Thursday
Mar182010
TWiRT 24 - Amplitude Modulation
Thursday, March 18, 2010 at 12:28AM Foundation Series - The TWiRT engineers discuss and explain AM - generating, amplifying, transmitting
Kirk Harnack - Executive Director, Int'l Business Development, Telos-Omnia-Axia
Tom Ray - VP, Engineering, Buckley Broadcasting, WOR, New York, W2TRR
Chris Tobin - CBS Radio, New York
Chris Tarr - Entercom, Milwaukee, GeekJedi, and Broadcast Engineering Info
Some resources that exemplify our discussion points:
Definition of Amplitude Modulation
AM demonstrated on an oscilloscope - not the way I would have shown it, but it's instructive.
Interactive AM demo - Adjust the on-screen controls to get an idea of AM parameters.
Download link...
Reader Comments (4)
On this episode, Chris Tarr (or was it Tom Rey?) mentioned that AM skip is more a function of frequency, not a function of transmission mode, and that FM transmissions would skip pretty well on AM frequencies.
Wow! If this is so, have their been any attempts in the past 50 years (here or elsewhere in the world) to convert AM statiions to FM on the existing AM band? If not, why not, and if so, what killed it?
Thanks for a great show. I learned a lot. I thought there was too much buildup to get into the meat of the subject. The first 5 minutes of fun-n-games perhaps could be skipped.
Bandwidth and money are the likely causes for not converting AMs to FM - 10 kHZ per station for AM vs 200 kHz for conventional FM. This would cut the number of stations in the band significantly and the owners are not likely to spend the millions (billions?) necessary to make the conversion. And the politics of reassignment? Ouch!
For the record, ham radio operators have been known to toy with FM on skip frequencies.
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