Any audible signals on a 40 Hz AM radio?
 

"Jorden Verwer" wrote in message
nl.net...
Dave wrote:
how do you explain negative frequencies??


are they going back in time?
No.

taking information to before it was sent?
No.

or do they appear before the signal starts?
No.


A phase inversion is all there is to it.


oh, you're no fun! i was looking for a lively debate of the possibilities
of sending the winning lottery numbers back in time with the negative
frequencies... that would keep radium busy for days!

Any audible signals on a 40 Hz AM radio?
 

On Sat, 13 Sep 2008 08:42:53 +0100, 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.

Ummm... Mr Radium clearly specified that he's using AM as in amplitude
modulation. If there were a different method of modulation employed,
methinks he would have specified it. You can get more bits per baud
out of relatively narrow bandwidths. The various HDRadio schemes:
http://en.wikipedia.org/wiki/HD_Radio
are good examples with about 40Kbits/sec in a 9KHz bandwidth. However,
they don't use AM.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Any audible signals on a 40 Hz AM radio?
 

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.

Cheers

IAn

Ian;

If it were possible to utilize 40hz at a high data rate it wouldn't take
15 minutes for the US Navy to send a 3 character message to it's
submerged submarines. As for the phone companies sending 56kbps down a
3khz phone line. They use something like 4 descrete tones and phase
shifts to do that and not at the rated speed either but something less
as a practical matter.

Dave WD9BDZ

Any audible signals on a 40 Hz AM radio?
 

Jeff Liebermann wrote:
On Sat, 13 Sep 2008 08:42:53 +0100, 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.

Ummm... Mr Radium clearly specified that he's using AM as in amplitude
modulation. If there were a different method of modulation employed,
methinks he would have specified it. You can get more bits per baud
out of relatively narrow bandwidths. The various HDRadio schemes:
http://en.wikipedia.org/wiki/HD_Radio
are good examples with about 40Kbits/sec in a 9KHz bandwidth. However,
they don't use AM.




Depends on your definition of AM. There are many types of amplitude
modulation, ask any radio amateur - and then of course there's VPAM.

Cheers

Ian

Any audible signals on a 40 Hz AM radio?
 

David G. Nagel wrote:
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.

Cheers

IAn

Ian;

If it were possible to utilize 40hz at a high data rate it wouldn't take
15 minutes for the US Navy to send a 3 character message to it's
submerged submarines.

That's becuase the technology was developed ages ago.

As for the phone companies sending 56kbps down a
3khz phone line. They use something like 4 descrete tones and phase
shifts to do that and not at the rated speed either but something less
as a practical matter.
.

Multiphase AM schemes are common place; they are used in mobile phones
for instance. It's the old trade off between bandwidth and S/N just like
in FM but in reverse. Check out VPAM.

Cheers

Ian

Any audible signals on a 40 Hz AM radio?
 

You guys are all dupes who have fallen for "Radium"s
old tricks of asking insane questions and then sitting back
and laughing at people trying to make sense of them.

"Radium" is a notorious, long-time Usenet Troll. There
is absolutely no future in trying to reply to any of his/
her/it's questions.

Any audible signals on a 40 Hz AM radio?
 

Richard Crowley wrote:
You guys are all dupes who have fallen for "Radium"s
old tricks of asking insane questions and then sitting back
and laughing at people trying to make sense of them.

"Radium" is a notorious, long-time Usenet Troll. There
is absolutely no future in trying to reply to any of his/
her/it's questions.


Actually, I think each and every poster should be given all the respect
which his/hers/its'/??? question deserves ... which I did! :-P

Regards,
JS

Any audible signals on a 40 Hz AM radio?
 

"Richard Crowley" wrote in message
. ..
You guys are all dupes who have fallen for "Radium"s
old tricks of asking insane questions and then sitting back
and laughing at people trying to make sense of them.

"Radium" is a notorious, long-time Usenet Troll. There
is absolutely no future in trying to reply to any of his/
her/it's questions.

who is trying to make sense?? its better, and more fun, to add to the
stupidness of it... much like answering art. a troll is a troll is a
troll... bait them and have fun.

Any audible signals on a 40 Hz AM radio?
 

"Dave" wrote ...
"Richard Crowley" wrote ...
You guys are all dupes who have fallen for "Radium"s
old tricks of asking insane questions and then sitting back
and laughing at people trying to make sense of them.

"Radium" is a notorious, long-time Usenet Troll. There
is absolutely no future in trying to reply to any of his/
her/it's questions.

who is trying to make sense?? its better, and more fun, to add to the
stupidness of it... much like answering art. a troll is a troll is a
troll... bait them and have fun.

Yeah, I like having nonsense fun as much as the next guy.
But "Radium" seems incapable of distinguishing between
nonsense and actual technical discussion. It just encourages him.

Any audible signals on a 40 Hz AM radio?
 

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