Edwin H. Armstrong made some of the greatest contributions to radio in the twentieth century. He is mostly known for three key inventions: regeneration, super-heterodyning, and frequency modulation. He was born in New York City on Dec. 18, 1890. His father was vice president of the United States branch of the Oxford University Press and his mother was a teacher. At the age of fourteen he decided to be an inventor after reading Boy's Book of Inventions and being inspired by Guglielmo Marconi. As a teen he built a 125 ft. high antenna mast on the family's lawn. In 1910 he enrolled in Electrical Engineering at Columbia University and during his junior year made his first major discovery, regeneration.
One of the devices he aquired was an audion tube, invented by Lee De Forest in 1906. Not much had been done with the audion tube, the first triode vacuum tube. Armstrong discovered that the gain of a triode amplifier could be greatly increased by feeding some of the amplifier output, using positive feedback, back into the input. This could be done again and again until it reached a level where it became a stable and powerful oscillator and thus able to transmit radio waves.
Using less feedback the amplifier became a very sensitive receiver. He got his engineering degree in 1913 and filed for a patent on his discovery, licensing it to the Marconi Co. in 1914.
World War I had begun and Armstrong was commissioned as an officer in the U.S. Army Signal Corps. Captain Armstrong was assigned to detect enemy communications and while in the war he invented the super-heterodyning priciple which incorporated the regeneration technique. Super-heterodyning greatly increased the sensitivity and selectivity of the radio receiver and is still used in most radios and television sets today. Armstrong returned to Columbia as an instructor after the war. In 1920 he sold his rights to the super-heterodyne receiver and the regeneration technique to Westinghouse and they started the nation's first radio station, KDKA in Pittsburgh, PA. It wasn't long before RCA, which was formed from the Marconi Co., bought up all of Westinghouse's radio patents and those of AT&T among others.
De Forest said that regeneration was his idea and challenged Armstrong's patent from 1914. de Forest had filed for similar patents using variations of the regeneration technique, after he saw what Armstrong had done, and sold them to AT&T. He was outraged that someone as young as Armstrong had outdone him. deForest lost case after case but persisted for over ten years. The only evidence of precedence deForest had was a note in a lab book from 1912 stating that a certain circuit emitted a howl when tuned a certain way. The howl was feedback causing the circuit to oscillate, which deForest didn't understand at the time. AT&T lawyers were able to get a ruling from a non-technical judge in favor of deForest and they ran with it, eventually breaking Armstrong's patent. RCA and other radio companies were well aware of Armstrong's position but offered no help since it was in their best interest for deForest to win so that they could retain control of the patent for another ten years. Meanwhile, Armstrong had already made a similar device called the super-regenerative circuit which he sold to RCA for a large block of stock. He became a millionaire with the success of radio. In 1923, he married Marion MacInnes, secretary to the president of RCA,David Sarnoff.
After loosing the patent fight, Armstrong went to work on radio's static problem. Frequency modulation had been tried in the 1920s but because a narrow band had been used it sounded worse than AM. Armstrong saw that an FM signal didn't have to have a narrow range of frequencies but could vary over a wide range and have a better signal to noise ratio. He got FM working in 1933 and presented it to RCA but they were not interested. They had used most of his licenses to build an industry worth almost $2 billion and weren't about to change a good thing. So Armstrong developed FM on his own.
He did a field test in 1934. He transmitted an organ recital simultaneously on AM and FM from an RCA tower on the Empire State Building to a home on Long Island. The FM signal came through loud and clear. The AM was full of static and other electrical noise. It was noted that FM had a much wider audio range, the discovery of Hi-Fi. Armstrong also found that a single FM carrier could transmit two radio programs at the same time, thus he discovered multiplexing. Armstrong began to license FM to smaller companies and by 1939 he'd set up a pilot broadcasting service in New York and New England. RCA soon petitioned the FCC to give FM's frequency assignments to television which was just getting off the ground. The attack was so obvious that the FCC gave the whole band from 44 to 50 MHz to FM. This range would have contained TV's channel 1. They also required TV sound to be carried on FM.
Armstrong was on the verge of success when WWII broke out.
Armstrong let the military use his FM patents for free during the war. When the U.S. discovered that the Germans were using AM they were able to jam it. FM could virtually not be jammed. By the end of the war Armstrong had developed his continuous wave FM radar and was able to bounce a signal off the moon. RCA had also been busy and after the war in 1945 they and a few other companies convinced the FCC to move the FM band from the 44-50 MHz range to the 88-108 MHz range. The FCC also voted to limit FM transmitting power and banned radio relays from central stations to mountaintop antennas. FM broadcasters now had to use AT&T's coaxial cable systems at excessive costs.
By 1948 Armstrong had finished redesigning all of his systems but RCA had been building televisions and FM receivers for eight years and paid absolutely nothing to Armstrong in licensing fees. In a few years his patents would expire so he took action with a patent infringement suit against RCA in 1949. RCA's lawyers kept Armstrong on the stand for over a year with trivial and irrelevant questions. Two years went by and RCA was called upon and revealed a pile of research that it had done in the 1930s. To top it all off, Sarnoff claimed that RCA had invented FM on its own with no help from Armstrong. Armstrong was so upset he refused anything but an all out win but RCA kept him tied up in court until his patents finally ran out. RCA could easily afford an army of lawyers but Armstrong was nearly broke and had sold most of his assets. He asked RCA for a $2.4 million settlement but they came back with $200,000 which didn't even cover Armstrong's legal fees. Armstrong approached his wife for some of the money he had given her to put toward their retirement and after a bitter fight she moved out and went to stay with her sister.
Edwin Armstrong spent the Holiday Season alone. A month later on Jan. 31, 1954 he put on his coat and hat and walked out the window of his 13th floor apartment. His body was found the next morning on a third story overhang. A month later RCA announced that it had reached an all time high earnings of over $850 million. Armstrong's widow pursued the twenty-some infringement suits and over a period of about 13 years won over $10 million.
Armstrong bio (http://users.erols.com/oldradio/ehabio.htm)
Edwin Howard Armstrong (http://world.std.com/~jlr/doom/armstrng.htm)
Edwin Armstrong - The creator of FM radio (http://www.webstation.com/fecha/armstrong.htm)