[IGSSTATION-4749] C2 data in data files from HYDE
jeff.freymueller at gi.alaska.edu
Fri Jan 20 13:29:33 PST 2012
Author: Jeff Freymueller
This morning, a message on the teqc mailing list caused me to take a look at recent data files from the IGS station HYDE. Since June 20 of 2011, it appears that the receiver at HYDE has used L2C tracking. Definitely it reports C2 data instead of P2 data for satellites that broadcast C2. I believe this goes against the IGS recommendations, and the station operators should correct it. Some receivers can track both L2(C) and L2(P) along with C2 and P2, but processing the C2 and L2(C) observables remains problematic. If the data files are to be widely used, the RINEX files ought to include only L2(P) and P2, and not L2(C) and P2. I'm speaking here of the RINEX version 2 files, which I think are still the files almost everyone uses.
I think the correct approach is to change the configuration of the receiver, so that it can report P2 for all satellites, and L2 from P2. For receivers that do track L2C, it is possible to remove C2 data from the data files using teqc:
teqc -O.-obs C2 file1 > file2
However, doing this does not change the L2 data, and if the P2 data are missing then there will be only single frequency pseudorange data. I find that files from receivers that track L2C but have the C2 stripped out are frequently problematic, but this may be software-specific due to some things that arise in GIPSY for these files. Using L2(C) in general can be a problem, because I believe there still is no universal standard for the definition of the L2(C) phase.
Dr. Jeffrey T. Freymueller Office: 907-474-7286
Geophysical Institute Fax: 907-474-7290
University of Alaska, Fairbanks Home: 907-479-3550
PO Box 757320 Cell: 907-378-7556
Fairbanks, AK 99775-7320 email: jeff.freymueller at gi.alaska.edu
Download Alaska GPS data: ftp://gps.alaska.edu/pub/gpsdata/
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