1. Does a Bear GPS in the Woods?
Evaluating the use of surveying-grade GPS in challenging terrain
Jason Flagg
Syracuse University

2. Motivation
Test effectiveness of survey-quality GPS equipment in challenging terrain
Establish important positions at HBEF for GIS
Establish control points for future surveys (existing USGS benchmarks)

3. Equipment Info Six Trimble 5700 series receivers
Simultaneous measurement at base and rovers
“Post-processing” of data produces network of baselines connecting points

4. Accuracy Known point in Lincoln measured from Plymouth as if unknown
Northing (m)
Easting (m)
Measured
Published
Diff.
0.016 m
Error
1 in 1,942,000

5. Precision Under Good Conditions
Marker at HB headquarters measured from both Lincoln and Plymouth
Northing (m)
Easting (m)
Lincoln
Plymouth
Diff.
0.020 m
Precision
1 in 940,000

6. Precision Under Adverse Conditions
USGS benchmark along Hubbard Brook Rd. measured three separate times
Base setup at:
Northing (m)
Easting (m)
Elevation (m)
Lincoln (5/15)
HBHQ (5/15)
HBHQ (5/17)
St. Dev. (m)
0.007
0.006
0.062

7. Precision Under Adverse Conditions
Precision also measured by “loop closure”
Three legs of a triangle measured independently
Closure error for this triangle was – m over total distance of 11,500 m

8. Other Measurements Freeze Plots Weirs Rain Gages “Wedge” Plots
Watersheds 1 & 6 Boundaries
Open to more suggestions

9. Special Thanks To:
Chris Johnson
Nate Jones