FM radio

The invention: A method of broadcasting radio signals by modulating the frequency, rather than the amplitude, of radio waves, FM radio greatly improved the quality of sound transmission. The people behind the invention: Edwin H. Armstrong (1890-1954), the inventor of FM radio broadcasting David Sarnoff (1891-1971), the founder of RCA An Entirely New System Because early radio broadcasts used amplitude modulation (AM) to transmit their sounds, they were subject to a sizable amount of interference and static. Since goodAMreception relies on the amount of energy transmitted, energy sources in the atmosphere between the station and the receiver can distort or weaken the original signal. This is particularly irritating for the transmission of music. Edwin H. Armstrong provided a solution to this technological constraint. A graduate of Columbia University, Armstrong made a significant contribution to the development of radio with his basic inventions for circuits for AM receivers. (Indeed, the monies Armstrong received from his earlier inventions financed the development of the frequency modulation, or FM, system.) Armstrong was one among many contributors to AM radio. For FM broadcasting, however, Armstrong must be ranked as the most important inventor. During the 1920’s, Armstrong established his own research laboratory in Alpine, New Jersey, across the Hudson River from New York City. With a small staff of dedicated assistants, he carried out research on radio circuitry and systems for nearly three decades. At that time, Armstrong also began to teach electrical engineering at Columbia University. From 1928 to 1933, Armstrong worked diligently at his private laboratory at Columbia University to construct a working model of an FM radio broadcasting system. With the primitive limitations then imposed on the state of vacuum tube technology, a number of Armstrong’s experimental circuits required as many as one hundred tubes. Between July, 1930, and January, 1933, Armstrong filed four basic FM patent applications. All were granted simultaneously on December 26, 1933. Armstrong sought to perfectFMradio broadcasting, not to offer radio listeners better musical reception but to create an entirely new radio broadcasting system. On November 5, 1935, Armstrong made his first public demonstration of FM broadcasting in New York City to an audience of radio engineers. An amateur station based in suburban Yonkers, New York, transmitted these first signals. The scientific world began to consider the advantages and disadvantages of Armstrong’s system; other laboratories began to craft their own FM systems. Corporate Conniving Because Armstrong had no desire to become a manufacturer or broadcaster, he approached David Sarnoff, head of the Radio Corporation of America (RCA). As the owner of the top manufacturer of radio sets and the top radio broadcasting network, Sarnoff was interested in all advances of radio technology. Armstrong first demonstrated FM radio broadcasting for Sarnoff in December, 1933. This was followed by visits from RCA engineers, who were sufficiently impressed to recommend to Sarnoff that the company conduct field tests of the Armstrong system. In 1934, Armstrong, with the cooperation of RCA, set up a test transmitter at the top of the Empire State Building, sharing facilities with the experimental RCAtelevision transmitter. From 1934 through 1935, tests were conducted using the Empire State facility, to mixed reactions of RCA’s best engineers. AM radio broadcasting already had a performance record of nearly two decades. The engineers wondered if this new technology could replace something that had worked so well. This less-than-enthusiastic evaluation fueled the skepticism of RCA lawyers and salespeople. RCA had too much invested in the AM system, both as a leading manufacturer and as the dominant owner of the major radio network of the time, the National Broadcasting Company (NBC). Sarnoff was in no rush to adopt FM. To change systems would risk the millions of dollars RCAwas making as America emerged from the Great Depression. In 1935, Sarnoff advised Armstrong that RCA would cease any further research and development activity in FM radio broadcasting. (Still, engineers at RCA laboratories continued to work on FM to protect the corporate patent position.) Sarnoff declared to the press that his company would push the frontiers of broadcasting by concentrating on research and development of radio with pictures, that is, television. As a tangible sign, Sarnoff ordered that Armstrong’s FM radio broadcasting tower be removed from the top of the Empire State Building. Armstrong was outraged. By the mid-1930’s, the development of FM radio broadcasting had become a mission for Armstrong. For the remainder of his life, Armstrong devoted his considerable talents to the promotion of FM radio broadcasting. Impact After the break with Sarnoff, Armstrong proceeded with plans to develop his own FM operation. Allied with two of RCA’s biggest manufacturing competitors, Zenith and General Electric, Armstrong pressed ahead. In June of 1936, at a Federal Communications Commission (FCC) hearing, Armstrong proclaimed that FM broadcasting was the only static-free, noise-free, and uniform system—both day and night—available. He argued, correctly, thatAMradio broadcasting had none of these qualities. During World War II (1939-1945), Armstrong gave the military permission to use FM with no compensation. That patriotic gesture cost Armstrong millions of dollars when the military soon became all FM. It did, however, expand interest in FM radio broadcasting. World War II had provided a field test of equipment and use. By the 1970’s, FM radio broadcasting had grown tremendously. By 1972, one in three radio listeners tuned into an FM station some time during the day. Advertisers began to use FM radio stations to reach the young and affluent audiences that were turning to FM stations in greater numbers. By the late 1970’s, FM radio stations were outnumberingAMstations. By 1980, nearly half of radio listeners tuned into FM stations on a regular basis. Adecade later, FM radio listening accounted for more than two-thirds of audience time. Armstrong’s predictions that listeners would prefer the clear, static-free sounds offered by FM radio broadcasting had come to pass by the mid-1980’s, nearly fifty years after Armstrong had commenced his struggle to make FM radio broadcasting a part of commercial radio.