[FOSS-GPS] rtklib: simple DGPS post-processing experiment, improvements with rtklib 2.4.0

[Tomoji Takasu]

Dear Timo

Thank you for testing RTKLIB 2.4.0.


> It really seems that a huge number of points stay inside a radius of
> just 2.5 centimeters. Can this really be true?


Check Q (Quality Indicator) values in the solutions.

Fixed (Q=1, integer ambiguity resolved) solutions
usually have the accuracy of 1 cm as horizontal STD
and 2 cm as vertical STD with a short baseline
(<10 km).

Tomoji TAKASU


--------------------------------------------------
From: "Timo Juhani Lindfors" <timo.lindfors at iki.fi>
Sent: Friday, August 13, 2010 6:04 AM
To: "Open Source GPS-related discussion and support" 
<foss-gps at lists.osgeo.org>
Subject: Re: [FOSS-GPS] rtklib: simple DGPS post-processing 
experiment,improvements with rtklib 2.4.0

> Hello Tomoji,
>
> I upgraded my internal Debian package of rtklib to version 2.4.0 and
> reran all the commands I mentioned in my earlier email. Here's a
> summary of changes in output I got:
>
> Timo Juhani Lindfors <timo.lindfors at iki.fi> writes:
>> Single mode (-p 0)
>> ==================
>> http://iki.fi/lindi/gps/experiment/2/p0-neo1-scatter.png
>> http://iki.fi/lindi/gps/experiment/2/p0-neo2-scatter.png
>
> http://iki.fi/lindi/gps/experiment/2/p0-neo1-scatter-2.4.0.png
> http://iki.fi/lindi/gps/experiment/2/p0-neo2-scatter-2.4.0.png
>
> => no changes
>
>> DGPS mode (-p 1)
>> ================
>> http://iki.fi/lindi/gps/experiment/2/p1-neo1-scatter.png
>
> http://iki.fi/lindi/gps/experiment/2/p1-neo1-scatter-2.4.0.png
>
> => no changes
>
>> Kinematic mode (-p 2)
>> =====================
>> http://iki.fi/lindi/gps/experiment/2/p2-neo1-scatter.png
>
> http://iki.fi/lindi/gps/experiment/2/p2-neo1-scatter-2.4.0.png
>
> => remarkable improvement! Scatter with radius of 0.00005 degrees is
> now gone and most of the points are very tighly packed in the middle
> with some slow random walk.
>
> Here's the same scatter in UTM coordinate system so that the units are
> meters in various zoom levels:
>
> http://iki.fi/lindi/gps/experiment/2/p2-neo1-scatter-utm5-2.4.0.png
> http://iki.fi/lindi/gps/experiment/2/p2-neo1-scatter-utm1-2.4.0.png
> http://iki.fi/lindi/gps/experiment/2/p2-neo1-scatter-utm0.30-2.4.0.png
> http://iki.fi/lindi/gps/experiment/2/p2-neo1-scatter-utm0.10-2.4.0.png
> http://iki.fi/lindi/gps/experiment/2/p2-neo1-scatter-utm0.03-2.4.0.png
>
> It really seems that a huge number of points stay inside a radius of
> just 2.5 centimeters. Can this really be true?
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