My friend Bob just emailed this to me. Figured I'd pass it along to the group.
Merry Christmas
John
Happy Birthday AM from Bob WA2BSP Rocky Hill, NJThe Birthday of AM - December 24, 1906
In 1901 Reginald Aubrey Fessenden invented a high-frequency
alternator which produced a continuous radio wave, unlike
Guglielmo Marconi's intermittent spark-pulse radio wave
generator used to send Morse code. It was a great
improvement over Marconi's intermittent generator and was
essential to the development of amplitude modulation.
Fessenden invented the way to modulate the amplitude (the
distance from " peak" to "trough") of radio waves.
A microphone was used to convert ordinary sound into an
electric signal which was superimposed on the continuous
radio waves. The modulated radio waves, now matching the
amplitude of the electric signal, were sent out over the
transmitting antenna. At the receiving antenna, the radio
waves are converted back into electric signals and
demodulated; the radio wave carrier is removed, leaving
behind the audio signal that is amplified and sent to a
loudspeaker.
On Christmas Eve, 1906, Fessenden made the world's first
radio broadcast. He transmitted his voice, as well as violin
and recorded music a distance of several hundred miles to
ships on the Atlantic Ocean.
(from:
http://www.bookrags.com/research/amplitude-modulation-woi/)
The latest AM technology is in a book titled: "Single- and
Multi-carrier Quadrature Amplitude Modulation: Principles
and Applications for Personal Communications, WLANs and
Broadcasting"
SEE ALSO:
http://www.vigyanprasar.gov.in/dream/nov2001/article1.htmhttp://en.wikipedia.org/wiki/Timeline_of_radiohttp://en.wikipedia.org/wiki/Reginald_Fessendenhttp://en.wikipedia.org/wiki/Alexanderson_alternator
