Solved

GPS accuracy

Posted on 2006-06-29
4
296 Views
Last Modified: 2008-03-17
I just got a Garmin forerunner 201 wrist-mount GPS and am wondering how accurate the distance measurements are. I took it to a university 400 meter track and did a measured mile, and it showed 1.16 miles for distance, off by 16%.  On another track, it measured 1.02 miles.  Both were on open fields with good satellite coverage. On the highway, it tracks almost exactly with mile measurements posted on the side of the road, as long as it maintains the satellite reception.  So how accurate is the 201, and GPS in general?  I know there are a lot of variables that affect accuracy, but 16% inaccuracy under ideal conditions sure seems like a lot.
0
Comment
Question by:maharlika
  • 2
4 Comments
 
LVL 2

Assisted Solution

by:XY_GT
XY_GT earned 25 total points
ID: 17007771
The box that you got with it may have some of the accuracy specs on it.

Usually the GPS should only be out by around 5-15 meters. With different technologies such as DGPS the accuracy increases alot.

A good resource for more information about the GPS accuracy is http://en.wikipedia.org/wiki/GPS#Accuracy
0
 
LVL 17

Accepted Solution

by:
Thibault St john Cholmondeley-ffeatherstonehaugh the 2nd earned 50 total points
ID: 17007884
If you were running around a track rather than going in a straight line then the frequency of the units updating may affect the calculated distance. If it only recalculates its position once a second then it may assume a straight line between the two points, or the software may try to fit he points to a curve, but neither may be the actual journey taken.
Did you try the same track and distance walking as well as running?
0
 
LVL 6

Assisted Solution

by:kbens0n
kbens0n earned 25 total points
ID: 17007897
Also, make sure the firmware is up-to-date here:

http://www.garmin.com/support/download_details.jsp?id=437#Instruct
0
 
LVL 17

Assisted Solution

by:Thibault St john Cholmondeley-ffeatherstonehaugh the 2nd
Thibault St john Cholmondeley-ffeatherstonehaugh the 2nd earned 50 total points
ID: 17008201
This quote from here doesn't look very hopeful:
http://home.socal.rr.com/diverhank/ForeRunner201.htm#_Toc98428435

"Based on reports from users, for a typical 5K run, expect distance error anywhere from 0.0 mile to 0.5 mile.   For longer runs, errors may be worse."

Not sure why the error is measured in miles and the distance in Kilos, but half a mile over 5 km is almost exactly 16%.





0

Featured Post

Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

I've been asked to discuss some of the UX activities that I'm using with my team. Here I will share some details about how we approach UX projects.
Digital marketing agencies have encountered both the opportunities and difficulties that emerge from working with a wide-ranging organizations.
Articles on a wide range of technology and professional topics are available on Experts Exchange. These resources are written by members, for members, and can be written about any topic you feel passionate about. Learn how to best write an article t…
Saved searches can save you time by quickly referencing commonly searched terms on any topic. Whether you are looking for questions you can answer or hoping to learn about a specific issue, a saved search can help you get the most out of your time o…

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question