Is it true that the distress signals sent from the Titanic in 1912
would still be audible today? I understand that the high frequency
radio waves used on the Titanic would use propogation through the
ionosphere to bounce around the atmosphere, but wouldn't the signals
from 90+ years ago be completely degraded or absorped by now? If this
is true, how can it be proved?

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Request for Question Clarification by techtor-ga on 05 Jul 2004 22:47 PDT

Greetings Kingo57,
Perhaps you are referring to the 1978 event wherein the ocean liner
QE2 received the morse code distress call of the Titanic, years after
the sinking. This case was thought to have been a UFO-created event,
wherein a UFO or alien observing the earth recorded the message and
sent it back later on. Another theory is that there was a time warp,
allowing the two ocean liners to actually communicate with each other
through it. While this event, along with others like it, has been
doubted of its authenticity, it does remain a very interesting subject
for mystery buffs.

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Clarification of Question by kingo57-ga on 06 Jul 2004 01:27 PDT

First I've heard of the 1978 event. I'm trying to disprove this theory
to a friend of mine who's convinced it's true... ie. I just need the
SCIENTIFIC PROOF behind why these signals wouldn't be around today.
The one story I did hear is of radio buffs who like to gather annually
in a particular location to pick up radio communications first sent in
the vietnam war. It all sounds like rot to me... but I'd like to be
able to prove that for definite.

The short answer is NO , it is a common misconception that radio
signals keep bouncing of the heaviside layer for ever , the only thing
the heaviside layer does is propagate a radio signal to about 9 times
optical , the only theoretical way you would be able to pick up the
distess calls from that long ago is flying out of the solar system at
more then the speed of light to go approximately 90 years in the past
and thus overtake the radio signals send out then because they do
propagate through space indefinately (which makes you think that no
alien race would ever want to contact us if they see some of our tv
shows or hear some of our radio broadcasts)

Thanks Corwin02. 
Can you just clarify... what do you mean when you say 9-times optical?
Is that an increase in the size/range of the signal? Does the signal
bounce back off the earth at all (even if only for a very short time)?
If not, is that because of scattering/absorption of the signal?

VHF Signals basically need line of sight to operate as in if there is
a mountain range between you and your target chances are slim the
target will hear you

assuming a +30Mhz signal and about 40Kw of power a VHF radio will get
about 30Km or range on a flat surface , however by bouncing of the
Heaviside layer the signal can reach up to 270 Km and even bounce over
mountain ranges hence the term optical as in line of sight (although
30 Km would stretch even the best binoculars)

30 km = about 18.6 miles
270 Km = about 167.7 miles

Nine times is a rule of thumb; often the range is less, rarely more.
Signals that bounce off the heaviside layer repeatedly circle the
Earth about 6 times per second, So you can see billions of trips would
have occured since 1912. Sometimes the heaviside layer behaves like a
magnifing mirror, but most of the time, it just reflects (rather
poorly) without concentrating the signal, so the signal strength
decreases as the square of the distance, both circling the Earth and
traveling into space. Since 1912 the distance is about 92 light years,
so by now the signal is extremely weak, compared to 2004 best radio
telescope technology.
 We can't settle your argument, as most all the signals ever produced
still exist, but they are spread extremely thin, such that they can
not be detected with 2004 technology, not even the ones seconds old
instead of years old, with rare exceptions.  Neil