Development of Hong Kong GNSS infrastructure Wu Chen Department of Land Surveying and Geoinformatics (LSGI) Hong Kong Polytechnic University Hong Kong 1
Research Areas Research Areas GNSS Positioning and applications GNSS Reflectometry and Remote Sensing Seamless indoor/outdoor Positioning Technologies SLAM for 3D modelling and positioning Wide cooperation with Academic Institutes, Industries, and Government Agencies Research Funding for last 4 years: 40M Donations from Industry in last 4 years: 6M 2
Work with Government Agencies Lands Department Civil Engineering and Development Department Police Department Hong Kong Post Logistics and Supply Chain Management Research Centre 3
Close Link with Industries 腾讯 华为 中海达 北斗星通 合众思壮 武汉北斗研究院 Motorola Autotoll ESRI (HK) Leica 4
GNSS Infrastructure Background GNSS Based Services Global Services GPS, GLONASS, Beidou (III), Galilieo Regional Services Beidou (I, II), IRNSS Satellite Based Augmentation Systems (SBAS) WAAS, EGNOS, MSAS, QZSS, GAGAN,. Local Services Ground Based Augmentation systems (GBAS) (Aviation) DGPS Services (Marine) GNSS RTK Network (Surveying) 5
GNSS Development in Hong Kong Lands Department GNSS control network SatRef Network (18 stations) Marine Department DGPS system for marine navigation Automatic Identification System (AIS) for port management Airport Authority Considering a GBAS system for landing 6
HK GNSS Reference Network (SatRef) Upgraded to multi-gnss Receivers in 2015 7
Problems identified 1. HK SatRef has been established for many years, but the users are mainly surveyors 2. SatRef was based GPS only, need to be enhanced with multiple GNSS to improve performance and reliability 3. Hong Kong suffers from ionosphere anomaly effects 4. High rise buildings in urban area: strong multipath and low availability 8
Develop an GNSS based infrastructure to support Economic Development in HK 1. Develop multiple PNT services to support Hong Kong economic development and for the public to obtain reliable and accurate positioning data at low cost 2. Utilizing multiple GNSS positioning systems (i.e. GPS, Beidou, GLONASS), together with ground based augmentation systems, to solve urban positioning problem, and to provide reliable and secured positioning services 3. Develop better algorithms and models to improve positioning performance under the disturbances of ionosphere to improve accuracy and reliability of PNT services 4. Real-time Ionosphere Monitoring to support GNSS integrity and DGNSS services 5. 3D Water Vapour observation for weather forecasting 9
Collaboration with Government Agencies and Industries Development Users HK LD HK Post HK LD PolyUl Hong Kong Positioning Infrastructure HK PD 10 Companies LSCM HK CEDD Autotoll 10
Reliable 3D RTK services Platform of multiple GNSS to support RTK centimeter positioning Establish an multiple GNSS network (include GPS/Beidou/ ) Provide reliable RTK positioning service High quality geoid height at user site Support single-frequency RTK Other users server Multiple GNSS network 11
Concept of GNSS heighting 12
Gravity Survey Arrangement Gravity Survey: 635 points (46 old gravity points) GPS/levelling control points: 136 points Evaluation of gravity survey results: 69 check points, accuracy is 0.02mgal 13
Hong Kong Geoid Model (1 cm) 14
Multiple GNSS Systems GPS only: 12 GPS+GLONASS+Beidou: 33 15
GNSS Positioning in different environments Distance (mm) Height (mm) BeiDou - - GLONASS with BeiDou - - GPS - - GPS with BeiDou 1547-3522 GPS with GLONASS - - 16
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Field Experiments GPS/GLONASS GPS/Beidou/ GLONASS DGNSS Ambiguity Float Solution Ambiguity Fixed Solution
System Architecture for DGNSS GPS Beidou GLONASS Reference Poles GPS enabled Mobile Device GNSS observation Measurements or NMEA Data RTCM Correction Data ( X, Y, Z) Logistic Application Server Platform Lands Department Active GNSS network 19
Mobilephone DGNSS Tests 20
N(m) -1.158 x 104-1.159-1.16-1.161-1.162-1.163-1.164-1.165 Pos err(m) Mean Rms RTK Mobile 4.0 4.1 DGNSS 1.5 1.9-1.166 1500 1510 1520 1530 1540 1550 1560 E(m) 21
Vehicle Test 22
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Multipath Mitigation for mobile users Reflected Path Immigration Department Direct Path Direct Path Blocked (NLOS) N E
Paths of All GNSS Satellites N E
GNSS: urban areas, Multipath Mitigation Urban area: multipath, errors can reach a few tens meters Using multipath mitigation algorithms: <10 m Tests in Mongkok
Wanchai: Multipath Mitigation NMEA (red) Multipath mitigation (Green) N E 26.0 12.5 7.1 6.5 27
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Spatial distribution of water vapor 29
Height (km) Height (km) Electron Density Distribution in HK Reconstructed electron density distributions on 1 March 2011 (12:00 LT and 14:00 LT ) Electron Density Distributions over Hong Kong Date:March 1, 2001 Local Time: 12:00-13:00 Electron Density Unit: Ne/cm-3 4.2559e+006 Electron Density Distributions over Hong Kong Date:March 1, 2001 Local Time: 14:00-15:00 Electron Density Unit: Ne/cm-3 4.2559e+006 200.00 200.00 300.00 3.42283e+006 300.00 3.42283e+006 400.00 400.00 500.00 2.58976e+006 500.00 2.58976e+006 600.00 600.00 1.75668e+006 1.75668e+006 700.00 700.00 800.00 923609 800.00 923609 900.00 900.00 14.50 17.00 19.50 22.00 24.50 27.00 29.50 32.00 latitude (degree) 14.50 17.00 19.50 22.00 24.50 27.00 29.50 32.00 latitude (degree) 30
Summary: Hong Kong GNSS Infrastructure Develop DGNSS services for HK Correction accuracy < 0.5 m Mobilephone ~ 2 m Dense Built-in Areas Accuracy < 10 m for mobile users Develop high precision HK Geoid model Accuracy ~ 1 cm Develop Multiple GNSS RTK service Accuracy ~ 1-2 cm (3D) Ionosphere monitoring Support DGNSS (accuracy and integrity) water vapour observation (support weather forecasting) 31
Thank you 32