[time-nuts] gLAB PPP noisy clock residuals

Anders Wallin anders.e.e.wallin at gmail.com
Wed May 24 01:10:25 EDT 2017


> I have not been able to get a copy of the nrcan-ppp softwarepackage, so I
> am looking elsewhere. ESA gLAB looks like it might fit the bill. The
> problem, in short, is that the data I get from  postprocessing with gLAB is
> much, _much_ noisier than the results I get from submitting the RINEX files
> to NrCAN-PPP online service.
>

Hi Ole!
I did a comparison of a few PPP results some years ago, maybe you saw it
already
http://www.anderswallin.net/2013/12/comparing-gps-ppp-solutions/

For the web-service running NrCAN, there was an URL API that allows running
the filter/algorithm forward and backward ("filtfilt" in matlab or numpy),
to get rid of the initial transient in only the forward solution. You could
ask the maintainers, or I can try to dig in my archives (I should have
python code that submits RINEX to the service and retrieves the results).

>From my link above it looks like the troposphere-models are quite
different.
Here is a recent ".sum" summary file from a NrCAN run:
https://pastebin.ca/3816315
in section 2.7 it has the troposhpere model type, and in section 3.1 a
parameter "TZD random walk       (mm/hr):        5.000"
if you dig in the ESA gLAB settings, can you set the ZTD-model identically
and see what happens?

If you post your RINEX:es and other relevant data I can try processing also
and see what I get.

cheers,
Anders


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