1. Oscar L. Colombo GEST/NASA Goddard Space Flight Center Maryland, USA
PRECISE REAL-TIME DIFFERENTIAL NAVIGATION USING NTRIP STREAMS FROM CONTINUOUSLY OPERATING, WIDE-AREA GNSS NETWORKS.
Oscar L. Colombo
GEST/NASA Goddard Space Flight Center Maryland, USA

2. COMMENTS
NTRIP data freely available from GNSS networks provide an invaluable test-bed for innovation.
SBAS networks now begin operations, or are under development, in several countries, including developing ones, while more plan to build their own in the future.
Wide-area precise real-time kinematic positioning (with “floated ambiguities”) typically needs a long time (30min – 1.5 hs) assimilating data before the solution converges to its full precision.
New signals (L2C, L5, P5) can help shorten the convergence time, but their transmitter code biases have to be corrected using estimated values. Also the non-integer part of un-differenced L1, L2 ambiguities could be calibrated with data from the world-wide IGS network, to assist wide-area point-positioning.
The IGS (or some IGS’ ACs) could help by providing some, or all, of the corrections mentioned above, much as CODE does now with the P1-C1 biases.

3. NTRIP Sites, Many Available through BKG (Mostly 1 Hz GPS data, Raw or RTCM 2.x, 3.0)
Map: BKG, Frankfurt

4. Some countries are developing or considering SBAS, DGPS, Precise DGPS
Some countries are developing or considering SBAS, DGPS, Precise DGPS. More could soon join them.

5. Source: BKG, Frankfurt

6. USA Off-Line Test, April 2004

9. The “IT” Real-time navigation software has been developed with support from the US Navy (NSWC-Dahlgren Division)

10. Spanish Sites’ Test, 25 February 2008

11. Iberian Test Sites, April 28, 2008

14. A WORD OF CAUTION: First Sunspot of Cycle 24 Already Sighted

15. Near Solar Max., Ionospheric Scintillation can be a serious problem at low latitudes (Tropical Anomaly)
Prof. Claudio Brunini, UNLP