Abstract: Identifying valid data cells of a call in a redundant path combining unit of an asynchronous transfer mode switch having duplicated switching planes includes identifying the plane of the last data cell to be passed in respect of a particular call, checking that a sequence number associated with the data cell is not one greater than that stored in a storage device, checking that the last data cell to be passed on the particular call was from the same plane, checking if the data cell is a duplicate of the last data cell to arrive on this plane, and passing the data cell to an output store if (c) is true and (d) is not true and storing in the storage device the sequence number of the data cell. A transceiver receives and transmits data and a first store is connected to the transceiver for storing plane identification data and data cell sequence number data.

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.

Abstract: An asynchronous time division multiplex switching arrangement comprises a serial to parallel converter arranged to receive input packets of data which include routing information, in serial form and convert the packets of data to parallel form. A random access memory is provided in which each packet of data is entered at an addressed location into the memory, and the address is entered in a respective first-in first-out output queue at the tail. The address at the head of the queue is accessed and the packet of data is read from the random access memory into a parallel to serial converter and the packet of data is serially delivered to the associated output.

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.

Abstract: A method and apparatus is provided for detecting a frame alignment word in a data stream. The apparatus comprises a storage circuit (9) arranged to receive a data stream and pass each bit of the data stream serially through each location of the storage circuit. A template pattern means (10), arranged to generate a template pattern, is connected to the storage circuit (9) and arranged in bit groups, each group generating an output signal when it identifies a group of bits corresponding to its template pattern. A decoder circuit (B) is arranged to receive the output signals from the groups and generate a decoder output signal when a specified number of groups match the template pattern indicating that the frame alignment word has been detected.

Abstract: The fault detection and bandwidth monitoring arrangement provides a counter in association with each virtual circuit crosspoint. The counters may be provided with a common or individual threshold value which when exceeded causes alarm signals to be generated. The counter arrangement is arranged to record the averaged imbalance of receive and transmit data at each switch port involved in the virtual circuit connection, and additionally is arranged to measure the difference between the net data flows of the corresponding incoming and outgoing ports. Therefore, it is possible to distinguish between the go/return traffic imbalance and an information loss situation in the switch.

Abstract: A method of and an apparatus for article registration are disclosed in which surface characteristics such as component locations of printed circuit boards are viewed and compared with a model. The differences so determined are stored for subsequent use in, for example, the placing of components on the boards.

Abstract: A telecommunication apparatus in which data messages are routed across a switch, each message comprising a message portion and an incoming message identity portion, includes circuitry for generating from the incoming message identity portion an outgoing message identity portion, a switching circuit for utilizing the incoming and outgoing message identity portions to route the message to an output port, circuitry for utilizing the outgoing message identity portion to generate a further message identity portion, and comparator circuitry for comparing the incoming and further message identity portions to detect faults.

Abstract: An asynchronous time division (ATD) switch for carrying out packet switching. In one embodiment a switch has 256 ports running at 155 M bits and is capable of switching incoming data cells at each of the input ports to any one of 256 output ports. At each input port a switch sequentially distributes the received data cells over 16 outputs each of which is connected to a different DMR circuit. There are 256 DMR circuits each having 16 inputs and 16 outputs. A DMR circuit is a fixed space switching device which has N inputs, N time intervals and N outputs and operates cyclically so that each input goes to each output for 1/Nth of the time. The inner stage of the ATD switch comprises 256 central switches each having 16 inputs and 16 outputs. Each central stage switch has its 16 inputs connected to 16 different DMR circuits. The fourth stage of the switch consists of another array of 256 output DMR circuits with each central switch being connected to 16 different output DMR circuits.

Abstract: A mounting arrangement is provided for securing printed wiring boards within guide members. The guide members are arranged in a vertical plane and each guide member is provided with part of a knuckle arrangement. A further corresponding part of the knuckle arrangement is provided upon a vertical support structure, and the vertical support structure is allowed to pivot through 90.degree. thereby closing the guides and securing the printed wiring boards therein, or alternatively permitting the guides to be opened to allow removal of the boards therefrom. The knuckle arrangement is so designed that the parts are snap-fitted together for ease of assembly and maintenance. The support arrangement is sufficiently rigid to prevent distortion when used, thus ensuring maximum component height.

Abstract: A data communications network comprises a plurality of terminals (30, 31, . . . 34) which are interconnected by a contra-rotative ring pair of lines (35, 36), so as to be able to send data to and receive data from all the other terminals in the network. Each terminal has a pair of stations (A, B), each linked to said pair. The network is characterized in that one station associated with any one terminal is arranged to be as distant as possible in a topological sense from its associated pair.

Abstract: An apparatus for testing optical fibre links in a data communication network includes communication equipment (13) for generating and receiving traffic over one or more fibre links X at a wavelength .lambda.2, optical test instrumentation (10) for generating test signals at a wavelength .lambda.1, different from .lambda.2, and circuitry (11) for superimposing a test signal from the test means onto a traffic signal from the communication equipment (13).

Abstract: A digital communication apparatus interleaves multiple bit sequences of a predetermined length from a plurality of input signals all at one rate to a single output data stream at a higher rate. Normally the multiple bit sequences will be bytes.

Abstract: The apparatus comprises at least one standby optical fibre transmission path and at least one worker optical fibre transmission path. Each end of the paths is terminated by an associated transmit and receive electro-optic converters. The converters are connected to respective electrical protection switching devices. At least one optical switching means interfaces the electro-optic converters with the optical fibres at one end of the transmission paths and is arranged to switch the optical transmission between worker and standby fibres when a fault is detected.

Abstract: Coin validation apparatus having a coin chute including a hard striking surface upon which a coin entering the apparatus is directed. A microphone is positioned to detect acoustic vibrations of the coin after it strikes the striking surface. An output from the microphone is applied to a fast fourier transform device to produce a signal analysis of the coin vibration. A weighbridge measuring apparatus which is made up of a flexible strip of resilient material carried on a support at each end is provided. The coin rolls across the flexible strip to cause a temporary deflection of a center portion of the strip. A strain gauge located at the strip center to produce an electrical signal representative of the deflection. A classifier compares the signal analysis and the strain gauge signal with stored data representative of a set of standard coins, for classifying the coin as a particular coin value.

Abstract: A digital communications apparatus for receiving a plurality of parallel digital input signals (IN1 . . . IN1 6) all at one rate, and for interleaving multiple bit sequences of a predetermined length from each of the input data streams into a single data stream at a higher rate. The apparatus has a plurality of first stage blocks (BIC1) each adapted to receive a plurality of the input data streams and to output a similar number of data streams at the same bit rate but with the bits of the incoming data signals interchanged. The first stage blocks are connected to a plurality of second stage blocks (BIC2) each connected to said first stage blocks (BIC1) in such a manner that each secondary stage block is connected to a first stage block by a single data stream so that the secondary stage blocks (BIC2) interchange the bits of the already bit-interchanged input signal to generate a plurality of digital output data streams.