[bprater]

Differential GPS is what drones use for light shows or mapping or anything requiring high fidelity. This gives them centimeter-level precision, at the cost of a large sensor array on both the ground and the drone. If you are adding this to a drone, you'd also need to include orientation and other parameters in your data stream, as you'd only be getting XYZ from GPS. Unfortunately, no simple hardware exists for your request.

[jvanderbot]

Pixhawk exists. https://pixhawk.org/

[ganzuul]

Differential GPS should be eminently hackable and cheap, including the antennas in question, but it's an open question if we even want that right now because spoofing would be no more difficult.

[MayeulC]

GPS-RTK is not that hard or expensive: https://docs.centipede.fr/ (in French).

https://docs.centipede.fr/docs/make_rover/rover_v5_1.html lists a €180 GPS module, which is not dirt-cheap, but still affordable.

[michaelt]

RTK GPS isn't hard in theory, only in practice.

To maintain a high-precision fix, you have to maintain particularly good tracking (a 'phase lock') of 5 or 6 satellites. That can be demanding - you practically need line of sight to the satellites.

That might be practical if you're flying drones outside in free space - but if you're flying in a stadium with a lot of seating? Or dodging in and around trees with lots of foliage? By all means test it out, but don't imagine it'll be easy :)

I've also heard second-hand reports that the PLL signal tracking built into many GPS modules isn't really tuned for >4g acceleration because 99.9% of GPS modules end up in cars and phones. With the consequence that trying to track acrobatic flight leads to more lost signals than you'd expect, based on the excellent view of the sky. I haven't seen that firsthand, though - it's just what I've been told.

[tonyarkles]

I've been using UBlox F9P/F9R units recently and it's really quite amazing how good it is. The ground receiver doesn't require a large array of anything, the base station fits in the palm of my hand and mounts onto a regular photography tripod. The radios we use to send the RTCM3 stream to the drones are quite tiny too, the antenna's about as long as my finger.

[bjacobt]

How’s the accuracy on cloudy days? I’ve been playing with uBlox ZED-F9P and accuracy degrades unless I’ve clear sky.

[tonyarkles]

Like the other replies said, I’d suspect you might have an issue with your setup. We’ve used 3 different antennas and they’ve all (to my knowledge) performed beautifully.

I see your email address is in your profile. Today’s a stat holiday in many parts of Canada, but I’ll look around tomorrow and see if I might have some data to support/refute my assertion. Our pilots, nominally, write down the weather for every flight, so I might actually have some clear sky/cloudy data that I could share from the base station.

[fortysixdegrees]

Something is up with your setup. Check that the active antenna you are using meets the F9Ps relatively high gain requirements for the LNA amplifier.

Actual impact on accuracy for outdoor short baseline rtk should be close to non existent.

[mr337]

I agree, we have these deployed in the field and have no issues with weather due to using more than the L1 band. Something isn't configured correctly or something failing, such as the antenna.