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Old July 4th 07, 09:27 PM posted to sci.electronics.basics,rec.radio.shortwave,rec.radio.amateur.antenna,alt.cellular.cingular,alt.internet.wireless
John Fields John Fields is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 58
Default AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency

On Wed, 04 Jul 2007 09:11:58 -0700, isw wrote:

In article ,
"Ron Baker, Pluralitas!" wrote:


You win.

When I conceived the problem I was thinking
cosines actually. In which case there are no
phase shifts to worry about in the result.

I also forgot the half amplitude factor.

While it might not be obvious, the two cases I
described are basically identical. And this
situation occurs in real life, i.e. in radio signals,
oceanography, and guitar tuning.


The beat you hear during guitar tuning is not modulation; there is no
non-linear process involved (i.e. no multiplication).


---
That's not true.

The human ear has a logarithmic amplitude response and the beat note
(the difference frequency) is generated there. The sum frequency is
too, but when unison is achieved it'll be at precisely twice the
frequency of either fundamental and won't be noticed.


--
JF