RTK big drifting in closed area

Hello everyone, so i previously bought Here+ RTK GPS base station to combine with Here 3 GPS paired with Cube Orange autopilot on my drone. Everything is fine on the clear weather and in open area, Mission Planner shows RTX Fix position in the corner. However when i put drone inside big hangar and try to fly there, in the corner shows 3Dgps and the drone constantly drifts. Its just not possible to fly there in Loiter mode. How can I have a good GPS position in a closed area considering that the GPS is lost the moment I go in there even with RTK Base station?

If you are flying in a closed environment , your RTK antenna won’t see enough satellites to gain a precise RTK position.
It is not possible to have such precise positionning in a closed area.

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Hi, thank you for an answer. Well its the opposite, RTK base station is on open area and the drone is inside. Thats why i dont understand why it changes to 3Dgps.

Also i have to mention that its not completely closed area, from the one side it has clear connection between RTK and drone, with telemetry.

Even if your RTK Base sees satellites, your drone needs to see them too.
Your RTK base sends corrections to your RTK on drone, but in order to use these corrections, your RTK on drone needs to have a position first , i.e. it needs to see satellites.
If you read this doc for example, it clearly indicates that

Place vehicle and base stations so that their GPS antennas have a clear view of the sky (i.e. this will not work indoors!). During operation, please place the base station in an outdoor environment with sufficient sky coverage to obtain a good satellite signal. Place the base station on a stable and elevated platform, such as a tripod.
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Yeah i understand that, so in your opinion there is no chance for drone to fly indoors with good gps lock in loiter mode? There is no equipment to achieve that?

I cant get good gps lock with Here 3 gps on my drone, it constantly drifts, and when i try to fly with him inside big metal construction with RTK base outside (big metal construction is open on one side so RTK Base is practically outside on clear sky), the drone cant mentain position, it just lose himself and start to move arround really fast with big oscillations. Thats why i ask is there any equipment so the drone can mentain perfect position inside any construction such as house, factory etc…

You should try to fly in Alt_Hold mode

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Should take a look at how rtk gps works. Having the base out is not enough :slight_smile:

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Or try indoor position beacons.


Sounds like your RTK set-up (outside) is fine, but the GPS on the drone (inside) just isn’t getting a stable fix. The drone has to constantly see a minimum number of satellites before it can get a good fix. THEN it applies the RTK corrections and all is well. Good luck!


Maybe optical flow could help? I’m not sure though.

It would Loiter in position if that is what’s desired. But that’s about it…

That’s what they asked for. They wanted something that would keep the craft stationary (virtually ofc, no craft can maintain a perfect position hold in the air) at a point in the air when they’re inside a building. So it made sense to me, otherwise idk how to help them. I do have an optical flow sensor and recently found out I could use it for the same, so I’ve set it up via i2c. Probably good to check out the Arducopter Wiki or Documentation idk what it’s called.

He’s asking for GPS based position. Optical Flow will not provide that.

Thats why i ask is there any equipment so the drone can mentain perfect position inside any construction such as house, factory etc…

Hi everyone and thank you for answers… So it would loiter in position, but can the drone move around the factory and pass between the rows unhindered along the pre-drawn path on the mission planner? Can you explain me what position beacons are?

No, not with just Flow Hold. It holds Loiter position based on ground texture and visible features. It might be useful for you in that limited way but it will do nothing in regards to Mission routing accuracy.

I don’t think you are referencing the Wiki guides: Non-GPS Navigation

This is a position beacon example. Pozyx Indoor Position Beacon

But using google to search for it would have given you more information. like this one:


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Because you are basically flying inside a Faraday Cage. The structure of the hanger is interfering with and distorting the signal from the satellites. If you had read and understood the associated documentation it clearly states that the onboard GPS must have a clear unobstructed view of the sky. This applies whether you are running RTK or not.