1. Evaluation of accuracy and availability of GNSS Satellite-Based Augmentation Services in Thailand
GPS/GNSS
GPS/GNSS
Monsak Socharoentum and Wasan Pattara-Atikom
National Electronics and Computer Technology Center, THAILAND
October 13, 2016

2. With SBAS: Positioning Accuracy 10  2 meters
Corrections
Corrections
Raw
measurements
Accuracy
10 meters  1-2 meters

3. SBAS coverage in the world
WAAS
(USA)
EGNOS
(Europe)
MSAS
(Japan)
GAGAN
(India)
SDCM
(Russia)
BDSBAS
(China)
Thailand
Anyway, are SBAS signals also useful for others (such as Thailand)?
If so, how is the positioning accuracy performance?

4. Research questions and experiment setting
“Does and how SBAS improve GNSS positioning accuracy in Thailand?”,
“What is the performance of operational SBAS and experimental SBAS?”, and
“If SBAS is used for vehicle tracking, what is the behavior of the vehicle positions?”

5. Table 1. Experiment setting
Test
Comparison Pair
Static
Existing vs. experimental SBAS
Vehicle tracking
GPS vs. GPS+QZSS SBAS
RTK Positioning
Figure 3. (a) QZSS prototype receiver, (b) u-blox receiver,
(c) installation locations

6. Reference Point Setup Spacial thanks to RTK Survey 1-2 cm. accuracy
Then all four receivers were placed on the top of the pole
Data collection period was 10 minutes
Spacial thanks to
TOPCON Thailand
supports survey grade receivers
Department of Land, Thailand
supports RTK VRS account

7. GNSS Receiver Specifications
Huawei P7 L10
Prototype QZSS receiver
ublox EVK M6N
GNSS
Receivers
GPS (USA) GLONASS (Russia)
GNSS
Constellations
GPS (USA)
GPS (USA)
SBAS No
Yes (QZSS)
Yes (MSAS)

8. Plot of positions in static test
Table 2. Circular Error Probable (CEP 95%) and Root-Mean-Square-Error (RMSE)
Plot of positions in static test
 Receivers
CEP (meters)
RMSE (meters)
GNSS
SBAS function
Android smart phone
9.19
5.28
GPS+
GLONASS
N/A
Prototype QZSS receiver
5.36
3.66
GPS
QZSS
u-blox receiver
2.02
1.90
MSAS

9. Precision Accuracy Circular Error Probable 95% (meters)
Root Mean Squared Error (meters)
Circular Error Probable 95% (meters)
Huawei 9.19
QZSS 5.36
ublox 2.02 No
SBAS
SBAS
SBAS

10. Bus tracking with and w/o SBAS (non urban canyons areas)
Red: GPS + QZSS augmentation
Blue: GPS w/o augmentation

11. Spatial position deviations in urban canyons

12. Satellites availability tracked by QZSS prototype receiver
Inbound
Satellites availability tracked by QZSS prototype receiver
Outbound
0-3:  Red
4-8: Yellow
>=9: Green
Inbound

13. Effect of poor signal availability in urban canyons

14. Conclusion
correction information generated from Japan can significantly improve the accuracy of GPS positioning in Thailand.
2 meters CEP 95% is possible to be achieved
Vehicle tracking: Positions from SBAS can be used for detecting a particular traffic lane that the vehicle is moving along including the course of transition such as U-turn.

15. Acknowledgement
We are gratefully appreciated the company/organization below for their kindly supports.
TOPCON Thailand supports high-end GNSS receiver and two technicians for RTK operation.
Department of Land, Ministry of Internal Affair, Thailand supports RTK VRS account
HONDA Motor Japan supports the QZSS prototype receiver.
JAXA optimizes and broadcast QZSS’s correction information.