I'm trying to learn this process. So lets say im out in the middle of no where and going to map an area. No cell service, so I set up base station over an unknown point then connect to RTk P4 and fly. Will that process produce the 1cm to 3cm accuracy? When do you have to enter in the antenna height? Does the base station have to be inside the mapped area? Also, if able to connect to a Ntrip service, do I just connect the drone or is the base station connected some how?  Any Help would be great.

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Will that process produce the 1cm to 3cm accuracy? yes BUT the model will have high relative accuracy (let's say 1 to 3 cm) but low absolute accuracy (up to 3 meters)
When do you have to enter in the antenna height? y personally dont use antenna height, instead i use control / check points
Does the base station have to be inside the mapped area? not necessarily
if able to connect to a Ntrip service, do I just connect the drone or is the base station connected somehow? just the drone and its controller (and i know it beacuse i of forgetting base station)

thanks for the reply.  I can also use the base station  in handheld mode to mark my GCP or known point correct? Important to add antenna height when doing that correct?  Has anyone just tried to has the antenna height measurement to the photos altitude after the flight? would that work?      

yes but the base station needs corrections from an NTRIP or other source in order to use it as a rover for marking GCPs.

Ok, I thought that once the base station is in place, let it sit for a while and thru its antenna it would get its location from all the satellites. Then you would add the antenna height to get the correct location of that spot its set up on. If I had to use a Ntrip connection, I might as well just Ntrip to the Drone and leave the base out of it. But if I have no connection, then the base station can't find itself on earth?

Slot Tech Posted at 4-4 15:01
Ok, I thought that once the base station is in place, let it sit for a while and thru its antenna it would get its location from all the satellites. Then you would add the antenna height to get the correct location of that spot its set up on. If I had to use a Ntrip connection, I might as well just Ntrip to the Drone and leave the base out of it. But if I have no connection, then the base station can't find itself on earth?

It can find itself, but not with high precision unless it has a source of corrections. The corrections are used to resolve noise in the GNSS signal caused by atmospheric interference, multipath, etc.

You're right that if you let it sit for some time the position will be more accurate, but it is more likely to be in the decimeter rather than cm range without corrections.


Maybe this will help:
https://www.esri.com/news/arcuser/0103/differential1of2.html#:~:text=The%20underlying%20premise%20of%20differential,location%20to%20the%20known%20location.

Ok ,Thank you. I'm starting to understand a bit more. If one was to use a single AeroPoints board along with the base station and phantom rtk out in the middle of no where (no ntrip) woyld that be my best solution? I could get the cvs file from the Aeropoint board and use all that info in Drone Deploy for an accurate elevation map.

Slot Tech Posted at 4-5 11:11
Ok ,Thank you. I'm starting to understand a bit more. If one was to use a single AeroPoints board along with the base station and phantom rtk out in the middle of no where (no ntrip) woyld that be my best solution? I could get the cvs file from the Aeropoint board and use all that info in Drone Deploy for an accurate elevation map.

You can do your flight w/o RTK and do PPK processing to get precise positioning with no NTRIP or known benchmark coordinates over which to place the D-RTK 2.

Slot Tech Posted at 4-5 11:11
Ok ,Thank you. I'm starting to understand a bit more. If one was to use a single AeroPoints board along with the base station and phantom rtk out in the middle of no where (no ntrip) woyld that be my best solution? I could get the cvs file from the Aeropoint board and use all that info in Drone Deploy for an accurate elevation map.

if you don't have internet access you can fly with DRTK2 correction and the do PPK with rinex files wich are stored in DRTK2.... remember to use control / check points so you can log data with your drtk2 and use it as gnss (wich it is fact)

Ok. Thanks for the help guys with all my questions! I'm trying to understand all this and find it interesting. Glad you kind people are here to help me.

So they say you need to ADD the height of the antenna to the elevation. But wouldn't you have to subtract it for the ground level if the pointer was touching the ground?

Slot Tech Posted at 4-6 16:23
So they say you need to ADD the height of the antenna to the elevation. But wouldn't you have to subtract it for the ground level if the pointer was touching the ground?

if you are entering into GS RTK the coordinates of the benchmark over which the D-RTK 2 base station is located, you enter the X & Y (Lat and Lon ) in decimal degrees and the Z in Height Above Ellipsoid (HAE).

The XY&Z you are entering are really for the antenna phase center (APC), not the coordinate on the ground. The X&Y don't need to be adjusted as long as the pointy tip of the pole is on the point and the pole is plumb.

The Z needs to be adjusted by ADDING the antenna height to the HAE of the point on the ground. This gives you the APC height, which is what the software wants.

Z of benchmark + antenna height = APC height

Got it now, thanks for helping me understand. I kept thinking in terms of the ground level coordinates. Im going to be doing maps of earth moving sites before and after work is done, to compare elevation differences. I just need to do all my maps on the same method so I get good calculations when comparing the before work started to when done. I plan on using our DOT cors network for everything so I dont have to worry as much, but I might be in a valley with no cell service at times.  

So when you go and ADD the antenna height to the altitude, do you just reenter what the lat and long values are then hit settings to save them?

I am considering getting into crop surveying. This would be very helpful. Can you point me in the right direction for materials.

patiam Posted at 4-5 11:04
It can find itself, but not with high precision unless it has a source of corrections. The corrections are used to resolve noise in the GNSS signal caused by atmospheric interference, multipath, etc.

You're right that if you let it sit for some time the position will be more accurate, but it is more likely to be in the decimeter rather than cm range without corrections.

Does DJI or any other service provider offer training with the Phantom RTK? I am just learning about what drones can do. I recently passed my test for part 107 and want to get started.

https://forum.dji.com/forum.php? ... D699%26typeid%3D699
https://forum.dji.com/forum.php? ... D699%26typeid%3D699
https://forum.dji.com/forum.php? ... D699%26typeid%3D699
https://forum.dji.com/forum.php? ... D699%26typeid%3D699
+ many more threads here.
also lots of useful info on YouTube and other websites

Slot Tech Posted at 4-9 12:55
So when you go and ADD the antenna height to the altitude, do you just reenter what the lat and long values are then hit settings to save them?

Yes, that's always been a bad GUI design fail- to SAVE the settings, you must tap the SETTINGS button (there is no SAVE button).