[teqc] Choose common satellite from two RINEX data

Lou Estey lou at unavco.org
Tue Nov 18 08:05:05 MST 2008


Hideki Yamada,

 > I want to make two new observation files using only common satellites of
 > both files at each epoch from two original Rinex files (observation files).
 >
 > Please ask me how to command in order to perform above request, if it is
 > possible to do it.

This is an unusual request, and there's nothing built into teqc to do this
in one easy step, but it can be done in a couple of steps as long as you
fill in the middle (manually or with a script).

First, qc each original RINEX file.  This step need not have navigation
RINEX files, and the short report is all you need e.g.
`teqc +qcq RINEXorig.obs > RINEXorig.qc`

Next, you have to parse the lines in the short report qc files that list
SVs _without_ observations, e.g. for one qc:

NAVSTAR GPS SVs w/o OBS :  1   2   4   5   9  10  12  14  15  18  21  22
                           24  29  30  31

     GLONASS SVs w/o OBS :  1   2   3   4   5   6   7   8   9  10  11  12
                           16  19  20  21

Let's suppose the qc for the next file shows:

NAVSTAR GPS SVs w/o OBS :  1   4   5   9  10  12  14  15  18  21  22  23
                           24  29  30  31

     GLONASS SVs w/o OBS :  1   2   3   4   5   6   7   8   9  10  11  12
                           16  18  20

The SVs _with_ data are those not listed in either list, between PRNs 1-32
for GPS or slot #s 1-14 for GLONASS.  So, for GPS, you start with a list
of integers, 1-32, and kick out any integer that occurs in any GPS list as
being without data, and you do this for your two (or more) RINEX obs files and
determine the SV overlap for the files.  (Perl would be an excellent choice
of language in which to write a script to do this step.)

 From your remaining overlap list for each satellite system (GPS, GLONASS, ...),
you now have the information that you need to build SV filter list options
for teqc.

Using the above as an example, this SV filter list options would be
+G3,6-8,11,13,19,20,25-28,32 for GPS and +R13-15,17,22-24 for GLONASS
(or you can list the SVs individually, comma delimited); see

http://facility.unavco.org/software/teqc/notice/19990107.html#editing
and
http://facility.unavco.org/software/teqc/log.html (entry for 2007 May 18)

Then apply the SV filter list options to the original RINEX obs files:

teqc +G3,6-8,11,13,19,20,25-28,32 +R13-15,17,22-24 RINEX_1.obs > filtered_1.obs
teqc +G3,6-8,11,13,19,20,25-28,32 +R13-15,17,22-24 RINEX_2.obs > filtered_2.obs

Note on "mixed" observation files (data from more than one satellite system):
teqc filters for one system have no effect on the other systems, so, e.g., if
you had a mixed observation file with both GPS and GLONASS, as above, and
you used only a +G or -G filter list for GPS, the GLONASS SVs would not be
filtered at all for either +G or -G.

Hope this helps.

cheers,
--lou


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