Major Edwin Howard Armstrong

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Major Edwin H Armstrong  was undoubtedly the most important electrical engineer  working between the two World wars, and indeed his first patent came at the start of the first war, a regenerative circuit using positive feedback. He later discovered that the Audion amplifier would oscillate as feedback was increased, and therefore could be used to transmit as well as receive signals.  During the First World War,  as a captain in the US Army Signal Corps ,he was detailed to Paris to help set up a wireless communications system. At that time, this was a  fairly new idea, and for which he was awarded the Legion d' Honneur in 1919, a fitting compliment to the IRE (now IEEE) Medal of Honour he had earned two years before.

Whilst in France he sought a means of overcoming the noise interference from man made and natural electro-magnetic emissions so prevalent in AM and revisited the superheterodyne  principle, which had been vaguely mooted since Fessenden's time but which nobody knew how to make work satisfactorily. Armstrong  demonstrated his technique in December 1919, and later sold his patent to Westinghouse. By the 1930s the Superhet had  rendered TRF radios obsolete. In 1922 he discovered the superregenerative circuit.




Not content with revolutionising both transmission and reception technologies, Armstrong turned his attention to the way the wave itself could be modulated. From 1934 he began to experiment with FM broadcasting from the Empire State Building, and on June 17 1936 he presented a demonstration whereby a jazz record was played first on conventional AM and then, halfway through, it was switched to FM. The clarity and tone quality were highly noticeable,causing one observer to remark ""If the audience of 50 engineers had shut their eyes they would have believed the jazz band was in the same room. There were no extraneous sounds."


By 1937 Armstrong had up and running the first FM radio station, W2XMN, broadcasting from Alpine in New Jersey on 42.8 MHz, but in 1945 the American FCC ordered, probably at the behest of RCA (though in fairness this higher frequency did have several technical advantages), that all transmissions in FM had to be between  88 and 108 MHz, rendering all Armstrong Receivers useless at a stroke, and Armstrong's networks did not survive the shift. FM in the United States was set back decades.


At this point RCA claimed invention of the FM system and won an action in the American Supreme Court.

Armstrong was unable to claim royalties on any FM receiver sold in the United States and with the collapse of his business interests  and ongoing legal battles he was left penniless and in poor mental health. His wife left him after he lashed out at her with a fire poker in his anguish, and alone and  mentally disturbed he removed the air-conditioning unit from his flat on the 13th floor and dressed in has hat and coat jumped to his death. He was 63. Later, the courts found in favour of Armstrong.


Armstrong was not a man willing to compromise. Most people found him intimidating and severe. Nor was he a scientist, his opinion was that anybody who had actual worked in the  development of radio understood that  it  was the product of experiment and work based on reasoning, rather than on mathematical calculations and formulae . His legacy is still with us almost 100 years later; the superheterodyne is the dominant receiver on the market and in commercial broadcasting FM is still the most popular choice for listeners despite the advent of digital communications systems.