Difference between NMEA and POS files

I’ve been using RTKNavi to process two CORS stations (26Km apart) and noticed a difference between the logged RTK NMEA output from RTKNavi and the POS file from RTKpost using the converted RCTM files from logged output of RTKnavi

I load the NMEA into RTKPlot and the centre of the cluster is one location and load the POS file and get a different centre location. If I load both at the same time (Solution 1 and 2) they overlap.
What I’m doing wrong or incorrectly interpreting ?

What it appears to be, is a discrepancy between the cursor? position (bottom right) and the log position (lower left) for the same place on the screen with the POS file - they read the same with the NMEA file

(This version 2.4.3 b31 of RTKplot)

I think it’s a bug in that version, watch out with versions of RTKlib giving different results !

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What filter did you use? Forward/Backward/Combined?

Maybe try version b33 from their support site?
https://docs.emlid.com/reachrs2/common/tutorials/gps-post-processing/

You could try going backwards to b28 as well…

I used the combined filter, but version 2.4.3 demo5 b26 seems to give the results I would expect.

It seems with some many different versions of RTKlib most with minor bugs and varying results.

I will try your suggested links as well - thank you.

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One odd thing I have noticed is when I load a POS file into version b33 waypoints show in the wrong place on RTKplot

In version 2.4.3 demo5 b26 the waypoint is in the correct expected place with the exactly the same files loaded. It seems every version of the RTKlib suite has it’s own errors.

Hi @myozone,

Thanks for noticing this!

May I ask you to share your logs? You can send it on support@emlid.com, if it contains some sensitive information.

We should try to reproduce this behavior and fix it. I’ll keep you posted on the results.

Hi David,

Just want to let you know that we’ve reproduced these issues. We’re going to fix it in the next RTKLib versions.

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