"Ian Thompson-Bell" wrote in message
...
Green Xenon [Radium] wrote:
Hi:

What would be heard on a 40 Hz AM DX receiver that uses the most
sensitive type of magnetic loop antenna? I doubt there would be any
hissing since that artifact would involve high-frequency sounds and a
40 Hz carrier cannot transport modulation-signals higher than 40 Hz
[violation of Nyquist theorem].

Not strictly true I think - depends on the modulation scheme - how else do
you think we manage to get 56K bps down a 3KHz phone line.

Cheers

IAn

if you really want to have fun try plugging in a 40hz carrier with a 100hz
modulation and do the sum and difference frequencies to find the
sidebands... how do you explain negative frequencies?? are they going back
in time? taking information to before it was sent? or do they appear
before the signal starts?