View Single Post
  #194   Report Post  
Old July 8th 07, 05:24 AM posted to sci.electronics.basics,rec.radio.shortwave,rec.radio.amateur.antenna,alt.cellular.cingular,alt.internet.wireless
Ron Baker, Pluralitas![_2_] Ron Baker,    Pluralitas![_2_] is offline
external usenet poster
 
First recorded activity by RadioBanter: May 2007
Posts: 92
Default AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency


"Rich Grise" wrote in message
news
On Tue, 03 Jul 2007 22:42:20 -0700, isw wrote:

After you get done talking about modulation and sidebands, somebody
might want to take a stab at explaining why, if you tune a receiver to
the second harmonic (or any other harmonic) of a modulated carrier (AM
or FM; makes no difference), the audio comes out sounding exactly as it
does if you tune to the fundamental? That is, while the second harmonic
of the carrier is twice the frequency of the fundamental, the sidebands
of the second harmonic are *not* located at twice the frequencies of the
sidebands of the fundamental, but rather precisely as far from the
second harmonic of the carrier as they are from the fundamental.


Have you ever actually observed this effect?

Thanks,
Rich


I have.
I tuned to the third harmonic of a strong local
AM broadcast station. There it was. Quite
a surprise. It is a bit distorted but intelligible.
Another odd thing is that it comes and goes
somewhat abruptly.