[teqc] Chokering, Multpath and L2

Jim Ray (NGS 301-713-2850 x112) jimr at ngs.noaa.gov
Thu Jul 14 13:00:45 MDT 2005

holler at ufpr.br wrote:
> Date: Tue, 12 Jul 2005 22:33:23 -0300 (BRT)
> From: holler at ufpr.br
> To: teqc at ls.unavco.org
> Subject: [teqc] Chokering, Multpath and L2
> Hi to all,
> When analyzing some data I perceived that the errors for Multpath were
> bigger, for the Chokering antenna, in the L2 carrier. I do not understand
> because this happens.
> The analyses had been based with the following parameters:
> teqc +qc -s -plot -set_mask 00 -set_comparison 00 76570410.00o
> The archive generated with the result follows in annex.
> Very obliged for the attention of all.
> Wilson Holler

Dear Wilson,

If you care to compare your MP values with IGS stations also using the
Trimble 4000SSI receiver, you can check the individual stations listed at
for these stations with use the same receiver:
  barh brst ebre esti geno glsv gmas goug guat harb hofn lind mana
  mate medi nklg not1 pado slor ssia syog tlse uzhl vesl yebe
On the individual station pages, you will see plots of the MP1 and MP2
for the last 45 days.

It seems to me that the values you are getting are fairly consistent with
the stations above considering that you set the elevation cutoff at 0 deg.
That allows a lot of very poor quality data to be included in the statistics.
You might consider using a more reasonable cutoff of 5 to 10 degrees, which
should give MP measures similar to those for the IGS sites.  (It seems to
me that some of the IGS stations must be applying heavy code smoothing
to their C/A data too.)

It also appears that your receiver is set to ignore SVs flagged as
unusable.  In fact, even though PRN31 has been set unusable for some
months, the data quality is fine, especially if you use precise orbit

--Jim Ray

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