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Re: fish finder was [PSUBS-MAILIST] More on inertial guidance
Hi All:
I realize the current thread is on GPS, but having took Stephen's cue to
access the Raytheon website I started looking at some of the other
products. I'am currently checking out the online handbook for their fish
finder. I like this unit. Has provisions for forward and sidescan and a
big display. Has an optional paddlewheel on the transducer to collect speed
and movement data. I have not read far enough into it yet, but I would be
willing to bet that this info probably integrates into the GPS system (or
vice-versa) to give dead reckoning position when GPS is temporarily
disabled. Fascinating stuff. Seems to me this would be a valuable piece of
hardware for the psub not only to avoid collisions, but also to detect
bottom structures and objects. Anybody using a fishfinder on their sub?
Excuse me while I read on.
Later,
Big Dave
-----Original Message-----
From: SJSVOB@aol.com <SJSVOB@aol.com>
To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
Date: Sunday, March 19, 2000 9:29 PM
Subject: Re: [PSUBS-MAILIST] More on inertial guidancce
>NMEA GPS serial data looks like the following:
>
>$GPGGA,135150.00,3838.6729,N,09015.4367,W,1,03,4.2,156.3,M,,M,,*66
>
>I can't remember what all the data is offhand, the latitude and longitude
is
>obvious, 156.3 is the altitude, in there somewhere is the number of
>satellites currently tracking. I might have taken that snapshot before my
>Motorola Encore GPS unit locked on to all the satellites available.
>
>Ratheon has some modular components which communicate with one another
using
>Ratheon's SeaTalk technology:
>http://www.raymarine.com/products/index/instruments/index.html
>
>Check out the ST80. It has a dead reckonening mode. I would think this
>system would be great for psubs. When you lose the GPS satellites the
system
>would probably just switch to dead reckoning mode. I wonder how hard it
>would be to put the transducers outside the pressure hull and not have them
>get destroyed.
>
>I was thinking it might be interesting to construct a device which would
sit
>between the GPS unit and the SeaTalk network. The device could accept NMEA
>info from a GPS, or create it's own information, and then send it through
to
>the SeaTalk network. That device could be capable of determining position
>based on the acoustic links being described in this thread.
>
>You could add a 3-d bathymetric charting solution in there, but I don't
think
>it would be capable of pinpointing your 3D position, only your position
>relative to the surface. I don't think manufacturers of systems like
SeaTalk
>envisioned them being taken to the depths. For that additional "feature"
you
>probably have to pay big time.
>
>I'd be interested in discussing these ideas further? Anyone have any
reason
>to think this system would or wouldn't work?
>
>Stephen Svoboda
>