Question

Hi; I'm Iván, a student from Spain, Now im trying to use the GPSTk apps to obtain TEC maps over Europe. I have used DiscFix and ResCor to preprocess the RINEX data (observables and ephemeris) of several EUREF stations. The problem is when i run IonoBias over this ERINEX: The resulted biases are bigger than most of the STEC data so the VTEC values calculated in TECMaps are negative. Here is a example of the resulting TECMaps log:

Process at time = 2013/5/28 3:34: 0.000=1742/185640.000

1742 185640.0 1 50.14000 359.29800 0.58 -17.855 12840.0 1 1

1742 185640.0 2 55.14500 346.62000 0.59 -28.080 4320.0 4 1

1742 185640.0 3 49.49600 337.72900 0.36 -12.650 1500.0 10 1

1742 185640.0 4 48.79300 353.16300 0.59 -17.844 3510.0 13 1

1742 185640.0 5 51.94100 349.68800 0.76 -27.967 10890.0 17 1

1742 185640.0 6 53.44000 355.57200 0.94 -42.522 12840.0 20 1

1742 185640.0 7 51.38900 354.64000 0.85 -32.718 7260.0 23 1

1742 185640.0 8 57.56400 3.65600 0.45 -18.448 6060.0 31 1

1742 185640.0 1 42.72100 10.12000 0.74 -26.515 12840.0 1 2

1742 185640.0 2 49.45900 358.63800 0.43 -16.820 1680.0 4 2

1742 185640.0 3 38.85500 11.56400 0.46 -12.355 12840.0 11 2

1742 185640.0 4 41.74100 5.50400 0.67 -27.454 3720.0 13 2

What could be the problem? Is IonoBias running properly or should i try to use another method to obtain the satellite+receiver biases?

I have run the example given in the GPSTk suite, obtaining proper results.

-- IvanRodriguez - 01 Jul 2013

Answer

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Hello Ivan,

Sorry for the delay in responding to your question.

One possible reason for your larger biases could be due to poor least squares calculations, which can be due to not having data from enough stations or a lack of diversity in station distribution.

Another possibility that has caused negative VTEC values in-house are high receiver hardware biases associated with Trimble receivers, as TECMaps does factor these values into its VTEC calculations. Even if your data is not from Trimble receivers, it is good to take hardware biases into consideration.

Hope this helps and thanks for your interest in the GPS Toolkit.

-- BryanParsons - 06 Aug 2013 No such template def TMPL:DEF{PROMPT:supportquery}

Topic revision: r2 - 06 Aug 2013, BryanParsons
 

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