Abstract: In a telecommunication network, a method of determining the accuracy of the real time clocks associated with each element of the network is disclosed. The method comprises sending a marker signal at a predetermined reference time along with the traffic signals to one or more elements in the network, and arranging the element to record the time of the arrival of the marker signal using its clock. The recorded time is then compared with the reference time at the network management center so as to determine the accuracy. In order to correct an inaccurate clock, a message signal is sent, so as to cause the clock to be adjusted by the difference between the reference and its recorded time.

Abstract: An SDH (Synchronous Digital Hierarchy) telecommunications network has a plurality of interconnected nodes (1, 2, 3, 4). Working channels (7,6) are defined between respective pairs of nodes (1,2 and 3,4) with one common protection channel (5) serving a plurality of working channels (5,6) such that in the event of a fault on a working channel traffic signals passing from a first node (3) to a second node (4) along that working channel (6) are switched onto the protection channel (7). The first node (3) is then operative to transmit a channel trace signal along with the traffic signals which serves to identify the respective channel. The second node (4) is operative to monitor for the presence of a channel trace signal on the protection channel (7) for which it is the terminating node and upon detection thereof to switch traffic signals associated with that trace signal on the protection channel (7) into the second node (4) for connection to an onward destination.

Abstract: The fitting of boundary buffers on the exit from a telecommunications network can greatly reduce the relative wander. Adaptive boundary buffers have a phase adjusting circuit, for determining the phase error between a recovered line clock and a recovered return clock from receiving equipment of a telecommunications system, the phase of the recovered return clock being advanced or retarded by the value of the phase error and the phase of the recovered line clock being retarded or advanced respectively by less than the value of the phase error, so as to produce a phase adjusted Output Line Clock.

Abstract: A telecommunications system is required by a system operator to have a high availability, especially in so far as central processing is concerned, as failure of this can render a significant portion of the system inoperative. A telecommunications system has connected to an interface at least two remotely attached computing platforms, each computing platform being arranged to receive, process and provide a response to each functional request from the interface, the system responding to the first response received from the computing platforms. The computing platforms may provide high availability, while themselves being low availability devices.

Abstract: Using a known Intelligent Network Architecture a service invocation message is addressed via a Sorter to an appropriate Server. After interrogating the caller when necessary, the Server may re-address the message directly to another Server within the same organization or consortium, which may in turn repeat the process. Thereby a Service Provider representing a large business organization or consortium offers a single umbrella service and is able to introduce new services or sources of information, and to cease, re-configure or resituate the existing services with no effect whatever upon public network or message network equipment.

Abstract: In a digital telecommunication system having data packages carrying identification data, the identification data is characterized in that it is unique to the package within a station and does not depend on the identity of the originating station.

Abstract: A telecommunications system comprises a plurality of subscriber and/or junction terminals connected to a local exchanges the local exchange having an Intelligent Network message terminal, a Service Router addressable from the local exchange via the message terminal and a Signal Transfer Point. The local exchange is able to identify an intelligent Network service request from an originating one of the plurality of subscriber and/or junction terminals and to address and transmit a message via the message terminal to the Service Router via the Signal Transfer Point. The message is readdressed and transmitted to an appropriate Intelligent Network Service Delivery Point and upon receipt of the message by the Service Delivery Point a connection between the Service Delivery Point and the originating one of the plurality of subscriber and/or junction terminals is initiated by the Service Delivery Point.

Abstract: An Add-Drop Multiplexer (ADMUX) for use in a synchronous digital hierarchy telecommunication system is provided with a by-pass whereby, in use, it can be made to interface with a higher bit rate transmission system.

Abstract: A telecommunications transmission system carries multiple tributary data streams with SDH compatible multiplexing and demultiplexing arrangements that include a tributary justification algorithm utilizing both byte and bit justification means as well as a double-ended payload protocol. The byte justification means employs an offset clock with a nominal constant frequency offset from the transmission system clock so that the offset clock can be used to force regular rate of byte justifications of constant sign. The bit justification means employs the difference between the tributary clock and the offset clock to determine the bit justifications necessary to multiplex the tributary data stream and the bit justifications are normally of complementary sign to the forced regular byte justifications except where the frequency of the offset clock lies between the frequency of the transmission clock.

Abstract: An optical communications network having a Head End Unit connected to a plurality of groups of Network Termination Equipments (NTE) and/or Optical Network Units (ONU), the downstream communication being by Time Division Multiplex, has a group multiplexed onto a stream and a plurality of streams are combined into a higher speed multiplex and the upstream communication is by Time Division Multiplex Access.

Abstract: Video on Demand allows, for example, a coded TV signal or film to be transmitted to a subscriber over a standard two-wire metallic telephone line. A similar apparatus for connecting unidirectional mobile data output to a destination via a standard metallic telephone line, the apparatus comprising a High Bandwidth Subscriber Link Transmitter Unit connected between the data source and a connection point on the telephone line and a High Bandwidth Subscriber Link Receiver Unit connected to a further connection point on the telephone line would enable a signal such as from a video camera to be input at or subscriber terminal and transmitted over a metallic telephone line.

Abstract: In an optical fibre clamping device to prevent relative movement between an optical fibre and a tube within which the optical fibre is located, a body part includes a through passageway to receive the optical fibre. The body part includes a first clamp to engage the tube and a second clamp to engage the optical fibre.

Abstract: In many applications, for example in a telecommunications system, it is necessary to identify a unique data sequence at a high speed serial data interface within one bit period of the complete sequence being received. This pattern recognition is often used in order to synchronize the receiver to the frame timing of an incoming data stream and thus identify the octet boundaries. It is usually required to react to this pattern within one data bit period at the interface in order to synchronize internal counters. A data stream pattern recognition apparatus recognizes a predetermined pattern of sequential data within a data stream by including a state machine having at least as many state units connected in series as there are bits in the predetermined pattern, the state machine transfers sequentially from state to state on receipt of each bit of the series.

Abstract: A basic call in a telecommunications network provides a transmission path between two users. Additional functionality is provided by a set of services, wherein, if a number of services is invoked during the same call, it is important that the services do not interact adversely with one another. For detecting service interactions, a service abstract is produced based on a Basic Call State Model and a data processing sequence performed by basic call state processing and by the services in respect of a global data item.

Abstract: In a telecommunications time division multiple (TDMA) optic network system, network termination equipments (NTE's) are enabled to communicate with a head end by the NTE encoding a message as a signal including error correction on the existing signal traffic, monitoring the errors at the head end and extracting the message from the errors.

Abstract: A pure ATM based multiplex is incapable, especially at low carrier rates, of satisfactorily carrying constant bit rate traffic or/human communication traffic. A multiplex format having a plurality of constant bit rate timeslots in which a timeslot is not in use for constant bit rate traffic can have that timeslot used for message based traffic to provide a composite constant bit rate/message based data stream.

Abstract: Statistical multiplexing gain is desirable on ATM links, especially on high-cost international links, and is provided where STM traffic is carried as cells on an ATM bearer. The cells have a bit-stream based AAL format including a map for indicating any STM idle channels. The STM idle channels are not transmitted in the cells. Preferably, the format is AAL Type 1 for structured data, and the map is carried using an extension mechanism of that format.

Abstract: A line communication system for linking a plurality of telephone subscribers to a public telephone exchange, wherein the subscribers are each located within the same general area, and wherein each subscriber is fed from the same mains electricity sub-station with mains electricity is provided. The line communication system provides subscriber apparatus which includes a cordless telephone (CT) handset and a frequency convertor for each subscriber. The handset is hard-wired to the mains electricity supply conductors via the frequency convertor so that CT signals at UHF are down-converted to HF for transmission through the mains electricity conductors. A CT base station is connected to the public telephone exchange. The CT base station is connected to the mains electricity supply conductors via a further frequency convertor for HF line communication purposes.

Abstract: A shared object is created which is copied to all system nodes requiring access to the object and a used-by table is created identifying the nodes holding a copy of the object. When the object is updated by operations at one of the nodes then the copies identified by the used-by table are also updated.

Abstract: A telecommunication switch protection arrangement has information sent in the form of an information frame through a switch. The information in the frame is reorganized in the switch between input and output and checked for parity by using a V4 byte in the frame before being sent from the switch.