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).
http://en.wikipedia.org/wiki/Reginald_Fessenden
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<http://en.wikipedia.org/wiki/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<http://en.wikipedia.org/wiki/Barretter_detector>,
which was followed by the electrolytic
detector<http://en.wikipedia.org/wiki/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 <http://en.wikipedia.org/wiki/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.
The initial work took place at Cobb Island,
Maryland<http://en.wikipedia.org/wiki/Cobb_Island,_Maryland>,
located about 80 kilometers (50 mi) downstream from Washington,
DC<http://en.wikipedia.org/wiki/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<http://en.wikipedia.org/wiki/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<http://en.wikipedia.org/wiki/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.)
[Non-text portions of this message have been removed]
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