<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Jim,</div><div>yes. Just an intermittent signal every 10 seconds or so. I have</div><div>read about text type communication systems.</div><div>Here is a passage from a paper that talks about a buoy device.</div><div><br>
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<p><span style="font-size: 11.000000pt; font-family: 'Times New Roman'">An underwater GPS is primarily a combination of a GPS and an acoustic positioning
system and consists of two types [12-19]: a sea surface buoy system using a long baseline
and carrying a GPS receiver, which can track, monitor, and dynamically position
underwater targets from a sea surface, coastal land, and a plane and has a large operating
range but can only position underwater targets that carry acoustic transponders in certain
waters; and a system which uses a mother ship equipped with a short baseline or ultra
short baseline transceiver and a GPS receiver, which is mobile and flexible but also can
only position targets equipped with acoustic transponders. Therefore, this paper proposes
a way of positioning combining an ultra short baseline, a forward-looking sonar and a
GPS receiver, overcoming the limitation of the existing underwater GPS positioning
technology that it can only position targets equipped with acoustic transponders and
realizing the real-time positioning of the longitude and latitude coordinates of any
unknown targets in any waters in the WGS84 ellipsoidal coordinate system, and it is also
highly mobile.</span></p><p><span style="font-size: 11.000000pt; font-family: 'Times New Roman'">Alan </span></p>
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</div><div>Sent from my iPad</div></div><div><br>On 25/03/2017, at 6:06 AM, via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote type="cite"><div>
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<div><font size="3">Alan,</font></div>
<div><font size="3">Transmit GPS positions wirelessly where? You didn't
mean down to the sub, did you?</font></div>
<div><font size="3">Jim</font></div>
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<div>In a message dated 3/23/2017 10:07:37 P.M. Central Daylight Time,
<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a> writes:</div>
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<div>Jim,</div>
<div id="AppleMailSignature">re the tow behind buoy (pronounced boy); it would
be possible to make a </div>
<div id="AppleMailSignature">buoy with motors on it that tracked your sub &
transmitted GPS positions</div>
<div id="AppleMailSignature">wirelessly. Minn kota have a system that controls
their thruster to keep</div>
<div id="AppleMailSignature">a boat steady on a certain coordinate. </div>
<div id="AppleMailSignature">Alan</div>
<div id="AppleMailSignature"><br>Sent from my iPad</div>
<div><br>On 24/03/2017, at 3:43 PM, via Personal_Submersibles <<a title="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>
wrote:<br><br></div>
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<div><font size="3">Here's a link that gives quite a bit of information
including a reference to their Windows-based software. Once you open
the link, the more you scroll down the more you will see; it goes a long
way! <a title="http://www.seismic.com.au/assets/pdf/SBG_Systems-Ellipse_Series_Brochure.pdf" href="http://www.seismic.com.au/assets/pdf/SBG_Systems-Ellipse_Series_Brochure.pdf">http://www.seismic.com.au/assets/pdf/SBG_Systems-Ellipse_Series_Brochure.pdf</a></font></div>
<div><font size="3"></font> </div>
<div><font size="3">GPS is great as a starting point before you submerge and
for telling you where you are once you surface. Too bad radio signals
don't propagate so well under water. In the past we've discussed
mounting a GPS antenna on a Diver Below buoy with a cable running to the
sub. I don't recall what was said regarding theoretical depth
limitations for such a setup as well as the hydrodynamics of towing
it.</font></div>
<div><font size="3"></font> </div>
<div><font size="3">It would be really interesting to see how well your INS
position matches up with your GPS when you resurface. I like the idea
of knowing just where you are with reasonable precision when submerged,
being able to return to a precise location on another day, being able to
search or survey methodically, navigating from A to B to C,
etc.</font></div>
<div><font size="3"></font> </div>
<div><font size="3">Jim T.</font></div>
<div> </div>
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<div>In a message dated 3/23/2017 7:55:50 P.M. Central Daylight Time, <a title="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>
writes:</div>
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<div class="moz-cite-prefix">On 3/23/2017 6:40 PM, Brian Cox via
Personal_Submersibles wrote:<br></div>
<blockquote cite="mid:20170323154013.EA88CFB6@m0087798.ppops.net" type="cite">
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<div>There needs to be an underwater GPS
!!</div></div></blockquote><br>I remember a discussion, long ago, about a
GPS antenna on a mast. I don't recall any
resolution.<br><br><br>Mike<br><br>
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