ReachView RS+ and Phantom 4 RTK

Two days ago I tried to use the University Reach RS+ as NTRIP base using the Emlid caster in order to fly with a Phantom 4 RTK UAV (P4RTK).
I successfully created the caster and configured the P4RTK to receive the corrections.

The process was smooth and the drone logged into the NTRIP service but the solution stayed as SINGLE.

Anyone has tried the same? (Reach RS+ and P4RTK)
Could it be that the P4RTK, that has a double freq. receiver, doesn’t recognise corrections from the Reach RS+ single freq. ?

I think it has more of something to do with the format that the corrections are coming in, but also it could be that since it was limited to L1 that the P4RTK wasn’t maintaining enough satellites to stay fixed. This is a common problem trying to use this drone with 3rd party GNSS hardware. Have you thought about doing PPK? If you are trying to produce true survey grade results you should. Even the kit as sold by DJI with the native receiver has been proven to fall into float conditions at times and unless you use some GCPs you are not getting the 2-3cm relative accuracy that is advertised and you are definitely not getting absolute accuracy.


I think the P4 RTK expects Multi-frq when working with NTRIP.

For post-processing, an L1 base would probably work fine.

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Hi Micheal,
thanks for your feedback.

The issue is that in the P4RTK rtk screen there were no base satellites, so yes it seems that using Reach RS+ as NTRIP caster I am missing some messages that are required by the L1/L2 receiver onboard the P4RTK.
On the other hand I used the same caster with a second Reach RS+ and I worked nicely.
My hope was to find someone that already faced this issue…

PPK: I did have good results using VRINX created by my local provider.
On the other hand, I didn’t obtained good fixes (only float solutions) using a Reach RS+ as base (but I thought it was due to wrong settings in RTKlib, I read a thread on this regard here in the forum).

Do you know what version of RTKLIB you were using. I have had to use two different version depending on whether I am using my RS+ kit or the RS2. I have had the best luck with b28 on RS+ and b33 on RS2.

That was my idea, that is fed by the fact that I found a tutorial for using RS2 as NTRIP base for P4RTK and not using Reach RS+

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Hello Micheal,
yes you are right.

I forgot that (almost an year ago) I found “my” way to process P4RTK .obs data using a Reach RS / Reach RS+ as base station (kinematic solutions).
After several attempts I got good results using Rtklib "demo5b33b2":
it is a branch customized for improved performance with low-cost single frequency and dual frequency receivers.
So it seems to be tailored for my needs!

Kudos for rtkexplorer!

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Hi Marco,

We indeed haven’t tested Reach RS+ as a base for DJI Phantom 4 RTK. However, I agree that the Phantom most likely requires multi-band corrections.

This is because Phantom shows the base’s satellites number only if the RTK solution status is fix.