The programme demonstrates and explains the operation of three switch systems commonly used in telephone exchanges.
|Module code and title:
|T321, Telecommunication systems
|First transmission date:
|Restrictions on use:
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|Malcolm Hamer; G.(Gaby) Smol
|BBC Open University
|Crossbar; Diodes; Models; Reed relay; Strowger; Switching systems
|Shots of a relay (an electromechanical switch) in operation. Malcolm Hamer introduces the programme. Hamer demonstrates a simple Reed relay. He explains how it works and points out its advantages over other relays. Shots of a Reed relay under magnification. Hamer next explains how a switching network made up of Reed relays works. He demonstrates using a five by five relay matrix. Animatior over the matrix helps to clarify points made. Gaby Smol at a G.P.O. telephone exchange made up mostly of Strowger two motion selectors. Shots of a Strowgerselector in operation. Commentary by Smol explains how it works. In order to explain and demonstrate in more detail how Strowger selectors work, Smol demonstrates a Strowger uni selector. Smol next looks at a Strowger two motion selector in detail. He points out the component parts of the mechanism and explains their function. Smol then generates several signals by hand to illustrate the relay at work. Smol, using an animation, explains how a complete matrix is built up out of Strowgers. Malcolm Hamer, with a cross bar switch, explains how this mechanism works. An animated matrix diagram is superimposed over the switch. Hamer points out the component parts and explains their function. Hamer demonstrates the cross bar switch relay. Hamer then uses a simplified model of the cross bar switch to illustrate its main features and show them in action. Hamer sums up the programme with a brief comparison of the three switches examined.
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