Patents Assigned to STC plc
  • Patent number: 5278991
    Abstract: In a cellular radio system having a two layer cell structure comprised by macrocells (1) overlaying microcells (2), handover occurs only via the macrocell layer. Thus when the quality of a call handled by a microcell (2) deteriorates below predetermined criteria the call is handed up rapidly to the umbrella macrocell and is only handed back down to a microcell when the handset has been in that microcell for a predetermined time and the quality of the link thereto exceeds predefined criteria.
    Type: Grant
    Filed: February 14, 1991
    Date of Patent: January 11, 1994
    Assignee: STC PLC
    Inventors: Peter A. Ramsdale, Philip S. Gaskell
  • Patent number: 5265263
    Abstract: In a cellular radio system including a plurality of cells (e.g. cell sectors or micro cells) (4, 5, 8, 9, 10, 11) each normally using a respective channel for interference reduction purposes, a number of the cells are arranged in groups (6) and in the event of a cell associated with equipment moving within a group (6), all cells (4, 5, 8, 9, 10, 11) of that group use a common channel whereby to facilitate handover between them.
    Type: Grant
    Filed: February 14, 1991
    Date of Patent: November 23, 1993
    Assignee: STC PLC
    Inventors: Peter A. Ramsdale, Philip S. Gaskell
  • Patent number: 5237593
    Abstract: A first (receiver), for example, pseudo random binary sequence (PRBS) generator (6) is synchronized with a second identical PRBS generator (2) at a tramsitter by adding a PRBS (u(x)) to a data stream (w(x)). The data stream includes a known value at periodic intervals. The received data is framed (5) and thus the position of the known data values determined. The received data is sampled at these positions to produce a sequence of samples (s(x)) comprising a sampled version of the transmitter PRBS. The phase of the transmitter generator (2) is determined for the samples and the phase of the receiver generator (6) adjusted to correspond. (FIG. 1). Implementation with sequence generators other than binary sequence generators are also discussed.
    Type: Grant
    Filed: May 1, 1990
    Date of Patent: August 17, 1993
    Assignee: STC, PLC
    Inventors: David A. Fisher, Simon D. Brueckheimer
  • Patent number: 5228026
    Abstract: A communication procedure suitable for a cordless telephone system involves time division duplex radio communication between a handset 11 and a base station using alternating bursts of transmission over a single radio channel. Once a radio link has been set up, initial transmissions carry a synchronization logical channel S and a signalling logical channel D multiplexed together, but the link may switch to bursts carrying a communications logical channel B for the speech data and the signalling logical channel D. Burst synchronization is achieved by the asynchronous detection of words in a synchronization channel S. These words have bit patterns reducing the probability of incorrect asynchronous detection of them. If one part ceases to receive handset signals from the other, it transmits a special signal, informing the other part. This enables both parts to detect the failure of a link at substantially the same time, so that their actions to re-establish the link are synchronized.
    Type: Grant
    Filed: November 26, 1990
    Date of Patent: July 13, 1993
    Assignees: British Telecommunications Public Limited Company, Ferranti Creditphone Limited, GEC Plessey Telecommunications Limited, Mercury Communications Limited, Orbitel Mobile Communications Limited, Shaye Communications Limited, Phonepoint Limited, STC PLC
    Inventors: Richard Albrow, Nigel E. Barnes, Graham E. Beesley, Chris Cant, Malcolm Crisp, Michael T. Dudek, Rupert Goodings, David C. Odhams, Peter N. Proctor, Ian Rodgers
  • Patent number: 5220643
    Abstract: A neural plane, which can form the basis of a neural network or a component thereof, is comprised by an optical modulator, an electrical non-linearity circuit and an optical detector interconnected whereby in use the non-linearity circuit controls the modulator in dependence on the detector output. There are parallel arrays (10, 11, 12) of such modulators, non-linearity circuits and detectors (M, T, D, 30, 33, 34). The modulator, non-linearity circuits and detectors have components formed in a common semiconductor substrate (20), for example by VLSI techniques with a silicon substrate, the modulators (30) may be comprised by liquid crystal on silicon in that case (FIGS. 4, 7).
    Type: Grant
    Filed: May 24, 1990
    Date of Patent: June 15, 1993
    Assignee: STC PLC
    Inventor: Neil Collings
  • Patent number: 5220622
    Abstract: A holographic optical correlator includes a matched optical filter and control means therefor including a memory. In use searching for occurrences of an item to be found is carried out by the control means controlling the input and Fourier transform planes of the filter and a coherent light source for parallel optical processing of the memory content and the output plane of the filter provides information to the control means as to the location in the memory of occurrences of said item. The complexity of the detector means in the output plane can be reduced in comparison with previous proposals by moving the item to be sought step-wise across the input plane. The detector means then may comprise a single column of detectors which are required to detect a peak correlation signal within a predetermined range.
    Type: Grant
    Filed: November 21, 1990
    Date of Patent: June 15, 1993
    Assignee: STC PLC
    Inventor: Robert W. A. Scarr
  • Patent number: 5208812
    Abstract: A communication procedure suitable for a cordless telephone system involves time division duplex radio communication between a handset 11 and a base station 3 using alternating bursts of transmission over a single radio channel. Once a radio link has been set up, initial transmissions carry a synchronization logical channel S and a signalling logical channel D multiple together, bu the link may switch to bursts carrying a communications logical channel B for the speech data and the signalling logical channel D. Bursts synchronization is achieved by the asynchronous detection of words in a synchronization channel S. These words have bit patterns reducing the probability of incorrect asynchronous detection thereof. If one part ceases to receive handset signals from the other, it transmits a special signal to inform the other part. This enables both parts to detect the failure of a link at substantially the same time, so that their actions to reestablish the link are synchronized.
    Type: Grant
    Filed: November 26, 1990
    Date of Patent: May 4, 1993
    Assignees: British Telecommunications Public Limited Company, Ferranti Creditphone Limited, GEC Plessey Telecommunications Limited, Mercury Communications Limited, Orbitel Mobile Communications Limited, Shaye Communications Limited, Phonepoint Limited, STC PLC
    Inventors: Michael T. Dudek, Rupert Goodings, Emlyn Jones, David C. Odhams, Peter N. Proctor
  • Patent number: 5201017
    Abstract: Soliton-type interaction is eliminated in optical fibre communications system by making the fibre appear to be a passive optical pipe to a signal to be transmitted along it. In particular, the signal to be transmitted is intensity modulated and at a first wavelength which is greater than the minimum dispersion wavelength of the fibre by a predetermined amount. This signal is launched simultaneously into the fibre with a signal of dark pulses of the same format but at a wavelength less than the minimum dispersion wavelength by the predetermined amount. As a result the light transmitted in the fibre is of constant intensity and soliton-type effects, which rely on intensity variation for their formation, do not occur.
    Type: Grant
    Filed: October 30, 1990
    Date of Patent: April 6, 1993
    Assignee: STC PLC
    Inventor: Kevin C. Byron
  • Patent number: 5161153
    Abstract: A broadcast facility is provided in a synchronous network comprising a number of nodes (b 20l ) coupled via a star coupler (b 21l ). Data is transmitted via the network in a sequence of frames. Each node with a public write to send transmits it to all system nodes (including itself) in the next available frame. Each node has its own identifying characteristic, e.g. a unique assigned frequency. These identifying characteristics determine the notional order in which data packets within a frame are received thus providing each frame with a timestamp.
    Type: Grant
    Filed: October 5, 1990
    Date of Patent: November 3, 1992
    Assignee: STC PLC
    Inventor: Richard J. Westmore
  • Patent number: 5161155
    Abstract: An automatic telephone system enabling subscribers access to more than one network (3,4). The subscriber's line (2) accesses the networks (3,4) via a highway providing at least two traffic channels (B) and one signalling channel (D). The signalling channel (D) conveys call setting and other signalling for calls set up via any traffic channel (B). Access of a particular traffic signal channel to a particular network is provided by an intelligent multiplexer/concentrater (1) in response to a network identifier carried by the signalling channel, for example an appropriate value of a SAPI (Service Access Point Identifier) in the case of an ISDN I-Series signalling system.
    Type: Grant
    Filed: September 21, 1989
    Date of Patent: November 3, 1992
    Assignee: STC PLC
    Inventors: Arthur J. Dyer, Stephen C. Redman
  • Patent number: 5160972
    Abstract: A method of installing a cable, particularly but not exclusively in a duct filled with flowing liquid, wherein, as the cable is deployed, the strain in the cable is determined by sending a signal down the cable and receiving a signal back from the cable. The speed of deployment is adjusted according to the strain detected. Preferably the system is applied to optical cables, and a radio frequency signal is modulated on an optical carrier. Optical connection to the cable on the rotating drum is made via an optical slip-ring. The front end of the cable has a silvered end termination for reflecting the modulated signal back along the fibre to be detected by an optical receiver, and there is a vector voltmeter for determining the phased difference between the signals to thus determine the strain in the cable.
    Type: Grant
    Filed: September 9, 1991
    Date of Patent: November 3, 1992
    Assignee: STC PLC
    Inventors: David L. Walters, Martin Healy, Ernest C. Marlow, David F. Harrison
  • Patent number: 5159607
    Abstract: Apparatus for synthesizing complex composite RF signals comprising a source of unmodulated RF carrier signal, means for splitting the RF carrier signal output of the source into equal components, separate modulating means to which respective carrier signal components are applied, signal combining means to which the outputs of the modulating means are applied, and separate computerized in-phase and quadrature baseband control signal generating means the outputs of which are applied to respective modulating means to effect modulation of the respective carrier signal components.
    Type: Grant
    Filed: January 28, 1991
    Date of Patent: October 27, 1992
    Assignee: STC PLC
    Inventor: Arnold G. Read
  • Patent number: 5124827
    Abstract: Relaxation effects of a uniform mode ferroelectric liquid crystal cell with obliquely evaporated alignment layers, characterized by the reduction in apparent tilt angle consequent upon removal of a switching stimulus, are eliminated by a poling treatment that typically comprises the application of a relatively low frequency (c. 500 Hz) relatively large amplitude (c. 60 volts peak-to-peak) electric potential difference across the thickness of the liquid crystal layer.
    Type: Grant
    Filed: January 28, 1991
    Date of Patent: June 23, 1992
    Assignee: STC PLC
    Inventor: Anthony B. Davey
  • Patent number: 5121644
    Abstract: Cable deployment in a fluid filled pipeline under pressure is monitored by use of a strain gauge device coupled between the leading end of the cable and a drogue. The strain gauge measures the pull of the drogue on the leading end of the cable and the strain gauge signal is transmitted back to the other end of the cable via the cable conductors. Changes in fluid flow rate, features of the pipeline, and failure of the drogue to inflate can be detected quickly by monitoring the strain gauge signal, so that the cable feed rate can be changed accordingly in order to maintain satisfactory deployment.
    Type: Grant
    Filed: February 13, 1991
    Date of Patent: June 16, 1992
    Assignee: STC PLC
    Inventors: Alan C. Grey, John L. Stokes
  • Patent number: 5117196
    Abstract: The gain of an optical amplifier is maintained constant by employing a portion of the amplified optical signal in a feedback loop. In one arrangement this is used to control the output of a pump signal source accordingly. The portion of the said signal corresponds to spontaneous emission (ASE) at a control wavelength or band of wavelengths different to the wavelength of the optical signal output. In the case of an erbium, for example, optical fibre amplifier the portion is preferably ASE at 980 nm, the amplified signal being at 1.535 .mu.m, i.e. completely different transitions in the amplifying medium are used for gain and ASE feedback in order to lessen requirements on the filter used to extract the portion for the feedback loop.
    Type: Grant
    Filed: April 23, 1990
    Date of Patent: May 26, 1992
    Assignee: STC plc
    Inventors: Richard E. Epworth, Kevin C. Byron, Robert A. Baker, Nigel Taylor
  • Patent number: 5115207
    Abstract: A fact acting automatic gain control system comprising a single or serial multistage arrangement. In one multistage embodiment (FIG. 1) each stage (13) has a first state with a predetermined gain and a second state with unity gain. The output of each stage determines what state is finally adopted although initially when a signal is input it is in the first state due to the action of a sequence controller (14). The predetermined gain values may comprise a binary sequence which descends in the direction towards the output. If the level detector (7) threshold is exceeded, the stage is set to the second state. A particular use of the system is to ensure burst mode pulses reaching a receiver are of similar amplitude. A similar arrangement can be employed for phase alignment ratther than gain control. In another multistage embodiment (FIG.
    Type: Grant
    Filed: July 19, 1990
    Date of Patent: May 19, 1992
    Assignee: STC PLC
    Inventor: David W. Fry
  • Patent number: 5115444
    Abstract: A switchable multichannel external cavity injection laser incorporates a diffraction grating between a linear array of n reflectors and a common reflector to define a set of n optical cavities having different frequency bands. Each of the (n+1) reflectors is provided by the optically distal end of an associated semiconductor laser amplifier whose optically proximal end is arranged to be substantially non-reflective.
    Type: Grant
    Filed: December 11, 1990
    Date of Patent: May 19, 1992
    Assignee: STC PLC
    Inventors: Paul A. Kirkby, Ian H. White
  • Patent number: 5110224
    Abstract: A flexible termination between a submersible repeater housing and a submarine cable comprises a double ball link bar (20) and a cooperating socket (12) coupled to the repeater housing (1) and a similar socket (11) coupled to the cable. This enables a compact lightweight flexible termination having a large angle of flexure. In an alternative embodiment a double gimbal arrangement is used.
    Type: Grant
    Filed: November 15, 1990
    Date of Patent: May 5, 1992
    Assignee: STC PLC
    Inventors: Kenneth Taylor, Roy Allen
  • Patent number: 5111324
    Abstract: An optical receiver incorporating a voltage dependant impedance arranged to shunt excess AC photodetector signal away from the receiver amplifier in response to light level.
    Type: Grant
    Filed: June 8, 1990
    Date of Patent: May 5, 1992
    Assignee: STC PLC
    Inventor: Fazlollah R. Jahromi
  • Patent number: RE34516
    Abstract: An aerial optical fiber cable comprises a glass-fibre-reinforced plastics core member (1) having a slot (2) with a zero lay angle accommodating loose-tubed optical fibres (3, 3A) and sheathed with a longitudinal tape (13) bound with a binder (915) and over-sheathed with a plastics extrusion (14). The cable is self-supporting and completely non-metallic and ia suitable for telecommunications and data transmission services alongside overhead power transmission systems. An alternative embodiment (FIG. 2 ) is not self-supporting but is similar in design and adapted for support from a support wire, and another embodiment has a rectangular slot housing one or more ribbon elements. The cable is simple and cheap to make.
    Type: Grant
    Filed: December 31, 1990
    Date of Patent: January 18, 1994
    Assignee: STC PLC
    Inventor: Ian Houghton