[teqc] GeoGenius

Lou Estey lou at unavco.org
Thu Sep 2 09:05:37 MDT 2004


hi John,

> I don't know what is all the fuss about the GeoGenius .OBS files, because
> GeoGenius has the capability to export Rinex in both standard and compressed
> forms.  That is all not to mention, importing Rinex and several different
> binary formats.
> 
> John Galvin

Good question.  The fuss (or maybe consternation) is that not all
RINEX is the same, or necessarily correct.  Andrew Miner at CWU,
Brian Frohring at Trimble, and I have been having some off-line
discussion, and to summarize for the group:

Andrew has been having problems processing the Z-12 RINEX at
http://www.gps-survey.com.  (Qc with teqc indicates "clock slips",
which means inconsistent handling of the millisecond resets
between phase, pseudorange, and time tag.  This could be due
to a receiver problem, or a bad RINEX translation.)  For review,
RINEX of receivers using millisecond clock resets should, at the
resets, have:

smooth phase and pseudorange, ms jumps in time tag

or

ms jumps in phase and pseudorange, smooth time tag

(both with the correct sign in the ms jumps, of course)

Teqc currently only produces the former (following the original
methodology of Werner Gurtner's TRRINEXO and ASRINEXO).  Other
translators, like Topcon's tps2rin, produce the latter.  Many
of you are familiar with Jeff Freymueller's clockprep program,
which converts RINEX of the former flavor into RINEX of the latter
flavor for GIPSY.

Brian looked at the Terrasat RINEX of the Z-12 and found that
it has smooth phase and time tag and ms jumps in the pseudorange.
I.e. it's basically a "raw" RINEX-like translation of the Z-12 data,
but it doesn't follow the RINEX specification with regard to
the receiver millisecond clock resets.

I hasten to mention that a teqc qc indicating clock slips does
_not_ necessarily mean a bad translation, though.  Just yesterday
here at UNAVCO we confirmed that an Ashtech microZ (don't know
the firmware offhand) yields RINEX giving clock slips when connected
to an off-spec external oscillator and normal RINEX when connected
to a good external oscillator.  (More on this if anyone is interested...)

--lou



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