[at-l] Handheld GPS accuracy

Frank Looper nightwalker.at at gmail.com
Sun Dec 6 19:40:35 CST 2009


My current GPS has Barometric corrections included. That's why it is
so accurate.

It also has a SirF Star 3 chip in it. No one should buy a GPS for the
trail without one.

Mine is a Garmin Etrex Vista HCX. It is absolutely the best all-around
handheld mapping GPS out there today, in my experienced opinion.
Rockdancer, look on Amazon for GPS and maps. You can get Road and Topo
maps for that unit, switch them in seconds, and they go on a chip the
size of a little fingernail. I saved around $200.00 by buying all 3
from Amazon instead of Garmin. The street versions are called City
Navigator NT. The Topos I have are called US Topo 2008. Here are some
links. Always compare by clicking the link a little lower on the page
where it will say something like "87 new from 69.99" or something
like. There is a lot of competition. The SDmicro cards are cheap as
well. 2GB is, I think, the max size for that unit, but it's all you
really need. I'll happily send out a list of which maps are needed to
put the whole AT on one card.

Some Good links.

http://www.amazon.com/Garmin-eTrex-Vista-HCx-High-Sensitivity/dp/B000PDR1LS/ref=sr_1_1?ie=UTF8&s=electronics&qid=1260149598&sr=1-1

http://www.amazon.com/Garmin-Navigator-America-Detailed-United/dp/B000H3CKG2/ref=sr_1_1?ie=UTF8&s=electronics&qid=1260149642&sr=1-1

http://www.amazon.com/Garmin-MapSource-Topo-U-S-2008/dp/B000RAASFK/ref=sr_1_1?ie=UTF8&s=electronics&qid=1260149690&sr=1-1





On Sun, Dec 6, 2009 at 5:29 PM, Ryan Brooks <ryan at hack.net> wrote:
> Altitude is not always altitude: :-)
>
> http://bhgc.wikidot.com/tutorials:differences-between-pressure-and-gps-altitude
>
> http://www.navitrack.net/  (scroll down).
>>
>> Arthur Gaudet
>> Lowell, MA
>> Rockdancer97 at comcast.net
>> "The vessel with the pestle has the brew that is true."
>>
>> I showed him the GPS
>>
>>>
>>> that I was using to gather data with. It was absolutely the best
>>>
>>> hand-held mapping GPS available at the time. So is my current one, but
>>>
>>> it is not the same one.
>>>
>>>
>>>
>>> Anyway, the GPS had been sitting still for 10 minutes or so, making a
>>>
>>> fixed waypoint, and the satellite pattern was especially good that
>>>
>>> day. The expected Horizontal error was around 5 feet. Vertical is
>>>
>>> always about double the horizontal. The GPS disagreed with the GATC on
>>>
>>> elevation by about 30 feet at that shelter, as it did most of the way
>>>
>>> through Georgia. It turned out that when Del Doc had gathered data in
>>>
>>> the area in '02, there was a problem with the antenna that he was
>>>
>>> using. When the cartographer went to re-do the maps, he had to use the
>>>
>>> old 80s-vintage Topos as overlays in his GIS to guess at a lot of the
>>>
>>> elevations and shelter locations. When they later re-gathered the data
>>>
>>> with a newer, better GPS, the companion and my GPS started magically
>>>
>>> agreeing, or at least being very close.
>>>
>>
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>>
>
>



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