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Author Topic: About errors in distance due to heights and moving arm.  (Read 1507 times)

AndersBrontosaurus

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About errors in distance due to heights and moving arm.
« on: September 19, 2011, 06:25:09 am »

Hi.
I've been wondering about 2 things concerning distancemeasuring.

1. The more variations in height during a track, the bigger error in distancemeasuring but does anybody know if there is a tendency to get a measure that shos a too long or a too short distance?

2. Since we carry the watch on a moving part (the arm), how much does this moving back and forth affect the measuring compared to if you wear the gps on the upperarm like polar or fixed like a bikecomputer mounted on the steeringbar? I have a standardtrack I've been running several times and will testdrive it with a car someday when the gates on the track are open to see what happens but does anybody have an idea about this? Maybe there's somekind of algorithm to compensate for the arm's movement back and forth already?


Anders
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canadien

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Re: About errors in distance due to heights and moving arm.
« Reply #1 on: September 19, 2011, 11:30:00 am »

Hi Anders,

this is a concern for me as well. But I am trying to figure it out on flat. First question. What is the watch you bring with you.
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AndersBrontosaurus

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Re: About errors in distance due to heights and moving arm.
« Reply #2 on: September 20, 2011, 08:41:08 am »

Hi Anders,
this is a concern for me as well. But I am trying to figure it out on flat. First question. What is the watch you bring with you.
I always run with my 615. sometimes I also bring the 505.
I ran a coopertest on a flat  trackfield (is this the right word? The 400m track around a footballfield, you know?) and the accuracy was then within 20 m maybe even better when it comes to the distance. The watch did of course claim that it was a couple of climbings and downhills on the track anyway but as i said, the measured distance was very satisfying.

Anders
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canadien

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Re: About errors in distance due to heights and moving arm.
« Reply #3 on: September 20, 2011, 03:48:11 pm »

Well from my side what I am thinking on flat is also like you wrote in your point #2. Even with two good devices there is always a notable difference when running at slow speed. So I always wonder how much arm movements can affect the total distance. Cause, if I am right, the proportions of arm variation in total distance should logically decrease with higher speed (ex if gps record every 1sec.) and this is what I see in my tests. As for your watch 615 is probably as good and reliable as 625, but the behavior I am talking about is more pronounced on 505.
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TWG_TECH8

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Re: About errors in distance due to heights and moving arm.
« Reply #4 on: September 25, 2011, 02:07:40 am »

Hi,

Regarding my experience, the wearing height doesn't affect the distance measuring. But we get a tendency distance different with right or left arm.
We think it causes by the radius difference of course field.
The terrain will also affect the distance measuring; since the GPS only output the plane coordination. So we calculate distance accordingly.

Sincerely,

Geoffrey
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AndersBrontosaurus

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Re: About errors in distance due to heights and moving arm.
« Reply #5 on: September 25, 2011, 03:28:38 am »

Hi,

Regarding my experience, the wearing height doesn't affect the distance measuring. But we get a tendency distance different with right or left arm.
We think it causes by the radius difference of course field.
The terrain will also affect the distance measuring; since the GPS only output the plane coordination. So we calculate distance accordingly.
Sincerely,
Geoffrey

Interesting with right-left.
Is there a way for me to figure out which arm is best to wear the watch on depending on where on the planet I live?
Yes the terrain affect the measuring. Do you know if the watch tends to give a too short or a too long distance if you run in terrain with a lot of change in altitude? This is not only for knowing the distance I've run but it also affects the speedcalculations.
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