Re: ppp averaging and circular error of probability

[Hans Mayer]

Hi Greg,

On 12.09.22 01:31, Greg Troxel wrote:
> It's more that math is difficult than English.  What I meant is that
> there is a probability distribution for measurement outcomes, and things
> like CEP are estimates of that (unknown) distribution.

I agree.


> > |UBX-CFG-GNSS: |
> >
> > |msgVer 0 numTrkChHw 60 numTrkChUse 60 numConfigBlocks 6
> wow, that really needs unmunging!


sorry, later I saw it was really bad formatted.


> > gnssId 0 TrkCh 8 maxTrCh 16 reserved 0 Flags x11110001 GPS L1C/A L2C enabled
> > gnssId 1 TrkCh 3 maxTrCh 3 reserved 0 Flags x01010001 SBAS L1C/A enabled
> > gnssId 2 TrkCh 10 maxTrCh 18 reserved 0 Flags x21210001 Galileo E1 E5b enabled
> > gnssId 3 TrkCh 2 maxTrCh 5 reserved 0 Flags x11110001 BeiDou B1I B2I enabled
> > gnssId 5 TrkCh 0 maxTrCh 4 reserved 0 Flags x15110001 QZSS L1C/A L2C enabled
> > gnssId 6 TrkCh 8 maxTrCh 12 reserved 0 Flags x11110001 GLONASS L1 L2 enabled
> So you have good support for most constellations with limited to 5
> BeiDou, and SBAS.  And possibly 4 channels for QZSS which if you are in
> Europe you won't hear.  It's an interesting question which SBAS is in
> use (ENGOS?)  and if it has correctionsfor all 4.

Yes, I am in Europe and I see QZSS.

During the last 24 hours they are representing 1.4% of all seen 
satellites. But none of them was used.

> > > I would suggest that you record a day or so of raw data, convert to
> > > RINEX, and submit to CSRS-PPP to both get a position, and look at the
> > > error statistics.  Before you do, make sure that you have a stable or
> > > repeatable antenna position, where it's stable to better than 1 cm.  You
> > > also may want to pay attention to the "North Reference Point" (see
> > > https://www.ngs.noaa.gov/ANTCAL/FAQ.xhtml  ) if you have a more serious
> > > antenna, and make one up if not for repeatability.
> > Thanks for this hint.  I will look for the antenna diagram
> I don't think that antenna has a cal file, but I'd say the NRP is
> opposite the cable so that the cable is south.  Or rather that's the
> convention I'd adopt.  But if you can find a stated plan from u-blox or
> someplace like NGS, definitely follow that.  I doubt it matters; it just
> seems to be best practice to be consistent.  And, if it's fixed in place
> and you don't intend to move it -- then just don't move it!

It should be easy to turn it into the right position. I only have to 
crest the roof.


// Hans