Copter 3.4.6 with Novatel RTK,HDOP can't be updated in real time

The recent use of NOVATEL RTK, but found a problem, HDOP parameters can not be updated in real time, resulting in HDOP has been a high value, so the aircraft can not be unlocked. Only after the RTK power to the future, to RTK normal positioning, and then to the flight control power, HDOP at this time in a normal range can be used. But there is still a problem, HDOP has not been updated in real time, no matter how the number of satellite changes


I’m sorry but from your description I couldn’t understand what the problem is. Is it that you think HDOP isn’t being updated? How do you know that?

Also, please post a log.

Thank you very much for your response! I am sorry that my English is very poor.
I was observing the HDOP before taking off by the ground station(Mission Planner) ,I found it has not been updated so it has been in a great value(RTK search satellite process, the beginning of the search satellites less lead to HDOP relatively large, after the search for more satellites, HDOP should be in a smaller value).
I carried out a test,I found that if disconnect the RTK and flight control data connection,until RTK found more satellites and then connect it with the flight control, then HDOP for the smaller normal value,Then I block the RTK antenna, RTK search satellites quality should be worse, then HDOP should become larger, but the results I found the ground station shows the HDOP consistent unchanged.This means that RTK is not updated in real time,so it is very strange!

Hi Kira, what message are you logging from NovAtel board? Did you check the satellites number in GGA message?

Hi zhu,I am not using the NMEA message format, but with the binary.

I’m not sure if there is a problem with ArduPilot side, the driver is pretty simple, but I think there aren’t many people using it. If you post a log of this situation it might help understand what is happening.

Got your idea. You may need to contact NovAtel support to report this bug.

Or, you can contact me for Tersus dual-frequency RTK board. (I’m sure it’s an advertising, hahaha. I played with many RTK boards and chips, and also work with Tersus GNSS)

Thank you for your response!I uploaded a log as follows: (4.4 MB)
As you can see from the log, even if the number of satellites has changed, HDOP has remained unchanged.

I suspect that there is a problem with the underlying driver code.

haha,Thank you for your response all the same!But RTK is so expensive that I can not afford two…

Not really. The cost has been going down these years.

what novatel model are you using?

It’s OEM617D.Do you have any good advice?