New Github Branch: Demo2


I have created a new Github branch in my repository and called it demo2.  It includes the code and configuration changes as well as the data from the two sets of kayaking data in the last few posts.

Specifically it includes the following modifications from demo1:


Both data sets are in the rtklib\data\demo2 folder. Fore1.ubx and Aft1.ubx are the first data set. Fore2.ubx and Aft2.ubx are the second data set. Note that both data sets have 5 samples per second. In demo1, the data had only 1 sample per second. This will affect any input configuration parameter that has units of counts, since generally the time periods should not be dependent on the sample rate. The receiver is actually sampling at a much higher rate than the output so, in general, increasing the output sample rate should only increase the resolution of the data, not the precision or accuracy.


  • Added an additional position variance constraint for fix-and-hold to avoid erroneous holds occurring before the kalman filter has had time to converge as described in the previous post.
  • Updated the writes to the trace file to make the trace output more meaningful for my experiments

Configuration File:

  • pos2-arthres: 0.999 → .002 ( variance threshold, the original value was unused)
  • pos2-arlockcnt: 30 → 150 (Both values are 30 secs, different sample rates)
  • pos2-arminfix 10 → 100 (10 sec → 20 sec)
  • pos2-minfixsats 4 → 5   (minimum valid satellites for fix)
  • pos2-minholdsats 5 → 6  (minimum valid satellites for hold)
  • remove unused parameters (arthres2, arthres3, arthres3, armaxiter)

I’m always interested in other people’s experiences. Please leave a comment if you find other interesting observations with this data or code or configuration changes, or if you have any questions about them.

5 thoughts on “New Github Branch: Demo2”

  1. Can we hope to see your improvements to be adopted by and show up in T.Takasu’s official RTKLIB repository?


    1. Hi Kilgore (a fellow Vonnegut fan I assume). I do hope to get some of my most obvious and non-controversial changes adopted in the official repository. For example I submitted the arlockcnt fix to there a while back and it has recently been incorporated in the latest official release. I have also just submitted a request to support the half cycle valid bit on the M8N.

      For some of the other changes, I am less certain they belong in the official repository. My changes are focused on one small corner of the world of GPS (low cost) and tested on an even smaller corner (low-cost UBlox) and I am not sure how well they all will translate into the larger realm that RTKLIB supports. As I get more feedback on some of my other changes (positive or negative) and build confidence in them I will probably submit additional requests.


  2. Hey rtklibexplorer,
    first of all – great blog! Thank you for sharing your work.
    I’m experimenting for a while now with two Raspberry 2, NVS08C Chips and Tallysman TW3710 Antenna. One is working as a base station, the other one is a moving rover. I also use a circle simulator (r=1.5 m) to test the precision. One time, it should work on realtime, calculated with rtkrcv on the RasPi. Next to my own reference data i use a virtual reference station from CORS Network by the Bavarian government. I have access to a high precision receiver to run tests for the total accuracy of my solutions. I managed to gather a lot of raw data, but my outcome is not satisfying. The circumstances are alright, no tall buildings/trees near my test site. Still, i get a lot of wrong fixes and very low AR ratio. I tried a lot of different settings with 2.4.2 and 2.4.3. So your approach on fixing some bugs and improving the code is very promising. I usually have two instances of rtkrcv in kinematic mode running on the RasPi while logging the raw data for further processing (with different base data).
    Now i tried your version rnx2rtkp from demo1 and demo2 but i receive an error message about MSVCR100D.dll which is related to the Microsoft Visual C++ 2010 Redistributable package. I tried reinstalling the packages but i don’t get it to work. Thanks to Michael for building the GUI with Embarcadero.
    Keep up the good work,


    1. Hi Julian. It looks like I might have put the debug version of the rnx2rtkp.exe in the bin folder in Gituhb. (I’m guessing that is what you ran when you got the dll error). I just uploaded the release versions of rnx2rtkp.exe for demo1 and demo2 to my Github repository so you might try again and see if these work.


      1. Thank you. Now it works fine.
        In the meanwhile, i found out why i am getting poor results. If i include GLONASS to my position calculation, used satellites start to jump. After recompiling rtkrcv on Pi 2 with the hardfloat flag, it’s working!
        Greetings, Julian


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