[pct-l] GPS, distance and speed.

[kdpo at pacbell.net (Ken Powers)]

I am sure the GPS reports what I call flat miles. I think the guides also
report flat miles too. The GPS just measures distances using lat/longs. Some
GPS have altimeters, but they seem to be quite inaccurate. On long hikes I
tend to reset mine 2-3 times a day. If the GPS tried to us the altitude gain
in the equation you might get some surprising results.

 I have looked at the pace and speed reported by my GPS. I agree that it can
be inaccurate, but it seems to average most of the time. Except maybe the
altitude change. What is interesting is that the maximum speed is also kept
and sometimes reads 30 mph. Now that is fast walking!

Ken
----- Original Message ----- 
From: "Steve Setzer" <steve_pct@hotmail.com>
To: <pct-l@mailman.backcountry.net>
Sent: Saturday, April 10, 2004 12:46 PM
Subject: Re: [pct-l] GPS, distance and speed.


> The other problem is that GPS may not take into account the vertical
> component of your route. For example, if you travel a mile in the
horizontal
> plane, but also climb a mile vertically while doing so (I know that would
be
> really steep) your actual distance travelled is 1.4 miles (the equation
for
> the hypotenuse of a triangle) while the GPS may report your distance as a
> mile (just using the lat/long coordinates).
>
> I know that my GPS - the Garmin Geko 201 - consistantly under-reports
> mileage when I'm on steep, switchbacking terrain but is right on for
> straight, flat trails.  I'm not sure if its becuase of the vertical
distance
> or the reason that Dude mentioned in his emails.  Maybe both.  You could
> probably find this info from the GPS company.
>
> Steve
>
>
> >The short answer is "yes".  However, I would caution against relying on
> >any GPS for pace and distance because the way that they calculate both
> >makes them inherantly inaccurate.  The GPS is not in constant
>
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