Reginald Fessenden – Dec 23 1900: First transmission of the human voice via radio

Via Scoop.itMediaMentor

Dec 23 1900: First transmission of the human voice via radio by the Canadian inventor Reginald Fessenden (1866 – 1932) / 23 décembre 1900 : Première transmission de la voix humaine à la radio par l’inventeur canadien Reginald Fessenden (1866 – 1932). [excerpt] US Weather Bureau contract and the first audio radio transmission In 1900 Fessenden left the University of Pittsburgh to work for the United States Weather Bureau, with the objective of proving the practicality of using a network of coastal radio stations to transmit weather information, thus avoiding the need to use the existing telegraph lines. The contract gave the Weather Bureau access to any devices Fessenden invented, but he would retain ownership of his inventions. Fessenden quickly made major advances, especially in receiver design, as he worked to develop audio reception of signals. His initial success came from a barretter detector, which was followed by the electrolytic detector that consisted of a fine wire dipped in nitric acid, and for the next few years this later device would set the standard for sensitivity in radio reception. As his work progressed, Fessenden also evolved the heterodyne principle, which combined two signals to produce a third audible tone. However, heterodyne reception was not fully practical for a decade after it was invented, since it required a means for producing a stable local signal, which awaited the development of the oscillating vacuum-tube. Cobb Island on the Potomac River, scene of the first successful radio transmission of speech on December 23, 1900. The initial work took place at Cobb Island, Maryland, located about 80 kilometers (50 mi) downstream from Washington, DC. While there, Fessenden, experimenting with a high-frequency spark transmitter, successfully transmitted speech on December 23, 1900 over a distance of about 1.6 kilometers (one mile), which appears to have been the first audio radio transmission. At this time the sound quality was too distorted to be commercially practical, but as a test this did show that with further technical refinements it would become possible to transmit audio using radio signals. As the experimentation expanded, additional stations were built along the Atlantic Coast in both North Carolina and Virginia. However, in the midst of promising advances, Fessenden became embroiled in disputes with his sponsor. In particular, he charged that Bureau Chief Willis Moore had attempted to gain a half-share of the patents — Fessenden refused to sign over the rights, and his work for the Weather Bureau ended in August, 1902. (This incident recalled F. O. J. Smith, a member of the House of Representatives from Maine, who had managed to gain a one-quarter interest in the Morse telegraph.)


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