Reach RS+ Off By 300 meters

Hi all,
Been using Reach RS+ for a few days now with NTRIP corrections. It has been working perfectly (cm grade accuracy) for the last couple days. I logged some points on saturday but today when I try to come back to those points, the current gps location is 300 meters offset from the points. I know the points are accurate due to a current drone overlay. Is there some coordinate selection issue?

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off by 300m in only one direction?

No it was in 2 directions. When I tried to stakeout the recorded point it said i was directly over the area when in reality the point was 300 meters to the North East

I wonder if you had a bad fix. If one day they are correct and one day they are not, then maybe there was an issue with satellite reception during one of the point collection periods.

Do you have the log files from both times?
How is the sky view at those particular points?

Both points were in an open field (new construction). It was cloudy/rainy on both days. I don’t think I have log files from the first day but I did export a system report from today. Do you want the system report or the file from the log tab? (381.9 KB)

I’d be looking for the raw data files from the log tab. System report is not necessary for this I don’t think.

It could also be some issue with the NTRIP moving the base location (VRS) and Reach not getting that message. I’m not an NTRIP user, so maybe someone else could shed some light on that possibility.

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I will try to get a hold of our NTRIP provider. Thanks for your guidance.

Did you input the coordinates manually from the previous trip?

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No, I just went back into my saved project on the survey tab.

Brought the unit back to our yard and it is working perfectly. Probably a user error. :slight_smile:

Can you describe your NTRIP settings? VRS or single mount point as @bide suggests? Maybe you didn’t tick the NMEA GGA message if VRS.

It is a VRS system.

Did you even have a fix when off by 300 meters?

Yea, that’s why this is so strange to me. Was between 400 to 999.9.

Yes, we had one of those here last week and it cost me almost the whole weekend to undo.

Pesky users. You just can’t trust them. :slight_smile:

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How many points? Is it easier to start over?

The points aren’t a big deal. We are still getting used to/testing the device. Just have to be able to trust the gps location, especially when you are burying pipes and have to be able to come back and dig them up.

I would suggest a base and rover scenario. In our experience of static site surveying trying to rely on interpolations from CORS/VRS and even single point average derived corrections is never a comfortable process. While 300m is a huge variation and something else obviously happened, you really want to consider gathering a coordinate and entering that coordinate into the base for the remainder of the project if you expect precisely repeatable results. One second could be 30-40m.

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We have been discussing that option, and may very well go that route. It is just a lot easier not to set up a base station and move it around to our different job sites. My question on the base rover scenario is this… I understand that between the rover and the base you can achieve cm level accuracy, but if the base is not on a known location how long does it have to sit there and collect coordinates for it to achieve absolute cm accuracy. (Assuming clear sky view,full constellation of satellites, best conditions)