In article ,
Rich Grise wrote:

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?

Sure. (In a previous life, I designed AM and FM transmitters for RCA).
Just get a short-wave radio, locate yourself fairly close to a standard
AM transmitter, and tune to the harmonics. you'll find, in every case,
that the audio sounds just the same as if you were listening to the
fundamental.

Works for FM, too, but the situation is somewhat more complex.

Isaac