Inaccurate Position Flight Mode with Here antenna


Today I did my first flight to test a new Pixhawk 2.1 with Here antenna (original ProfiCNC/Hex product).

PX4 flight stack, FC mounted on a hexa which flew amazingly with the Pixhawk 1 and M8N GNSS.

Omitting that flight reactions are tweaky, my concern is that flying with Position Flight Mode, the bird doesn’t keep its position as expected.

14 satellites liked, 0.3 HDOP, but the drone doesn’t keep its position as the Pixhawk 1 with APM and M8N used to keep like a pole.

The Pixhawk 2.1 with Here antenna allows to move the drone of a few meters and I must control it manually almost like flying in Stabilize mode.

Why it doesn’t stuck on its stable GPS position?

Thanks to all those of you that will help me solving this issue.

Anyone that could answer to this issue? Thanks.

You’re more likely to get help if you upload a log to

How can I download the full log from the controller?

Do I have to do it through Qgroundcontrol?

Sorry but I’m not with the bird right now.

Logs are stored on the SD card in. You can also download them with the Log download widget in QGC’s Widgets toolbar menu.

The Pixhawk 2.1 does not have SD card.

@Riccardo yes it does if you look under the usb port on the cube itself. You can also download over USB through QGroundControl. Once you have a flight log showing the problem upload it to

Sorry you’re right, I’ve missed it!

Here you are one of the flights:

Another one:

It sounds like a position PIDs issue. How to safely tune the position PIDs?

Hi. Any answer to my last question?


It’s fairly safe to do it in flight if you make small changes. The relevant parameters are in the Multicopter Position Controller group in QGroundControl. MPC_XY_*

Thanks. Small changes you mean like 10/20% of the shown value? For instance 0.2 can be incremented to 0.22?

Yes exactly. If possible also have someone with the transmitter in hand ready to take control in manual.

One more question: Pixhawk manual states to do NOT make PID tuning with carbon fiber props. Many of us use carbon props. What do I have to do? Land-tune-fly or I can actually tune while flying?

I’m not sure what the basis of that advice is, but we should find out and expand the documentation.