Very true - it's really just making sure that if one of those twenty occurs, we can catch it before the crews are completely done with the project, so they can go reobserve.
For us it's the right balance between overkilling observations (reducing efficiency) and having to return to the site after the field work was officially wrapped up. A decent trade-off for in-town work. For high-stakes or out-of-town work, we will repeat observations four times throughout the day, and that has always yielded quality results.
95% sounds pretty good, until you restate it as "1 in 20 of our measurements are out of spec"
Sounds like somebody has a case of the Mondays....
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The bionicman alluded to my point. It's possible to get completely different geometry by subtracting satellites then reactivating them. You can turn on odd ones then even ones. This can be a bit time consuming but if you are concerned with geometry it does that.?ÿ
Even a quicker, easier thing to do, is up the elevation mask for the first shot then lower it for the second. This of course blocks anything lower than the mask and again creates a different geometry. The point of the different geometry was to wait long enough that the satellites move, but with so many up simply change the geometry without waiting.?ÿ
Frankly, I don't worry about it anymore, there are so many satellites up the geometry becomes the least issue.
I'm not saying the geometry issue isn't a real thing, just that it's possible to negate it as you stand at the point; first principle thinking. And you can change the geometry far more than the 20 minutes will accomplish.
A long or longish hike/drive to a point or points means I'm not going back. I will spend extra time to get satisfied my point is good, but I'm not spending 20 minutes waiting, nor am I going back for a second shot if it takes 20 minutes or more to access the point.?ÿ?ÿ
If we are doing a subdivision it's best to set the points, then return as you drive or walk back and check them, but much of my work is not that type of work.?ÿ
RTK is CM accuracy, so it??s working as best it can. And the length of an RTK observation is not to be looked at as one length because of length. With RTK, you are observing a position offset from the base position, I.e. +0.75X, -3000.96Y, -1.75Z. Once your precision values stop getting lower, there??s little use to keep observing. Store it.
@mightymoe that greatly depends on how many constellations you are observing, your obstructions, and what type of feature you are locating. ?ÿIf you ever do a point derivation report in TBC of a multiple observation of one point name, sometimes your first observation is the least accurate in its calculation!
I never used a bipod or steady sticks.?ÿ I always figured if the machine was going to average the measurements then I might as take out the systematic error of a slightly bent rod or bubble error out by loosely holding the rod and letting it float around the center of the bubble and rotating rod as counting down the seconds.?ÿ Seemed to work for me.?ÿ Jp
I level my rods on a fairly frequent basis. They are never out very much. I guess I thought if they were out rotating them would cancel out any error. But I see your point. If the rods are in pretty good shape the the amount of correction would be smaller than the accuracy of RTK. Thank you for pointing that out.?ÿ
I still rotate the rod 180 when taking critical shots, but it is less for potential error in the rod and more for potential sighting error of the bubble.?ÿ