"Randy Yates" wrote in message
...
Bob Cain writes:

ruffrecords wrote:

To produce FM there needs to be a non-linearity. If you detect FM
there is a good chance a non-linearity exists. But it is not due to
the doppler effect.

Exactly,

Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that
WILL happen whether or not you decide it can WHENEVER a sound wave
source and observer are moving relative to each other. Period. This
isn't open for debate.

This whole argument is based on the wrong assumption that the high
frequency source is "riding on" the low frequency source like a whistle on a
train. It is NOT! Both sounds are being produced simultaneously by the
complex electrical waveform driving the speaker cone which moves in
accordance. Assuming that the speaker is being driven within its linear
limits, the cone's motion accurately follows the driving signal, and it is a
linear system.
Forget the train/whistle anology, it is not an accurate representation for
what goes on with a speaker, period!