As we celebrate 30 years of what has become the marvel of the World Wide Web it is perhaps worth remembering back even further to where our digital age really all began. While the American Claude Shannon and Bell Labs are rightfully credited with being the founders of the information age, we Brits can still take pride in the fact that one of our own was right there at the start also…..
Alec Reeves was born in Redhill in 1902 and spent his whole career as an engineer working for the telecommunications sector. Before computers became a thing, it was the telegraph and then telephone networks that were the future of the modern world and much research was poured into improving those systems. Although transatlantic cables and plenty of new switching stations had made long distance calls a reality, sadly the quality of reception was visibly declining also. This is because every time a signal ran down the wire it would naturally pick up some distortions (or noise) and as automatic relays were used along the route to shuffle the signal ever further distances, this only served to magnify all that noise. Thus, as the demands of the telephone system grew, it became obvious that the existing analogue system would not be able to reliably keep up.
Working on the first transatlantic telephone system for the International Western Electric Company ( the only company he ever worked for) Reeves would have been only too aware of all the problems. During the late 1920s and 1930s he transferred to the company research department in Paris and there worked on somewhat related problems for long distance radio as well as microphone transmissions. In 1937, probably as a culmination of what he had learned thus far, Reeves came up with and patented an ingenious solution called Pulse Code Modulation (or PCM for short).
PCM cleverly converted out normal analogue speech into electrical pulses which could then travel vast distances without distortion. Just as importantly, multiple signals could be mixed in and sent together down the same route removing the need for an unyielding mass of multi-strand cables. PCM has become the basis for much of our digital communications today, but at the time of invention Reeve’s clever idea was sadly not cost effective to implement with the pre-war technology. Therefore despite the patent, Reeves did little with PCM himself and just continued normal work until the war started. It was not until the invention of the transistor in 1948 that PCM finally found a solid commercial footing.
While PCM was a great idea in theory, it really required the new digital age to set it in motion. During the Second World War Bell Labs in the US had taken up Reeve’s idea and created a machine that could encrypt the nationally important conversations between the US and UK. Called ‘SIGSALY’ it relied on PCM to convert the conversations into those pulses, then turn them back into analogue sound at the other end. As the Germans had no way of cracking these signals it became a very useful and secret weapon for the allies.
When the war finally ended Bell Labs realised that they had an internationally important invention on their hands and in 1948 released a series of papers and talks all about this new technology. These papers included information about using PCM as a digital pulse, including the new equipment they had created to encode the signals from analogue to digital. It is at this point that Claude Shannon, a cryptographer from Bell Labs who and had been suggesting for a few years that we should turn our information digital, was to grow in prominence.
Of course, as with so many other inventions, there was a real-time lag between announcing this new wonder technology and the world actually taking it on-board. During the 1950s digital technology was still very much in its infancy and the only ones able to put much financial effort into digital encoding were the military. While they were not that interested in the sound quality of long-distance phone calls, they were struggling with their new ballistic missiles. These missiles required a constant and secure stream of information between the missile and its base to make sure they hit their long-distance targets accurately and they could not afford for those signals to be either intercepted nor corrupted by atmospheric changes. For this a digital signal was the most effective. Although created to win wars, those working on the space program understood the value of PCM for them and adapted it quite rapidly to help send people and probes up into space. Interestingly the first images we all saw from the Moon in 1969 were sent back to earth via PCM.
Alec Reeves died in 1971 aged 69 just at the time that his invention was beginning to have a major global impact. Today in our digitally rich communication world we owe so much to Reeves, but despite an OBE at the time and even a Royal Mail stamp in his honour shortly after he died, few people know his name or recognise the important contribution he made to the field of communication.
Photo attribution: lady at laptop by Marco Verch; Telegraph key by spurekar; signal sampling graph via Wikipedia; ww2 receiver by PhotosNormandie; Claude Shannon via Wikipedia; digital rack by Pete.stephenson;