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The Spirit of Radio: A Primer |
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Dr. Samuel Says -
Bidness
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Written by Dr. Samuel Centralia, Ph.D., D.D.S., Esq.
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Tuesday, 23 September 2008 |
So I was on the MENSA online forums the other day, discussing my recent wish list item regarding iPods and satellite radio. This sparked a whole conversation about radio, and the perennial, greatly exaggerated reports of its impending demise. Ever since the dotcom boom, pundits have been predicting the death of old media like radio, newspapers and books. And yet these institutions have proven remarkably tenacious.
Radio in particular keeps on keeping on, for which I am thankful. NPR
is, of course, a national treasure. And I even like the local morning
radio shock jocks I can pick up from our underground bunker here at
Dyscern World HQ. Anyway, I had a request recently from one of the kids
on the MENSA list. (Several grade school students have managed to hack
the forums, and we figured if they could do that, then they may as well stick around.) Young Jimmy wanted a primer on what AM and FM are all
about, since -- to him -- radio is just another antiquated technology,
like 8-track tapes.
 So this one goes out to Jimmy: AM (amplitude modulation) and FM
(frequency modulation) designate specific kinds of radio transmissions.
In a radio transmission, information is imparted to a carrier wave by
varying its amplitude, frequency, or duration in a process called
modulation. AM and FM go about this differently -- AM by creating
"side-band" frequencies in the carrier wave, FM by varying the number
of cycles the wave goes through. (It gets pretty technical.) In the
United States, the Federal Communications Commission (FCC) regulates
broadcast frequencies. For AM radio, it's 535 kilohertz to 1.7 megahertz; for FM, 88 megahertz and 108 megahertz.
Also, regarding radio and portable gadgets, astute reader Tom wrote
back to remind everyone that Pandora Internet radio has some cool
mobile apps. Those Pandora guys have been around a long time, and they
do noble work. Drop by, won't you?
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