RE: [PSUBS-MAILIST] Undersea communications & retractable buoy

["Jay K. Jeffries" <bottomgun@mindspring.com>]

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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