engineering

Highgate Wood telephone exchange

Highgate Wood telephone exchange is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Highgate Wood telephone exchange rather than just read about it. In short: Highgate Wood telephone exchange was the first all-electronic telephone exchange in Britain. It was built in Grand Avenue, in the London suburb of Muswell Hill, by members of the Joint Electronic Research Council (JERC).

Key takeaways

Highgate Wood telephone exchange belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Highgate Wood telephone exchange to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Highgate Wood telephone exchange from memory before moving on to harder problems.

Reference excerpt

Highgate Wood telephone exchange was the first all-electronic telephone exchange in Britain. It was built in Grand Avenue, in the London suburb of Muswell Hill, by members of the Joint Electronic Research Council (JERC).

Introduction On Wednesday 12 December 1962, the 800-line Highgate Wood exchange was accepted by the Postmaster General, Reginald Bevins, MP, on behalf of the Post Office, from the five manufacturers who had helped to build it, the first all-electronic telephone exchange in Britain and one of the first in the world to go into public service. It had already carried public traffic experimentally for brief periods during the previous few weeks. He also announced on that day the building of three more advanced electronic exchanges to be installed and in operation within the next two years at Goring-on-Thames (high speed TDM 100 channel), Pembury (low-speed TDM 30 channel), and at Leighton Buzzard. The only one that was completed was the TXE1 at Leighton Buzzard, the other two being quickly abandoned. The Highgate Wood Electronic Exchange had been the result of six years' co-operative research and development between the Post Office and five principal British manufacturers of exchange equipment. This was coordinated through the Joint Electronic Research Committee (JERC). Although different contractors had been responsible for the system design, installation and manufacturing of various sections of the exchange, the commissioning had been the work of teams drawn from each of the parties to the agreement. The Highgate Wood Exchange was not entirely typical of the systems which were to follow it. Each of the three new exchanges, all of which were to operate completely on their own, with no standby exchange as was the case at Highgate Wood, were to be designed to try out actual service conditions. Two of them were based on slightly different applications of the time-division pulse-amplitude modulation (TDM) principle, and the third, at Leighton Buzzard, on space-division switching. All three were to be fully transistorised so that they were going to be more compact than Highgate Wood (which had about 5,000 transistors and 500 valves) and would have needed less power. They were also expected to show a significant improvement in reliability that had been a problem at Highgate Wood. The model of Highgate Wood had worked "reasonably satisfactorily" [see Harris 2001] in the laboratory but the analogue transmission was too noisy on the long cable runs in an actual exchange. The problem was thought to be the earthing arrangements. TDM exchange operation in the UK did not become possible until pulse-code modulation (PCM) was developed, providing a digital transmission solution which led to System X. The trial at Highgate Wood was unsuccessful. Roy Harris states that it carried mainly artificial traffic and was looked after on a care-and-maintenance basis until it was taken out of service in 1965. The Connected Earth website calls Highgate Wood a "magnificent failure". For the UK it meant that an intermediate approach which would extend the usefulness of the Strowger switch technology would be needed. This led to the implementation of reed relay and crossbar technologies alongside Strowger extensions until the arrival of digital SPC exchanges in the mid-80s.

Exchange design One of the JERC's first decisions was to build an electronic exchange using the "Switched Highways" system, which employed time division multiplex techniques (TDM), while at the same time continuing research on alternative solutions to the problem of electronic switching. The "Switched Highways" system was invented by L.R.F Harris at Dollis Hill in 1952. It was also decided that the experimental equipment should provide the full service and maintenance facilities of a comparable electro-mechanical exchange. At the same time, the techniques used had to be demonstrably capable of serving the largest existing exchanges. Moreover, the experiment was to be conducted in an exchange giving public service and therefore fully interconnected with the public network. This meant that it would need conversion equipment to enable it to inter-work with the existing system and to use the existing subscribers' apparatus and line plant. For these reasons the Highgate Wood installation was bigger than the small number of lines would have seemed to warrant and about 400,000 electronic components were fitted. Much of the control equipment could have served an exchange of about 7,000 lines. The exchange used both valves and transistors. There were approximately 5,000 transistors and 500 valves. The valves were used in the more crucial areas, as the transistors of the day were not up to the required performance.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Highgate Wood telephone exchange

Start with the simplest possible case. Write down what Highgate Wood telephone exchange claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Highgate Wood telephone exchange before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Highgate Wood telephone exchange ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Highgate Wood telephone exchange

In research: Highgate Wood telephone exchange appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Highgate Wood telephone exchange in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Highgate Wood telephone exchange is common in secondary-school and first-year university syllabi. It links to neighbouring topics Commercial buildings in England, Former buildings and structures in the London Borough of Haringey, History of telecommunications in the United Kingdom, so understanding it makes those chapters shorter.
In everyday life: Look for Highgate Wood telephone exchange outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Highgate Wood telephone exchange in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Highgate Wood telephone exchange means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Highgate Wood telephone exchange out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Highgate Wood telephone exchange in simple terms?

Why does Highgate Wood telephone exchange matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Highgate Wood telephone exchange?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Highgate Wood telephone exchange.