[teqc] converting data and statistics

Lou Estey lou at unavco.org
Sun Mar 22 10:33:43 MDT 2009


> i logged SBAS and GPS raw data with my uBlox (LEA-4T) GPS receiver.
> 
> How could i tell teqc to generate rinex file with only GPS data?
> i wrote:
> teqc -O.s G foobar.ubx > foobar.09o
> and i got all the data (GPS and SBAS instead of only GPS)

Option '-O.s' currently only edits the 'TYPE' field in the first header
line of the resultant RINEX obs file.

For editing SVs, see `teqc +help` or:

http://facility.unavco.org/software/teqc/notice/19990107.html#editing

Assuming there's no GLONASS or proto-Galileo data in the input and
just GPS and SBAS (as would the case with data from a ublox), probably
the command that you want is:

teqc -O.s G -S foobar.ubx > foobar.09o

> i tried to do statistics on my data (+qc)
> i wrote:
> teqc +qc -nav foobar.09n foobar.09o > foobar.qc
> 
> and i got that all my measurement was ignored
> Possible obs >   0.0 deg: 102308
> Possible obs >  10.0 deg:  82269
> Complete obs >  10.0 deg:      0
>  Deleted obs >  10.0 deg:  82082
> 
> Obs reported w/ code | phase : 117262
> Obs deleted (any reason)     : 117262
> Obs complete                 :      0
> 
> is it possible to do statistics (+qc) directly from the raw data? 
> (adding navigation file)

Yes, but that's not the problem here.  If the data is from a
ublox receiver, it's L1-only.  The qc algorithms are for dual-
frequency data, e.g. L1- and L2- from GPS, where both the phase
and a code pseudorange for both carrier frequencies are needed
for a "complete" observation (for qc purposes).

Doing a qc on L1-only data, you probably want to try:

teqc -P -L2 +qc -nav foobar.09n foobar.09o > foobar.qc

i.e. -P == "no P-code data" and -L2 == "no L2 data".  Even here,
though, the qc will not return the same type of stats that it
would on dual-frequency data.

Qc-ing raw data is a little trickier.  Generally you have to
specify a window that you are interested in, though this does
not necessarily mean specifying a start and end time.  E.g. if
you use the +dX option, this specifies a window length from the
first valid epoch in the raw data.  If you want the ASCII "plot"
files, then you might have to also specify the sample interval
using -O.int.

--lou

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Louis H. Estey, Ph.D.              office:  [+001] 303-381-7456
UNAVCO, 6350 Nautilus Drive           FAX:  [+001] 303-381-7451
Boulder, CO  80301-5554            e-mail:  lou  unavco.org
      WWW:  http://www.unavco.org   http://jules.unavco.org

"If the universe is the answer, what is the question?"
                                                -- Leon Lederman
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