RS2 NTRIP Antenna Phase Center correction

Could it be that the Emlid RS2 is not able to handle antenna type corrections in real-time? I noticed this strange behaviour when changing to an EUREF station (which broadcasts ARP + antenne type), so I tested it with two different data streams from the exact same reference point. One is broadcasting the APC position with NULLANTENNA in RTCM message 1007/1008 and the other one broadcasts the ARP and includes the antenna type.

If I measure a point in Reachview, the resulting elevation in the base position differes by exactly the phase center offset of the used base antenna. Is the RS2 unable to use a lookup table in real-time apply the antenna corrections? I did the same test with Leica equipment (GS14) and obtained the correct position.

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Hi Sean,

Yes, it seems you got the point. Reach RS2 doesn’t use antenna type and expects antenna phase center height in 1006 message. Broadcasting GPPNULLANTENNA in 1008 messages is quite common. That’s why now it works this way. As a current workaround, you can just add this offset manually to the points’ heights or work in PPK with our Stop&Go feature.

Overall, we’d like to make Reach compatible with most NTRIP services, including EUREF. So now we need more data on this case. Could you share any examples? Raw logs and RTCM3 messages from the EUREF base would be of great help.

Hi Julia,

Thank you for the clarification. Apparently it is stated in the EUREF guideline to broadcast ARP + antenna type. See 3.3.7 and 3.3.9 in this document:

There might be quite a lot of people using this open network, so I think it is good to make it clear that the use of these reference station in combination with an Reach RS2 will result in an error in the elevation measurement.

I don’t have the RAW and RTCM3 messages of the station that I used. Those can also not be downloaded, so needs to be logged in real time. Via https://www.epncb.oma.be/ you can access the stations. The mount point I used was DLF100NLD0.

When using the Emlid Caster, is the NULLANTENNA method used? So the APC location is broadcasted?

Hi Sean,

Yes, you are right. We’ll think about the solution for EUREF users. Thank you for sharing the info! It will be quite useful in our research.

Emlid Caster is just a way of transmitting the corrections from your base to the rover via the Internet. So these requirements are related directly to the base station. For now, to work with Reach RS2 as a rover, your base station indeed should broadcast APC height in 1006 message.