Question

Dear GPSTk,

I used the DiscFix app for cycle slips detection and correction. I did not choose smoothing or debiasing options at all. The first several lines in the original files:

05 12 01 00 00 00.0000000 0 9 02 04 06 10 13 23 24 25 30 103743822.79749 80839351.85649 19741792.73049 19741793.29649 19741795.68349 103743819.30249 861.00049 542.00049 757.00049 110256129.89448 85913884.99048 20981042.98449 20981043.94548 20981048.19448 110256124.39749 608.00049 243.00048 217.00048 126230893.27546 98361756.26846 24020940.21548 24020941.20246 24020946.24346 126230893.77748 153.00048 14.00046 16.00046 123666871.84246 96363819.44646 23533023.66448 23533023.59546 23533029.52346 123666874.34948 235.00048 36.00046 34.00046 117773345.34047 91771452.35547 22411521.54348 22411522.53547 22411525.94447 117773340.84448 343.00048 68.00047 60.00047 118201888.85047 92105375.16947 22493071.36448 22493071.59847 22493073.23847 118201887.35748 344.00048 94.00047 92.00047 129107599.34446 100603342.68045 24568358.45248 24568358.57246 24568365.04345 129107594.83648 152.00048 12.00046 9.00045 127531717.20346 99375379.98646 24268478.38648 24268479.18146 24268483.34946 127531713.72048 180.00048 17.00046 11.00046 114213732.69848 88997728.25447 21734149.60148 21734150.73048 21734154.67847 114213726.20548 400.00048 106.00048 88.00047

Then the first epoch data in the output:

05 12 1 0 0 0.0000000 0 7G02G04G10G13G23G24G30 103743822.79719 80839351.85619 19741793.29649 19741795.68349 110256129.89418 85913884.99018 20981043.94548 20981048.19448 123666871.84216 96363819.44616 23533023.59546 23533029.52346 117773345.34017 91771452.35517 22411522.53547 22411525.94447 118201888.85017 92105375.16917 22493071.59847 22493073.23847 129107599.34416 100603342.68015 24568358.57246 24568365.04345 114213732.69818 88997728.25417 21734150.73048 21734154.67847

Here you can see two sets of observables are removed in the first epoch. And data removal also happens in the other epochs for at least two GPS satellites. Can anyone tell me why it happens?

Thanks and regards, Ian

-- IanYANG - 10 Apr 2013

Answer

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Hello Ian,

It looks as if the first set of observables contained data that is not supported for DiscFix output. I believe DiscFix only outputs L1, L2, P1 (or C1), and P2, although whether that is the standard default, I'm not 100% sure.

Best thing to do is check the header file in your first obs file and check the data types against the data, and see what data types DiscFix is omitting in its output (second obs file). That will tell you what data types DiscFix outputs as default.

Hope that helped.

-- BryanParsons - 12 Apr 2013

Hi Bryan,

My apologize for making my question confused.

It is not referring to the obs type, I think. Actually the whole data of two GPS satellites get lost in the output (for the first epoch, there are 9 GPS visible in the input file, but only 7 left in the output). And the Rinex version is 2.11.

-- IanYANG - 15 Apr 2013

Hello IanYang,

In order to view your data correctly, I had to use the 'edit' option and copy it from that source. After looking at the correctly formatted data, I can see what you are talking about.

The only explanation we can surmise, at the moment, is that DiscFix filtered Satellites 6 and 25 from the output file because those observations were not deemed viable candidates for analysis. This could be due to corrupted data, short time intervals, or other criteria that caused DiscFix to omit the observations.

Hope that helped.

-- BryanParsons - 17 Apr 2013 No such template def TMPL:DEF{PROMPT:supportquery}

Topic revision: r4 - 17 Apr 2013, BryanParsons
 

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