David Willmore wrote:
This is different from what I would expect to happen.
To start with, one takes a carrier or some power, then
one modulates its amplitude. This process spreads some
of the energy into the symetrical side bands--taking
power out of the carrier, thus causing 'downward
modulation' of the carrier, right?
I beg to differ. A properly modulated AM signal will have
a carrier of constant amplitude, unaffected by the modulation.
That's why SSB was born, to eliminate altogether a spectral
component that didn't carry any information content.
FM is another case... Its spectrum can be computed with
the Bessel functions and shows a carrier of amplitude changing
with the modulation index, going down to zero for certain
values of it, as Jim Moritz pointed out in a past message.
73 Alberto I2PHD
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