Current Static GPS Equipment Standards and Capability

[LincolnPE]

I wanted to check in with the experts on the current state of static GPS equipment and technology. Is it possible to achieve standard deviation errors of position at 0.254mm horizontal and vertical accuracy for structural deformation monitoring with any of today's equipment? How about 1mm?

If it is possible, how long would the equipment typically be required to occupy a station to achieve 0.254mm accuracy, and then how long for 1mm accuracy? Four to six reference monuments would be used per USACE guidelines.

Any reference to capable equipment and white papers would be appreciated.

 

[IRstuff]

That's probably optimistic:

http://trl.trimble.com/docushare/dsweb/Get/Document-611507

more like 1 cm, and that's with close to ideal conditions for GPS only


A total station would get you to the low mm's:

http://construction.trimble.com/sit...22482-1867_Trimble_SPSx30_UTS_DS_0611_sec.pdf

Anything better than that, you'd probably have to roll your own, but it looks like what you really need is high repeatability, so something like:

https://www.sick.com/de/en/distance...istance-sensors/dme5000/dme5000-123/p/p204095

or this:

http://www.fuentek.com/technologies/Distance-Measurement-System.php

Much depends on absolute distance; the shorter the more likely to get the repeatability that you want.

Isn't this normally done with strain sensors?


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[LincolnPE]

This is for use in the civil world for the monitoring of structure movement. This is typically done by surveyors with levels.

 

[IRstuff]

I got that; I was trying to get some scale. Are we talking meters or km? It's possible that a total station with a decent distance measurement could do a boatload of averaging and get down into the single digits of millimeters of repeatability. I would assume that you don't necessarily need absolute accuracy, but rather, you need repeatability in that you're looking for changes relative to your monuments. Note that when you are looking at mm, even your alignment to a monument is a task all by itself.

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[LincolnPE]

Thanks, my question is only about the latest state of the art for static (not RTK) GPS accuracy technology . I'm getting ready to interview surveyors for the project, and looking for some current background information based on true non-vendor experience with the latest static GPS technology.

 

[IRstuff]

Not sure that anyone does standalone GPS; the accuracy isn't there. They likely do differential GPS, which gets them down to the cm level

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