optical network system. In another embodiment, a method includes detecting a condition of a network component in an optical network system, and writing environment data of the network component to a non-volatile storage medium.

Abstract: A wavelength division multiplex optical ring network comprises optical fibre (1-4) arranged in a ring configuration and a plurality of doped fibre optical amplifiers (17-20) arranged in the ring. The spectral response in the ring is configured such in use amplified spontaneous emission (ASE) noise circulates around the ring in a lasing mode to clamp the gain of each doped fibre optical amplifier. Each optical amplifier (17-20) includes respective control means (28) which in use control the optical amplifier to produce a substantially constant output power or to maintain a substantially constant pump power. In the event of loss of the lasing peak, detection means switches the doped fibre optical amplifiers to a different mode of gain control, for example, a mode to produce constant gain at the value before the loss of the lasing peak. Optionally, after a predetermined delay, the optical amplifiers may revert to constant output power or pump power mode.

Abstract: The present disclosure relates to fiber optic networks carrying sensitive information such as classified government communications, sensitive financial information, proprietary corporate information, and associated systems and methods for secure transmission where fiber tampering is easily detected. The present invention provides improved security systems and methods for fiber optic communication links. Specifically, a hollow-core photonic bandgap fiber is deployed as a transmission medium. A secure fiber optic communication link is established over the hollow-core photonic bandgap fiber with a monitoring mechanism. The monitoring mechanism is configured to detect large losses and large spectral variability each indicative of loss introduced by malicious intrusion attempts. Further, the monitoring mechanism allows easy differentiation of intrusion relative to normal system variations thereby reducing false positives and missed intrusions.

Abstract: In accordance with the teachings of the present invention, a system and method for managing wavelength drift in an optical network is provided. In a particular embodiment, the method includes receiving traffic in one or more optical channels transmitted by one or more transmitters, each channel having successive timeslots, each transmitter assigned to transmit in a channel in allocated timeslots in the channel. The method also includes determining whether the traffic received in a particular channel in a particular timeslot was transmitted by one of the transmitters that was not assigned to transmit in the particular channel.

Abstract: A method and apparatus for restoration of operating conditions of a WDM optical ring network comprising a plurality of amplifiers linked together in a ring after a break or fault has occurred in the network. The method comprises in response to repair of the break or other fault, increasing output power or/and pump power of an amplifier in the network such that the output power or/and pump power increases substantially in accordance with a ramp function.

Abstract: An optical spectrum monitor includes a tunable optical detector that receives optical channel monitoring signals from an optical channel and receives a control signal that selects a frequency of an optical channel monitoring signal for detection. The tunable optical detector detects the optical channel monitoring signal selected by the control signal and generates an electrical signal related to a power of the detected optical channel monitoring signal. A processor analyzes a plurality of differences between selected optical channel monitoring frequencies and their corresponding ITU frequencies and then generates the control signal at the output that corrects for at least one of systematic band offset and systematic band tilt in the optical channel monitoring frequency.

Abstract: The specification describes optical performance monitors which are simplified by coupling single tunable optical filters to multiple channels being monitored. Optical measurements for more than one channel may be made simultaneously. The optical system architecture is preferably an optical performance monitor for a WDM system. In a system designed according to the invention n channels may be monitored using n photodetectors, n optical splitters, but only n/2 tunable optical filters. Additional system simplification may be obtained using optical switching elements coupled to the optical splitters.

Abstract: A fiber optic device is connectable to a fiber optic cable connector to provide an optical communication channel. The fiber optic device is operable to detect a plurality of engagement conditions of the fiber optic device relative to the connector and to provide output signals indicative of a present engagement condition.

Abstract: In exemplary embodiments, all-optical pattern recognition for an optical input signal is achieved by wavelength-converting the input signal and then passively correlating the wavelength-converted signal based on a specified data pattern. By performing wavelength conversion using a CW laser signal having wavelength stability greater than that of the input signal, errors resulting from wavelength sensitivity of the passive correlator can be reduced. By performing both wavelength conversion and OOK-to-BPSK format conversion prior to the passive correlation, limitations in the number of available OOK patterns can be avoided. By performing the passive correlation in a bi-directional manner, feedback signal can be generated to control the operations of the passive correlator and/or the laser signal source(s).

Abstract: A system generates optical pulses, that include two frequencies within one optical channel, at a first end of an optical link, and receives the optical pulses at a second end of the optical link. The system also sets a frequency difference for the two frequencies of the optical pulses, calculates a relative group delay difference for the two frequencies of the optical pulses, and calculates a residual chromatic dispersion of the channel based on the frequency difference and the calculated relative group delay difference.