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RE: [PSUBS-MAILIST] Undersea communications & retractable buoy
Alex,
Water is a different issue, especially saltwater.
R/Jay
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Alex
Sent: Friday, October 30, 2009 9:35 AM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Undersea communications & retractable buoy
For listening only you could get away with a ferride rod antenna couldn't
you.
I knew someone who built radios for communication to people inside caves.
The main problem was of course fitting an antenna in. Then the other thing
was that inside the cave the radio frequency was pretty quiet making it easy
to listen, but on the surface there was a lot of noise on the frequency so
that the guy in the cave needed a lot of transmitter power to reach the
surface. I think they used something in the 50 - 100Khz frequency range.
Alex
On 30-Oct-2009 Jay K. Jeffries wrote:
> Alex,
> A UQC uses ultrasound on a carrier and single side-band for efficiency.
>
> 1.9 MHz has limited penetration into the water column and Extreme Low
> Frequency (ELF) due to its very low frequency (used by the Navy) can
> carry very little data (typically 3-letter codes) and has to have VERY
> long antennas driven by a lot of power to reach submarines (so the
> submarine has to deploy a VERY long antenna also).
> R/Jay
> KF4DBI
>
> -----Original Message-----
> From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Alex
> Sent: Thursday, October 29, 2009 11:33 PM
> To: personal_submersibles@psubs.org
> Subject: RE: [PSUBS-MAILIST] Undersea communications & retractable
> buoy
>
> I was thinking: You know there are the hydrophones that work quite
> well for communicating. I was just reading about them working to 500ft
> depth, but I suppose with a lot of background noise and stuff it could be
a problem.
>
> What if, you were to use amplitude modulated ultrasound to
> communicate? You could have a 50khz carrier and that would eliminate
> the interference problem!
>
> Also, how well do regular radios work for this purpose? How well would
> the 160m
> (1.9MHz) HAM band work for this? If you were to bring a pocket AM
> radio down in the sub with you and have it inside the transparent dome
> how far down could you go and have it still work? You know those
> "atomic clocks" set themselves by picking up the 60khz signal from
> Colorado I think it is, how far under could you use one of those?
>
> The military uses something like 15khz to transmit globally to the
> their submerged submarines.
>
>
>
>
>
>
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--
Mailed with XFmail on 30-Oct-2009.
God saved Noah, but Noah had to build an ark!
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