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Re: [gpsd-users] eps / other error fields
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From: |
Gary E. Miller |
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Subject: |
Re: [gpsd-users] eps / other error fields |
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Date: |
Wed, 12 Oct 2016 11:45:18 -0700 |
Yo Carl!
On Tue, 11 Oct 2016 21:36:18 +0100
Carl Sutton <address@hidden> wrote:
> I seem to have everything running, but errors seem wildly off.
Unlikely.
> According to the docs the eps field is "meters/second", with a good
> connection I have values of 200+ m/s
Those are calculated using standard equations.
> Actual speed is reading at around 0.001 m/s
But you are skipping a lot of relevant facts. Like how many sats in
view, what is the sat signal strength and geometry.
> My lat/lon (according to google maps) is accurate to around 8 meters.
> Errors for lat/lon is showing at 20/100 meters...
Apples and oranges. You can't compare a probability density with a
single mesurement. The error estimates are for a 95% probablity over a
long time scale. The one sigma error estimates are much smaller than
the CEP(95) ones.
If you kinda want to know where you are, then a one sigma accuracy
is good enough. But is you are auto-driving your car in a parking
lot then even 95% probability of trading paint is not good.
> Any ideas what is going on, or am I not understanding something?
You need to run gpsprof for 24 hours, then look at that plot. Your
idea of how accurate your GPS will seriously drop.
RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
address@hidden Tel:+1 541 382 8588
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