Abstract: A method and system is provided for compensating polarization mode dispersion (PMD) in an optical communications system includes a controller designed to control a broadband PMD compensator to differentially delay light at each one of a plurality of selected wavelengths. At least one of the selected wavelengths lies between an adjacent pair of channel wavelengths of the optical communications system. A performance parameter value indicative of PMD is measured at each channel wavelength of the optical communications system. An estimated performance parameter value is then calculated at each selected wavelength, and an error function calculated as a function of wavelength based on the estimated performance parameter values. The broadband PMD compensator is then controlled to minimize the value of the error function.

Abstract: A method of creating/terminating a connection associated with an end-to-end path defined through a communications network. According to the invention, cross-connection download/undownload processes in each intermediate node of the end-to-end path are triggered substantially in parallel. A confirmation message indicative of successful completion of respective download/undownload processes in each intermediate node is subsequently propagated to an end-node of the path.

Abstract: A system provides evaluation of stability of an on-frequency repeater. A unique signature is imposed on RF signals transmitted by the repeater, and RF signals received by the repeater are analyzed to detect signal components corresponding to the signature. The signature signal is composed of a sequential series of signal pulses separated by a quiescent period. Respective transmit and quiescent power levels of signal components of the input signal received by the repeater are detected. These power levels are then used to estimate the system stability.

Abstract: There is provided a method and a system for determining the concentration of chromophores and reconstructing images in turbid media, such as animal tissues, using a continuous wave optical approach. In particular the approach is based on measurements of attenuation signals and the calculation of concentrations of chromophores using a predetermined scatter law. The system comprises a continuous wave photon migration model calculator coupled to an optical source and detector for estimating concentrations of chromophores and scatter parameters used in image reconstruction.

Abstract: Performance monitoring and equalization of DWDM optical links equipped with optical add/drop multiplexers (OADMs) at one or more sites is effected by selecting a direction of transmission and the end sites from the point of view of equalization. Performance monitoring and equalization of DWDM optical links equipped with optical add/drop multiplexers (OADM) is presented in this application. This approach in involves conceptually converting a multiple ends system to a “two-end” system with analogous channels (AC) to simplify the network management and equalize the DWDM channel performance. All analogous channels are treated as originating at a source analogous end and terminating at a destination analogous end for the purpose of equalization. The input power for all ACs, is adjusted at the source AE to obtain equal channel performance at the destination AE.

Abstract: A protection switching technique associated with an OP-n sublayer of a communications network is presented. Among the advantages presented by this protection switching technique of the present invention are the ability to provision logical protected subnetworks that are not constrained to the topology of the physical line systems, the ability of a single high capacity link system to support multiple protected subnetworks, the ability to provide complex protection schemes such as m:n protection within the physical link system.

Abstract: A high speed D/A converter includes a phase aligner, and a vector summation block. The phase aligner operates to ensure precise phase alignment between corresponding bits of a parallel N-bit digital signal having a data rate of at least 2 GHz. The vector addition block performs a vector addition of the phase-aligned bits of the parallel N-bit digital signal. Each bit of the parallel N-bit digital signal can be weighted to ensure a correct additive contribution to the analog signal level appearing at the output of the D/A converter. Vector addition of the weighted bits can be accomplished using a microwave signal combiner network in the form of either a multistage parallel cascade of impedance matched junctions, or a linear cascade of junctions.

Abstract: A method and apparatus for using sacrificial bits in a data stream to adjust sampling parameters for the data stream is described. The sacrificial bits are a predetermined sequence of a predetermined length. The sampling parameters are perturbed during transmission or reception of the sacrificial bits in order to provide information useful in adjusting the sampling parameters of the apparatus. Adjustment is accomplished by computing a bit error rate during the perturbing of sampling parameters in order to probe edges of an eye closure of the detected signal. The advantage is faster homing on optimal sampling parameters with little sacrifice of transmission capacity.

Abstract: Failures within a communications network are compensated for by establishing a set of two or more communications paths across the network between a source node and a destination node. At the source node a status of each one of the set of communications paths is maintained, and the data traffic is load-balanced across those ones of the set of communications paths having an operational status. In the event of failure of a physical network resource, a failure notification message is propagated to the source node, which registers a non-operation status of each path traversing the failed resource. Load-balancing of the data traffic continues across the remaining operational paths. Traffic may be prioritized based on service level agreements and quality of service protection guarantees.

Abstract: An optical communications system is adapted for connection to an optical fiber link of an optical communications network. The system obtains a fiber identifier respecting the optical fiber link; a respective optimum setting of one or more parameters of the optical communications system; and adjusts a respective value of each parameter in accordance with the respective optimum setting. The fiber identifier can be obtained from a value of at least one fiber transmission property of the optical fiber link. The fiber transmission property value is used to search a look-up table of class definitions, each class definition including a respective class identifier and at least one corresponding characteristic transmission property value. A class identifier is selected as the fiber identifier from the class definition for which each characteristic transmission property value most closely matches a corresponding fiber transmission property value.

Abstract: A directional coupler for a modem has a high common mode noise rejection characteristic with low transmit signal leakage, and reduced distortion of components mixed with a received signal. A primary filter network is connected to a communications circuit. The primary filter network has an output connected to an input of an amplifier. A feedback network is connected between the input and output of the amplifier. The primary filter network, the amplifier and the feedback network are arranged to provide a virtual ground at the input of the amplifier, and a filter characteristic which attenuates frequencies in the transmit signal band. The advantage is reduced component count while providing excellent transmit signal rejection and reducing received signal distortion.

Abstract: A method and system enable cross connection of an incoming data stream to one or more outgoing data streams. Each data stream comprises respective incoming and outgoing frames. Each frame includes one or more rows, and each row comprises a respective plurality of data segments. A reserved memory space is provided having a data storage capacity equal to an integer multiple of a data segment and less than one complete row. A data segment of an incoming row of an incoming frame is written to the reserved memory space. Subsequently, the data segment of the incoming row is read to an outgoing row of an outgoing frame from the reserved memory space. The writing and reading steps are timed such that the data segment is read from the reserved memory space before being over-written by another data segment.

Abstract: A mixing device for low speed precision mixing of contents of a vessel has a support member adapted to be rotatably supported in spaced relationship from a bottom portion of the vessel and separated therefrom by a gap, and a brush assembly depending from the support member for sliding engagement with the bottom portion of the vessel. Low speed rotation of the support member within the vessel causes the brush assembly to sweep the bottom portion of the vessel while mixing the contents of the vessel. The brush assembly can be made of a resilient coil or a plurality of filamentary or lamellar elements, affixed to the support member. This device provides controlled and repeatable mixing and is well suited for use in drug dissolution measurement apparatuses used for assessing drug release characteristics of solid oral pharmaceutical products.

Abstract: A method and apparatus for remotely updating firmware saved in a FLASH memory of a communication device connected to a network is presented. The FLASH memory is partitioned into at least a first and a second portion. A first firmware load is stored in the first portion. During run-time of the first firmware load, at least a portion of an updated firmware load is transmitted through the network to the communication device. The transmitted portion of the updated firmware load is temporarily stored in a buffer of the communication device. At least a portion of the first firmware load is copied into a random access memory (RAM) of the communication device. Execution, from the RAM, of the copied portion of the first firmware load is triggered. Under control of the copied portion of the first firmware load, the transmitted portion of the updated firmware load is saved to the second portion of the FLASH memory.

Abstract: An Enhanced Communication Services layer is adapted for connection intermediate a content application layer and a transport services layer of a communication network. The content application layer is adapted to generate payload data of a service instance. The transport services layer includes a physical fabric of the communication network and is adapted for end-to-end transport of the payload data across the communication network. The Enhanced Communication Services layer comprises a Contact Agent, an Exchange Agent and a Transport Agent, The Contact Agent is adapted to discover information identifying parties involved in a service instance. The Exchange Agent is responsive to the Contact Agent, and adapted to select, from a network space comprising one or more transport services, a best match set of transport services for the service instance. Finally, the Transport Agent is responsive to the Exchange Agent for engaging the selected set of transport services for the duration of the service instance.

Abstract: This invention relates to fabrication techniques for the creation of new optical elements, an asymmetric (non-reciprocal) diffraction grating and a passive nonlinear optical (visible, microwave, etc.) isolator (diode). It may have potential applications in the field of optical detection (spectrometers) and communications (circulators, wavelength division multiplexing circuits, etc.), etc. One of applications of this proposal is the significant reduction of the noise level in optical communication systems or any other optical systems using laser sources. Another potential interest of these diodes is the fabrication of integrated laser gyroscopes for applications in aviation, etc.

Abstract: In method of controlling an optical amplifier dynamically adapts to both configuration and performance changes of a communications system. An error vector is calculated to indicate a difference between respective detected values and target values of a parameter of a light beam downstream of the optical amplifier. A sensitivity matrix indicative of a sensitivity of the detected parameter value to incremental changes in a control variable of the optical amplifier is calculated. A predicted optimum value of the control variable is then calculated using the error vector and the sensitivity matrix. Calculation of the predicted optimum control variable value can be iterative, with the sensitivity matrix calculated either during each iteration, or at the beginning of each optimization run. As a result, optimization of the amplifier control variables is performed based on a sensitivity matrix that accurately reflects the performance of the amplifier.

Abstract: A system for provisioning a dynamic multicast group over a differentiated services (DS) network includes an a plurality of edge nodes, each of which includes a respective multicast traffic engineering entity. An ingress node is adapted to serve as a source of data traffic of the dynamic multicast group. An egress node is adapted to serve as a sink of the data traffic of the dynamic multicast group. The multicast traffic engineering entity of the egress node is adapted for receiving information respecting a predetermined service level specification (SLS) of the dynamic multicast group; and provisioning a distribution path from the egress node back to the ingress node, on the basis of the received information respecting the SLS.

Abstract: A modular rotatable food tray supported by a vertical support member features tray segments that are easily removable and free standing. Each tray segment has a depending clip that is received in a hub of a bearing for rotatably supporting the tray. The individual tray segments may be removed for filling and cleaning, and segments of different configuration can be used for different purposes. The trays can also be removed for serving away from the support member.