Here3 RTK not getting RTK fix


Our custom built multicopter is equipped with a here3 connected to the cube orange flight controller. We’ve been flying it successfully using the GPS positioning of the HERE3 but recently have started trying to fly with the Here+ RTK base.

Our Here+ RTK base is able to survey-in and when the designated accuracy is reached it goes into RTK Streaming. However, when looking at QGC the Here3 never changes from 3D fix to RTK fixed, even when the RTK is streaming we stay in 3D lock and haven’t been able to achieve RTK positioning.

Our initial thoughts are that the RTK accuracy is set pretty high such that the GPS accuracy might actually be better so the autopilot chooses not to go for the worst positioning provided by RTK. We want to test this but our current environment doesn’t allow us to get low enough RTK accuracy. I would think that the HERE3 would automatically kick into RTK when the RTK is streaming but it just isn’t working.

Can anyone help?


Did you figure it out? I am having the same problem!

I’m having this issue - but there are so many things in between - I think I need more information to properly debug. Have you guys found a way to get logs from the NMEA injection to see if those messages are actually making it into PixHawk system awareness/solver?

could you clarify what you mean by the NMEA injection? not sure how to check logs regarding rtk status

I’m attempting to provide direct correction information from a Sparkfun RTK Facet - into the pixhawk cube using a Here3+ and a simple serial radio module. This way I don’t need a mavlink computer in the middle.

I have more information that I think I’ve figured out which makes my ask different. I’m looking to inject NMEA strings directly… but pixhawk is expecting RTCM streams that contain the NMEA data. So I think what I want is a different ask… and I’ve created a new message about it.

Sounds good. If you do figure out why the GPS doesn’t get RTK lock even though RTK is streaming (via QGC) please let me know

No luck on my end :confused: let me know if you figure it out

I assume what you want to do can be done in ucenter. ucenter can listen udp messages, there is probably a way to connect both qground and ucenter at the same time.

Has anyone managed to figure this out? I still have this problem