ESP-XBee on a Topcon AGI-3. Message issues

I realise this isn’t exactly AOG based but it is derived from my AOG project.

I have made a small board to send correction signals to a Topcon AGI-3 with an ESP32-XBee running as a client. I’ve tested it tonight and it works fine. RTK fix no problem.

I have two questions. What messages will work with the AGI-3? I was under the impression only 1004 and 1012 would work for satellite data and these are the messages I have RTKLIB producing. However I seem to have an issue with my glonass (1012) messages. Basically all I have on 1012 is SNR’s and L2 pseudorange. As a result I only seem to be getting GPS satellite corrections. I think!

We tried the Topcon on an euref station that I have access to that doesn’t send 1004 and 1012’s. It got an RTK fix with more satellites but slightly less accuracy (it is a lot further away). It sends messages 1006,1019,1020,1033,1075,1085,1095,1125,1230 and 4049.

Mine is sending 1004,1005,1008 and 1012 on the mount point I’m using for the Topcon.

Hope this makes sense and someone can point me in the direction of further information.

Why don’t you set RTKLib also produce the 1075-1125 with 1006?
1019 → 1033 is only for VRS networks like Euref.

Off topic but very interesting to see that the AGI-3 receiver worked with MSM-messages. Quite some time ago MSM-support was discussed at the, someone tested the AGI-4 (also a dual constellation receiver) with MSM messages and it did not work.

Perhaps there has been a SW update or something if now even AGI-3 accepts MSM messages. I should some day try my AGI-4 with the F9P as a base as I don’t have any other MSM source to test. My own base provides older RTCM3 messages only.

Yes, I’d read MSM messages wouldn’t work too. I only tested the Daresbury euref station out of interest and was surprised it worked!! I see there is mention of a bug in some versions of RTKLIB affecting 1009 to 1012 messages.

Hopefully I’ll try the AGI-3 (not mine) later today with different messages. I’m sure it has been updated very recently.

Board I cobbled together to connect to the AGI-3.


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Ok we now have the AGI-3 running on just a 1005 and 1077. It ignores a 1087. It’s showing a 5mm accuracy and a steady 10 satellites.

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…to add to that, I’m not sure why the 1087 doesn’t work. We have glonass enabled on the AGI-3. I need to try to get RTKLIB to produce the 1012’s properly and see if that works.