And Frequency Modulation is immune to static interference, unlike AM, where static can drive the signal to pieces. Our equipment for short-range field radios by the infantry, the tank people…everybody…was Frequency Modulation. In World War II…this comes to me because I was in the Signal Corps and used an awful lot of stuff based on his patents. And those are the fundamental radio circuits to this day.įred – “Nancy mentioned that Armstrong gave some of these patents to the government?” The four major inventions of Armstrong are there, listed, Regenerative, Super-Regenerative, Super-Heterodyne, and FM…Frequency Modulation. The windows behind Harry Houck (in the photo) are actually this building. So, that’s the real McCoy from Armstrong’s patent dispute…and Harry Houck worked with Armstrong in France as a soldier…Armstrong was a Major in the Signal Corps in World War I, and Harry Houck worked with him…and we were honored to have Harry come up here and bring one of Armstrong’s early feedback radios with him and talk about it. It is called regeneration.įred – “Is that a drawing of the circuit there?”Īrmstrong got involved in many patent disputes with Lee de Forest, and that is a coil that Armstrong had made when he was a younger fellow, but it was an exhibit in the federal patent dispute. And this would elevate the sensitivity of the circuit tremendously. He’s the guy that suggested using a tickler coil in the plate circuit of a radio receiver, so that a little of the output energy would be coupled back into the input, to cause the circuit to oscillate. (National Register)įred – “What was Armstrong’s achievement?”Īrmstrong’s first major achievement gave him the nickname of “Feedback Armstrong”. And we have the Massie Wireless Station next door, the world’s oldest surviving, fully-equipped wireless station. The other interesting thing is that Underhill was a friend of Massie…Walter Massie. Anyway, that’s how we happen to have that picture. Underhill was very impressed with the staying power of the young fellow, because he was just a kid. 5, (1936) 689–740.So, as Underhill’s son has told it to me, that’s the fellow, the younger guy on the right we knew…Armstrong would come over and sit in Underhill’s office while Underhill was at the drafting board pushing his sliderule, and he would ask him questions, and Underhill would answer the questions. He added that several engineers described the invention 'as one of the most important radio developments since the first earphone crystal sets were introduced' " (Wikipedia article on Edward Howard Armstrong, accessed 07-12-2009).Īrmstrong's first paper on FM radio was " A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation," presented to the New York section of the Institute of Radio Engineers on November 6, 1935, and first published in Proceedings of the IRE, 24, no. There were no extraneous sounds,' noted one reporter. 'If the audience of 50 engineers had shut their eyes they would have believed the jazz band was in the same room. He played a jazz record over conventional AM radio, then switched to an FM broadcast. A June 17, 1936, presentation at the Federal Communications Commission (FCC) headquarters made headlines nationwide. However RCA had its eye on television broadcasting, and chose not to buy the patents for the FM technology. "Armstrong conducted the first large scale field tests of his FM radio technology on the 85th floor of RCA's (Radio Corporation of America) Empire State Building from May 1934 until October 1935. Edwin Howard Armstrong developed wide-band frequency modulation, FM radio, which delivered clearer sound, free of static.Īrmstrong received a patent on wideband FM on December 26, 1933.
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