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Old July 8th 07, 08:17 PM posted to sci.electronics.basics,rec.radio.shortwave,rec.radio.amateur.antenna,alt.cellular.cingular,alt.internet.wireless
Jeff Liebermann[_2_] Jeff Liebermann[_2_] is offline
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Default AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency

"Bob Myers" hath wroth:

"Jeff Liebermann" wrote in message
.. .
An audible beat tone is produced by the constructive and destructive
interference between two sound waves in air. Look at a pictorial
representation (in the time domain) of the sum of sine waves,of similar
amplitudes, one at, say, 1000 Hz and the other at 1005, and you'll
see it.

Bob M.


I beg to differ. There's no mixing happening in the air.


Nor did I say there was. The phenomenon of interference
between two compression waves in a given medium is not
an example of "mixing."


You didn't say that. You that a beat note would be produced. From
your posting at:
http://groups.google.com/group/sci.electronics.basics/msg/f18c6dfefbd55a82
"An audible beat tone is produced by the constructive and
destructive interference between two sound waves in air."

That's wrong. There's no audible beat note produced in the air.

You can demonstrate it to yourself with a suitable audio spectrum
analyzer and tone generators. I recommend "Visual Analyzer 8"
http://digilander.libero.it/hsoft/
Generate two sine waves at any frequencies. Use a cheap microphone to
pickup the audio and display it with the audio SA. You won't see any
sums, differences, or intermodulation products unless you over drive
the microphone or try to produce the tones from a single loudspeaker.

Kindly supply a suitable correction or explanation. I'll gladly
entertain the possibility that I'm wrong.

That was exactly my point. Please read ALL responses I've
made re this topic.


My appologies for not reading all of the 269 posting to this thread.
The thread is a classic case of topic drift. I though I would check
the topic de jure and found your posting.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558