Edwin Howard Armstrong

From New World Encyclopedia

Edwin Armstrong
Developed and advanced the utility of FM technology.
BornDecember 18, 1890
New York, NY
DiedJanuary 31, 1954
Occupationelectrical engineer and inventor

Edwin Howard Armstrong (December 18, 1890 – January 31, 1954) was an American electrical engineer and inventor. He was one of the most prolific inventors of the radio era, with a vision that was ahead of his time. His main inventions were the regenerative circuit, the super-regenerative circuit, the superheterodyne receiver, and FM radio. Unfortunately, his life was marred by bitter lawsuits over patent rights with other inventors, particularly Lee De Forest, and, eventually, with Radio Corporation of America (RCA), the broadcasting company that once paid for his inventions. He ended his life by committing suicide.[1]

Overview of his life

Edwin Howard Armstrong was born in Chelsea, New York City, in 1890. Born of John Armstrong and his wife, Emily Smith, he was raised Presbyterian. His father was a successful businessman, and his mother, a retired school teacher. He also had two younger sisters, Ethel and Edith. He studied at Columbia University and later served as a professor there. His wife, Marion, once worked as secretary of David Sarnoff, president of RCA, but the couple did not have any children.

Armstrong invented the regenerative circuit (patented in 1914) while he was a junior in college at Columbia University, New York City, the super-regenerative circuit (patented 1922), and the superheterodyne receiver (patented 1918). (There was a dispute regarding who invented superheterodyne radio. For example, Walter Schottky claimed that he had independently invented superheterodyne radio too.) He developed the superheterodyne when he was in the Army, during World War I. Stationed in France, he rose to the rank of major. For the rest of his life, his friends informally addressed him by that title.

Many of Armstrong's inventions were ultimately claimed by others in patent lawsuits. In particular, the regenerative circuit, which Armstrong patented in 1914, as "Wireless receiving system," was subsequently patented by Lee De Forest in 1916; De Forest then sold the rights for his patent to AT&T. Between 1922 and 1934, Armstrong found himself embroiled in a patent war, between himself, RCA, and Westinghouse on one side, and De Forest and AT&T on the other. This patent lawsuit was the longest ever litigated to its date, at 12 years. Armstrong won the first round of the lawsuit, lost the second, and stalemated in a third. Before the Supreme Court of the United States, De Forest was granted the regeneration patent in what many now believe was a misunderstanding of the technical facts by the Supreme Court.

Later, he lost a vicious legal battle with his former employer, RCA. Penniless and despondent, he committed suicide on the night of January 31, 1954, in New York City. He was buried in the Locust Grove Cemetery, Merrimac, Essex County, Massachusetts.[2]

FM radio

Even as the regeneration-circuit lawsuit continued, Armstrong was working on another momentous invention. While working in the basement lab of Columbia's Philosophy Hall, he created frequency modulation radio (FM), patented in 1933 (U.S. patent 1941066) with the title of "Radio signaling system." Rather than varying the amplitude of a radio wave to create sound, Armstrong's method varied the frequency of the wave instead. FM radio receivers proved to generate a much clearer sound, free of static, than the AM radio dominant at the time. In 1922, John Renshaw Carson (AT&T), who was the inventor of single side band (SSB), published a paper in the Proceedings of the Institute of Radio Engineers (IRE) that FM did not appear to offer any particular advantage.[3].

The greatness of Armstrong was that he managed to demonstrate FM's great advantage even though a lot of people might have lost interest in FM after reading Carson's negative comment on the technology. Armstrong published a classical paper on FM in the Proceedings of the IRE in 1936,[4] which was reprinted in the August 1984 issue of Proceedings of the IEEE.

Today the consensus regarding FM is that narrow band FM may not be so advantageous in terms of noise, but wide band FM can bring great improvement in terms of signal to noise ratio if the signal is stronger than a certain threshold. Hence, Carson was not totally wrong, and the Carson bandwidth rule for FM is still important today. Thus, both Carson and Armstrong have contributed significantly to the science and technology of radio. The threshold concept was discussed by Murray G. Crosby (inventor of Crosby system for FM Stereo) who pointed out that for wide band FM to provide better signal to noise ratio, the signal should be above a certain threshold.[5] Thus, Crosby's work supplemented Armstrong's paper in 1936.

However, FM radio, which threatened to destroy AM radio, proved to be too revolutionary for RCA, Armstrong's then employer. Armstrong was asked to remove his transmitting equipment from RCA's Empire State Building offices, in order to make way for television equipment after his 1935 demonstrations of the technology. In 1937, Armstrong financed construction of the first FM radio station, W2XMN, a 40 kilowatt broadcaster in Alpine, New Jersey. The signal (at 42.8 mHz) could be heard clearly 100 miles away, despite the use of less power than an AM radio station.[6]

RCA began to lobby for a change in the law or FCC regulations that would prevent the FM radios from becoming dominant. By June of 1945, RCA had pushed the FCC hard on the allocation of electromagnetic frequencies for the fledgling television industry. Although they denied wrongdoing, David Sarnoff and RCA managed to get the FCC to move the FM radio spectrum from (42 to 50 MHz), to (88 to 108 MHz), while getting new television channels allocated in the 40-megahertz range.

This single FCC action rendered all Armstrong-era FM sets useless overnight, and protected RCA's AM-radio stronghold. Armstrong's radio network did not survive the frequency shift up into the high frequencies; most experts believe that FM technology was set back decades by the FCC decision. This change was strongly supported by AT&T, because loss of FM relaying stations forced radio stations to buy wired links from AT&T.

Furthermore, RCA also claimed invention of FM radio and won its own patent on the technology. A patent fight between RCA and Armstrong ensued. RCA's momentous victory in the courts left Armstrong unable to claim royalties on any FM radios sold in the United States. The undermining of Yankee Network and Patent Court battle brought ruin to Armstrong, by then, almost penniless and emotionally distraught. His near obsession with radio and total involvement in the patent fight also destroyed his marriage, apparently one of the few close personal relationships Armstrong ever developed.

Alone and driven to despair over the FM debacle, Armstrong, dressed in full coat and hat, jumped to his death from the thirteenth floor window of his New York City flat on January 31, 1954. His widow, Marion, renewed the patent fight against RCA and finally prevailed in 1967. It took decades following Armstrong's death for FM radio to meet and surpass the saturation of the AM band, and longer still for FM radio to become profitable for broadcasters. However, Armstrong's invention, and his genius, were ultimately proven in the marketplace by today's broad acceptance of the FM band.

Armstrong was of the opinion that anyone who had actual contact with the making of the development of radio understood that the radio art was the product of experiment and work based on physical reasoning, rather than on the mathematicians' calculations and formulae (known today as part of "mathematical physics").


In 1917, Armstrong was the first recipient of the IRE's, now IEEE Medal of Honor. For his wartime work on radio, the French government gave him the Legion of Honor in 1919. He received, in 1942, the AIEEs Edison Medal "For distinguished contributions to the art of electric communication, notably the regenerative circuit, the superheterodyne, and frequency modulation." The ITU added him to its roster of great inventors of electricity in 1955. In 1980, he was inducted into the National Inventors Hall of Fame, and was on a U.S. postage stamp in 1983. The Consumer Electronics Hall of Fame inducted him in 2000, "in recognition of his contributions and pioneering spirit that have laid the foundation for consumer electronics."


Armstrong received 42 patents in total; a selection are listed below:


  1. Tom Lewis, Empire of the Air: The Men who Made Radio (New York: E. Burlingame Books, 1991). ISBN 0060182156
  2. Find a Grave, Edwin Howard Armstrong. Retrieved June 22, 2007.
  3. J.R. Carson, Notes on the theory of modulation, Proc. IRE, vol. 10, no. 1 (Feb. 1922): 57-64. Retrieved June 22, 2007.
  4. E.H. Armstrong, A method of reducing disturbances in radio signaling by a system of frequency modulation. Proc. IRE, vol. 24, no. 5 (May 1936): 689-740. Retrieved June 22, 2007.
  5. M.G. Crosby, Frequency modulation noise characteristics, Proc. IRE, vol. 25, no. 4 (April 1937): 472-514. Retrieved June 22, 2007.
  6. Current Biography 1940, p. 23-26.

ISBN links support NWE through referral fees

  • Lessing, Lawrence. Man of High Fidelity: Edwin Howard Armstrong; A Biography. New York: Bantam Books, 1969.
  • Brittain, James E. The Legacies of Edwin Howard Armstrong. Littleton, CO: The Radio Club of America, 1991.
  • Armstrong, Edwin H. Edwin H. Armstrong: Papers. Washington, D.C.: Smithsonian Institution, 1972.
  • Lewis, Tom. Empire of the Air: The Men who Made Radio. New York, NY: HarperCollins, 1991. ISBN 0060182156.

External links

All links retrieved September 21, 2017.


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