Sent in by Ray Potter

A 'Telecom' article from July 1981


In north London's Studd Street, British Telecom has a machine that talks to itself, the quietest room in the country and thousands of pounds' worth of equipment to test light bulbs ...

Not just light bulbs, but an incongruous range of complex as well as comparatively simple equipment. FRANCESCA FERRIDGE has been into the Dr Who-style world of Telecom's quality assurance division.

Theirs is an environment of impressive and expensive equipment, with surroundings ranging from rooms lined entirely with glass fibre wedges to spherical and rectangular chambers .coated in snow-white paint.

For two days last mouth the advanced test facilities in the three London laboratories, recently refurbished and re-equipped, went on public show.
Staff demonstrated the division's vital work - checking equipment, materials and components supplied by industry to ensure that they comply with the relevant specifications. This ensures that Telecom and its customers get the best value for money spent in running and modernising the nation's telecommunications service. It also helps maintain standards for future telecommunications equipment.

The London laboratories deal with acoustics, electrical standards and photometry. In the acoustics section factors such as the performance of microphones, receivers and bells used in telephones are measured. Contract work performed for outside organisations includes testing the operation of hearing aids.
Some of the test equipment used is highly specialised. It includes the British Modal Speaking Position machine which uses an artifical mouth and ear to simulate the use of a handset, and even rotates the handset to represent the natural movements of the user.
Microphones are tested in a soundproofed room by measuring levels of noise through different channels.

The laboratory also features an anechoic chamber - a soundproofed and acoustically "dead" room designed to eliminate echoes so that sound can be measured without interference. For experiments in which sound levels need to be accurately measured, reflections from floor, walls and ceiling of the test room must be avoided. To reduce the breakthrough of noise the chamber is built as a room within a room. The inner room is isolated from the rest of the building. It is built of 230mm reinforced concrete and weighs 118 tons.
The entire interior of the chamber is lined with wedges of glass fibre.

Equipment in the photometry laboratory measures the light output and life of filament lamps Ranging in size iron those used for industrial lighting down to the miniature indicator bulbs used in telephone switchboards. It also measures the light distribution of reflective road signs and the warning lamps used for guarding road works.

In electrical standards, the main task is calibrating electrical measuring equipment. This involves setting equipment to meticulous accuracy standards. The laboratory has received approval from the British Calibration Service for making a wide variety of direct current, low frequency and radio frequency measurements to Telecom equipment.

The electrical standards section also has an anechoic chamber, but designed to work with radio microwaves instead of sound. It consists of a wooden chamber lined with metallised plastic foam wedges which absorb radio waves and prevent reflections which might affect measurements. Its main work is in detecting radiation levels from transmitting aerials and microwave ovens.
Mr Hooker said: "Our work is very complicated and we reach extremely high standards. We have superb equipment and staff who are enthusiastic about their work. Things move very quickly in this field some of our lads are doing work that only learned professors in universities did in the past."

British Telecom's quality assurance division also has laboratories in Birmingham and Islington, London.

Larger pictures
Carlos at the optical bench
Jim Barfoot looking serious
Buzz Billet (sorry, Stan) dozing? also Jim opening his boiled egg

(I seem to remember being taught: "Bulbs grow, lamps glow"- Ed.)

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