In article ,
Ian Thompson-Bell wrote:

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.

Because it's not the *line* that limits the rate; it's gear at the
central office. Even so, 56k modems need to cleverly bypass some of the
CO stuff.

By using clever modulation techniques and error correction, a nominal
3600 Hz analog telco channel can manage about 32 kbps, but in that case,
the symbol rate (baud rate) is 2400 baud per second, well within the
passband of the channel.

Isaac

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

"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.
--
http://audiopages.googlepages.com

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?

Around 40 Hertz, tops.


- 73 de Mike N3LI -