PPK RTK using M8T and RTKLIB

Hi all,

I am running some PPK tests with M8T modules using patch antennas for base and rover (Drotek and CSG Shop).
The data, i.e. the ardupilot_dataflash.log.obs and the ubx raw data can be processed with RTKPOST. However, I only get a float and not an integer solution. Unfortunately, the resulting *.pos file coordinates are very “noisy” and less precise compared the GPS data logged directly in the dataflash log.

The screenshot shows an example.
Blue: GPS coordinates of the *.log
Orange: processed coordinates of the resulting *.pos file

I guess the problem is a combination of antenna, ground plane and interference. My question is if anybody managed to get an integer fix using M8T modules with patch antennas on rover and base?

Best regards,

Hi Thorsten,

We are currently making some tests with our receiver (Argonaut), which we used as a base station and rover receiver. For the base station, we used a geodetic-grade antenna (Septentrio PolaNt), which, as expected give a large fix rate (77% of the time in a 5h data take).

On the rover side, which was flown in a fixed wing drone, we used the internal patch antenna of Argonaut. The fix rate was much poorer, but we got some fix (2% of the time in a 10 minute fly).

You can have more details on the test set-up in this post:

If you need further clarifications, please do not hesitate to contact us.



Hi Thorsten,

There are many options you can play with in RTKPOST. For example, you can change the min ratio of fix ambiguity smaller, and you will have a higher fix rate, but the reliability will be corresponding reduced.

The best way is to use a real RTK/PPK board with dual-frequency tracking ability.



Hope U found a solution to your problem.
i’m working on something similar to your work & i need your help.

Using mission planner & the misions log, i found the way to extruct a kml (or gpx) file, i need a way to convert this files to an obs one, so i can use the RTKPOST to generate the pos file.

i did try that using RTKCONV ver.2.4.3 b29, & it wont work, with the error “file format can not be reconized”. I think because the input should be a RTCM, RCV RAW or RINEX OBS file.


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