Re: fish finder was [PSUBS-MAILIST] More on inertial guidance

["D. Blake" <dblake@bright.net>]

I'm sorry, I guess it doesn't have forward scan.  It has bottom and
sidescan.  I guess it wouldn't be that good for preventimg collisions
afterall.  Still, it would be nice for all the other info.
Big Dave
-----Original Message-----
From: D. Blake <dblake@bright.net>
To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
Date: Monday, March 20, 2000 1:12 PM
Subject: 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
>>
>