1. GPS Services Group C&C Technologies, Inc., www.cctechnol.com/cnav C-Nav GcGPS System Background and Accuracy

2. 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

3. The RTG Family

4. Why High Accuracy? Stand alone GPS but… Ionosphere delay free Extended carrier smoothing Improved orbit and clock correctors Troposphere delay modeling + estimation

6. This Week’s Schedule

7. Check Your Watch for Altitude!

8. Vertical Error (?) Vs Earth Tide

9. C-Nav Accuracy C-Nav GGA vs Zero Gravity Surveyed Position 95% Horizontal95% Vertical Static RTG0.18 +/- 0.04 m0.35 +/- 0.05 m Static RTG Predicted tides 0.18 +/- 0.04 m0.24 +/-0.04 m Static RTG - Reference 0.18 +/- 0.04 m~0.19 m Dynamic RTG0.13 +/- 0.7 m0.25 +/- 0.05 m

10. 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.

11. 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

13. RTG Vertical re Chart Datum

14. Sea-Surface Height

15. Vessel Receiver Noisy Probably Antenna Location LafayetteHoustonVessel Mean0.3080.2800.402 SD0.0650.0430.173 RMS0.3150.2830.438 146% GST Vertical Error Estimate

16. 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