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Re: GPS Who knows how to use em???



Come to the next Trailduster's meeting and will give you a lesson. Tough to
do in e-mail and even tougher for a Magellan because I own a Garmin GPS12.

I will note that they may not be all that accurate in calculating mileage -
particularly if that mileage is done at slow speed. The problem is that the
military deliberates throws in fudge factor (known as Selective Availability
or SA). Their gear has compensation, consumer gear does not. The unit may
accumulate mileage if you are standing still (and if it does not, it is
because at certain arbritrary speed defined by the manufacturer the mileage
accumulation assumes no movement - I believe in the case of the Garmin
mileage accumulation continues but displayed speed goes to 0 at something
like 1 or 2 mile per hour as measured including the error factor which means
a real speed of perhaps minus 1 to plus 4 mph depending on 'direction' of
the SA versus your direction). Generally speaking SA causes the system to
overstate distance traveled. At higher speeds (such as driving down a
highway, the amount of 'false travel' caused by SA  would be smaller portion
of the true distance traveled.

One other issue is that the unit measures horizontal distance. The slope
distance on trip with any elevation gain will be somewhat longer. Don't know
how ride distance is measured, but since wheels have been used, I assume
slope distance.

Duncan Fletcher
dfletche@gte.net


----- Original Message -----
From: Sue Brown <sbrown@wamedes.com>
To: <ridecamp@endurance.net>
Cc: <darkcat@yahoo.com>; <dfletche@GTE.NET>
Sent: Tuesday, December 28, 1999 9:12 PM
Subject: Re: GPS Who knows how to use em???


> >debbie Zanot darkcat@yahoo.com
> >I know I should be thankful (and I am) that Santa brought
> >me a Magellan 315 GPS <snip>
> >There is a problem...The owners manual...Now like all
> >instructions and manuals they are GREAT after someone shows you
> >how to work the damn thing. I know that "someone" out
> >there in the vast world of endurance riders has a simple
> >explaination of how to track miles ridden on trail...
> >I am patiently waiting for your answers..
>
> Me too!  Any useful hints would be most appreciated if sent my way also.
I
> got a Garmin GPS 12 and really need someone to 'splain this thing to me!
> ;-)  Well, not totally...I've made it thru the first couple of pages of
> instructions and can identify the separate frames and their parts...but
now
> I need outside guidance from someone with prior experience.  I'm very
right
> brained and these directions don't have enough pictures!! <bg>
>
> Duncan -- any classes in the area?
>
> Sue
>
> sbrown@wamedes.com
> Tyee Farm
> Marysville, Wa.
>
>



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