GPS Services Group C&C Technologies, Inc., C-Nav GcGPS System Background and Accuracy.
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Transcript of GPS Services Group C&C Technologies, Inc., C-Nav GcGPS System Background and Accuracy.
![Page 1: GPS Services Group C&C Technologies, Inc., C-Nav GcGPS System Background and Accuracy.](https://reader036.fdocuments.in/reader036/viewer/2022062518/5697bf781a28abf838c81b1f/html5/thumbnails/1.jpg)
GPS Services GroupC&C Technologies, Inc.,
www.cctechnol.com/cnav
C-Nav GcGPS System Background and Accuracy
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Overview• What is C-Nav• Empirical accuracy measurements to
date.• Interesting issues• Hand off to Pete and John
– Interesting application to hydrography
– Latest developments in C-Nav
• Closing summary
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The RTG Family
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Why High Accuracy?
Stand alone GPS but…
• Ionosphere delay free
• Extended carrier smoothing
• Improved orbit and clock
correctors
• Troposphere delay modeling + estimation
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This Week’s Schedule
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Check Your Watch for Altitude!
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Vertical Error (?) Vs Earth Tide
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C-Nav AccuracyC-Nav GGA vs Zero Gravity Surveyed Position
95% Horizontal 95% Vertical
Static RTG 0.18 +/- 0.04 m 0.35 +/- 0.05 m
Static RTG Predicted tides
0.18 +/- 0.04 m 0.24 +/-0.04 m
Static RTG - Reference
0.18 +/- 0.04 m ~0.19 m
Dynamic RTG 0.13 +/- 0.7 m 0.25 +/- 0.05 m
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Tidal Datums
• Chart datum is based upon historic water levels
• Chart datum is irregular wrt geoids and ellipsoids.
• You can determine chart datum at a point with a tide gauge.
• To projected it away from the tide gauge requires knowledge of tides.
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Let the Experiment Begin!!
• Performed during NOAA hydrographic survey in Gulf of Mexico
• Used well surveyed cross-lines as ground truth
• Used verified tides to check ground truth• Collect C-Nav data on survey vessel and at
two monitoring stations• Analyze data
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RTG Vertical re Chart Datum
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Sea-Surface Height
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Vessel Receiver Noisy Probably Antenna Location
Lafayette Houston Vessel
Mean 0.308 0.280 0.402
SD 0.065 0.043 0.173
RMS 0.315 0.283 0.438
146%
GST Vertical Error Estimate
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Give it to Pete and John
• 0.2 m to 0.4 m vertical at 95% in preliminary test.
• ~0.3 meters vertical at 95% in tidal datum w/ blockage & 100nm baseline.
• Post processing required to deal with Earth tides.
• Squirrelly transformation into tidal datum.• Sensitivity to blockage and multipath