Phantom 4 Pro RTK/PPK

This is just my iteration using a newly designed mounting system.

Michael, I have flown mine but I think my original Reach RTK has problems. I have ordered the M+ and waiting on Emlid to ship it.

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Problems in what way?
From your image, I think a larger ground plane would you wonders !

I would like to know also what kind of problems you’re experiencing.

We made the first steps with the kit a few days ago. First, we tested how exactly we could determine a known geodesic point on the ground. We left the drone with the kit for 45 minutes at this point (open, flat terrain without obstacles). Setting: Kinematic, Fix Hold). The PPK showed a difference to to the well-known coordinates of 25cm X axis, 1.2m Y axis and 4m Z axis at 16km baseline to CORS Station OAX2. After 30 seconds Fix-Solution which never broke again (99.9% fix).
After that we also hit the same point for 45 min with a Reach RS and did the same PPK. This gave a deviation of 3cm X axis, 4cm Y axis and 5cm Z axis. We think that this huge divergence between Phantom Kit and Emlid Reach RS is due to the inclination of the Tallisman antenna on the Phantom. After that we wanted to make the first flight, but the battery was empty. 90 minutes of battery life is very little for field trials. So our first recommendation: Take two or three batteries with you. However, we still flew a mission without switching on the Emlid M + to observe the stability of the Phantom. Very calm and stable flight behavior at first glance. This week we will do a test flight with Photoshooting.
But we are not quite clear how we can integrate the time delay into the PPK (for the moving drone) with RTK-LIB
All in all, we find this a good installation and are confident to get fixed the above mentioned deviation.

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Great stuff. You might think about using a plumb bob or tripod and tribrach to spot the Tallysman then move the drone and spot the point. Just to make sure.

Also, check this out for the processing.

The angle of the Phantom in flight must be taken into consideration when determining the offset of the antenna to the camera sensor and it would change with different speeds and probably with winds of different strengths and from different angles. Probably “close” is all you will be able to get without inputting flight telemetry in real time into the equation.

Hopefully closer than 1-3m…

Definitely better than the stock positioning I would think unless the image capture timing is off which could actually make it worse. It will be fun to see what you get.

The top ground plane is angled to counter the tilt in forward flight. This will never be perfect but it is accounted for in Brian’s setup. My lipo went bad and my new batteries will be in tomorrow. Will get back to testing then :slight_smile:

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I ordered a 5 pack of the batteries here for $30

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Christian, you can see something went wrong here. Since my Lipo bats wont be in until tomorrow, going to set it out today and overserve for a while with a USB power supply to see what it looks like over a several hour period.

edit: reuploaded image with correct flight time markers.

I am going to put a cover over the antenna and see how that does as well.

The problem the angled ground plane is that you get multipath from below the horizon or even from a steeper angle from nearby ground, when/if the drone is at an aggressive attitude.

Sounds like I need to figure out the mean angle of attack and design an alternative mount. I already have a great prospect in our GPS parts, but it’s too big so I think I will start with a shorter mast and slightly larger base plate. I actually thought about this earlier this morning and I am assuming the Tallysman is so high is because of coordination with the blades? Like the DJI P4RTK bringing it down 6-inches would go a long way to mitigating this error.

It needs the distance because of interference from the Phantom. Bring it down lower, and you’ll see an increase of cycle slips. Also remember to isolate (Faraday style) the reach module.

Also, if you increase the ground plane, and bring it down lower, you’ll cover the GNNS reception of Phantom, and you’ll have bigger problems than just cycle slips :stuck_out_tongue:


Hmm, usually when I replace batteries or move the Phantom around, I have have tendency to lean in over it. Even the Phantoms build-in GNSS will then report loss of sats, and go into attimode for the duration.
Can that be your problem ?
As I see it, the Phantom needs to be left “alone” from start of log-collection over flight and all the way to end of flight/log collection end.

Once I receive my new Lipo batteries today and also when I get the M+, I can do some extensive comparison test to look for repeated issues and narrow down any problems (if any) that exist. So I wont’ post up any info until I actually have good info to post. I am certain that I will get this running very smooth and reliable :dart:

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Makes sense. Putting the data in CAD now so I can share a dimensioned plan of my setup.

Here we go. First the tilt data from DJI.
Max Tilt Angle S-mode:42° A-mode:35° P-mode:25°

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Ok, just did a test by setting up my base and P4P in my house so I know it will be garbage data, but hopefully I can use it to learn how to use RTKLIB. I’m going to search the forums, but do I need to run RTKPOST first or just RTKLIB? Here it goes…