In this neck of the woods we have a solid, state run system provided through the NCGS.?ÿ
However, ive observed the system drifting In the horizontal, typically in the north or the east. No real predictability; however, only happens on the order of days, not minutes or hours. Probably more of a shift than a drift. On the order of 1 tenth either east or north. And, on another unpredictable day, it will "return" to the previous location.
For what it's worth, a trusted colleague agrees with this observation.?ÿ
My question: can i use a base "translation" in survce, while using vrs, to constrain this shift?
the hope being, with good procedure and initial checks against a prior days control, a translation would hold state plane results consistent at the existing control and keep any given shift from skewing additional points with regard to 'non shift' points. All while keeping me in state plane ?ÿ
If that idea passes muster, would you please share a proper procedure for this in survce 5.x (or higher)? If not, i'd like to hear your thoughts. ?ÿ
BTW: I found a Mark Silver video for base translation; however, he is running base> rover not vrs.
Thanks for any input! May the survey gods smile on all your look points and, although Math isn't the definitive survey answer, when good math and good surveying intersect, generational differences slip away and field life is good!
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It's probably not any drift in the system. And remember that VRS?ÿis?ÿRTK or more appropriately called nRTK or network RTK. Satellites are in different geometric positions where your accuracy will vary through the day, everyday.?ÿ Higher PDOP is a result of satellite geometry and if satellites are very near each other that's about the same as having 1 less satellites because those 2 satellites are not well spaced apart. Remember that the further you are away from your RTK base (this includes the VRS/nRTK base that's being used) the greater variability you'll have in your RTK positions. To reduce uncertainties in RTK, use a local base station instead of VRS/nRTK.
Thanks, Robert. Understanding that vrs is rtk, I have my pdop settings pretty tight at 2.0, with other statistical safeguards being clamped pretty tight. Aside: I am a proponent of base> rover when surveying for rpp.
For when I'm using VRS (deeming it appropriate for the current task): What I'm looking to do is constrain drift (or shift) in the vrs solutions by 'calibrating' subsequent vrs sessions to initially established control. Other than temporal variations in satellite geometry creating shifts during a given session (isloated by regular checks to established control and, perhaps, re-calibration), I think a tighter result would result.
Being the empirical type, I will experiment. Guess I was figuring someone out there was already doing it. Or, had tried and decided it wasn't fruitful.
Have a good one,
ps> just stumbled onto:
