RTK instability with no moving rover and base

Q&A forumCategory: QuestionsRTK instability with no moving rover and base
András Tóth asked 2 months ago

Hi All,
 
My problem is that, I have realized this signal from the ROver station with u-center app. 
This is the picture about the signal what I can see if I measure the position accuracy: https://drive.google.com/file/d/1cIGtwaf9B8KSzFbh32COPTExZ8FKrTnA/view?usp=sharing
 
I don’t know what could be the problem. It is really important to have good position because we would like to drive a platform along positions on a map really fast based on the signal from RTK. But there are minutes without stable position. The platform is about 60cm wide, so 80cm accuracy is not good enough. 
 
The Base station is at the middle of the garden. It is not moving. During the target normal usage it won’t move (Base station), but maybe I missed a good tutorial how I can fine-tune for our use-case. The rover of course will move fast for reaching point on any path, but if there will be minutes with instable RTK then we will fail.
 
Thank you in advance!
 
Best regards, András

Ardusimple Staff replied 2 months ago

First check would be to see the stability of the RTK corrections. Enable ubx-cfg-rtcm and see if there are interruptions of the data stream.

András Tóth replied 2 months ago

Dear Ardusimple,

Fist of all, thank you for your great support again.
I tried to fix it as you suggested, but I miss somwhere, because there is no RTCM, where did I miss this?

https://drive.google.com/file/d/1qDh-bU1MMF974vy8FN3WO_gKlxW3CCLL/view?usp=sharing

Thank you in advance!

Best regards, András

András Tóth replied 2 months ago

I tried to check between the messages: https://drive.google.com/file/d/1oEMb8JU5AH_ROktriIxh9lVwEwrrIQzR/view?usp=sharing

But I was not able to find any RTCM related message. I don’t know what to look for. The No RTK LED was off during taking the picture. Through the XBEE the messages are coming.
Yesterday evening it seemed to be much more reliable , but wothout any movement or reconfiguration it became worst and worst, nit it is accurate only just for some sec and back to bad

Thank you again.

Ardusimple Staff replied 2 months ago

Oh, my mistake, i didn’t type the message correctiy. UBX-RXM-RTCM sorry.

András Tóth replied 2 months ago

Thanks again you feedback. I could find yesterday evening and during the night this and started to test: https://drive.google.com/file/d/1t4xprS-LQAbCG8SplMiEA-9oE9Qc339G/view?usp=sharing

I would say it seems ok. The RTCM messeges are coming during that phase too, when the NO RTK LED is on and the accuracy is 0,8m. Is it possible to change the settings of the base station where I can force for higher stability. Rover and Base stations are still at the same place in these two days.

Thank you again!!

András Tóth replied 2 months ago

Hi

Can you please help me? I could see the RTCM messages while the accuracy is bad. Do you have any idea, what can I fine tune?

Ardusimple Staff replied 2 months ago

Hi Andras,
From a screenshot is very difficult to guess… but from the screenshot it seems like you changed a few parameters, can you go back to the original configuration files and test again? they are a good starting point to confirm that the setup is ok. Does it work also bad with the original configuration files?

András Tóth replied 2 months ago

Hi ArduSimple,

Thank you for your feedback. I have to be honest, I have not changed any major thing. When I ordered the package, then I asked for preconfiguration. So if the settings are not the default then I have got it from you in this state. Anyway I tried to jump back to default settings. But on u-blox site the FW 1.12 has disappeared, because there is the 1.13. I tried to use that and I hope it is backward compatible. I don’t know, the system is under test now, but please if you think the configuration is not okay with the new firmware, is it possible to get the old firmware somehow?

So there is no major change, I tried to switch on some messages but nothing serious. I could find another thread on the forum who had the same problem. I tried to ask him too, but no answer there.

Thank you in advance!

Best regards, András

András Tóth replied 2 months ago

And this time the ZigBee communication seems to be down… The antennas are at the same place, but ZigBee messages are not changed between the Rover and Base.

Ardusimple Staff replied 2 months ago

Oh, maybe we should have started with that, i didn’t know you had a custom config.
Unfortunately we can’t confirm that the 1.12fw will work well on 1.13fw, there’s a few changes in configuration parameters on 1.13.

next step i think is to see logfiles from you, not only pictures. send an email to info@ with pictures of your setup so we can see the boards, and logfiles in parallel from base and rover , with extra messages enabled ubx-nav-pvt, ubx-rxm-rtcm, ubx-mon-comms, ubx-mon-msgpp.

András Tóth replied 2 months ago

HI, thank you very much. I have sent the link about the log and config and everything else. Please let me know, if I missed somthing.

Thank you in advance!