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Vertical Error with Conventional Total Station

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(@surveyor1985)
Posts: 16
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Topic starter
 

I have been using trimble robotics for the past 10 years where you can close out traverses with very little error. I recently started my own buisness and could not afford the 30k price tag that comes with robots these days so I purchased a Nikon N 5" conventional gun which is the new version of the NPL 322. Horizontal error is pretty small but I have noticed that I usually have a decent amount of vertical error after setting a traverse point and setting up on it/backsighting the point that I set it from. Usually 5 hundredths at 300' and sometimes 8 hundredths at around 600'. Ive used conventional total stations early in my career but do not remember how good the vertical was. Is this common or is there something going on with my gun? My rod height and instrument height are always correct and I am running survey pro. Maybe there is some kind of collumation that could be done? Thanks for your input.

 
Posted : January 25, 2021 7:58 pm
(@dave-lindell)
Posts: 1684
Supporter
 

There's a built-in feature for adjusting the vertical on my Nikon DTM-520.?ÿ Easy peasy.

I used it every day for 71 remeasures of a traverse used to detect movement.?ÿ I picked a sight on the horizon about 10 miles away and measured the vertical angle face-right and face-left and let the instrument do the adjustment per the prompting.

 
Posted : January 25, 2021 8:15 pm
(@surveyor1985)
Posts: 16
Member
Topic starter
 

@dave-lindell Does this usually tighten up the vertical? I read up on it in the manual and will give it a shot. Thanks for the info

 
Posted : January 26, 2021 6:38 am
 jph
(@jph)
Posts: 2332
Member
 

@surveyor1985

It usually fixes the vertical issues, unless you have something broken on your instrument.?ÿ If you sight something in direct mode, and then flop and sight it, how do the vertical angles compare?

That said, depending what you're doing, 0.05-0.08' may not be that big of an issue.?ÿ If it's boundary, or woods or suburban topo, it's nothing.?ÿ If it's in the city or utility work, yeah, you want that tightened up.

 
Posted : January 26, 2021 7:18 am
(@paul-in-pa)
Posts: 6044
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Most definitely have to do F & R (foresight and backsight) to carry good elevations on a traverse. When doing that I have often had traverses that closed vertically better than horizontally and I never measured vertical to better than the nearest 0.01' using a 5" gun.?ÿ

Paul in PA

 
Posted : January 26, 2021 7:42 am

(@surveyor1985)
Posts: 16
Member
Topic starter
 

Thanks guys. I will do the adjustment and let yall know how it turns out?ÿ

 
Posted : January 26, 2021 8:32 am
(@dmyhill)
Posts: 3082
Supporter
 

If the vertical is adjusted and the tilt is adjusted, then I would expect very good results. In any case, if you need better than 0.05' at 500', I would consider an F&R observation (of each point) to be best practice for a 5" instrument.

 
Posted : January 26, 2021 10:33 am
(@david-kendall)
Posts: 129
Member
 

Try to turn double or triple angles on the important shots.?ÿ I recently checked a 500 foot shot with RTK for novelty purposes and had 0.05' vertical slop at 500' which I was pretty happy with.?ÿ I typically measure two forward angles and two reverse angles for control and I expect more error on small vertical angles

 
Posted : January 26, 2021 11:32 am