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Transcript of GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site...
![Page 1: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/1.jpg)
GPS Accuracy TestingGPS Accuracy Testing
Using:Using:““RTK” (Real Time Kinematic)RTK” (Real Time Kinematic)
&&““One Step Transformations” (Site One Step Transformations” (Site
Calibrations)Calibrations)
![Page 2: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/2.jpg)
GPS Accuracy TestingGPS Accuracy Testing
• Procedure
• Results
• Summary and conclusions
![Page 3: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/3.jpg)
ProcedureProcedure
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•Found a suitable test site
•Established “True” positions
![Page 5: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/5.jpg)
NGS 1st Order Vertical Control
10+ Miles
![Page 6: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/6.jpg)
NGS Cooperative
Base Network Control Station
For Horiz.
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Measured 3 to 4 points in each area using Rapid Static
![Page 8: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/8.jpg)
•Set points at 1\2 Mi. increments
•Used new control
•Tied with Rapid Static
![Page 9: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/9.jpg)
•Transformed to North Zone
•Calculated one combined scale
factor
•Converted all to LDP
![Page 10: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/10.jpg)
•Ran Digital Levels
•“True” positions established
![Page 11: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/11.jpg)
•Collected RTK data to compare against “true”
positions
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•Set Base at north end
•3 to 4 Transformation points in each area
•All the rest measured as topo
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Repeated with base at the south end
![Page 14: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/14.jpg)
Used:
•RTK WGS 84 data collected with base
at north end
•LDP coordinates from rapid static
Created the following
transformations:
![Page 15: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/15.jpg)
3/4 Mile Square
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3/4 x 6 Mile
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3/4 x 10 1/2 Mile
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Used data from base at south
end
3/4 Mile Square
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3/4 x 5 Mile
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3/4 x 10 1/2 Mile
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After comparison decided to test East-
West
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Established “True” positions in an East-
West orientation
Used Rapid Static GPS only for x, y, & z
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Used primary control
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4 Transformation
points in 3 areas Points at 1\2 Mi.
increments using Rapid
Static
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Converted to LDP
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RTK with base at West end
Measured topo and
transformation points
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Repeated with RTK base at
east end
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Transformation at West end
1 Mile Square
Same pattern of transformations
as the North-South course
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1 x 5 Mile
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1 x 11 1/2 Mile
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Transformation at East end
1 Mile Square
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1 by 6 Mile Square
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1 by 11 1/2 Mile Square
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Each set of data was converted with 3 transformations
Then compared to “True” Values
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ResultsResults
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3/4 Mile Transformation
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
0 2 4 6 8 10
Distance From North Base in Miles
Err
or
in F
ee
t
EAST
NORTH
ELEV
Poly.(NORTH)
Poly.(EAST)
Poly.(ELEV)
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5 Mile Transformation
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
0 2 4 6 8 10
Distance From North Base in Miles
Err
or
in F
eet
EAST
NORTH
ELEV
Poly.(NORTH)
Poly.(EAST)
Poly.(ELEV)
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10 Mile Transformation
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
0 2 4 6 8 10
Distance From North Base in Miles
Err
or
in F
ee
t
EAST
NORTH
ELEV
Poly.(NORTH)
Poly.(EAST)
Poly.(ELEV)
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1 Mile Transformation
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
0 2 4 6 8 10
Distance From West Base in Miles
Err
or
in F
ee
t
EAST
NORTH
ELEV
Poly.(NORTH)
Poly.(EAST)
Poly.(ELEV)
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5 Mile Transformation
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
0 2 4 6 8 10
Distance From West Base in Miles
Err
or
in F
ee
t
EAST
NORTH
ELEV
Poly.(NORTH)
Poly.(EAST)
Poly.(ELEV)
![Page 41: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/41.jpg)
11 Mile Transformation
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
0 2 4 6 8 10
Distance From West Base in Miles
Err
or
in F
ee
t
EAST
NORTH
ELEV
Poly.(NORTH)
Poly.(EAST)
Poly.(ELEV)
![Page 42: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/42.jpg)
Summary & ConclusionsSummary & Conclusions
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Goal was to answer the Goal was to answer the following:following:
• Verify the accuracy of RTK.
• Can hard surfaces be collected with enough accuracy to pass confidence point standards?
• Can confidence points be collected with GPS single observation?
![Page 44: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/44.jpg)
Goal was to answer the Goal was to answer the following:following:
• How are elevations affected as you go outside of a transformation (site calibration) set?
• How is accuracy affected by distance from the base?
• What is the break point?
![Page 45: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/45.jpg)
What is the accuracy of RTK?What is the accuracy of RTK?
Horizontal =10mm (0.033 ft.) + 1 ppm
Vertical =20mm (0.066 ft.) + 1 ppm.
Recommends One Step Transformations less than 6 mi. sq.
• Leica states that 99.9% System 1200
![Page 46: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/46.jpg)
What is the accuracy of RTK?What is the accuracy of RTK?
• One ppm for 6 mi. = 0.032 ft.
• Plus 0.066 ft. vertical spec.
• Equals 0.098 ft.
• 99.9% should equal or be less than 0.10 ft.
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What is the accuracy of RTK?What is the accuracy of RTK?
• 180 measurements & many transformations
• When: Inside transformation 0 to 3 mi. to base GDOP less than 6 VDOP less than 4
• All less than 0.10 ft.
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What is the accuracy of RTK?What is the accuracy of RTK?
• When:
Inside transformation 3 to 6 mi. to base GDOP less than 6 VDOP less than 4
• 4 out 0.10 ft. in height
![Page 49: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/49.jpg)
What is the accuracy of RTK?What is the accuracy of RTK?
• Measurements exceeding 0.10 ft.
Vertical Error in ft. Miles From Base0.13 3.00.11 5.20.14 5.70.11 5.8
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What is the accuracy of RTK?What is the accuracy of RTK?
• There will be some “Fliers”.
• Good conditions at test site.
![Page 51: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/51.jpg)
Can hard surfaces be collected Can hard surfaces be collected with enough accuracy to pass with enough accuracy to pass confidence point standards?confidence point standards?
• Yes
• Be aware of the pitfalls
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Can confidence points be Can confidence points be collected with GPS single collected with GPS single
observation?observation?
• Yes
• Single GPS observation O.K. for topo
• Single GPS observation O.K. for confidence points
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How are elevations affected as How are elevations affected as you go outside of a you go outside of a transformation set?transformation set?
• Elevations and Northings adversely affected
• Eastings to a lesser degree
• Affect not always immediate
![Page 54: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/54.jpg)
How is accuracy affected by How is accuracy affected by distance from the base?distance from the base?
• Not as well defined
• Inconsistent beyond 5 to 6 mi.
![Page 55: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/55.jpg)
What is the break point?What is the break point?
• 5 to 6 miles from base
• GDOP over 6
• VDOP over 4
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What is the break point?What is the break point?
• This testing indicates 98% better than 0.10 ft. at 0 to 6 miles
• 0 to 5 miles from base 99.5%
• 0 to 3 miles 100%
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ConclusionConclusion
The following conclusions are based on the
test results:
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ConclusionConclusion
• Ok for Confidence Points and Hard Surfaces
• Distance from base and outside transformation degrades accuracy.
• Expect “Fliers”
![Page 59: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/59.jpg)
ConclusionConclusion
• GDOP over 6 or VDOP over 4 will generate poor results.
• Keep One Step transformation size to 6 miles square or less.
![Page 60: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/60.jpg)
ConclusionConclusion
• Stay close to the base, the closer the better within reason, no farther than 3 miles if possible.
• Stay within the transformation boundary as close as possible.
![Page 61: GPS Accuracy Testing Using: “RTK” (Real Time Kinematic) & “One Step Transformations” (Site Calibrations)](https://reader035.fdocuments.in/reader035/viewer/2022062314/56649d9c5503460f94a84b04/html5/thumbnails/61.jpg)
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Any Questions?
We’re all ears