[pct-l] Garmin's advice on using GPS to measure distance

[brick@fastpack.com (Brick Robbins)]

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Here is a post I copied from the ultra list.

Thought you gear-heads might like Garmin's advice on using GPS to measure 
distance travelled by foot (run or walk, it's the same thing...)
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Date:    Mon, 8 Jan 2001 14:03:13 EST
From:    Peter Fish <WTC48@AOL.COM>
Subject: Measuring distance with GPS

I wrote to Garmin tech support:

<<I am going to do a transcontinental run later this year, and would like 
to use my eMap to record the distance travelled each day (about 30 miles). 
However, it seems to lose the signal occasionally when I carry it on a run, 
causing the mileage to be underestimated.  I have tried using an external 
antenna, and various ways of carrying it -- upright, flat, etc. -- but 
nothing seems to work.  Perhaps I need to establish waypoints at all the 
significant changes of direction, so that distances would be calculated by 
the linear route on the map, rather than the physical distance through 
which the unit is carried, as this is changed every time the signal is 
lost.  Thanks for any advice you can give me.

Peter Fish  >>

And received this reply:

<<Dear Mr. Fish,

     Thank you for your message.  You have hit upon the weakness of GPS, 
loss of signal.  There are a series of factors that will cause the loss of 
signal such as overhead obstruction or interference with the antenna.  A 
track log is a terrific method of measuring distance traveled, but loss of 
signal can ruin your reading.  You can use the eMap to measure distance 
using the cursor, but it is more line of sight and not according to the 
curvature of the road.  A series of waypoints can be transferred to a 
computer to calculate distance once you have completed a days run.

Truthfully, I recommend using a pedometer which is independent from 
satellite reception.  Thank you again for your message.

Best Regards,

Thad McCanse
GARMIN INTERNATIONAL
Customer Service Representative
1-800-800-1020
www.garmin.com >>