Patents Assigned to Standard Telephones & Cables Limited
  • Patent number: 4431869
    Abstract: In a telephone line feeding arrangement, the line current is monitored by a multi-resistor network (R.sub.p R.sub.s) and the output of the network applied to the inputs of an operational amplifier (A3). The output of this amplifier, which is a voltage whose value depends on the line current, is compared by a comparator (A4) with a reference voltage (V.sub.R) to produce a control voltage for a variable voltage (VVS), the output of which provides line feeding voltage.In an alternative, the monitoring is effected by connecting the two line wires each via a resistor to one of the inputs of an operational amplifier (A6) whose output is a voltage dependent on line voltage. This voltage is applied to an input of another operational amplifier (A7) where it is in effect added to a reference voltage (V.sub.R). The output of this amplifier (A7) is used to control the variable voltage source (VVS), which in turn controls a constant current source (CCS) whose output provides line current.
    Type: Grant
    Filed: December 3, 1980
    Date of Patent: February 14, 1984
    Assignee: Standard Telephones and Cables Limited
    Inventor: Anthony W. Sweet
  • Patent number: 4385380
    Abstract: In a fully digital telephone switching system, a digital switch may serve a number of PCM sub systems each having separate forward and reverse highways and each serving a number of subscribers' lines. The highways are grouped in blocks of eight, from which intelligence is received in serial byte-interleaved form and converted by serial-parallel converters to parallel byte-interleaved form. While in this form they are switched to other channels and applied to a super-multiplexer which they leave in parallel byte-interleaved form from which they are restored by another converter to serial byte-interleaved form for application to the switch's outputs. For the reverse channel the arrangement is the reverse of the above, i.e. serial-parallel conversion, switching and parallel-serial conversion to the line multiplex highways. For local calls a loop-back connection is provided via a fixed delay of half a frame time. Thus, if the outputs fail, the arrangement can still handle local calls.
    Type: Grant
    Filed: March 3, 1981
    Date of Patent: May 24, 1983
    Assignee: Standard Telephones and Cables Limited
    Inventors: Frederick H. Rees, Daniel F. Martin, Joseph P. Ryness
  • Patent number: 4357495
    Abstract: The direct current line feed for a telephone subscriber's line is derived from a variable voltage source connected to the line. In one case, the source is series connected in one leg of the line while in the other case it is connected across the line. In the first case there is a constant current source across the line while in the second case the voltage source is a constant current device. In both cases a pair of matching resistors is connected across the line with the center tap grounded to provide a high resistance balanced termination for the line. In both cases a high impedance monitor is connected across the line to monitor the voltage conditions on the line, and this, via a control circuit controls the voltage source and the separate constant current device if provided. This enables line voltage to be adjusted to take account of line length without introducing undesirably large dissipation.
    Type: Grant
    Filed: February 9, 1981
    Date of Patent: November 2, 1982
    Assignee: Standard Telephones and Cables Limited
    Inventors: Anthony W. Sweet, Michael P. Dyer
  • Patent number: 4345115
    Abstract: A telephone subscriber's line interface for a system in which the telephone instrument and the connections therefrom to the exchange use analogue, while the exchange is digital is described, in which electro-mechanical components are eliminated.To achieve this a microprocessor serves a group of lines on a multiplexed basis, responding to conditions of the line as determined via a high impedance monitor and analogue-to-digital conversion means. It also responds to control inputs from the rest of the exchange. In response to the above inputs it controls line feed, signalling, etc. via digital-to-analogue conversion means and a line driver.
    Type: Grant
    Filed: December 8, 1980
    Date of Patent: August 17, 1982
    Assignee: Standard Telephones and Cables Limited
    Inventor: Anthony W. Sweet
  • Patent number: 4345117
    Abstract: To limit the line current dissipation in a telephone system it is considered desirable, especially in electronic systems, for the line current feed to be constant current. In the present arrangement the constant current supplied to the line is made adjustable in accordance with line conditions, especially the voltage between the line wires. A high impedance monitor is connected across the line to monitor the voltage between the two wires and to produce therefrom a reference voltage which is applied to the constant current generator so as to cause it to generate a current for line feed whose value is determined by the line voltage.
    Type: Grant
    Filed: November 20, 1980
    Date of Patent: August 17, 1982
    Assignee: Standard Telephones and Cables Limited
    Inventor: Anthony W. Sweet
  • Patent number: 4300230
    Abstract: A digital switching arrangement for use in a telecommunications exchange handling channels of digital information in time division multiplex form. The digital switching arrangement being particularly suited for use in stored program processor controller environments. The arrangement comprises a digital switching network and a control equipment. The control equipment includes an input queue and an output queue each arranged to store processor input and output messages respectively. The control arrangement is arranged to asynchronously process each output message to process switching network path connections and to generate in the input queue an input message indicative of the actions performed. Each output message includes switching network identification information indicative only of the identities of the incoming and outgoing exchange highways and channels to be involved in the switching network path to be processed.
    Type: Grant
    Filed: October 15, 1979
    Date of Patent: November 10, 1981
    Assignees: The Plessey Company Limited, The Post Office, Standard Telephones & Cables Limited, The General Electric Company Limited
    Inventors: Alexander S. Philip, Allen Parkinson, Michael G. Foxton, Frederick H. Rees, Graham Howard, Anthony E. Shuttleworth
  • Patent number: 4251684
    Abstract: Queuing of interexchange messages in a multi-exchange digital telecommunication network is provided using a dynamic store into cells of which the messages are placed. A subsidiary control store has a cell for each cell of the message store and each of these cells contains a control word which contains the status-busy/free of its message cell, plus details of the message including the user for which it is stored when the cell is busy. These details include message priorities, so that queues of messages awaiting attention can be assembled in the store.
    Type: Grant
    Filed: November 13, 1978
    Date of Patent: February 17, 1981
    Assignee: Standard Telephones and Cables Limited
    Inventors: Frederick H. Rees, Dan Bleicher
  • Patent number: 4233471
    Abstract: A system for centralized reporting of alarm conditions in a multinode data handling system includes an alarm concentration unit at each node of the system for collecting alarm conditions. Each alarm concentration unit is coupled to a signal transmission unit which generates alarm messages and transmits the messages to a centralized node. The centralized node includes means for comparing each received messages with previously received messages stored in a memory and for amending the memory when the most recent received message differs from a previously stored message.
    Type: Grant
    Filed: December 27, 1978
    Date of Patent: November 11, 1980
    Assignee: Standard Telephones and Cables Limited
    Inventors: John A. W. Butcher, Michael A. Salino
  • Patent number: 4212028
    Abstract: In a method and apparatus for transcoding digital PAL color television signals between (i) a 2fsc format consisting of an encoded signal of PAL type sampled at 2fsc and (ii) a 3fsc format consisting of a luminance signal Y at 2fsc and a chrominance signal C sampled at fsc and comprising U+V and U-V on alternate lines (or either the luminance signal or composite chrominance signal by itself), avoid the need to convert the signal to analogue PAL form as an intermediate step. Converting from the 2fsc to the 3fsc format, over the chrominance bandwidth undelayed and 1- and 2-line delayed samples are combined in the proportions 1/4:1/2:1/4, and below the chrominance band the 1-line delayed samples are low-pass filtered, these together providing the luminance signal Y. To provide the chrominance signal C the undelayed and 2-line delayed signals are combined in the proportions -1/4:1/4. The low- and band-pass filters are digital transversal filters operating on adjacent samples in the signal.
    Type: Grant
    Filed: August 30, 1978
    Date of Patent: July 8, 1980
    Assignees: The Marconi Company Limited, Standard Telephones and Cables Limited
    Inventor: John O. Drewery
  • Patent number: 4197523
    Abstract: A digital switching telecommunications exchange handling pulse code modulated information samples in time division multiplex form on incoming and outgoing junctions. The exchange includes a receive interface for each incoming junction and a transmit interface for each outgoing junction and a pair of identical time division multiplex switching networks providing interconnection paths between any incoming junction channel and any outgoing junction channel. Under non-fault conditions exchange calls use indentical paths in each network and the transmit interfaces include error checking and comparison arrangements for each pair of information samples received under fault conditions the transmit interfaces can be arranged to select the non-faulty sample on a per channel basis or can be biased to select one network exclusively.
    Type: Grant
    Filed: January 23, 1978
    Date of Patent: April 8, 1980
    Assignees: The Plessey Company Limited, Standard Telephones & Cables Limited, The General Electric Company Limited
    Inventors: Alexander S. Philip, Stephen Niewiadomski, Frederick H. Rees, Anthony E. Shuttleworth
  • Patent number: 4058836
    Abstract: Reduction of noise in a television signal is achieved by comparing signals from successive frame or field scans and noting the differences. Low amplitude differences are assumed to represent noise and are attenuated. Differences above a predetermined level are assumed to represent movement and are not so attenuated by a factor K. Where there are inherent differences between the signals compared, for example they are different fields of an interlaced scan or are color signals with different subcarrier phases, the signal from the earlier scan is modified to compensate for these differences and provide a signal for comparison which is a better estimate of the expected signal on the later scan.
    Type: Grant
    Filed: April 26, 1976
    Date of Patent: November 15, 1977
    Assignees: The Marconi Company Limited, Standard Telephones & Cables Limited
    Inventors: John Oliver Drewery, Martin Weston
  • Patent number: 4012772
    Abstract: Sequential/interlace scan conversion of NTSC or PAL color television signals is effected by an encoder the output of which is connected to the input of scan conversion apparatus. Controllable phase shift means is included in either the color signal input or the subcarrier input of the encoder and is adapted to vary the phase of the modulated subcarrier for each line of the received color signal by an essentially integral number of quarter cycles in dependence upon the line number. The control is such that the conversion apparatus provides an encoded output signal with the color subcarrier in PAL or NTSC format. The invention can also be used in converting between different types of interlace systems.
    Type: Grant
    Filed: September 9, 1975
    Date of Patent: March 15, 1977
    Assignees: The Marconi Company Limited, Standard Telephone & Cables Limited
    Inventors: John Philip Chambers, Derek Thomas Wright
  • Patent number: 4003020
    Abstract: Digital words are transmitted together with associated parity or checking digits. The parity bits are each related to a group of bits of the same significance from several different words. At a receiving station, a parity bit is generated for the same group from the incoming words and compared with the corresponding received parity bit. When the generated and received parity bits differ, a value is estimated for each word containing a bit from the respective group, and the estimated and received values for the word are compared to detect any word containing an erroneous bit, which bit is then corrected.This invention relates to the transmission of digital signals.In digital television systems the video signal is commonly represented by a series of eight-digit binary numbers. If any of the bits are altered by errors, then the effect appears as a brightness error in the picture, the magnitude of which depends on the significance of the affected bit.
    Type: Grant
    Filed: June 30, 1975
    Date of Patent: January 11, 1977
    Assignees: The Marconi Company Limited, Standard Telephones & Cables Limited
    Inventor: Christopher Keith Perry Clarke
  • Patent number: 3943489
    Abstract: A time-division multiplex (TDM) control system for controlling a plurality of devices from a central point includes a transmitter whose output is coupled over a common path to a plurality of receivers respectively located adjacent to the devices. The transmitter provides a repetitive cycle of a predetermined number of time slots during which a control signal is provided at any one or all of the time slots. Each receiver is assigned a given time slot corresponding to one of the time slots in the repetitive cycle of the transmitter, and each receiver is responsive to the control signal during its given time slot. Each receiver is operative to control one of the devices in response to the control signal.
    Type: Grant
    Filed: September 5, 1974
    Date of Patent: March 9, 1976
    Assignee: Standard Telephone and Cables Limited
    Inventors: Arthur Edward Brewster, Donald Adams Weir, Christopher Alan Watson, Roger Geoffrey George, Michael James Phillips