1 GPS and GNSS Activities in Hong Kong Simon C W KWOK Geodetic Survey Section Lands Department Hong Kong 35th Civil GPS Service Interface Committee Fairfax, Virginia, USA March

2 Summary Current activities Differential services Development activities

3 GPS Timing / Frequency Activities Time standard : –Hong Kong Observatory (GPS clock is used as a back up of the cesium atomic clock) Frequency standard : –Standard and calibration laboratory of the Industry Department

4 GPS Timing / Frequency Activities Train scheduling : –Mass Transit Railway Timing source for telecommunication : –Mobile phone and paging company

5 GPS Survey/Geodesy/GIS Activities Lands Department will finalize the adjustment of 2000 GPS network –46 stations –Accuracy (5mm +0.2ppm At 95% confidence level) –Tie to ITRF reference frame Connect to 6 IGS global stations –(Coco Islands, Guam, Lhasa, Shanghai, Tsukuba, Yarragadee) Global accuracy (2cm repeatability)

6 10 km Hong Kong 2000 GPS Network

7 Linking Hong Kong datum to ITRF system

8 GPS Survey/Geodesy/GIS Activities Lands Department is implementing the Active GPS Control Station Network Phase I –6 Stations –shall be completed in Summer 2000 Phase II –7 stations –shall be completed in 2002

9 Layout of Active Control System

10 Active Control System

11 Active Control Station

12 GPS Survey/Geodesy/GIS Activities Highways Department is setting up a GPS system for monitoring three major bridges –Tsing Ma Bridge, Kap Shui Mun Bridge, Ting Kau Bridge real time system monitor the displacement –due to wind, temperature, seismic, traffic load 24-hours operation

13 GPS Bridge Monitoring System

14 GPS Survey/Geodesy/GIS Activities The number of GPS users in engineering and construction industry is increasing Engineering Survey Checking of piling Monitoring of slopes

15 GPS Survey/Geodesy/GIS Activities Agriculture, Fishery and Conservation –use GPS for positioning Environmental Protection –use GPS for collection of geographical information

16 GPS Land Navigation Activities Fire Services –Completed a feasibility study –Third Generation Command and Control System –Use GPS, digital map and information system for deployment of ambulance and fire engines –Implementation date : 2003

17 GPS Marine Navigation Activities Marine Police –Installing DGPS and Automatic Vessel Location System on the fleet of Police launch DGPS Service –Vessels in the Hong Kong waters can receive DGPS signal form Marine Department’s GPS reference station

18 Differential Services Maritime DGPS Radionavigation Service –Station name : Kau Yi Chau –Operated by Marine Department –RTCM (message type 1,2,3,5,6,16) –Range : 500 km –Radiobeacon, 289KHz, 200bps

19 Differential Services Continuously Operating GPS Reference Station –Station name : Fanling –Operated by Lands Department –RINEX data for post processing –5-second epoch rate –FTP download service

20 Development Activities Land Use Mobile Computing Application System –System Integration Telecommunication GPS data Digital maps Information database –Users Drivers, fleet management, transportation Mobile land users

21 Development Activities Maritime Use Tide Gauge and Chart Datum –Marine Department uses GPS to tie the level of automatic tide gauge to the local height datum –Monitor the sea level and predict tide for navigation and hydrographic survey –Determine the datum for marine charting

22 Development Activities Aviation Use ICAO Global Implementation Plan of Satellite-based System –Civil Aviation Department is conducting a study project ( ) –Analysis the system requirement for Communication Navigation Surveillance Traffic Management

23 Development Activities Survey/Geodesy/GIS Use Hong Kong Active Control Station Network –GPS infrastructure for metropolitan area –Support surveying and mapping (initial goal) –Multi-purpose (long term goal) –Users can measure baselines from at least 2 permanent stations which are within a distance of 10 km.

24 Layout of Active Control System

25 Redundancy Map

26 Development Activities Survey/Geodesy/GIS Use Active Control Station Network –High network density provides opportunity for Use low-cost single frequency receiver Short observation time (5 -10 min.) for post processing Maintain accuracy for RTK survey –10 km, cm-level accuracy Use fast (single epoch) integer ambiguity resolution –no initialization for RTK survey –fast integrity monitoring

27 Development Activities Survey/Geodesy/GIS Use Active Control Station Network –Use single epoch integer ambiguity resolution for rapid integrity monitoring of the network Use least square network solution Check GPS data quality Check station stability (sudden movement and long term movement)

28 Identify outliners in GPS data

29 Monitor the trend of station movement

30 Development Activities Survey/Geodesy/GIS Use Active Control Station Network –Develop GPS data quality indicators for the users Flag outliners of GPS data in RINEX file –Real time delivery of GPS data from multiple reference station

31 Development Activities Survey/Geodesy/GIS Use Active Control Station Network –Use multiple reference stations for RTK or single epoch positioning –Advantage Improve availability Provide redundancy (and quality indicator) to improve reliability Provide quality check to satisfy legal requirements (boundary survey, law enforcement)

32 Development Activities Survey/Geodesy/GIS Use What new equipment and standard are required Need development of new receivers for receiving RTK data from multiple base stations Need to develop quality indicator for positioning using multiple reference stations for implementation in the industry Need a standard format for efficient RTK data broadcast

33 Development Activities Survey/Geodesy/GIS Use Mission of the Active Control Station Network –GPS Spatial Reference Infrastructure for multi-purpose application (long term goal) –reduce equipment investment –reduce production time –reduce labor cost –improve reliability

34 Conclusion GPS infrastructure brings social and economic benefits to the society