Presented by: Technical contributions from: THE INTERNATIONAL ASSOCIATION OF GEODESY AND PRECISE POINT POSITIONING

Sunil Bisnath (Chair IAG WG4.5.2) Hydrographic Science Research Center, Department of Marine Science, The University of Southern Mississippi Hydrographic Science Research Center, Department of Marine Science, The University of Southern Mississippi USM GPS Workshop 2004 USM GPS Workshop March, Long Beach, Mississippi THE INTERNATIONAL ASSOCIATION OF GEODESY AND PRECISE POINT POSITIONING

PURPOSE OF PRESENTATION To describe new International Association of Geodesy (IAG) To describe new International Association of Geodesy (IAG) To describe IAG precise point positioning (PPP) activities To describe IAG precise point positioning (PPP) activities To comment on future of PPP and convergence of GPS processing techniques To comment on future of PPP and convergence of GPS processing techniques

OVERVIEW Description of IAG Description of IAG Description of PPP Working Group Description of PPP Working Group Some recent PPP results Some recent PPP results PPP questions to consider PPP questions to consider Convergence of GPS processing techniques Convergence of GPS processing techniques

DESCRIPTION OF INTERNATIONAL ASSOCIATION OF GEODESY

RESEARCH OBJECTIVES Promote study of all scientific problems of geodesy and encourage geodetic research Promote study of all scientific problems of geodesy and encourage geodetic research Promote and coordinate international cooperation in this field, and promote geodetic activities in developing countries Promote and coordinate international cooperation in this field, and promote geodetic activities in developing countries Provide, on an international basis, for discussion and publication of results of studies, this research and work Provide, on an international basis, for discussion and publication of results of studies, this research and work

IAG COMMISSIONS Commission 1. Reference frames Commission 1. Reference frames Commission 2. Gravity field Commission 2. Gravity field Commission 3. Earth rotation and geodynamics Commission 3. Earth rotation and geodynamics Commission 4. Positioning and applications Commission 4. Positioning and applications

COMMISSION 4 SUB-COMMISSIONS Sub-Commission 4.1. Multi-sensor systems Sub-Commission 4.1. Multi-sensor systems Sub-Commission 4.2. Applications of geodesy in engineering Sub-Commission 4.2. Applications of geodesy in engineering Sub-Commission 4.3. GNSS measurement of the atmosphere Sub-Commission 4.3. GNSS measurement of the atmosphere Sub-Commission 4.4. Applications of satellite and airborne imaging systems Sub-Commission 4.4. Applications of satellite and airborne imaging systems Sub-Commission 4.5. Next generation RTK Sub-Commission 4.5. Next generation RTK

COMMISSION 4 STUDY GROUPS Study Group 4.1. Pseudolite applications in positioning and navigation Study Group 4.1. Pseudolite applications in positioning and navigation Study Group 4.2. Statistics and geometry in mixed integer linear models, with applications to GPS and InSAR Study Group 4.2. Statistics and geometry in mixed integer linear models, with applications to GPS and InSAR Study Group 1.1. Ionospheric modelling and analysis (joint with Commission 1) Study Group 1.1. Ionospheric modelling and analysis (joint with Commission 1) Study Group 1.2. Use of GNSS for reference frames (joint with Commission 1) Study Group 1.2. Use of GNSS for reference frames (joint with Commission 1)

SUB-COMMISSION 4.5 WORKING GROUPS Working Group Network RTK Working Group Network RTK Working Group Carrier phase-based precise point positioning Working Group Carrier phase-based precise point positioning Working Group High precision positioning on buoys and moving platforms Working Group High precision positioning on buoys and moving platforms

DESCRIPTION OF PRECISE POINT POSITIONING WORKING GROUP

IAG WG CARRIER PHASE-BASED PRECISE POINT POSITIONING Terms of reference: To investigate issues related to development of new technology based on processing of un-differenced carrier phase observations without reference stations Terms of reference: To investigate issues related to development of new technology based on processing of un-differenced carrier phase observations without reference stations Objectives: To investigate problems related to development of point positioning technology, and to promote international research collaborations Objectives: To investigate problems related to development of point positioning technology, and to promote international research collaborations Membership: ~two dozen researchers and users from government, industry, and academia located around the globe Membership: ~two dozen researchers and users from government, industry, and academia located around the globe

MAIN ACTIVITIES Identify technical issues and problems unique to precise point positioning system development Identify technical issues and problems unique to precise point positioning system development Investigate error sources and handling of un- differenced GPS observations Investigate error sources and handling of un- differenced GPS observations Investigate and develop models and algorithms for processing of un-differenced GPS observations Investigate and develop models and algorithms for processing of un-differenced GPS observations Investigate effects of GPS Modernization and Galileo on precise point positioning Investigate effects of GPS Modernization and Galileo on precise point positioning Promote collaborations and standards development Promote collaborations and standards development Participate in organization of international conferences and workshops Participate in organization of international conferences and workshops

SOME RECENT PPP RESULTS

Global Products for GPS Point Positioning Approaching Real-Time Y. Gao 1 and P. Heroux 2 1 Department of Geomatics Engineering, University of Calgary 2 Geodetic Survey Division, Natural Resources Canada IGS Workshop & Symposium Berne, Switzerland March 1-5, 2004

GPS Products Enabling PPP SourceAccuracyLatencyUpdateIntervalFormatAccess Orbit Clock (cm) (ns) Orbit clock IGDG (Global) ?1 sec29 sec 1 secProprietaryUDP GPSC (Regional) sec2 sec20 sec 2 secMRTCARadio UDP Final daysWeekly15 min 5 minSP3 RNXFTP Rapid hoursDaily15 min 5 minSP3 RNXFTP UltraEST hours12 hr15 min SP3 FTP UltraPRD 10 5None12 hr15 min SP3 FTP POST-MISSION REAL-TIME

Point Positioning Possibilities ServiceModelUser DataCorrection Products User Dynamics Processed Frequency Access SCOUTDDRNXOrbit/NetworkStaticDualInternet OPUSDDRNXOrbit/NetworkStaticDualInternet AUSPOSDDRNXOrbit/NetworkStaticDualInternet Auto- Gipsy PPPRNXOrbit/ClockStaticDual CSRS- PPP PPPRNXOrbit/Clock/GIMStatic/ Kinematic Dual/ Single Internet SkyFixPPPProprietary Static/ Kinematic DualSatCom StarFirePPPProprietary Static/ Kinematic DualSatCom POST-MISSION/ PUBLIC REAL-TIME/ COMMERCIAL

Correction Precision: The Network Difference GPS*C Application InputUser PPP RMS (February 1-7, 2004) NetworkData Availability Data SourceOrbit Satellite Clock Estimates LAT (cm) LON (cm) HGT (cm) Regional (code) Real-TimeRT-CACSUltraCode (Carrier filtered) Regional (carrier) Real-TimeRT-CACSUltraCode & Carrier Global (carrier) 15 minutesIGS-LEO RT-IGS UltraCode & Carrier5610 Global (combined) DailyIGSIGRCode & Carrier349

P 3 – A Software Package for PPP Users Features Undifferenced code/carrier processing Different observation model implementations Precise tropospheric delay and receiver clock estimation Static and kinematic positioning Forward and backward data processing Post-mission PPP using IGS Precise ephemeris and clock products Real-time PPP using JPL and NRCan real- time precise orbit/clock products Easy-to-use interface On-line view of processing results Various utilities

Real-Time User Application Testing Aircraft Trajectory

RECOMMENDATIONS Global GPS Network  Real-Time access to tracking station data Global GPS Products  Ultra clocks at 5-minute interval to allow more timely post-mission PPP using high-rate GPS data.  Standard correction format for real-time orbit/clock corrections  Standard protocol for Internet distribution PPP Users  Fast ambiguity convergence algorithms for undifferenced processing (IAG SC4.5 "Next Generation RTK“)  Receiver independent real-time PPP applications  Standard serial format for orbit/clock correction input to GPS receiver.

PPP QUESTIONS TO CONSIDER

PPP QUESTIONS TO CONSIDER (1) Filter convergence: Filter convergence: –Resolve ambiguities? –Different linear combinations? –Improved pseudorange handling? Data access: Data access: –Real-time access to global tracking station data? e.g., free real-time IGS? –Standard protocols for access? –Standard formats for data?

PPP QUESTIONS TO CONSIDER (2) Error handling: Error handling: –Improved ionospheric modeling? –Improved tropospheric modeling? –Improved multipath mitigation? GPS Modernization and Galileo: GPS Modernization and Galileo: –Effect of C/A on GPS L2? –Effect of Galileo addition? PPP / sensor integration: PPP / sensor integration: –Effect of inertial data? –Effect of atomic clock data?

CONVERGENCE OF GPS PROCESSING TECHNIQUES

PROCESSING PROGRESSION AND CONVERGENCE GPS code (stand-alone) DGPS coderelative carrier (static)DGPS code - beaconRTK (local, baseline)Network RTK (regional, network)PPP (regional/global, stand-alone) DGPS carrier - beacon ??

CONVERGENCE OPTIONS No convergence: No convergence: –Nothing happens –One “wins” –Each “corners” a market Convergence – sort of: Convergence – sort of: –Cross-checking –Switching Convergence: Convergence: –Initialization aiding –Optimal weighting combination –Hybrid  true convergence