This document discusses real-time GNSS correction sources and their applications and accuracy levels. It describes satellite-based augmentation systems (SBAS), Omnistar satellite differential corrections, Trimble RTX internet and satellite corrections, single base radio/internet corrections, and real-time networks. Accuracies range from 10-15 meters for autonomous GNSS to 1-3 centimeters for fixed baseline survey systems using corrections. The document provides an overview of correction options for different uses like survey, mapping, and their availability in Hawaii.

1. Real Time Corrections
for GNSS Receivers
Karyn Nolan and Erik Anderson

2. Which tool do you use?

3. Different Applications Require Different Tools
 Accuracy varies with receivers -- read the specs!
Survey (cm)
Mapping (10cm-5m)

4. Accuracy
 Autonomous GNSS
 10-15m horizontal
 Differential GNSS - MGIS
 0.1 - 5m horizontal (depending on
equipment & correction source)
 “Fixed” Baseline GNSS - Survey
 1-3 cm
 Optical Total Station
 <1 cm

5. Real Time Correction Sources
 Autonomous
– 10 m with uncorrected GPS
 Satellite Based Augmentation System (SBAS) – 2-4 m in Hawaii
– WAAS - US
– EGNOS - Europe
– MSAS – Japan
– GAGAN - India

6. Satellite Based Augmentation System
< 1 - 5 m< 1 - 5 m

7. Trimble Positioning Services
Internet and Satellite Based Real Time Correction Sources

8. How It Works

9. Powered by the Global Network of Reference Stations

10. Real Time Extended (RTX)
 Satellite or Internet broadcast
 Hawaii is Internet Only
 Annual or seasonal subscriptions
 Post processing (free) service available
CenterPoint
RTX
(< 4 cm)
RangePoint
RTX
(< 50 cm)
ViewPoint
RTX
(< 1 m)
Trimble
xFill
CenterPoint
RTX Post-
Processing

11. RTX Satellite Broadcast

12. Omnistar
 Satellite Differential Subscription Broadcast
OmniSTAR HP
OmniSTAR XP/G2
OmniSTAR VBS

13. Trimble Positioning Services

14. Trimble Positioning Services

15. Real Time Correction Sources
 Autonomous – no correction source
 Satellite Based Augmentation System (SBAS)
– WAAS - US
– EGNOS - Europe
– MSAS – Japan
– GAGAN – India
 Omnistar (Satellite Differential Subscription Broadcast)
 RTX (only available over Internet in Hawaii)
 CenterPoint RTX Post-Processing also available for survey receivers
 Single Base Broadcast
– Radio or Internet
– Currently Testing on Oahu – UH and SITECH
– Maui soon!
– Monthly Subscriptions

16. Single Base Corrections

17. Single Base Corrections

18. Trimble Positioning Services

19. Real Time Correction Sources
 Autonomous – no correction source
 Satellite Based Augmentation System (SBAS)
– WAAS - US
– EGNOS - Europe
– MSAS – Japan
– GAGAN – India
 Omnistar (Satellite Differential Subscription Broadcast)
 RTX (only available over Internet in Hawaii)
 CenterPoint RTX Post-Processing also available for survey receivers
 Single Base Broadcast
– Radio or Internet
 Real Time Network (Trimble Virtual Reference System)

20. Real Time Network (RTN)
A network of base
stations streams
reference information
to a central server via
internet

21. Difference in Accuracy
between traditional RTK and RTN

22. Hawaii Real Time Network

23. Questions
Pacific GPS, LLC
(808) 538-7477
www.pacificgps.com
info@pacificgps.com

24. Resources

25. Trimble Resources
Documentation and Downloads
• www.Trimble.com/support
Trimble Knowledge Network (TKN)
• Solution Center
• Learning Center
Trimble.com
• www.Trimble.com/MappingGIS
• www.Trimble.com/Survey
• www.Trimble.com/timetodomore

26. Trimble Resources
www.trimble.com/timetodomore