What would the audio sound like on a receiver that picks up audio from
a radio station whose carrier wave is 10^200 miles long?

What would the audio sound like on a receiver that picks up audio from
a radio station whose carrier wave is 10^200 miles long?

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It will sound very weak unless the receiving antenna is a vertical
0.25*10^200 miles high with some longish ground radials.

"Reg Edwards" wrote in message ...
What would the audio sound like on a receiver that picks up audio from
a radio station whose carrier wave is 10^200 miles long?

===============================

It will sound very weak unless the receiving antenna is a vertical
0.25*10^200 miles high with some longish ground radials.

That's odd. I can get BBC Radio 4 perfectly well on an antenna which
is neither vertical, 0.25*1514 metres high, nor has radials of any
kind.

Actually, it's more likely to sound very inaudible. It's difficult to
achieve much bandwidth when you modulate a carrier of such low
frequency.

Radium wrote:
What would the audio sound like on a receiver that picks up audio from
a radio station whose carrier wave is 10^200 miles long?

It can sound as good as you want, if you are
willing to wait for a long coding delay.

--
local optimization seldom leads to global optimization

my e-mail address is: rb my last name AT ieee DOT org

On Tue, 28 Oct 2003, Roy McCammon wrote:

Radium wrote:
What would the audio sound like on a receiver that picks up audio from
a radio station whose carrier wave is 10^200 miles long?

It can sound as good as you want, if you are
willing to wait for a long coding delay.

What wavelengths are used for ELF communications to submerged subs?

--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html

Does this mean higher EM frequencies give better audio quality when
other factors are constant?

Stations in MHz range seem to have better quality than station in the
KHz range. KHz stations are more affect by disruption.

I guess this is an analogy to faster tape speeds giving better audio
quality than slower tape speeds when other factors are not affected.

(Richard Herring) wrote in message . com...
Actually, it's more likely to sound very inaudible. It's difficult to
achieve much bandwidth when you modulate a carrier of such low
frequency.

Timo Nieminen wrote:
On Tue, 28 Oct 2003, Roy McCammon wrote:


Radium wrote:

What would the audio sound like on a receiver that picks up audio from
a radio station whose carrier wave is 10^200 miles long?

It can sound as good as you want, if you are
willing to wait for a long coding delay.


What wavelengths are used for ELF communications to submerged subs?


I recollect 20-60Hz. The data rate is low. I suspect there are only a
few short commands such as: come near the surface so we can send you a
longer message.




--
local optimization seldom leads to global optimization

my e-mail address is: rb my last name AT ieee DOT org

(Radium) wrote in message . com...

(Richard Herring) wrote in message . com...
Actually, it's more likely to sound very inaudible. It's difficult to
achieve much bandwidth when you modulate a carrier of such low
frequency.

Does this mean higher EM frequencies give better audio quality when
other factors are constant?

Not necessarily, but it helps. With conventional (AM or FM)
modulation, really low carrier frequencies set an upper limit to the
bandwidth, and in any case there are practical problems when the
bandwidth is a significant fraction of the carrier frequency. (The
long-wave broadcast transmitter at Droitwich on 198 kHz (formerly 200)
has to have special pre-emphasis applied to the audio signal to
compensate for phase shifts in the antenna system across its
bandwidth.)

As Roy has hinted, digital modulation schemes can overcome these
problems, but at a cost - you need very high power (and it's difficult
to radiate high powers at long wavelengths) or a lot of processing
power to recover the information.

Stations in MHz range seem to have better quality than station in the
KHz range.

There are several reasons for that. Medium-frequency (kHz) broadcast
stations use amplitude modulation and are only spaced 9 or 10 kHz
apart, which restricts the audio bandwidth to less than half of that.
VHF (hundreds of MHz) stations use wide-band frequency modulation and
are more widely spaced, so the audio bandwidth can be much greater.
Also, FM is less susceptible to noise, and if two signals are present
FM detectors tend to lock to the stronger one, rather than detecting
both, so interference from weaker stations is less of a problem.

KHz stations are more affect by disruption.

That's because the signals are refracted through the ionosphere, which
(a) brings in unwanted signals from distant interfering stations and
(b) distorts the wanted signal.


I guess this is an analogy to faster tape speeds giving better audio
quality than slower tape speeds when other factors are not affected.

The connection is not as close as you might think.

"Radium" wrote in message
om...
Does this mean higher EM frequencies give better audio quality when
other factors are constant?

Stations in MHz range seem to have better quality than station in the
KHz range. KHz stations are more affect by disruption.

If talking about broadcast radio, it may be more the modulation used vice
the frequency. AM modulation will be more affected by say weather
disturbances in the atmosphere (lighting), than say FM.

I guess this is an analogy to faster tape speeds giving better audio
quality than slower tape speeds when other factors are not affected.

I have seen just the opposite on tape, especially when recording video
images from sat's.

(Richard Herring) wrote in message
. com...
Actually, it's more likely to sound very inaudible. It's difficult to
achieve much bandwidth when you modulate a carrier of such low
frequency.

Really? How can a slower tape speed have better quality than a faster tape speed?

"Dana" wrote in message ...
"Radium" wrote in message
om...

I guess this is an analogy to faster tape speeds giving better audio
quality than slower tape speeds when other factors are not affected.

I have seen just the opposite on tape, especially when recording video
images from sat's.