Post Processed Data does not match


I’ve found an interesting discrepancy between the reach data and the post-processed data and I’m wondering if there’s a particular reason for it.

Basically, I’m comparing the post-processed data to the recorded data from the rover, and I’m not seeing them match up very well at all. I made to sure match the parameters between the RTKPost application and the rover settings as closely as possible, but still both tracks don’t really appear to match. I also didn’t have a good fix on any of this data, which is why there’s huge drift for a non-moving rover.

Post Processed:

From Reach:

Could you send you logs, please?

I would love to provide you with them but the forum won’t allow me to upload attachments. Is there another way I can get you the files?

could you use dropbox, google disk or onedrive and post link to file here ?


That works. Here’s a link to the file on dropbox:

The zip contains the raw data (ref and rov files) along with the post-processed path (.pos) and the reach processed path (.llh)


You have some funky values going on here. Are you sure you have your setup correct?, no multipath and interference of some kind? And any minor adjusments displays different plot.
I would try record a better log with better visible satellites.
Do you have a pictures of your setup?
Also use latest RTKlib 2.4.3 b26

Edit: removed one picture, it was wrong

Hmm… That’s just not what I’d expect, minor adjustments shouldn’t radically change a gps plot like that. Regardless they should match the reach’s solution. I’m glad at least it’s not just me seeing that with the data. I can try to record better data but that wasn’t a particularly bad capture. I’m fairly certain I had a large selection of satellites visible with good signal power. I shall try something on the weekend.

I don’t have any good pictures of that location. I was moving around campus attempting to find a good area. There were better results elsewhere. Here’s a picture of my base and rover:

We purchased TW3740 antennas in an attempt to improve our results.

Did you have a minimum 10x10cm groundplate under your units?
Tinfolie will do.
By units i mean the antenna

The datasheets don’t recommend one. I’ll have a chat with Tallysman and see what they recommend. I was under the impression these new antennas don’t require one.

Haha, yes.

Its worth a shot

I talked to Tallysman about it, they mentioned that it’s not necessary, but it would be beneficial. I made some reflectors up and will hopefully do a couple more tests in a couple days.