Plessey Overseas Limited

Marconi Communications Gmbh

Gec Plessey Telecommunications Limited

Gpt Limited

The Plessey Company Plc

Bec Plessey Telecommunications Limited

John S Arnold

Alexander S Philip

Andrew Keith Joy

Andrew James Pickering

Michael David Jager

Raymond E Oakley

ATM local access

B-ISDN access

Telecommunications network

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.

Asynchronous time division switching arrangement and a method of

The asynchronous time division network transmits data by way of high rate bearers. The data is divided into fixed length packets. The network comprises a switching matrix having a number of input and output ports arranged in columns. Each data packet is routed from an input port to a defined output port via addressed switching nodes. Each node has a queueing means, and each queueing means of each output column is tested and priority is given to the first queueing means tested which holds more than one packet.

Asynchronous time division network

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.

Fault detection and bandwidth monitoring means for a packet switching

A data packet switching arrangement wherein data packets are switched into a transmission pathway according to their priority. Data packet priority is consequently determined in a ring and a priority token attributed thereto. A high priority token ensures its data packet is switched into the transmission pathway when next available. Lower priority tokens are held by respective packets until all data packet priorities have been determined and no higher priority tokens attributed, whereupon the respective data packet is switched into the transmission pathway when next determined.

Data packet switching

A conventional interface for 2-wire telephone lines to a digital switch includes line current feed resistors and a bridge circuit where the line impedance is compared with a compromise balance network. The accuracy of the balance determines the proportion of the signal received on the receive pair being retransmitted in the transmit direction. The ratio of these signals is known as the Trans-Hybrid loss and should be as high as possible for good quality speech. In practice the telephone line impedance increases with length as also does the DC resistance of the line and thus the line current, assuming a constant voltage source. It is proposed that the line current feed resistors be formed on a common substrate using well-established film deposition techniques and the balance resistor be formed on the same substrate using a material having a negative temperature coefficient. Thus on short lines the dissipation in the line feed resistors is high, raising the temperature of the substrate, thus reducing the value of the balance resistor and hence improving the balance.

Longitudinal balance arrangements for two-to-four wire telecommunication

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Northants, United Kingdom

John S Arnold