1. Real Time Network Activities at The National Geodetic Survey Neil D. Weston National Geodetic Survey, NOS, NOAA Silver Spring, Maryland -- 31 January, 2013

2. Background NGS Real Time Network (prototype only) 21 CORS Streaming near-real time observables Stream Delays – 0.005 to 2.000 s Uses NTRIP Caster to provide access 15 GPS + GLONASS sites; 6 GPS only sites Data format – RTCM 3.0, update to RTCM 3.1 in future Data rate – 1 second Data – L1 and L2 code and carrier observables, station ARP information and coordinates

3. RTN Stream Access 150+ users registered at NGS 30 occasional users Users typically access one stream Usage is very limited ** FAA, DGPS, NDGP CORS sites do not provide RTN streams

4. Geometric Spacing Sites are widely spaced No possible error modeling for the following: Ionosphere Troposphere Real Time Orbits No plans to add/include sites for additional coverage

5. RTN Applications Surveying / Engineering Machine guidance Precision Agriculture Mining GIS Scientific / Academic Monitoring services Others

6. RTN Considerations Precision / Accuracy Reliability Availability Required Procedures Interoperability of RTNs Formats – streams Applications

7. Additional Coverage would aid some federal agencies and help support public and private RTN Tie to the National Spatial Reference System (NSRS) RTN Expansion by NGS - Pros

8. RTN Expansion by NGS - Cons Competition – Feds will not compete with private sector Expensive to maintain network Possible bandwidth issues at NGS (Caster site) Communications costs for NGS Administrative costs increase as you add sites Each site provides limited coverage (25 – 75 km) GPS only network Very limited network coverage Prototype project only

9. Alternatives for Users Use a private network. Several have national coverage Fees – Vary between $1200 - $3000 per year Most provide GPS + GLONASS solutions Variety of services are offered Most are tied to the NSRS

10. Thank You Neil D. Weston neil.d.weston@noaa.gov +1 301-713-3191 neil.d.weston@noaa.gov