Edwin Howard Armstrong
American electrical engineer and inventor
Edwin Howard Armstrong
Edwin Howard Armstrong was an American electrical engineer and inventor. He has been called "the most prolific and influential inventor in radio history". He invented the regenerative circuit while he was an undergraduate and patented it in 1914, followed by the super-regenerative circuit in 1922, and the superheterodyne receiver in 1918. Armstrong was also the inventor of modern frequency modulation (FM) radio transmission.
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  • 1954
    Age 63
    Sometime during the night of January 31/February 1, 1954, with his wife in Connecticut and three servants having left for the day, Armstrong removed the air conditioner from a window in his twelve-room apartment on the thirteen-floor of River House in New York City, and jumped to his death.
    More Details Hide Details His body—fully clothed, with a hat, overcoat and gloves—was found in the morning on a third-floor balcony by a River House employee. The New York Times described the contents of his two-page suicide note to his wife: "he was heartbroken at being unable to see her once again, and expressing deep regret at having hurt her, the dearest thing in his life." The note concluded, "God keep you and Lord have mercy on my Soul." David Sarnoff declaimed any responsibility, telling Carl Dreher directly that "I did not kill Armstrong." After his death, a friend of Armstrong estimated that 90 percent of his time was spent on litigation against RCA. U.S. Senator Joseph McCarthy (R-Wisconsin) reported that Armstrong had recently met with one of his investigators, and "was mortally afraid that secret radar discoveries he and other scientists had made were being fed to the communists as fast as they could be developed". Armstrong was buried in Locust Grove Cemetery, Merrimac, Massachusetts.
  • 1948
    Age 57
    Outraged by this turn of events, in 1948 Armstrong filed suit against RCA and the National Broadcasting Company, accusing them of patent infringement and that they had "deliberately set out to oppose and impair the value" of his invention, for which he requested treble damages.
    More Details Hide Details Although confident that this suit would be successful and result in a major monetary award, the protracted legal maneuvering that followed eventually began to severely affect his finances, especially after his primary patents expired in late 1950. Bitter and overtaxed by years of litigation and mounting financial problems, Armstrong lashed out at his wife one day with a fireplace poker, striking her on the arm. She left their apartment to stay with her sister, Marjorie Tuttle, in Granby, Connecticut.
  • 1945
    Age 54
    In late 1945, Armstrong contracted with John Orr Young, founding member of the public relations firm Young & Rubicam, to conduct a national campaign promoting FM broadcasting, especially by educational institutions.
    More Details Hide Details Article placements promoting both Armstrong personally and FM were made with general circulation publications including The Nation, Fortune, the New York Times, Atlantic Monthly, and The Saturday Evening Post.
  • 1941
    Age 50
    He was awarded the 1941 Franklin Medal, and in 1942 received the AIEEs Edison Medal "for distinguished contributions to the art of electric communication, notably the regenerative circuit, the superheterodyne, and frequency modulation".
    More Details Hide Details 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 appeared 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." Columbia University established the Edwin Howard Armstrong Professorship in Computer Science in his memory. Philosophy Hall, the Columbia building where Armstrong developed FM, was declared a National Historic Landmark. Armstrong's boyhood home in Yonkers, New York was recognized by the National Historic Landmark program and the National Register of Historic Places, although this was withdrawn when the house was demolished. Armstrong Hall at Columbia was named in his honor. The hall, located at the northeast corner of Broadway and 112th Street, was originally an apartment house but was converted to research space after being purchased the university. It is currently home to the Goddard Institute for Space Studies, a research institute dedicated to atmospheric and climate science that is jointly operated by Columbia and the National Aeronautics and Space Administration. A storefront in a corner of the building houses Tom's Restaurant, a longtime neighborhood fixture that inspired Susanne Vega's song "Tom's Diner" and was used for establishing shots for the fictional "Monk's diner" in the "Seinfeld" television series.
    He held 42 patents and received numerous awards, including the first Medal of Honor awarded by the Institute of Radio Engineers (now IEEE), the French Legion of Honor, the 1941 Franklin Medal and the 1942 Edison Medal.
    More Details Hide Details He was inducted into the National Inventors Hall of Fame and included in the International Telecommunication Union's roster of great inventors. Armstrong was born in the Chelsea district of New York City, the oldest of John and Emily (Smith) Armstrong's three children. His father began working at a young age at the American branch of the Oxford University Press, which published bibles and standard classical works, eventually advancing to the position of vice president. His parents first met at the North Presbyterian Church, located at 31st Street and Ninth Avenue. His mother's family had strong ties to Chelsea, and an active role in church functions.
  • 1940
    Age 49
    He was an avid tennis player until an injury in 1940, and drank an Old Fashioned with dinner.
    More Details Hide Details Politically, he was described by one of his associates as "a revolutionist only in technology — in politics he was one of the most conservative of men". In 1955 Marion Armstrong founded the Armstrong Memorial Research Foundation, and participated in its work until her death in 1979 at the age of 81. She was survived by two nephews and a niece. 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.
    In 1940, RCA offered Armstrong $1,000,000 for a non-exclusive, royalty-free license to use his FM patents, but he refused this offer, primarily because he felt this would be unfair to the other licensed companies, which had to pay 2% royalties on their sales.
    More Details Hide Details Over time this impasse with RCA would come to dominate Armstrong's life. RCA countered by conducting its own FM research, eventually developing what it claimed was a non-infringing FM system. The corporation also encouraged other companies to stop paying royalties to Armstrong.
  • 1936
    Age 45
    In 1936 he published a landmark paper in the Proceedings of the IRE that documented the superior capabilities of using wide-band FM. (This paper would be reprinted in the August 1984 issue of Proceedings of the IEEE.) A year later, a paper by Murray G. Crosby (inventor of Crosby system for FM Stereo) in the same journal provided further analysis of the wide-band FM characteristics, and introduced the concept of "threshold", demonstrating that there is a superior signal to noise ratio when the signal is stronger than a certain level.
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    In June 1936, Armstrong gave a formal presentation of his new system at the U.S. Federal Communications Commission (FCC) headquarters in Washington, D.C. For comparison, he played a jazz record using a conventional AM radio, then switched to an FM transmission.
    More Details Hide Details A United Press correspondent was present, and recounted in a wire service report that: "if the audience of 500 engineers had shut their eyes they would have believed the jazz band was in the same room. There were no extraneous sounds." Moreover, "Several engineers said after the demonstration that they consider Dr. Armstrong's invention one of the most important radio developments since the first earphone crystal sets were introduced." Armstrong was quoted as saying he could "visualize a time not far distant when the use of ultra-high frequency wave bands will play the leading role in all broadcasting", although the article noted that "A switchover to the ultra-high frequency system would mean the junking of present broadcasting equipment and present receivers in homes, eventually causing the expenditure of billions of dollars." In the late 1930s, as technical advances made it possible to transmit on higher frequencies, the FCC investigated options for increasing the number of broadcasting stations, in addition to ideas for better audio quality, known as "high-fidelity". In 1937 it introduced what became known as the Apex band, consisting of 75 broadcasting frequencies from 41.02 to 43.98 MHz. As on the standard broadcast band these were AM stations, but with higher quality audio — in one example, a frequency response from 20 Hz to 17,000 Hz +/- 1 dB — because station separations were 40 kHz instead of the 10 kHz spacings used on the original AM band.
  • 1934
    Age 43
    From May 1934 until October 1935 Armstrong conducted field tests of his FM technology from an RCA laboratory located on the 85th floor of the Empire State Building in New York City.
    More Details Hide Details An antenna attached to the building's spire transmitted signals for distances up to. These tests helped demonstrate FM's static-reduction and high-fidelity capabilities. However RCA, which was heavily invested in perfecting television broadcasting, chose not to invest in FM, and instructed Armstrong to remove his equipment. Denied the marketing and financial clout that RCA would have brought, Armstrong decided to finance his own development and form ties with smaller members of the radio industry, including Zenith and General Electric, to promote his invention. Armstrong thought that FM had the potential to replace AM stations within 5 years, which he promoted as a boost for the radio manufacturing industry, then suffering from the effects of the Great Depression, since making existing AM radio transmitters and receivers obsolete would necessitate that stations buy replacement transmitters and listeners purchase FM-capable receivers.
    Armstrong had a standing agreement to give RCA the right of first refusal to his patents. In 1934 he made a presentation of his new system to RCA president Sarnoff.
    More Details Hide Details Sarnoff was somewhat taken aback by its complexity, as he had hoped it would be possible to eliminate static merely by adding a simple device to existing receivers.
  • 1933
    Age 42
    Working in secret in the basement laboratory of Columbia's Philosophy Hall, Armstrong slowly developed what eventually resulted in wide-band FM, in the process discovering significant advantages over the earlier "narrow-band" FM transmissions. He was granted five U.S. patents covering the basic features of new system on December 26, 1933.
    More Details Hide Details Initially, the primary claim was that his FM system was effective at filtering out the noises produced in receivers by vacuum-tubes.
  • 1928
    Age 37
    In early 1928 Armstrong began researching the capabilities of frequency modulation.
    More Details Hide Details Although there were few others involved in FM research at this time, he did have knowledge of a project being conducted by RCA engineers, who were investigating whether FM shortwave transmissions were less susceptible to fading than AM. In 1931 these engineers conducted a successful FM shortwave link transmitting the Schmeling-Stribling fight broadcast from California to Hawaii, and noted at the time that the signals seemed to be less affected by static, but the project made little further progress.
  • 1922
    Age 31
    A year later, in 1922, Armstrong sold his super-regeneration patent to RCA for $200,000 plus 60,000 shares of corporation stock, which was later increased to 80,000 shares in payment for consulting services.
    More Details Hide Details This made Armstrong RCA's largest shareholder, and he noted that "The sale of that invention was to net me more than the sale of the regenerative circuit and the superheterodyne combined". RCA envisioned selling a line of super-regenerative receivers until superheterodyne sets could be perfected for general sales, however, it turned out the circuit was not selective enough to make it practical for broadcast receivers. "Static" interference — extraneous noises caused by sources such as thunderstorms and electrical equipment — bedeviled early radio communication using amplitude modulation (AM) and perplexed numerous inventors attempting to eliminate it. Many ideas for static elimination were investigated, with little success. In the mid-1920s, Armstrong began researching whether he could come up with a solution. He Initially, and unsuccessfully, attempted to resolve the problem by modifying the characteristics of existing AM transmissions. One approach considered as a potential solution had been the use of frequency modulation (FM) transmissions, where, in order to encode audio, instead of varying (technically known as "modulating") the amplitude (strength) of a radio signal, as was done for AM transmissions, the frequency was varied. However, in 1922 John Renshaw Carson of AT&T, inventor of Single-sideband modulation (SSB), had published a Proceedings of the IRE paper which included a detailed mathematical analysis which showed that FM transmissions did not provide any improvement over AM. Although the Carson bandwidth rule for FM is still important today, this review turned out to be incomplete, because it only analyzed what is now known as "narrow-band" FM.
  • 1919
    Age 28
    In 1919, Armstrong filed an application for a U.S. patent of the superheterodyne circuit, which was issued the next year.
    More Details Hide Details This patent was subsequently sold to Westinghouse. The patent would be challenged, however, triggering yet another patent office interference hearing. Unfortunately, Armstrong ultimately lost this patent battle; although the outcome was less controversial than that involving the regeneration proceedings. The challenger was Lucien Lévy of France, who had also worked developing Allied radio communication during World War One. He had been awarded French patents in 1917 and 1918 that covered some of the same basic ideas used in Armstrong's superheterodyne receiver. AT&T, which was interested in radio development at this time, primarily for point-to-point extensions of its wired telephone exchanges, purchased the U.S. rights to Lévy's patent and contested Armstrong's grant. The subsequent court reviews continued until 1928, when the District of Columbia Court of Appeals disallowed all nine claims of Armstrong's patent, assigning priority for seven of the claims to Lévy, and one each to Ernst Alexanderson of General Electric and Burton W. Kendall of Bell Laboratories.
    He returned to the United States in the fall of 1919, after being promoted to the rank of Major. (During both world wars, Armstrong gave the U.S. military free use of his patents.)
    More Details Hide Details During this period, Armstrong's most significant accomplishment was the development of a "supersonic heterodyne" — soon shortened to "superheterodyne" — radio receiver circuit. This circuit made radio receivers more sensitive and selective and is still extensively used today. The key feature of the superheterodyne approach is the mixing of the incoming radio signal with a locally generated, different frequency signal within a radio set. This circuit is typically referred to as the mixer. The end result is a fixed, unchanging intermediate frequency, or I.F. signal. Since this intermediate frequency is unchanging, it is more easily amplified and detected by subsequent circuit stages that follow the mixer.
    Legal proceedings related to the regeneration patent became separated into two groups of court cases. An initial court action was triggered in 1919, when Armstrong sued de Forest's company in district court, alleging infringement of patent 1,113,149.
    More Details Hide Details This court ruled in Armstrong's favor on May 17, 1921. But a second line of court cases, the result of the patent office interference hearing, would have a different outcome. The interference board had also sided with Armstrong, but he was unwilling to settle with de Forest for less than what he considered full compensation. Thus pressured, de Forest decided to continue his legal defense, and appealed the interference board decision to the District of Columbia district court. On May 8, 1924, that court ruled that it was de Forest who should be considered regeneration's inventor. Armstrong (along with much of the engineering community) was shocked by this course of events, and his side appealed this unexpected decision. But although the legal proceeding twice went before the U.S. Supreme Court, in 1928 and 1934, he was unsuccessful in overturning the decision.
  • 1917
    Age 26
    The United States entered into World War One in April 1917, and later that year Armstrong was commissioned as a Captain in the U.S. Army Signal Corps, and assigned to a laboratory in Paris, France to help develop radio communication for the Allied war effort.
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    In response to the second Supreme Court decision upholding de Forest as the inventor of regeneration, Armstrong attempted to return his 1917 IRE Medal of Honor, which had been awarded "in recognition of his work and publications dealing with the action of the oscillating and non-oscillating audion".
    More Details Hide Details However, the organization's board refused to let him, and issued a statement that it "strongly affirms the original award".
  • 1915
    Age 24
    Although Lee de Forest initially discounted Armstrong's findings, beginning in 1915 de Forest filed a series of competing patent applications that largely copied Armstrong's claims, now stating that he had discovered regeneration first, based on August 6, 1912 notebook entry, while working for the Federal Telegraph company, prior to the January 31, 1913 date recognized for Armstrong.
    More Details Hide Details The result was an interference hearing at the patent office to determine priority. De Forest was not the only other inventor involved — the four competing claimants included Armstrong, de Forest, General Electric's Langmuir, and Alexander Meissner, who was a German national, which led to his application being seized by the Office of Alien Property Custodian during World War One. Following the end of World War One, Armstrong enlisted representation by the law firm of Pennie, Davis, Martin and Edmonds. In order to finance his legal expenses, he began issuing non-transferable licenses for use of the regenerative patents to a select group of small radio equipment firms, and by November 1920 seventeen companies had been licensed. These licensees paid 5% royalties on their sales, which were restricted to only "amateurs and experimenters". Meanwhile, Armstrong reviewed his options for selling the commercial rights to his work. Although the obvious candidate was the Radio Corporation of America (RCA), on October 5, 1920 the Westinghouse Electric & Manufacturing Company took out an option for $335,000 for the commercial rights for both the regenerative and superheterodyne patents, with an additional $200,000 to be paid if Armstrong prevailed in the regenerative patent dispute. Westinghouse exercised this option on November 4, 1920.
  • 1914
    Age 23
    On October 6, 1914, U.S. patent 1,113,149 was issued for his discovery.
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  • 1913
    Age 22
    Beginning in 1913 Armstrong prepared a series of comprehensive demonstrations and papers that carefully documented his research, and in late 1913 applied for patent protection covering the regenerative circuit.
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    Armstrong graduated from Columbia in 1913, earning an electrical engineering degree.
    More Details Hide Details He later received two honorary doctorates, from Columbia in 1929, and Muhlenberg College in 1941. In 1934, he filled the vacancy left by John H. Morecroft's death, receiving an appointment as a Professor of Electrical Engineering at Columbia, a position he held the remainder of his life. Following college graduation, he received a $600 one-year appointment as a laboratory assistant at Columbia, after which he nominally worked as a research assistant, for a salary of $1 a year, under Professor Pupin. Unlike most engineers, Armstrong never became a corporate employee. He set up a self-financed independent research and development laboratory at Columbia, and owned his patents outright. Armstrong began working on his first major invention while still an undergraduate at Columbia. In late 1906, Lee de Forest had invented the three-element (triode) "grid Audion" vacuum-tube. How vacuum tubes worked was not understood at the time. De Forest's initial Audions did not have a high vacuum and developed a blue glow at modest plate voltages; De Forest improved the vacuum for Federal Telegraph. By 1912, how vacuum tubes worked was understood, and the advantages of high vacuum tubes was appreciated.
  • 1909
    Age 18
    In 1909 Armstrong enrolled at Columbia University in New York City, where he became a member of the Epsilon Chapter of the Theta Xi engineering fraternity, and studied under Professor Michael Pupin at the Hartley Laboratories, a separate research unit at Columbia.
    More Details Hide Details Another of his instructors, Professor John H. Morecroft, later remembered Armstrong as being intensely focused on the topics that interested him, but somewhat indifferent to the rest of his studies. He was known for challenging conventional wisdom and being quick to question the opinions of both professors and peers. In one case he recounted how he tricked an instructor he disliked into receiving a severe electrical shock. He also stressed the practical over the theoretical, stating that progress was more likely the product of experimentation and work based on physical reasoning than on mathematical calculation and formulae (known as part of "mathematical physics").
  • 1895
    Age 4
    When the church moved north, the Smiths and Armstrongs followed, and in 1895 the Armstrong family moved from their brownstone row house at 347 West 29th Street to a similar house at 26 West 97th Street in the Upper West Side.
    More Details Hide Details The family was comfortably middle class. At the age of eight, Armstrong contracted Sydenham's chorea (then known as St. Vitus' Dance), an infrequent but serious neurological disorder precipitated by rheumatic fever. For the rest of his life, Armstrong was afflicted with a physical tic exacerbated by excitement or stress. Due to this illness, he withdrew from public school and was home-tutored for two years. To improve his health, the Armstrong family moved to a house overlooking the Hudson River, at 1032 Warburton Avenue in Yonkers. The Smith family subsequently moved next door. Armstrong's tic and the time missed from school led him to become socially withdrawn. From an early age, Armstrong showed an interest in electrical and mechanical devices, particularly trains. He loved heights and constructed a makeshift backyard antenna tower that included a bosun's chair for hoisting himself up and down its length, to the concern of neighbors. Much of his early research was conducted in the attic of his parent's house.
  • 1890
    Born in 1890.
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