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Events in telecommunications history

1950

A long-distance television cable was brought into service between London and Sutton Coldfield, the first of its kind.

The Edinburgh Director Area was inaugurated with the opening of Central and Fountainbridge Exchanges.

The control of the overseas services of Cable & Wireless Ltd from the United Kingdom was transferred to the Post Office. At the same time, the radio beam stations leased to Cable & Wireless were returned to the Post Office.

Field trials of the pressurisation of trunk and junction cables radiating from Leatherhead were held.

The success of the Strowger system to meet network demands - largely as a result of the arrangements under the Telephone Exchange Equipment Bulk Supply Agreement (signed in 1923) and the British Telephone Technical Development Committee (set up in 1933) - led to an important decision. There had been rapid advances in electronic techniques during and immediately following the Second World War which led the Post Office and their exchange equipment manufacturers to believe that electronic exchanges could be developed within a short space of time without pursuing alternative electro-mechanical systems. As a result, the decision was now taken to work towards a progressive change of the network from mechanical Strowger systems to electronic systems. This policy was jointly adopted and led in due course to a Joint Electronic Research Agreement (JERA) and the formation of the Joint Electronic Research Committee (JERC) in 1956. These initiatives were put in place to examine various possible solutions for electronic exchanges, and to avoid unnecessary duplication of research and development by sharing such work amongst the five manufacturers party to the Bulk Supply Agreement with the Post Office.

The hope was that the intermediate step of the introduction of register controlled crossbar systems, apparent in other telecommunications administrations elsewhere, would not be necessary under this policy. In the event, development of electronic systems proved more difficult than originally thought, and by 1957 the Automatic Telephone and Electric Company realised that to maintain their position in the export market they needed a viable crossbar system to market. As a result the company developed in time the 5005 Crossbar System. Original development of electronic systems was based on time-division- multiplex techniques and a prototype TDM exchange was built and installed in the Post Office Research Station at Dollis Hill. Parties to JERC co-operated in designing and building a large electronic exchange of the same type which was put into service by the Post Office at Highgate Wood in 1963. The experience of Highgate Wood showed that TDM techniques were uneconomic and difficult to achieve with the technology and components then available. The parallel space division approach, using reed relays for switching, proved more promising and development was concentrated in this area, leading eventually to the successful TXE2 and later the TXE4 systems.

Four submerged repeaters were fitted in tandem to a cross-channel cable.

The first phase of the Teleprinter Automatic Switching Scheme was introduced.

An Anglo-Danish submarine coaxial cable was laid.

Private Automatic Branch Exchanges Nos. 1 and 2 were introduced.

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