[FOSS-GPS] PPP with RTKLib: RINEX O- and N- files?

Anders Wallin anders.e.e.wallin at gmail.com
Fri Dec 20 03:50:20 PST 2013


This image shows the problem:
http://imagebin.org/283130

I am interested in the clock offset of my GPS receiver.
The two web-based PPP services produce approximately identical solutions.
They are spaced by an offset of ca. 3ns, but the shape of the curves are
very similar.
The CSRS-PPP solution lists the clock offset in a separate CLK(ns) column.
The JPL-APPS solution has a Clock(m) colum that I have converted to
nanoseconds (multiply with 1e9/3e8)

>From RTKPOST I output the time-stamps to the .pos file with 12 decimals,
and from that calculate the clock offset.
This is the blue data in the figure which is obviously much more noisy and
probably not the correct PPP solution.
What am I missing? Should I apply some correction to the .pos file
time-stamps? how?

Anders



> I am trying to compare my solution against web-pased PPP services at CSRS
> and JPL:
> http://webapp.geod.nrcan.gc.ca/geod/tools-outils/ppp.php
> and
> http://apps.gdgps.net/apps_file_upload.php
>
> these web-based PPP calculations give similar results, but I am not able
> to reproduce the data with RTKLib.
> For example the clock error plots are much smoother with CSRS-PPP and
> APPS, while the RTKLib output is very noisy.
> Does anyone know how to reproduce the results of these web-based services
> with RTKLib?
>
>
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