Abstract: A voltage controlled oscillator has a cross-coupled negative resistance cell formed as an integrated circuit connected to off-chip components of a high-Q resonant tank circuit. To counteract spurious oscillations brought about by package parasitics caused by the interconnection of the chip to the external components, the cell is provided with a degeneration impedance. Typically, a pure inductor is used if all the elements of the tank circuit are off-chip. In a case where the tank circuit includes an on-chip fixed capacitor, the degeneration impedance may take the form of a capacitor.

Abstract: An alarm signal processing circuit is provided for an integrated circuit having alarm signal generating circuitry for generating alarm signals having active and inactive states, and for connecting to a microprocessor. An alarm signal is stored in an alarm register which stores an inactive alarm signal until receipt of an active alarm signal, whereupon it stores the active alarm signal until receipt of an alarm register reset signal from the microprocessor. The alarm signal is also detected by an alarm detector which generates an event signal which is active when the alarm signal changes its status. An event register stores an inactive event signal until receipt of an active event signal, whereupon it stores the active event signal until receipt of an event register reset signal from the microprocessor. The event register outputs an event interrupt signal which is active when the stored event signal is active.

Abstract: Control-type continuous ramp converting apparatus and method therefore. The present invention provides real-time processing of neurons in the neural network, easy implementation and reduction of manufacture cost of high density neurons in the neural network.

Abstract: An active optical fiber for use in an amplifier or laser has an inner cladding and an outer cladding. An index grating is written into the inner cladding to provide coupling between cladding modes of pumping radiation conducted in the inner cladding. The periodicity of the index grating is selected to couple energy from cladding modes having minimal overlap with the core to cladding modes having relatively high overlap. The efficiency of pumping the radiation amplifying medium of the core is thereby improved. The fibre has utility in transmitters for broad band networks.

Abstract: A method for providing information to a caller about the present physical location of a subscriber with a telephone number. The information could include time of day, city or region, and whether toll charges apply or are increased. A method is also provided for giving a telephone user information about the present physical location of a subscriber with a portable number.

Abstract: A channel waveguide structure which can be incorporated into VLSI (very large scale integration) integrated circuits uses a SiGe (silicon germanium) alloy core and Si (silicon) top and bottom cladding layers. The core may consist of only a SiGe alloy layer or it may be formed as a superlattice containing Si layers alternating with SiGe alloy layers. LOCOS (locally oxidized silicon) regions are formed on the top cladding layer at spaced locations thereby defining lateral boundaries of channels in the core.

Abstract: A method and apparatus for assisting voice-dialing using a model of an individual's calling behavior to improve recognition of an input name corresponding a desired telephone number. When the individual picks up a telephone, activity is initiated in a neural network model of the individual's calling behavior that predicts the likelihood that different numbers will be called, given such predictors as the day of the week and the time of day. The model is constructed by training the neural network with data from the user's history of making and receiving telephone calls. The auditory output from an automatic speech recognition system and the output from the user model are integrated together so as to select the number that is most likely to be the number desired by the speaker. The system can also provide automatic directory assistance, by speaking the number aloud rather than dialing it. In one version, the system is a personal directory for an individual maintained on that individual's personal computer.

Abstract: A telecommunications system comprises a public network and one or more private networks each comprising a plurality of private exchanges (PBX's) coupled to the public network. Signal mapping from PBX to public format and inverse mapping from public to PBX format provides transparent signalling of PBX calls across the public network. This avoids the use of dedicated private lines for the private network traffic.

Abstract: An antenna assembly having an operating frequency and a vertical radiation pattern with a main lobe axis defining a downtilt angle with respect to the earth's surface. The antenna assembly comprises a plurality of antennas in first, second, and third antenna groups disposed along a backplane, the backplane having a longitudinal axis along which the antennas are disposed, and a phase adjustment mechanism disposed between the second and third antenna groups, such that adjustment of the phase adjustment mechanism results in variation of the vertical radiation pattern downtilt angle.

Abstract: In an optical TDM transmission system in which a set of N tributary channels at one bit rate are multiplexed on to a single multiplexed channel at N times the bit rate of the tributary channels, an amplitude modulation with a fundamental frequency matched to a subharmonic of the tributary bit rate is impressed on the multiplexed signal. At the demultiplexer this modulation is detected to provide a clock for separating the tributary channels in a manner which directs specific tributary channels to specific outputs without having to have recourse to reading any of the transmitted data itself.

Abstract: In an ATM network, the physical resources are shared by many connection and the bandwidth is allocated virtually to each connection. The connection admission control (CAC) algorithm uses traffic descriptors, desired quality of service (QOS) parameters etc., to compute a required bandwidth for a requested connection by which it makes a decision to admit or reject the connection. For admission control for a requested VBR connection, two required bandwidths are calculated in two different ways, both of which take into consideration impacts of CBR traffic which is being serviced. The admission decision is based on the lesser of the two bandwidths.

Abstract: The invention provides a mechanism for allowing a share memory/parallel processing architecture to be used in place of a conventional uni-processing architecture without requiring code originally written for the conventional system to be rewritten. Exclusive Access and Shared Read Access implementations are provided. A rollback mechanism is provided which allows all the effects of a task to be undone.

Abstract: Telecommunication switches (e.g., PBX's or local exchange carrier's Centrex-enabled switches) route calls in accordance with economic incentives (e.g., least cost routing) resulting from a bidding process between participating telecommunication Carriers (Carriers) by operation of a central processor, a computer referred to as a bidding moderator (Moderator). Each of the Carriers bidding for traffic over a route informs the Moderator of the rate it is willing to charge for (or other economic incentive it is willing to offer) service between two specific points in a telecommunication network, for example, from one NPA-NXX to another NPA-NXX, at some particular time. This "bid" rate may be lower than that Carrier's established rate for any of several reasons (e.g., the Carrier has excess capacity on that route at that time). The Carrier may change its bids as often as it likes during the day as traffic patterns change.

Abstract: An ATM communications system incorporates both broadband and narrowband services. A plurality of channels are adapted into groups, each group comprising a virtual circuit for transmission purposes. Each group is subsequently readapted back to individual channels. Any channel can be connected with any virtual circuit and each group of channels comprising a virtual circuit maintains time slot integrity throughout the adaptation and transmission process.

Abstract: A method and apparatus provide for operating and locating a digital cordless telephone (DCT) handset among an integrated network of base stations. The present system utilizes a standard communication protocol to establish radio communication links between terminals and a network of base stations, where each base station is directly interfaced to a local exchange and is capable of providing access to the public and/or private telephone network. Each base station is a network node that contains a copy of a common database that may be updated, as needed, to provide current information on the location of individual terminals. The common database contains various information on each base station, each terminal, and the latest location of each terminal at a particular base station.

Abstract: A quadrature downconversion stage in a radio frequency receiver compensates for leakage from the quadrature local oscillator to the input of the stage by deriving first and second feedback signals from the quadrature local oscillator. The first feedback signal is 180.degree. out of phase with the in-phase component of the signal supplied to the input of the stage and the second feedback signal is 180.degree. out of phase with the quadrature component of the signal supplied to the input of the stage. The invention reduces or cancels a d.c. offset that can appear at the output of the stage. Another advantage is the reduction of re-radiated signals resulting from the local oscillator leakage. The invention is particularly applicable to direct converters.

Abstract: An optical repeater is described which integrates an erbium doped optical fiber amplifier (EDFA) with a dispersion equalizer (DE) based on fiber gratings. The dispersion equalizer is based on parallel connection of two fiber gratings for single carrier wavelength operation, and on parallel connection of a cascade of two fibre grating branches, each carrying a plurality grating elements chirped for different wavelengths, for WDM operation at a plurality of wavelengths.The use of two gratings sections for each wavelength improves the optical bandwidth of the equalizer compared with single grating designs, doubling the effective bandwidth. Further, the grating DE is disposed between two fiber amplifier sections which share a single pump laser. Thus, this arrangement provides dispersion compensation and loss compensation in an optical repeater of lower cost, and smaller size, compared to a system of similar performance configured using discrete components.

Abstract: A system and method is implemented within a telecommunications network, such as a cellular telephone network, for maintaining updated profile information for each mobile subscriber registered within the network. Updated profile information about each mobile subscriber is maintained within a particular mobile switching center currently communicating with the particular mobile subscriber. This process is performed with minimal utilization of bandwidth between the various mobile switching centers in the telecommunications network by maintaining subscriber service profile information within mobile switching centers, even though the associated mobile subscriber has roamed from that mobile switching center. When the subscriber service profile information is updated, then the subscriber service profile information is downloaded to a mobile switching center currently serving the mobile subscriber.

Abstract: An amplifier circuit has an amplifying transistor which is switched on and off by a switching transistor under control of a control signal selectively applied to the switching transistor. In this way a selection is made whether or not to amplify an input signal on an antenna. The switching transistor forms part of the biasing circuit for the amplifying transistor such that when the switching transistor is on the amplifying transistor is biased off. A PIN diode and series resistor are together connected in shunt across the switching transistor such that the bias voltage which causes the amplifying transistor to be off causes the PIN diode to be forward biased thereby causing the antenna to be terminated with the resistor the value of which may be chosen to be 50 ohms.