SC – VRS Network To Support Surveying and Machine Control

Presentation Overview Introduction VRS Network Design Antenna Mounting Designs Server Network Design Modeling Network Testing Network Integrity Practical Applications

South Carolina Geodetic Survey Marine Transportation Highway Construction Obstruction Charting Utilities Surveying Engineering Mapping Infrastructure

Motivating Force for a Network Application

Antenna Hardware Stainless Steel Mount For Masonry Buildings Self Supporting 24 Foot Tower Tamper-Proof Leveling Head

Server Network Design Should IT Be a Shareholder? 5 6 7

Modeling ??? I(λ,φ) = I 0 +a λ ∆λ + a φ ∆φ 1 cm -1 cm 2 – 12hr Multipath Plots Areal Variant Ionospheric Model The solution of Integer Ambiguity is influenced by external variables Atmosphere - Tropo, Ion Clock Error - SV and Receiver SV Orbit Error Multipath Separation of Base and Rover

SC - VRS Network Design VRS Is Not Built In a Day! There Are Many Stakeholders!! They Are ALL Critical To Your Success

Test Network 11 Counties, 6700 Sq Mi, 10 VRS Base Stations, 50 Control Pts

VRS Absolute Accuracy Comparison of VRS and NGS Height Mod Control Absolute Accuracy Meters Allowable 2-D RMSE r 95% = * RMSE r = (2.0* * *1.2) 1/2 = 2.4 cm* Allowable 1-D RMSE v 95% = *RMSE v = (2.0* * *2.4) 1/2 = 3.1 cm* Time (sec) Horizontal (cm) Vertical (cm) *(Local Accuracy 2 + Eccentricty 2 + System Design 2 ) 1/2

Station SCBY Vertical Axis to 0.014m

Poor Choice for a Base Station! Vertical Axis to 0.055m Diurnal E-W Motion of a 90 Foot Spun Concrete Tower

Centimeters Each Depicted Value Is A Mean Of Two 5-Minute Observations Spaced Approximately 21 or 27 Hours Apart 95% Less Than 2.5 CM From Published Value Results From Test Of The SC RTN to Determine Accurate Ellipsoid Heights

Practical Applications

Tidal Datum Transfer 2 mile transfer 0.05 ft uncertainty VRS Elevation (ft)Leveling (ft)Difference Mean/SDV0.001/0.008

Classical Leveling vs VRS 1 st Order Class 2 Leveling 4 Surveyors 4 days 5.5km – 6mm 1 Surveyor 4 hours 12mm comparison VRS Elevation (ft)Leveling (ft)Difference Mean/SDV0.002/0.025

Comparison of VRS to Total Station Relative Accuracy Grid BrgAngle RtGrd Dist TPT1SURVEY068/00/55 TPT1TPT2207/30/58220/29/ VRS 220/29/ Total Station 139/30/03Interior Angle TPT2TPT1027/30/58 TPT2TPT3198/49/59188/40/ VRS 188/40/ Total Station 171/19/01Interior Angle TPT3TPT2018/49/59 TPT3SURVEY038/08/33340/41/ VRS 340/41/ Total Station 019/18/34Interior Angle SURVEYTPT1248/00/ VRS Total Station SURVEYTPT3218/08/33029/52/22Interior Angle 029/52/ /00/00VRS 359/59/59.1Total Station

Ellipsoid Height Distortions of 3CM or Greater

Network vs OPUS – 10 Minute Sessions Separated by 27 Hours Mean Std Dev Pub-ObsPub-PredObs-Pred Predicted values are weighted* means of the Network-OPUS Differences *Weight Equals Ratio of Base Station Separation Multiplied by Assumed Error

Network Integrity 24-Hour Coordinate Spread 1 cm N & E 1.5 cm Ellipsoid Ht Semi-Major Axis ~ 1 cm

Concluding Remarks Number of Registered Users Maintenance Plan Replacement Plan Integrity Monitoring Cost Subscription Fee Questions?