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Edwin Armstrong FM Radio Development

 Edwin Armstrong FM Radio Development


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After the First World War, Armstrong continued his researches into a variety of topics.

However one area that was challenging a number of people was the reduction of noise and in particular static noise that reduced the quality of broadcast radio transmissions and also the readability or radio communications transmissions.

Armstrong FM radio idea

Initially all researchers had been looking to reduce the bandwidth of a signal to reduce the level of noise that was picked up. As amplitude modulation was received in the minimum bandwidth possible to reduce noise, the audio bandwidth was also reduced making high fidelity transmissions impossible. When used in this manner, frequency modulation, FM offered few advantages over amplitude modulation which was the easiest for of modulation to use during the very early days of wireless.

One engineer had stated that static would always be an issue with radio or wireless transmissions. One very well respected engineer at AT&T had undertaken a study, and used various assumptions in his proof. These assumptions had not been re-visited when further people investigated the use of FM.

However it was Armstrong that took the idea of using FM, but with a wider bandwidth to reduce the level of noise. The Armstrong FM proof took a number of years. But using a variety of equipment he was able to prove conclusively that the use of wideband FM would provide some significant reductions in the level of noise. Additionally as the bandwidth was not limited, much greater levels of fidelity were possible.

Armstrong FM patents and demonstrations

Knowing he needed to ensure that all his inventions were fully protected, Armstrong, who was now a full professor at Columbia, ensured patents were in place before he demonstrated his ideas for FM publicly.

By 1934 Armstrong had patented a series of patents covering his ideas for a high quality broadcast system using frequency modulation, FM broadcast system.

With patents in place, Armstrong started to give demonstrations. At one in 1935 at the IRE conference, he arranged for a broadcast transmission from the house of a local friend. The radio transmission received at the conference demonstrated the very low level of noise achievable and the very high fidelity of the audio with its high frequency range.

While the demonstration of FM was a great success, it threatened the interests of several large companies. The unrivalled performance of FM was seen as a threat to the established AM networks that had been established, as well as upsetting he launch of the new television technologies that were starting to be developed. By having to change to FM major costs would need to be incurred in both areas and industry did not want this despite the step improvement in performance promised.

Fight for FM broadcast station

The next stage in Armstrong's development of FM was to try to build a trial broadcast station. However there was opposition from a number of quarters and the interests of large business sought to stifle any possible FM development and deployment, fearing huge costs in redevelopment and re-deployment of equipment.

An initial license for a trial broadcast station was also turned down by the Federal Communications Commission in the USA.

However Armstrong threatened to take his idea for FM abroad. This forced the FCC into granting Armstrong and FM licence to transmit in a small band that was specially allocated for FM broadcasting.

The world's first FM broadcast station started its radio transmissions in 1939 from a place called Alpine, located in New Jersey. The network, broadcasting under the name "Yankee Network" began to expand. Initially the station broadcast using the call letters W2XMN but later this was changed to WE2XCC.

As the Second World War came upon the USA, Armstrong devoted himself to military research, allowing the US to use his inventions royalty free for the war effort. Armstrong received the US Medal of Merit for his work during this time.

Armstrong, FM, & legal battles

However various companies had been doing their own development on FM and started selling radios ignoring any patents.

Also after the end of the Second World War in 1945, the FCC moved the FM band up in frequency and reduced the maximum power limit on FM stations. This considerably reduced their coverage as well as making all existing equipment obsolete. It placed yet another difficulty in the way of Armstrong's FM development.

Armstrong fought on, taking the matter to Congress. Yet even here the matter became embroiled in a quagmire of legal proceedings and took many years before the real issues could be heard.

Armstrong's death

The interminable legal battles took their toll on Armstrong. His capital was being spent on fighting companies much bigger than himself and his money was almost gone. He was actually involved in 21 infringement actions and as a result his health was also beginning to fail.

Things started to come to a head when arguments with his wife caused her to leave.

Then desperate and with nowhere to turn, on the night of 31 January 1954 he put on his overcoat, opened the window of his tenth floor apartment in New York and jumped to his death.

Armstrong's wife, Marion took up the fight along with Dana Raymond, who had been Armstrong's lawyer for many years. It took many years, the last being settled in 1967. This vindicated the name of Armstrong against the industry giants of the day.

Armstrong was given many honours. The ITU added Armstrong's name to the list of their pioneers in telecommunications alongside names including Ampere, Faraday, Gauss, Hertz, Kelvin and others. He was also added to the Consumer Electronics Hall of Fame, and awarded the Franklin Medal in 1941, and the US Medal of Merit.

It is a sad reflection on the life of this great man, is little known even today. He arguably gave more than names that are far more well known, and only well after his untimely death is he starting to be recognised for the genius he was.


Watch the video: Edwin Howard Armstrong (May 2022).