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A Historical Note on FM: Edwin H. Armstrong (1890-1954)
Today, nobody doubts that FM has a key place in broadcasting & communication. However, in 1960s, FM broadcasting seemed doomed because it was so uneconomical in bandwidth usage.
Superficial reasoning showed that it was feasible to reduce the transmission bandwidth by using FM. But the experimental results showed otherwise. Mathematical analysis by Carson showed that FM indeed required a larger bandwidth than AM. Unfortunately, Carson did not recognize the advantage of FM in its ability to suppress noise. So he concluded that FM introduces distortion and has no compensating advantages. In a later paper, he continues "We are unavoidably forced to the conclusion that noise, like the poor, will always be with us". The opinion of one of the most able mathematician of the day in the communication field, thus set back the development of FM by more than a decade. The noise suppressing advantage of FM was later proved by Major Edwin H. Armstrong, a brilliant engineer whose contributions to the field of radio systems are comparable to those of Hertz and Marconi.
Armstrong is one of the foremost contributors to radio electronics of the 21st century. He was credited with the invention of regenerative circuit while he was a junior at Columbia University, then the superheterodyne circuit while serving in the US army during WWI. Major Armstrong is the acknowledged inventor of the regenerative feedback circuit. Armstrong received his FM patents in 1933, he gave his famous paper accompanied by the first public demonstration of FM broadcasting on November 5, 1935 at the New York section meeting of the Institute of Radio Engineers (IRE, a predecessor of IEEE). His success in reducing static noise using FM was not fully embraced by the broadcast establishment, which perceive FM as a threat to its vast commercial investment in AM radio. To establish FM broadcasting, Armstrong fought long and costly battle with the radio broadcast establishment, which was abetted by FCC (Federal Communications Commission). By December 1941, 67 commercial FM stations had been authorized with as many as half a million receivers in use and 43 applications were pending. In fact, RTPB (Radio Technical Planning Board) made its final recommendation during the September 1944 that FM be given 75 channels in the band from 41 to 56 MHz.
Despite the recommendation from RTPB, FCC forced to shift the FM band & then in June 1945, FCC on the basis of erroneous testimony of technical expert, abruptly shifted the allocated bandwidth of FM 42-50 MHz range to 88-108 MHz. This dealt a crippling blow to FM by making obsolete more than half a million receivers and equipment (transmitters, antennas etc) that had been built and sold by the FM industry to 50 FM stations since 1941 for the 42-50 MHz band. Armstrong stand against the decision and later succeeded in getting the technical expert to admit his error. In spite all of this, FCC allocations remained unchanged. The broadcast giants, which had so strongly resisted FM, turned around and used his inventions without paying him royalties. Armstrong spent much of his time in court in some of the longest, most notable and acrimonious patent suits of era. In the end, with his funds depleted, his energy drained and his family life shattered, a despondent Armstrong committed suicide. In 1954, he walked out of a window of his thirteenth floor apartment in New York's River House.
Armstrong's widow continued the legal battles and won. By the 1960's, FM was clearly established as the superior radio system and Edwin H. Armstrong was fully recognized as the inventor of frequency modulation (FM). In 1980 Edwin H. Armstrong was inducted into the US National Inventors Hall of Fame, and his picture was put on a US postage stamp in 1983.
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Superficial reasoning showed that it was feasible to reduce the transmission bandwidth by using FM. But the experimental results showed otherwise. Mathematical analysis by Carson showed that FM indeed required a larger bandwidth than AM. Unfortunately, Carson did not recognize the advantage of FM in its ability to suppress noise. So he concluded that FM introduces distortion and has no compensating advantages. In a later paper, he continues "We are unavoidably forced to the conclusion that noise, like the poor, will always be with us". The opinion of one of the most able mathematician of the day in the communication field, thus set back the development of FM by more than a decade. The noise suppressing advantage of FM was later proved by Major Edwin H. Armstrong, a brilliant engineer whose contributions to the field of radio systems are comparable to those of Hertz and Marconi.
Armstrong is one of the foremost contributors to radio electronics of the 21st century. He was credited with the invention of regenerative circuit while he was a junior at Columbia University, then the superheterodyne circuit while serving in the US army during WWI. Major Armstrong is the acknowledged inventor of the regenerative feedback circuit. Armstrong received his FM patents in 1933, he gave his famous paper accompanied by the first public demonstration of FM broadcasting on November 5, 1935 at the New York section meeting of the Institute of Radio Engineers (IRE, a predecessor of IEEE). His success in reducing static noise using FM was not fully embraced by the broadcast establishment, which perceive FM as a threat to its vast commercial investment in AM radio. To establish FM broadcasting, Armstrong fought long and costly battle with the radio broadcast establishment, which was abetted by FCC (Federal Communications Commission). By December 1941, 67 commercial FM stations had been authorized with as many as half a million receivers in use and 43 applications were pending. In fact, RTPB (Radio Technical Planning Board) made its final recommendation during the September 1944 that FM be given 75 channels in the band from 41 to 56 MHz.
Despite the recommendation from RTPB, FCC forced to shift the FM band & then in June 1945, FCC on the basis of erroneous testimony of technical expert, abruptly shifted the allocated bandwidth of FM 42-50 MHz range to 88-108 MHz. This dealt a crippling blow to FM by making obsolete more than half a million receivers and equipment (transmitters, antennas etc) that had been built and sold by the FM industry to 50 FM stations since 1941 for the 42-50 MHz band. Armstrong stand against the decision and later succeeded in getting the technical expert to admit his error. In spite all of this, FCC allocations remained unchanged. The broadcast giants, which had so strongly resisted FM, turned around and used his inventions without paying him royalties. Armstrong spent much of his time in court in some of the longest, most notable and acrimonious patent suits of era. In the end, with his funds depleted, his energy drained and his family life shattered, a despondent Armstrong committed suicide. In 1954, he walked out of a window of his thirteenth floor apartment in New York's River House.
Armstrong's widow continued the legal battles and won. By the 1960's, FM was clearly established as the superior radio system and Edwin H. Armstrong was fully recognized as the inventor of frequency modulation (FM). In 1980 Edwin H. Armstrong was inducted into the US National Inventors Hall of Fame, and his picture was put on a US postage stamp in 1983.
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