Question

Hello everyone!

I am trying to run GPSTk to process some static GPS data that I have.

However, I found quite a lot of method available for double different (DDBase) and PPP(SolverPPP, PRSolve, rinexpvt).

Can you show me, which is the best GPSTk tool which provide most accurate station position result in the sense that it can comparable with GAMIT/GLOBK or BERNESE

Thanks for your help

Ha Tran,

-- HaTran - 29 Sep 2009

Answer

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Dear Mr. Tran:

Tools PRSolve and rinexpvt are code-based, while DDBase and PPP (example9) are carrier phase-based. Therefore, if you are looking for accuracy you must use either DDBase or example9.

Between those tools, the decision depends on the available data you have. If you have data from a GPS reference station whose position is known very accurately, and it is located closer to 20 km of your receiver, I guess you'll get better results with DDBase.

On the other hand, if you don't have a nearby GPS reference station (and your receiver is able to store L1 and L2 carrier phases), you should use PPP, implemented in "example9".

Be warned that PPP is a complex task that requires a lot of extra information in order to obtain the best results: SP3 precise ephemeris and clocks, antenna phase centers, ocean loading and pole movement parameters, etc. On the other hand, "example9" results have been favorably compared with tools like GIPSY/OASIS, MagicGNSS, GAPS and NRCAN.

Hope this helps.

Best regards,

Dago

-- DagobertoSalazar - 29 Sep 2009

Dear Dago,

Thanks for your answer,

In example9 use SP3 file for precise ephemeris and clocks which the sampling rate is 15 minute. How can I process higher sampling data which make use of IGS or CODE clock solution.

Best regards,

Ha

-- HaTran - 18 Mar 2010

Dear Mr. Tran

Now there no classes to handle these CLK files from IGS or CODE, and you have to write your own codes to handle those files, sorry.

I wrote some classes to process clk file for PPP, but it's rather ugly and little comments. it have to load three days clk files to process daily data, so it' also memory consuming and poor efficiency. But anyway, I'll send you these codes when I finsh my business trip one more week later.

I'll commit several classes processing clk files after the rinex3 branch was merged into the main branch, and patience please.

Regards,

Wei Yan

-- YanWei - 23 Mar 2010

Dear Mr. Wei

Thanks for your response. Waiting for your RINEX clock processing classes.

I wonder why we don't add a class to handle ERP file as well instead of provide some parameter by hand (e.g. example9 in pppconf.txt file).

Regards,

Ha

-- HaTran - 24 Mar 2010

Hi Ha!

Codes handling clk files have been send to you, please check your mail box.

There are classes to handle ERP files in GPSTk, take a look at the class 'EOPStore'.

Indeed, we have to feed some parameter by hand for example9 for some reasons:

1) 'examples9' is just one of the demo programs to show users how to use GPSTk libraries. After all, it's not a commercial software.

2) Earth orientation parameters are used to correct 'Earth Pole Tide', and it's trival. Updating ERP parameters make no difference to the final results.

For this question, Mr. Dagoberto Salazar can give you a better explaination, he really did a wonderful work!

By the way, a rinex3 clock storer is under developing in the rinex3_dev branch.

Regards,

Wei Yan

-- YanWei - 02 Apr 2010

Dear Yan,

Thank for your source code and answering my question.

Regards, Ha

-- HaTran - 30 Apr 2010 No such template def TMPL:DEF{PROMPT:supportquery}

Topic revision: r8 - 30 Apr 2010, HaTran
 

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