Abstract: Methods and apparatus for processing a received voice signal from a variable-delay network by a communications system that has at least one echo canceller. An echo canceller determines delay characteristics that are associated with the received voice signal and correspondingly modifies echo cancellation processing. In a variation of the embodiment of the invention, a first echo canceller sends silence descriptor information to a second echo canceller. The second echo canceller reconstructs a voice signal based upon the silence descriptor information and excitation vector information.

Abstract: Optical performance measurements are taken in an optical network and displayed in a form that allows an operator to enter fault information related to the measurements, or to automatically generate fault alarms to the operator, based on processing of the measurements. The optical measurements may be individual power measurements taken for each light-path at various points in each node it traverses, such as amplifiers, multiplexers/demultiplexers or at an interface with another node.

Abstract: A switch core is set forth that comprises a plurality of duplex switches that are interconnected with a interconnection fabric to implement, for example, strictly non-blocking operation of the switch core for reciprocal traffic. In one embodiment, an N-way reciprocal switch is implemented. The N-way reciprocal switch comprises a plurality of duplex switches numbering N of at least a 1×(N?1) switch type (e.g., the duplex switches have at least N?1 ports available for connection to implement the interconnection fabric). The interconnection fabric interconnects the plurality of duplex switches so that each duplex switch is connected to every other duplex switch used in the interconnection fabric by a single connection. A similar architecture using switches numbering N of at least a 1×N switch type are also set forth.

Abstract: A method for modeling digital signal processors (DSP) in a C++ environment is disclosed. In particular, the method models and converts an operation (or function) from a floating-point model to a given DSP fixed-point processor model. The invention defines a vector space for each DSP fixed-point processor, as a direct sum of each distinct fixed bit length data representation sub-space. The direct sum of all DSP fixed-point processor vector sub-spaces forms a working vector space. Furthermore, the invention defines an operator projection to be performed on the working vector space such that redundancy in the operational behavior of the DSP's to be modeled may be exploited. In the preferred embodiment, the working vector space is in a C++ environment. A C++ class is defined for each distinct fixed bit length data representation of a given DSP fixed-point processor. The behavior of the given DSP fixed-point processor is then modeled in a C++ environment using the library of classes.

Abstract: Telephone conversations carried over an internet protocol network or other asynchronous network can be monitored for quality and rerouted if the error rate of data transmission through the network exceeds some predetermined threshold value. One or more counters in a switching system along a pathway records the occurrence of missing, delayed, or out of sequence cells or data packets over time. At some predetermined threshold value, considered to be an excessive error rate, the switching system can be used to trigger a rerouting of the telephone call or subsequent calls to pathways with better error rates and therefore better transmission quality.

Abstract: A low-cost, high-speed data switching system and method uses several parallel switching systems or fabrics. In one of various embodiments, for example, the constituent data flows in a data stream can be selectively routed to a switching fabric that has the lowest input data rate. Data flows can be assigned to the various switching fabrics so as to balance the amount of data passing through each parallel system. Data flows can be re-assigned on an as-needed basis to insure maximum throughput. In the case where a data flow initially routed into one switching fabric must be re-routed to a different fabric, the ordering of data packets can be preserved by withholding the transfer of packets through the second fabric until the packets previously sent into the first fabric have cleared. Methods and apparatus of the present invention find application to parallel computing as well.

Abstract: An echo canceller circuit for use in an echo canceller system is set forth that provides sensitive double-talk detection. The echo canceller circuit comprises a second digital filter having adaptive tap coefficients to simulate an echo response occurring during the call. The adaptive tap coefficients of the second digital filter are updated over the duration of the call using a Least Mean Squares process having an adaptive gain a. A channel condition detector is used to detect channel conditions during the call. The channel condition detector is responsive to detected channel conditions for changing the adaptive gain a during the call. For example, the channel condition detector may detect the presence of a double-talk condition and set the adaptive gain a to zero. Similarly, the channel condition detector may detect the occurrence of a high background noise condition and set the adaptive gain a to a level less than 1 that is dependent on the detected level of the background noise.

Abstract: A method and apparatus for reducing the complexity of linear prediction analysis-by-synthesis (LPAS) speech coders. The speech coder includes a multi-tap pitch predictor having various parameters and utilizing an adaptive codebook subdivided into at least a first vector codebook and a second vector codebook. The pitch predictor removes certain redundancies in a subject speech signal and vector quantizes the pitch predictor parameters. Further included is a source excitation (fixed) codebook that indicates pulses in the subject speech signal by deriving corresponding vector values. Serial optimization of the adaptive codebook first and then the fixed codebook produces a low complexity LPAS speech coder of the present invention.

Abstract: A way of testing a wavelength division multiplexed (WDM) system without requiring connection to data source/sink equipment. A test signal is introduced onto a light path of interest in the system, and the test signal is monitored downstream for signal integrity. Lack of signal integrity is used to identify a fault in the lightpath. Alternatively, optical loopbacks may be used to localize and identify a fault in the lightpath. The lightpath includes a source optical node connected to a sink optical node via intermediate optical nodes. An optical signal introduced at the source node with a destination at the sink node may be looped back at any one of the intermediate nodes or the sink node to localize and identify a fault in the lightpath.

Abstract: An arbitration unit according to an embodiment of the present invention is disclosed. The arbitration unit includes an allocation unit that assigns a first number of slots in a frame to a first flow and a second number of slots in the frame to a second flow. The arbitration unit includes a scheduling unit that assigns first slot positions to the first number of slots in the frame and second slot positions to the second number of slots in the frame using a binary distribution tree.

Abstract: A communication system (10) receives a communication signal comprising first and second data with different compression levels, such as highly compressed and weakly compressed levels. A mode detector (15) detects the level of compression. One or more signal decoders (20, 22) decode the highly compressed data. An analyzer (30) determines the type of enhancement required. One or more processors (48, 50, 80) enhance the data as required. An encoder (60) reencodes the enhanced decoded data. Metrics (90) may aid the operation of the analyzer (30). The communication system may include telephones (120, 122, 124, 126). Processors (103, 104) enhance signals in opposite first and second directions between pairs of the telephones. A path (106) connects the processors in tandem. One or more switches (101, 102) disable signal enhancement for one of the processors depending on the compression level of the signals to avoid degrading call quality.

Abstract: A method and apparatus is provided for use in an inband signaling system for quickly resynchronizing devices in the system after synchronization is lost. Synchronization is quickly established by continuing to apply a synchronization technique even while the devices are synchronized, as opposed to starting the synchronization technique only after synchronization is lost.

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 wherein 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 fiber optic gasket includes one or more apertures to individually retain optical fibers from one or more fiber optic cards positioned within an enclosure. A slit within the fiber optic gasket associated with each aperture facilitates placement of an optical fiber within an aperture. The fiber optic gasket includes a layer of conductive material for electromagnetic interference protection. When installed in the enclosure, the fiber optic gasket comes in contact with a door that is removably connected to the enclosure. An electro-magnetic interference shield is provided at the interface between the door and the fiber optic gasket. Optical fibers can extend out of the enclosure without causing harmful electromagnetic energy from leaving or entering the enclosure.

Abstract: A pilot tone generator receives optical energy from an optical communication medium carrying a plurality of optical signals. Each optical signal carries data modulated at a unique wavelength and further modulated with a unique identification signal. The identification signal has an amplitude corresponding to an optical power of the associated optical signal. The pilot tone receiver detects each identification signal from the optical energy received and determines its corresponding amplitude. The pilot tone receiver calculates the optical power of each optical signal in the optical energy in response to the amplitude of the associated identification signal.

Abstract: A method and system for designing a bi-connected ring-based network is provided, which designs from scratch or converts an existing network to a dual-homed ring-based network. The network covers the locations capable of being bi-connected with one or more cycles/rings. The traffic demand is then routed via the cycles, in such a way so as to minimize the amount of network traffic management equipment required.

Abstract: A compact heat exchanger increases the cooling capacity within existing sizes of electronics cabinets. The heat exchanger includes a core having multiple thermally conductive members defining internal and external pathways. The internal pathways define inlets for receiving fluid from and outlets for passing fluid to the inside of the enclosure. The external pathways define inlets for receiving fluid from and outlets for passing fluid to the outside of the enclosure. The heat exchanger further includes an external pathway fluid driving mechanism coupled to the core in fluid flow relationship with the external pathways that causes fluid to flow in a first direction through the external pathways and an internal pathway fluid driving mechanism coupled to the core in fluid flow relationship with the internal pathways that causes fluid to flow in a second direction through the internal pathways in a manner facilitating heat exchange by the multiple thermally conductive members.

Abstract: An optical transceiver includes a housing with an optical connector in mechanical contact therewith. The optical connector at the optical transceiver allows for an optical connector at an end of a fiber optic drop cable to be connected directly to the optical transceiver. This transceiver housing/optical connector arrangement replaces labor and material intensive “pigtail” designs in which a “pigtail” fiber optic cable stemming from the optical transceiver connects to one side of a dual connector in an Optical Network Terminal (ONT) and a fiber optic cable from an Optical Line Terminal (OLT) connects to the other side of the dual connector. Thus, optical connections and associated materials and labor are reduced in an optical network terminal.

Abstract: Detectors determine the presence of valid sinusoids for DTMF, MF-R1 and MF-R2 protocols for encoding dialed digits. The detectors split electrical signals into subbands. Energies within the subbands are analyzed to determine a presence of sinusoids corresponding to frequencies of dialed digits. In one embodiment, the detectors comprise a PS-IIR filter to split the electrical signal into the subbands. The detectors further comprise at least one bank of filters, such as notch filters, corresponding to the number of possible relevant frequencies within the respective subbands. The detectors further comprise detection logic comprising tests, which may include analyzing the output(s) from the bank of filters. Optionally, a preclassifier is employed to predetermine which filters in the banks of filters are to be executed. The detectors, typically deployed in digital signal processors, allow for an increase in the density of detectors and provide robust performance in talk-off situations.

Abstract: Methods and apparatus for managing an optical network using pilot tones are provided. One method includes generating a list of pilot tones contributed by a selected node to each of its target nodes. Network pilot tone sources are re-configured so that a pilot tone source of any optical path incorporating one of the target nodes has a value distinct from the listed pilot tones. The selected node can then be added to the network. Another method includes generating a list including all selected network nodes to be incorporated into a new optical path and nodes adjacent to the selected network nodes. Network pilot tone sources are re-configured until a pilot tone source associated with the new optical path has a pilot tone distinct from that of any listed node. The new optical path can then be added to the network.