[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [gpsd-users] eps / other error fields

From: Gary E. Miller
Subject: Re: [gpsd-users] eps / other error fields
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.


> 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.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

Attachment: pgpps_yLjIIny.pgp
Description: OpenPGP digital signature

reply via email to

[Prev in Thread] Current Thread [Next in Thread]