Conference vicki::boats

I noticed that there's not much talk about GPS in here (only two notes
(961 and this one).  This is rather surprising to me, since I thought 
that GPS would be of extreme interest to boaters. Is there another
topic in here that discuses this (I searched for "GPS" and "global")?

Anyway, I'm looking for information on a GPS device that can be interfaced
to a PC.  Does anyone know of a place (notes conference or otherwise)
where I can find information on this topic.

I've already tried the Sattelite and IBMPC notes conferences.  I've been
pointed to the Short Wave radio and Ham Radio conferences, but havn't
had the time to check there yet.

Any help would be appreciated.

Thanks in advance,

Rob

I have had Loran C for some time.  I dont fully understand GPS and Dgps.

I have read several articles, but as yet my interest has not peaked 

enough to purchase one.  I'm reasonably satisfied with Loran, 

maybe i just not ready to make the switch.


Do you understand enough about gps to explain why someone

would/shoud make the switch.

JIm

I'm not really sure of the full capabilities of Loran or GPS.  I'm just
starting to learn about all of this.  I'm not a boater.  What, exactly
[but breifly] does Loran do and how does it work?

-Rob

The loran box is simply a reciever. There are transmitters along the

east coast, braod casting signals referred to as time delays or TD's.


Generally one choses 1 master and 2 slave stations.  The digits displayed

on the loran screen are the time delays.  There are 2 displayed, 


NOAA charts have lines on them, which are these TD's.

Preferrably you've chosen 2 which will intersect at 90 deg. angles.

the x and y axis.  find the intersection of these td's on the chart,

and YOU ARE THERE.  When navigating, one of the most important things

to know is where you are. If you know this, you can then proceed to

go somewhere.  



This is a very simplified explanation, as there are volumes written

on the principles of Loran, but this is how it works.


JIm

    RE: .0
    
    	There has been some discussion on GPS in the fishing conference at
    WAHOO::FISHING_V2.  I'd check for it under GPS, LORAN, or NAVIGATION.
    
    					B.C.

There are several useful discussions of both loran and GPS in the 
SAILING Notesconference (UNIFIX::SAILING). See Note 3.n for directories 
pointing to them.

Note 452.15 has a long discussion of GPS accuracy, including 
differential GPS.

re .0:

See SAILING Note 452.17 for interface information.

Alan

    
    Speaking of interfacing..... There is a former member of this
    conference that peddles a system called "LapMap" which interfaces
    a loran to a laptop PC. It's intended for aircraft, but what's
    the difference?
    
    I'm sure I can come up with a way to contact him if anyone is
    interested.
    
    Rick
    

I'm assuming that you're in New England...

I know it's been discussed hither and yon, but here it is in a nutshell.

The Coast Guard has Loran C stations in Caribou, Maine, Nantucket, and
Carolina Beach, South Carolina. (There are more, but these make up one
particular "chain.") These are slave stations, with the master being in
Seneca, New York. They operate on 100KHz. The master transmits a pulse,
and a specified number of microseconds later a slave transmits a pulse.
Your receiver receives the master and the slaves, electronically
distinguishes between them, and decides where you are based on the timing
relationships between the pulses. 

I enjoy 25-50 foot repeatability accuracy with mine, on the open water.
Absolute accuracy is not as good.

Art

Thanks for the pointers and info, folks.  I'll have to check out a few
sources.

My interest in GPS, however, is not for marine use, but for land use
(cross-continental), so a LORAN is out of the question.  I posted in here
because I couldn't find any other sources that might be discussing
GPS.  I posted something in the DLOACT::SATELLITE notes conference, so 
that's probably where the discussion should go.

I've gotten some references here, but would like to hear more about GPS.
If anyone has info on GPS or dGPS, please post in DLOACT::SATELLITE 
under the GPS note ... or post here if you must!

Thanks again,

Rob