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The Whitehall Forest GPS Test Site was developed in 2004. The positions of a set of nearby established survey monuments were determined using a survey-grade GPS receiver (Ashtech Locus GPS) according to protocols (static data, 4 hours of data collection, etc.) that would allow the positions to be considered and accepted by the National Spatial Reference System (NSRS). The positions of the monuments were processed using the U.S. Department of Commerce, National Oceanic and Atmospheric Administration's Online Positioning User Service (OPUS) (www.ngs.noaa.gov/OPUS). The positional precision of these monuments was less than 2 cm. The closed traverse network that represents the Whitehall Forest GPS Test Site corners was then established by registered surveyors using a Topcon GTS-211D instrument and the NSRS monuments as a base. The closure of the points within the Test Site (as represented by a closed traverse connecting the points) was estimated to be 1/92,137. Given this, we consider the GPS Test Site to be a highly accurate model around which GPS equipment could be tested in forested conditions.

Surveyed points have a brass survey cap that is flush with the ground, connected to a 2-foot piece of rebar, and surrounded by about 6 inches of cement (2 feet deep).

1. Ten points are in an older pine forest; trees are approximately 70 years old.

2. One point is in a young pine forest; trees are approximately 20 years old.

3. Twenty-six points are in an older hardwood forest; trees are approximately 70 years old.

RECENT NEWS:

07.28.17 : All survey monuments, and the poles and posts that identify them, have been checked.


05.19.17 : Static accuracy of mapping-grade receiver published in the journal MCFNS
This study assessed the effects of thinning on positions determined at the same place, on the same sidereal day. It further illustrates the effects of individual trees on positions determined.


04.29.15 : Static accuracy of mapping-grade receiver published in the journal PLOS ONE
This study assessed the holding position of a mapping-grade GPS receiver when data was being collected. We found weak to moderate evidence that the holding position can be significant with respect to static horizontal positional accuracy.



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