Real World Accuracy Issues


I’m based in the UK and work in construction. I wanted to be able to accurately set-out coordinated points, e.g. foundations, building lines etc.

The Reach system seemed ideal.

I bought two units, one acting as a base setup manually on a known coordinate (a station from a professional topographical survey). The other a rover.

The base station gets around 20-24 satellites GPS and GLONASS. The rover the same.

This is real world, so some buildings/trees in the vicinity - but in the scheme of things a fairly open site with good view of the sky.

So, at the moment I’m testing accuracy to see whether the system is fit for my purpose.

Unfortunately the best we can achieve is circa 1-1.5m discrepancy against known points from the topographical survey. Better than the GPS on my phone, but not good enough.

I’ve read a lot on this forum about AR validation being key. Albeit it seems there isn’t any easy answer to achieving the required AR value. The highest I’ve ever seen this number is 2.3. Typically it is around 1.2. This is with the rover between 2m and 30m away from base.

The base is outputting correction signals via LORA to the rover, which it receives loud and clear.

So, that is the situation, my question to the community is:

Am I missing something or is Reach not capable of cm/mm accuracy in the real world?

Appreciate your help.

Hello Peter,

I would say that the whole thing requires a bit of understanding what bad conditions really mean for an RTK system. I would start with investigating the link quality. Try to reduce the RTCM3 messages and rates. Then - check rover’s correction input, to see if the messages come in with the frequency you set up. That might just be the problem.

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