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

Anders Wallin anders.e.e.wallin at gmail.com
Sun Dec 22 12:54:29 PST 2013

I posted the PPP solutions I got so far on my blog:

If anyone knows how to reproduce the CSRS-PPP results with either gLAB or
RTKLib, let me know. I also posted my RINEX data-file if anyone wants to
try it.
The gLAB solution is already very close to the CSRS-PPP solution, but by
default gLAB produces data at 300s intervals (not 30s as CSRS-PPP) so I
haven't directly compared the time-series yet.
The RTKLib solution is off by ~4ns which is alarmingly much - although I
tried to feed RTKLib with the same input as gLAB, and tweak a number of
settings - but the 4 ns offset was always there :(

I could not get the other online PPP services to work:
AUSPOS works but I do not get a time-series of position/clock-offset as
OPUS works but I do not get a time-series of position/clock-offset as output
GAPS and magicGNSS rejected my RINEX file and gave an error message.


On Sat, Dec 21, 2013 at 11:47 PM, Felipe G. Nievinski <fgnievinski at gmail.com
> wrote:

> Might want to try http://gaps.gge.unb.ca/
> And the multi-solution comparison centre:
> http://gge.unb.ca/Resources/PPP/Purpose.html
> Another comparison:
> http://gpsworld.com/a-comparison-of-free-gps-online-post-processing-services/
> On Sat, Dec 21, 2013 at 1:51 PM, Anders Wallin <
> anders.e.e.wallin at gmail.com> wrote:
>> Thanks for the tip!
>> By extracting the receiver clock bias from the status-file, and playing
>> around with the RTKPOST settings I now get better results:
>> http://imagebin.org/283266
>> There's still a 4 ns offset between the CSRS and RTKLib solutions - I
>> don't know where it comes from??
>> ESA gLAB arrives at the same result as CSRS, so maybe I will look closely
>> at the gLAB settings next.
>> Thanks for your help - I will try to write a blog post about my findings
>> if/when I get at least three methods to agree on the results (CSRS, gLAB,
>> and RTKLIB)
>> Anders
>> On Sat, Dec 21, 2013 at 12:07 AM, Felipe G. Nievinski <
>> fgnievinski at gmail.com> wrote:
>>> I don't think you should use the time tag in the .pos file.
>>> I'd use instead the CLK records in the .stat file.
>>> See Appendix B.3 in the docs, "Solution Status File":
>>> *Receiver Clock‐bias States*
>>> *Estimated receiver clock bias parameters. The format of a record is as
>>> follows.*
>>> *$CLK,week,tow,stat,rcv,clk1,clk2,clk3,clk4*
>>> *week/tow : gps week no/time of week (s)*
>>> *stat : solution status*
>>> *rcv : receiver (1:rover,2:base station)*
>>> *clk1 : receiver clock bias GPS (ns)*
>>> *clk2 : receiver clock bias GLONASS (ns)*
>>> *clk3 : reserved*
>>> *clk4 : reserved*
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