Abstract: The disclosure relates to a method of monitoring a communications network comprising a plurality of node equipment 2, e.g. switches, and link equipment, e.g. fibre optic links, in which performance parameters of individual components of the node equipment are used to determine an overall performance parameter for the node equipment. By comparing like performance parameters for individual network elements, the performance of different types of network element can be compared with each other. Parameters which can be monitored include quality of service, cell discard, cell loss, and other measures of network performance. Connection tracing through the plurality of node equipment and link equipment is also achieved.

Abstract: Disclosed is a micromirror for a hybrid optoelectronic integrated circuit, a method for manufacturing the same, a micromirror-photodetector assembly and an assembly of hybrid optoelectronic integrated circuit for receiving light. The micromirror the present invention comprises a silicon substrate and at least one V-shaped groove formed in the silicon substrate and the V-shaped groove has an inclined surface reflecting light emitted from an optical waveguide to a photodetector. The alignment of the photodetector and the optical fibers is achieved without an additional attachment equipment, by inserting the optical fibers into the V-groove.

Abstract: In accordance with the present invention, there is provided a linear antenna array comprising a number of antenna elements and a feed network, wherein the feed network is operable to apply the cumulative effect of a progressive phase shift across the antenna elements of the array and a stepped complex operator shift to selected groups of antenna elements of the array, whereby a down tilted and null-free coverage by a resulting radiation pattern can thereby be provided. The complex operator can be phase, amplitude or a combination of both. The antenna array can be a layered antenna and the phase shifts in the feed network can be provided by differing length transmission paths, whilst any amplitude shift can be provided by unequal power dividers. In order to provide no down tilt and just null fill-in, then the progressive phase shift can be specified to be zero.

Abstract: A dispersion compensator exhibiting low polarisation mode dispersion is constructed from a polarisation beam-splitter, a .pi./4 rotation Faraday rotator, and a matched pair of polarisation maintaining fibres provided with a matched pair of chirped Bragg reflection gratings. The waveguides are oriented with respect to the beam-splitter so that light reaching the waveguides from the beam-splitter via the rotator is launched into both waveguides with a polarisation state aligned with the same polarisation axis (i.e. both fast or both slow).

Abstract: A method and apparatus for updating user data stored on databases distributed throughout a teleconmmunications network is described. A central database server stores a master copy of the user data from which a transaction journal may be created. The transaction journal includes every change in user data entered at the central database server during provisioning sessions. The remote nodes of the network contain databases which ideally store user data which is consistent with the user data records in the central database server. To achieve this the new transaction journal entries are propagated at regular intervals to the remote nodes. During a transition period, the central database server and the remote nodes are updated with new software.

Abstract: The current flowing in an output field effect transistor is sensed by a parallel circuit arrangement which derives a sensed current representing the current flowing in the output transistor. The parallel circuit arrangement comprises series-connected CMOS transistors which are connected together in order to derive a current output which is representative of the load current through the output transistor. In a short circuit protected output buffer, the sensed current is compared with a reference current and if it exceeds the reference current the amplitude of the drive signal to the output transistor is reduced.

Abstract: A communications network comprising N node elements operates N decision tables for controlling admission and control of data communications to the N node elements (FIG. 2). The performance of the network is optimised with respect to admission and control of commission data. Each node element generates corresponding performance data (FIG. 5), and the N decision tables and N performance data are collected at a central network controller. The network controller determines a set of new decision tables from the collected decision tables (FIG. 10) and distributes a new set of decision tables to each of the N node elements, which then proceed to operate the new decision tables throughout the network.

Abstract: A method for local routing of calls coming from the switched telephone network in a cellular mobile network includes, following a procedure of locating/authenticating the mobile subscriber transmitter/receiver with a fixed radio locating FRLT terminal, forwarding to the FRLT personal communications service subscription data, such as a radio receiver/transmitter (RTR) confidential code and identification number, in attributing a direct inward dialling number (DID number), to the transmitter/receiver and, within the FRLT, forwarding the DID number and the RTR confidential code to a service access authentication center (SAAC). Upon receiving an incoming call from a subscriber telephone handset (STH), an interrogation message with the RTR telephone number is forwarded to the SAAC, and from the SAAC to the FRLT. Upon reception of the interrogation message, a call message containing at least the DID number is forwarded from the SAAC to the FRLT.

Abstract: An optical interferometer incorporating a signal strength modulated optical phase delay, such as a Kerr effect element in one of its arms is employed to improve the cross-talk isolation/extinction ratio of an optical switch, amplitude modulator, or amplitude modulated optical transmitter. The Kerr element is constructed so that its intensity dependent optical path length is such as to provide destructive interference at the interferometer output when the light input to the interferometer is low, and constructive interference when the input is high. The place of the Kerr effect element can alternatively be taken by an electro-optic modulator driven with an electrical version of the data modulation appearing on the optical signal.

Abstract: In video on demand (VOD) problems may be caused by potential transmission, queuing and processing delays in the network which can lead to erratic and erroneous operation of VOD systems when responding to viewer commands. This problem is overcome by employing a video frame reference number in the return signalling channel to the video server so that the command is related to the correct frame. At the same time the viewers display is halted until the revised frame is re-received so that the display is re-enabled at the correct point in the program.

Abstract: A control system for an optical element such as an optical amplifier in an optical transmission system determines the transmitted optical signal power in each of a plurality of different optical wavelength bands, determines which of the powers is closest to a threshold, and controls an output power of the element, or controls a parameter which affects the threshold, on the basis of the power closest to the threshold. Since there is no longer any need to allow a margin for possible gain variations between different wavelengths, power output can be controlled with reduced upper or lower margins, and thus error rates reduced, or transmission distances increased.

Abstract: For economic reasons, space saving and simplicity in design, an assembly is provided of an electronic device and a flexible container with the electronic device inside the container and having electrical conductors extending from the chamber for connection to electrical equipment outside the container. To prevent overheating, the assembly also includes a heat transfer device. This device has a first heat conductive element inside the chamber, and thermally connected to the electronic device, and a second heat conductive element disposed outside the container. The two heat conductive elements are fastened together with the wall of the container clamped between them for conduction of heat to the second element. To avoid forming apertures in the wall for connection purposes, the second heat conductive element is formed with channels at its edges which receive edges of the first element and with the wall in between and lying within the channels.

Abstract: This invention relates to a flat printed antenna for transmission and/or reception of microwave signals of the type that includes particularlya plate of dielectric substratean earth plane formed by a first conductor layer deposited on a first face of the plate of dielectric substrate,a radiating element (30) formed by a second conductor layer deposited on a second face of the plate of dielectric substrate,means of feeding the antennaThis antenna has a fundamental mode, in which it generates a radiation pattern having a maximum in the direction perpendicular to the plane containing the radiating element, and at least one higher mode, in which it generates a radiation pattern with low elevation,According to the invention, the radiating element has at least one slot (31 to 34) allowing the control of the resonance frequency of a chosen higher mode.

Abstract: The present invention relates to a radio communications base station antenna. In a first embodiment, the arrangement comprises a plurality of antennas each capable of forming a separate narrow beam in azimuth, wherein the antennas are positioned such that the beams formed by the antennas overlap and the centre of each beam falls midway between the centre and first null of the adjacent beam to provide a uniform coverage in azimuth. The present invention can be deployed in mobile wireless terminals. The use of downlink beam-forming is proposed for systems such as Digital AMPS (D-AMPS). A downlink beam-former typically consists of a number of narrow beams formed by either multiple narrow beamwidth antennas or an array of elements in conjunction with a fixed beam-former. Signal processing techniques can then be used to select an appropriate beam directed towards the subscriber.

Abstract: A data communications system comprises a bus for transferring data, a plurality of devices sharing the bus by time-division multiplexing, wherein time is divided into time slots and a frame is assembled with a predetermined number of time slots, a processor for assigning to each of the devices time slots and for multiplexing data to be transferred to each of the devices into a data frame TXD and demultiplexing a data frame RXD including data transferred from each of the devices, wherein data transmission between the processor and each of the devices is performed during the time slots assigned to each of the devices, and an interfacing module, coupled with the processor and each of the devices, for multiplexing data transmitted from each of the devices to transfer to the processor.

Abstract: A system and method are disclosed for generating a submap for nodes located within a flat network without reproducing the entire flat network in the submap. One method for implementing a flat network in a hierarchical network management system includes the steps of selecting a node of the flat network to create a submap having a node symbol, wherein the node symbol corresponds to the node, and generating a temporary symbol, in accordance with a predetermined criterion, for a link originating from the node symbol and terminating at the temporary symbol to represent a connection between the node and a second node of the flat network, wherein the temporary symbol maintains a characteristic of the second node. One system for establishing a submap for a flat network includes a processing unit coupled to a network processor and a storage unit coupled to the processing unit for storing data.

Abstract: An arrangement for the detection of fraudulent use of a telephone subscriber's instrument in a mobile telephone system includes an input preprocessor (110), a neural network engine (111) coupled to the preprocessor, and an output postprocessor (112) coupled to the neural network engine. The preprocessor determines for each subscriber a first long term calling profile, a second short term calling profile, and a subscriber profile pattern comprising the difference between the first and second profiles. Each calling profile and subscriber profile pattern comprises a set of values for a respective set of call attributes. The neural network engine comprises a self organizing map trained to effect pattern recognition of the subscriber profile patterns and a multilayer perceptron adapted to determine for each recognized pattern a value indicative of the probability of a fraud being associated with that pattern.

Abstract: Several low power, low voltage swing, BiCMOS circuits for used in high speed chip-to-chip communications are described. In particular a BiCMOS low voltage swing transceiver comprising a driver and a receiver with low on-chip power consumption is reported. Operating at 3.3.V, the universal transceiver can drive and receive low voltage swing signals with termination voltages ranging from 5V down to 2V, without using external reference voltages and at frequencies exceeding 1 GHz. On-chip power consumption is much lower than that of known CML/ECL type transceivers having comparable speeds.

Abstract: An optically amplifying waveguide guides both the LP.sub.01 and the LP.sub.02 mode. Its erbium distribution profile is preferentially matched with the modal field distribution of the LP.sub.02 mode. The waveguide is provided with long period perturbations of a pitch and strength that resonantly couples signal power of different wavelengths from propagation in the LP.sub.01 mode to propagation in the LP.sub.02 mode and back again to propagation in the LP.sub.01 mode whereby the longitudinal distribution of gain along the waveguide at one wavelength is longitudinally displaced with respect to that at least one other wavelength.