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Telephone History
Privateline.com's Telephone History: Alec Reeves: Father of Pulse Code Modulation, Modern Digital Working

Pages: (1)_(2)_(3)_(4)_(5)_(6)_(7)_(8)_(9)_(10) (Communicating) (Soundwaves) (Life at Western Electric) next page -->

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ALEC REEVES 1902-1971

by David Robertson

(C) 2002 All rights reserved

Alec ReevesAlec Reeves was one the 20th Century's greatest, but least conventional, scientists. A brilliant engineer, his work made the 'digital age' possible. A pacifist, he altered the course - and perhaps the outcome - of World War II. Open-minded, he experimented with the paranormal and believed he was in regular contact with the 19th century inventor of electrical generation, Michael Faraday.

Reeves was born on 10 March 1902 in Redhill, Surrey. His father Edward was Surveyor to the Royal Geographical Society. Edward Reeves had met Livingstone, Stanley and Gordon of Khartoum - and used his mapping skills in an effort to resolve the bitter battle between American explorers Robert Peary and Frederick Cook who both claimed they were the first to reach the North Pole.

Alec studied engineering at Imperial College, London and in 1923 joined International Western Electric, a leading manufacturer of radio and telecommunications equipment. In 1925, the firm was taken over by Sosthenes Behn's International Telephone and Telegraph in Reeves went to work at ITT's laboratory in Paris, LMT. Here he worked with brilliant engineers like Maurice Deloraine and Henri Busignies (who later developed the HF/DF - 'Huff Duff' - system for detecting enemy submarines). Reeves and his colleagues built the first radio-telephone links across the English Channel and the Atlantic. Reeves also perfected the condenser microphone and made major advances in the use of single sideband transmission for short-wave radio.

Reeves appears to have had an enjoyable time in Paris. He later claimed he had played in the French Open tennis championships - which were indeed 'open' to anyone who wished to participate. He is also reported to have been seen on the roof of the LMT building conducting paranormal experiments - though one report said he was 'measuring moon-beams'.

It was in Paris that Reeves had the idea that made him famous - and which helped shape the modern world. Since Alexander Graham Bell invented the telephone in 1876, speech had been turned into a continuously-varying wave of electric energy. But 'analogue' systems have a big weakness: they amplify noise and errors as well as the original message. Reeves proposed a radical alternative. Instead of sending Bell's 'voice- shaped current', he proposed that the sound be sampled at regular intervals. The values of these samples would be represented by binary numbers and transmitted as unequivocal on-off pulses.

In principle, this was a return to the simple, robust technique used by the telegraph. Sending recognisable speech, however, meant networks would have to carry millions of pulses a second. And though Reeves' extraordinary patent of 1937 showed how this might be done in theory, the valve-based technology of the time was not up to the job. Pulse Code Modulation could not be implement economically until the invention of the transistor decades later. But economy was not always a priority. PCM was first used by Bell Labs for the complex and cumbersome radio system on which Churchill and Roosevelt talked in total secrecy for much of World War 2.

Reeves fled escaped just in time when the Germans invaded France - reaching England on a coal boat but losing most of his possessions on the way. He soon entered the world of Scientific Intelligence, joining the team led by Robert Watson-Watt and A P Rowe that was secretly developing radar. A committed pacifist, he accepted the need to defeat Hitler - a task to which he contributed decisively.

For in 1941, Britain faced a crisis. German bombs had reduced cities to rubble. But the invaders had been repelled and the RAF launched its own night bombing campaign against the factories that made the enemy's weapons and raw materials. It was a disaster: British airmen had neither the experience or equipment to navigate 'blind' and bombs fell miles from their target. Defeat looked certain.

Asked to address the night navigation problem, Reeves proposed a novel solution. A pilot would reach his target by flying in an arc centred a base station, called the 'Cat', and drop his bombs when he reached a precise distance from a second station - the 'Mouse'. An audible tone told him if he was deviating from the correct track and when someone said it sounded like an Oboe, the name stuck.

OBOE was so precise that a bomb dropped from 30,000 feet could land within 50 yards of its target. It was an amazing success. In March 1943, OBOE-guided planes destroyed the mighty Krupps Works at Essen which made most of Hitler's steel and guns. On the eve of D-Day, OBOE destroyed nine of ten heavy guns that could have decimated the invading force. The RAF used OBOE in over 9,000 raids. Reeves' invention - the world's first remote-controlled bombing device - had altered the course, and perhaps the outcome, of the World War 2. Nothing as accurate as this would exist until the days of the satellite and the laser.

In 1945 Reeves returned to ITT, working at Standard Telecommunications Laboratories on ways to increase the capacity and reliability of communications systems. He was a pioneer of semiconductor devices and among the first to exploit the possibility of using light to carry information. When 'waveguides' - pipes carrying high frequency signals - failed to work, Reeves thought of glass fibres. In the late 1960's, he inspired and led the team under Charles Kao and George Hockham that created the world's first practical optical fibre system.

Alec Reeves was a visionary who in the 1950s predicted that by the end of the 20th Century people would work from home, linked by optical fibre and receiving information over a screen. He was awarded over 100 patents, as well as a CBE.

But he had a less conventional side. He was deeply interested in the capacity and character of the human brain and, like earlier scientists such as Oliver Lodge (who demonstrated 'wireless' communication before Marconi) and J J Thomson (who discovered the electron), Reeves explored the paranormal. For most of his life, he conducted ever more complex experiments to measure the power of thought and to 'communicate' with the dead. He believed he was guided by the great Michael Faraday, who had died in 1876.

Alec Reeves - who died on 13 October 1971 - can fairly be called 'Father' of the Information Age. Pulse Code Modulation is the basis for all modern digital communications and media, the main motor for change in the 21st century and perhaps the key technology of the future. Without PCM, there would be no Internet, no digital radio or television, no digital land-line or mobile telephones, no CDs, DVDs or CD-ROMs. The idea of sending information in any form, anywhere at any time would still be the stuff of science fiction.

Editor's note: David Robertson is a science writer, television producer, and consultant who is compiling a biography of Alec Reeves. His e-mail is here:

ResponseCo@aol.com


For more on Alec Reeves, visit this well done web site, produced by a one time colleague of Reeves:

http://www.AlecHarleyReeves.com (external link)

Another interesting site is here. Let's hope it stays on the net:

http://homepage.ntlworld.com/quantium/ahr/pcm.htm (external link)


PCM illustration

[Editor's note] I've always liked the image above. It demonstrates the differences between old and new technologies, analog and digital, even if it shows a PCM preciseness impossible at the time Reeves invented the technique. It's from _The Lenkurt Demodulator_, circa early 1960s. That trade magazine took it in turn from TI. The photo appears to be of a integrated circuit or perhaps the top of a TI building. The text accompanying the photo says:

"Figure 3. Comparison of transmission by amplitude modulation and pulse code modulation. Both transmissions were made under identical conditions of noise and transmitting power. (4 db signal-to-noise ration). Improved transmission by PCM is obtained at expense of bandwidth."

For more on digitizing and PCM, click here. (internal link)

 

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