Alec Reeves Alec Harley Reeves , CBE ( March 10 , 1902 - October 13 , 1971 ) was a British scientist best known for his invention of pulse - code modulation ( PCM ) . He was awarded 82 patents . Early life . Alec Reeves was born in Redhill , Surrey in 1902 and was educated at the Reigate Grammar School , followed by a scholarship to the City and Guilds Engineering College in 1918 , and then postgraduate studies at Imperial College London in 1921 . Career . Reeves joined the International Western Electric Company in 1923 , and was part of a team of engineers responsible for the first commercial transatlantic telephone link . In 1925 Western Electric ' s European operations were acquired by ITT , and in 1927 Reeves was transferred to ITT ' s research laboratories in Paris . Whilst in Paris , he was responsible for a number of projects , including : a short - wave radio link between the telephone network s of Spain and South America , the world ' s first single - sideband radio telephone system , and developed a multi - channel carrier system for UHF radio telephones . He was also responsible for innovations in the design of automatic frequency control circuits , digital delay lines and condenser microphone s . Pulse Code Modulation . Reeves recognised the potential that pulse - code modulation had for reducing noise when speech is transmitted over long distances . With an analogue signal , every time the signal is amplified , the noise contained in the signal is also amplified and new , additional noise is added . With pulse code modulation , all that is required is to regenerate the pulses , hence the noise content of the signal is not increased . Reeves patented the invention in 1938 . Unfortunately his idea required quite complex circuitry ( by 1930s standards ) , that was not cost - effective , using Valves . Pulse code modulation was not used commercially until the 1950s , when the invention of the transistor made it viable , although it was used by Bell Telephone Laboratories during the Second World War for secure communications links , such as the one between Roosevelt and Churchill . World War II . Following the invasion of France by Germany in 1940 , Reeves escaped over the Spanish border and then made his way back to England aboard a cargo ship . He joined the Royal Aircraft Establishment at Farnborough and took part in the development of countermeasures against the German radio navigation systems , the so - called ' battle of the beams ' . Reeves was later transferred to the Telecommunications Research Establishment as part of a team of scientists and engineers developing Britain ' s own radio navigation aids . The first system they developed was called ' GEE ' , a system that performed well , but was susceptible to jamming and was not accurate enough for blind bombing of targets at night or through thick cloud . Together with Frank Jones of the Telecommunications Research Establishment , Reeves developed a new system called ' Oboe ' , which offered pin - point accuracy to within 50 yds ( 45m ) , and was resistant to jamming . ' Oboe ' was to prove invaluable to the Royal Air Force , during Bomber Command ' s offensive against Germany . Post War . After the war , Alec Reeves managed a team led by Charles K . Kao and George Hockham at Standard Telecommunication Laboratories - initially at Enfield , North London , and later at Harlow Essex - which invented optical fibre s as a means of communicating large quantities of information . Kao has recently ( 2010 ) been awarded the Nobel Prize his part in this achievement . Reeves worked at STL until retirement . He was awarded the Stuart Ballantine Medal in 1965 and also the CBE .