"Rollie" wrote in message
...
Amateur Radio Study Guides say radio (carrier) waves start at approx.
20,000 hertz...............


"Green Xenon [Radium]" wrote in message
...
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].

I also don't think power lines would have any perceptible affect on a
40 Hz receiver. In USA, the electric power has a frequency of 60 Hz --
in Europe, its 50 Hz. Since 40 Hz is below these power frequencies, I
doubt they would cause interference on 40 Hz. If I was receiving at or
above the power frequencies, I do think there would be disturbance but
not if below.

Would any interferences from outer space be perceptible on a 40 Hz AM
receiver? Galactic noise?


Thanks,

Radium


What about VLF communications from submerged submarines? They work at, would
you believe, Very Low Frequencies, a lot lower than 20kHz.

S.
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