Abstract: A channel in a multiple carrier communication system is equalized by computing a target spectral response, shortening the impulse response of the channel so that a significant part of an energy of the impulse response is confined to a region that is shorter than a target length and filtering the signal based on the target spectral response.

Abstract: An optical communication system includes a plurality of optical channels, each of which passes a single optical wavelength signal. Each of the plurality of optical channels includes an optical amplifier which is controlled to operate at a predetermined output power level independent of channel wavelength and input power level by operating each optical amplifier in a saturation mode. Pumping power for operating each optical amplifier in the saturation mode is supplied from shared optical pumps or a plurality of one per channel optical pumps.

Abstract: A system and method for a cell based wrapped wave front arbiter (WWFA) with bandwidth reservation are disclosed. The method for reserving bandwidth of a given priority using the WWFA for arbitrating bandwidth among virtual links between input and output ports, each virtual link supporting one or more priorities and corresponding to an arbitration unit (AU) of the WWFA generally comprises performing at least one arbitration pass of a wave front of the WWFA where AUs having a reserved bandwidth request of a given priority and reserved bandwidth credit of the given priority compete for the bandwidth associated with the wave front, and where AUs not having a reserved bandwidth request of the given priority and reserved bandwidth credit of the given priority do not compete for the bandwidth, and performing at least one subsequent arbitration pass where AUs having a reserved bandwidth request of the given priority compete for the bandwidth.

Abstract: A system supports 50 ms protection switching times independent of network architecture. The system includes multiple protection switch fabrics to perform facility protection switching for the signals and a central switch fabric to switch a subset of the signals in a non-facility protection switching manner among the protection switch fabrics. Linear and ring network configurations are supported by the system. The system has flexibility to perform Linear Automatic Protection Switching (LAPS), Unidirection Path Switched Ring (UPSR) protection switching, and Bidirectional Line Switched Ring (BLSR) protection switching without burdening the central switch fabric with unnecessary or redundant traffic.

Abstract: Packets having at least one cell are switched using input queues, output queues, a switch fabric, and a controller. Each input queue stores cells to be switched, and each output queue stores switched cells. The switch fabric couples the input queues to the output queues and has memory. The switch fabric stores cells moved from the input queues to the switch fabric and stores cells based on the output queues. The controller couples to the input queues and the switch fabric and determines input priorities for cells moving from the input queues to the switch fabric and output priorities for cells moving from the switch fabric to the output queues.

Abstract: The present invention that provides a network topology for an ATM network. The topology includes a source network element, at least one intermediate network element, and a distributed virtual path connecting the source network element and the intermediate network elements. The distributed virtual path includes a virtual circuit that originates from the source network element and a virtual circuit that originates from at least one of the intermediate network elements. The distributed virtual path originates from the source network element and may terminate on a destination network element or on the source network element (thereby forming a ring). The network elements may be, for example, computers, satellites or other communications devices.

Abstract: A wavelength division multiplexed optical communication system includes a plurality of optical line terminals which may be part of separate in service networks, each having a line interface and an all-optical pass-through interface including a plurality of pass-through optical ports, and each also including a plurality of local optical ports which are connectable to client equipment and an optical multiplexer/demultiplexer for multiplexing/demultiplexing optical wavelengths. The optical multiplexer/demultiplexer may include one or more stages for inputting/outputting individual wavelengths or bands of a predetermined number of wavelengths, or a combination of bands and individual wavelengths.

Abstract: An echo canceller circuit is set forth. The echo canceller circuit includes a digital filter having adaptive tap coefficients to simulate an echo response occurring during a call. The adaptive tap coefficients are updated during the call using a Means Squares process. A tap energy detector is also employed. The tap energy detector identifies and divides groups of taps having high energy from groups of taps having low energy. The high energy tap groups are smaller in number than the low energy tap groups. The high energy tap groups are adapted separately from the low energy tap groups using the Least Squares process. Still further, the high energy tap groups may be adapted using an adaptive gain constant a while the low energy tap groups are adapted using an adaptive gain constant a′, wherein a>a′.

Abstract: A testing processor executes a plurality of test steps of an assembly test on successive units. A server informs the testing processor of a sampling frequency for each test step. The testing processor only executes those test steps whose sampling frequencies indicate that they are to be run on a particular unit. Upon detecting a failure associated with a particular test step, the server may inform the testing processor to adjust the sampling frequency of the particular test step such that the particular test step is to be executed on every subsequent unit to be tested. Upon receiving no further failures associated with the particular test step for a given number of units, the server may notify the testing processor to adjust the sampling frequency of the particular test step such that it need not be executed for every subsequent unit to be tested.

Abstract: An improved phase-lock loop circuit comprising a phase detector, a loop filter, and a voltage controlled oscillator. The phase detector samples the phase-lock loop input signal at various points in a cycle of the phase-lock loop output signal and outputs a signal representative of the point of the phase-lock loop output cycle at which a logic state transition of the input signal is detected. In addition, a self-sweeping autolock circuit interacts with the loop filter in such a manner that the self-sweeping autolock circuit commands the loop filter to sweep its output signal when phase-lock is absent and the loop filter halts the sweep of its output signal when phase-lock is acquired.

Abstract: Systems and methods are disclosed for detecting framing data in a telecommunications signal. In one embodiment, a frame synchronizer circuit is provided that includes an interface for receiving bits of a telecommunications signal and storage for storing a framing state for the bit positions in the frame, the framing state for a given bit position indicating whether that bit position is a potential holder of the frame synchronization pattern. The frame synchronizer circuit also contains a state update function that determines the current-state for each bit position based on the bit position's previous state, and the value of the most recently received bit in that bit position. The encoding scheme makes use of shorter bit length symbols to represent statistically more frequently occurring states. In one embodiment, a single code word is used to record the state of a sequence of consecutively occurring bit positions that share the same state.

Abstract: A bezel for facilitating the connection between an external device positioned on one side of a communication panel and a module located on the other side of the panel where the panel has an opening for receiving the bezel. The bezel includes a housing defining an interior portion of the bezel, a first open end for insertion into the opening of the panel and the module, where the first open end receives a first communication connection from the module for connection with the external device, and a second open end having a removable cover. The second open end receives a second communication connection from the external device for connection with the first communication connection.

Abstract: A communications system includes a transmitter that generates symbols in a plurality of bins using a first timing signal and generates a reference signal by using the first timing signal. The transmitter transmits the symbols and the reference signal carried by a first signal, which is frequency multiplexed with a second signal from another transmission source. A demultiplexer frequency demultiplexes the first signal, which is downconverted in response to a control signal to generate a frequency downconverted signal, and a processing circuit is responsive to the frequency downconverted signal to identify the predetermined bin and to generate the control signal in response to the identification of the predetermined bin.

Abstract: A reduced-complexity, fast converging adaptive filter may be used for network echo cancellation applications, including applications having sparse echo paths. The new filter, referred to as a selective-partial-update proportionate NLMS filter, may be based on a proportionate NLMS (PNLMS) technique and selective partial updating of the adaptive filter coefficients. The new PNLMS filter may exploit sparseness of a communications channel to speed up the initial convergence of the NLMS technique included in the filter by weighting regressor data proportionately with an estimated magnitude of the channel impulse response. Selective partial updating is essentially a data selection method to reduce the computational complexity. The performance of the selective-partial-update PNLMS filter compares favorably to an adaptive filter using standard PNLMS for echo paths specified in ITU-T Recommendation G.168.

Abstract: In order to enhance the quality of a communication signal derived from speech and noise, the likelihood that the communication signals result from at least some speech is determined. A calculator calculates a first power signal representing the power of at least a portion of the communication signals estimated over a first time period and calculates a second power signal representing the power of at least a portion of the communication signals estimated over a second time period longer than the first time period. The calculator also generates a comparison signal having a value related to the likelihood that the portion of the communication signals result from at least some speech by comparing a first expression involving the first power signal with a second expression involving the second power signal.

Abstract: The specification discloses methods and apparatus for selecting the better of two or more copies of a cell in a cell-oriented redundant switching system connected to an external communications network. In the preferred embodiment, the best cell copy selection aligns redundantly transmitted cell streams before selecting cells for insertion in the data stream. Because the streams are aligned before the selection is made, the best cell copy selector compares each cell at the same instant in time, rather than basing its selection on past events.

Abstract: A reduced component optical switch module includes a plurality of ports wherein each port includes an optical input and an optical output. A plurality of switchable deflectors in combination with a plurality of non-switchable deflectors can be used to establish transmission paths between pairs of ports to support traffic reciprocity. In one embodiment, the ports and switchable elements are configured so as to provide substantially constantly transmission paths within the respective module. In another embodiment, additional deflector elements can be provided to implement loop-back functionality at one or more of the ports.

Abstract: An electrical system comprises an electrical circuit board for mounting electrical components and a circuit board sub-rack. The board includes a pivotally mounted ejector member which pivots to insert and eject the board from the sub-rack. The ejector member carries two grounding contact surfaces for engagement with the ground plane of the board and chassis area of the sub-rack when the ejector member is pivoted to its closed position. The contact surface of the ejector member mates with the board to frictionally hold the board in fully inserted position. The ejector member also includes a retaining arm which mates with the sub-rack for providing an insertion or ejection force to facilitate insertion or ejection of the board relative to the sub-rack.

Abstract: A channel in a multiple carrier communication system is equalized by computing a target spectral response, shortening the impulse response of the channel so that a significant part of an energy of the impulse response is confined to a region that is shorter than a target length and filtering the signal based on the target spectral response.

Abstract: Input interfaces convert a predetermined data frame structure, such as a Sonet STS-1, into an internal format comprising a predetermined number of rows and columns, the rows being a multiple of a number evenly divisible into the bytes contained in the internal frame format. A time-space switch switches the frame format while storing a row of bytes in a data memory. Output interfaces convert the switched data to the same type of data frame format received at the input.