GS15 vs. GS18 for Better GNSS Accuracy?

[@Helpimnoob]

Interesting to see. As a surveyor who recently upgraded from GS14 to GS18T it's been so incredible to see the difference in hardware. One of the big differences of course being that the GS14 doesn't have tilt and can only use GPS and Glonass. The difference has really been night and day. Though I have to say I'm not sure about the reliability of the tilt system. I do seem to get quite a lot more accuracy when I turn it off and just use the pole level. But for less needed accuracy I'm all for it.

[@gmeinero]

Looking quickly at the height column from the "GS18 old" test, there doesn't seem to be a normal or Gaussian distribution in the differences, which could indicate a systematic error. Maybe points 105 and 103 have some kind of mistake? In the "GS15" test, the distribution seems normal, although the difference at point 103 is too high compared to the others. With the "GS15 new" test, there seems to be a normal distribution, but there might also be a problem with point 105. Either way, a 6 cm average difference seems too much for these instruments and the type of test performed.

[@LhounJaaf]

Hello Rami First of all, I would like to thank you for the content and education you provide to surveyors. My question is did you use geoid height or ellipsoidal height in this example

[@RamiTamimi]

@@LhounJaaf we used Orthometric height which is Ellipsoid height minus Geoid height.

[@Panther-]

Hi Rami am based in the uk and work as a contruction manager.Am trying to get into work as a setting out engineer would your course be good to help with that.Luckily I have access to a gs18 and a ts16 and ts12 where I practice with an engineer every weekend.Do you teach using these machines in your course thank u

[@Jaceace87]

I’ve been thinking about joining your skool but I don’t wanna go to college to become a licensed surveyor I just want make really accurate 4d mappings for my CONSTRUCTION clients and investors. Should I enroll anyway, even though I’m not in college and if so, why thank you big fan of the channel

[@RamiTamimi]

The Survey School would be perfect for you!

[@Jaceace87]

@@RamiTamimi I’m in

[@bokkenka]

Might have been nice to put the bipod on the 18 to compare to the 15.

[@RamiTamimi]

@@bokkenka no need, the GS18 has a built in IMU which means it corrects the tilt of the pole.

[@bokkenka]

@@RamiTamimi I was just thinking of a slight jiggle holding it by hand. The totalstation's on a tripod. It's target is on a bipod. That stability on the 18 might have gotten even better accuracy.

[@johnleonard2202]

​@@bokkenka it becomes a propagation of error issue. The channel The Third Dimension has a lot of great videos around this idea, and I am slowly learning myself. By introducing the potential error from the GS18 tilt compensation, we aren't comparing just the receivers to each other. It's not an apples to apples comparison. No matter how good the IMU is, tilt compensation won't be the most accurate GNSS survey method, and should only be used where accuracy isn't critical. For tests like this, I'd like to see a run using the tilt compensation, and then a separate run without it and using the bipod etc. That way we can get a real world 'lazy' accuracy, and a best-case accuracy as well.

[@markmayer5788]

@@RamiTamimi The IMU is awesome, but not perfect. It is its own source of error. An interesting test - you might have done this already - would be to compare "plumbed up" accuracy with "tilted" accuracy.