12.540 Principles of the Global Positioning System Prof. Thomas Herring 12540Lec01 Overview of class Aim To introduce the principles of the operation of the gPs system and its applications There is flexibility in the exact content of the course depending on student interests Generic topics include millimeter accuracy positioning and kinematic GPS Emphasis is on fundamental principles and limitations 02/5/03 2540Lec01
12.540 Principles of the Global Positioning System Prof. Thomas Herring 02/05/03 12.540 Lec 01 1 Overview of class • Aim: To introduce the principles of the operation of the GPS system and its applications • There is flexibility in the exact content of the course depending on student interests • Generic topics include millimeter accuracy positioning and kinematic GPS • Emphasis is on fundamental principles and limitations 02/05/03 12.540 Lec 01 2 1
Class expectations This is a graduate level class. There is no final exam Grading in the class is based on homework (75%)and on a final written report (25% The report will be revised during semester and should be 2000-3000 words 8-10 double spaced pages Topic for the paper will be due around Spring 12540Lec01 Class behavior It will be acceptable in this course to work together on homework with the aim of better understanding the material and to refer to other books and published material provided that these additional materials are cited appropriately in the homework. Each student should complete the homework separately. It is not acceptable to simply copy the homework of another student 02/5/03 2540Lec01
02/05/03 12.540 Lec 01 3 • • • • break 02/05/03 12.540 Lec 01 4 • It Class expectations This is a graduate level class. There is no final exam Grading in the class is based on homework (75%) and on a final written report (25%) The report will be revised during semester and should be 2000-3000 words (8-10 double spaced pages) Topic for the paper will be due around Spring Class Behavior It will be acceptable in this course to work together on homework with the aim of better understanding the material and to refer to other books and published material provided that these additional materials are cited appropriately in the homework. Each student should complete the homework separately. is not acceptable to simply copy the homework of another student. 2
Basic course outline Classes 1: Coordinate and Time systems 2: Satellite orbital motions 3: Estimation procedures 4: GPS Observables 5: Propagation medium 6: Mathematical model of GPS observables 7: Methods of processing GPs data 22443442 8: Applications and examples of GPs 12540Lec01 Topics to be covered Coordinate and time systems When working at the millimeter level globally, how do you define a coordinate system What does latitude, longitude and height really mean at this accuracy Light propagates 30 cm in 1 nano-second, how is time defined 02/5/03 12540Lec01
02/05/03 12.540 Lec 01 5 Basic course outline • • • • • • • • Classes 2 2 4 4 3 4 4 2 1: Coordinate and Time systems 2: Satellite orbital motions 3: Estimation procedures 4: GPS Observables 5: Propagation medium 6: Mathematical model of GPS observables 7: Methods of processing GPS data 8: Applications and examples of GPS. 02/05/03 12.540 Lec 01 6 Topics to be covered • system Coordinate and time systems: – When working at the millimeter level globally, how do you define a coordinate – What does latitude, longitude, and height really mean at this accuracy – Light propagates 30 cm in 1 nano-second, how is time defined 3
Topics Satellite motions How are satellite orbits described and how do the satellites move What forces effect the motions of satellites What do gps satellite motions look like and what are the main perturbations to the orbits Where do you obtain GPS satellite orbits 12540Lec01 Topics GPS observables GPS signal structure and its uniqueness Pseudo-range measurements Carrier phase measurements Initial phase ambiguities Effects of GPS security: Selective availability (SA)and antispoofing(AS) Data formats(RINEX) 02/5/03 2540Lec01
02/05/03 12.540 Lec 01 7 Topics • orbits 02/05/03 12.540 Lec 01 8 Topics • GPS observables Satellite motions – How are satellite orbits described and how do the satellites move – What forces effect the motions of satellites – What do GPS satellite motions look like and what are the main perturbations to the – Where do you obtain GPS satellite orbits – GPS signal structure and its uniqueness – Pseudo-range measurements – Carrier phase measurements – Initial phase ambiguities – Effects of GPS security: Selective availability (SA) and antispoofing (AS) – Data formats (RINEX) 4
Topics Estimation procedures Simple weighted-least-squares estimation Stochastic descriptions of random variables and parameters Kalman filtering Statistics in estimation procedures Propagation of variance-covariance information 12540Lec01 opICS Propagation medium Neutral atmosphere delay Hydrostatic and water vapor contributions ionospheric delay( dispersive) Multipath 2540Lec01
02/05/03 12.540 Lec 01 9 Topics • Estimation procedures information 02/05/03 12.540 Lec 01 10 Topics • Propagation medium – Simple weighted-least-squares estimation – Stochastic descriptions of random variables and parameters – Kalman filtering – Statistics in estimation procedures – Propagation of variance-covariance – Neutral atmosphere delay – Hydrostatic and water vapor contributions – Ionospheric delay (dispersive) – Multipath 5
Topics Mathematic models in GPS Basic theory of contributions that need be to included for millimeter level global positioning Use of differenced data Combinations of observables for different purposes 12540Lec01 Topics Methods of processing GPS data Available software Available data(International GPS service, IGS; University consortium(Unavco) Cycle slip detection and repair Relationship between satellite based and conventional geodetic systems(revisit since this is an important topic) 02/5/03 2540Lec01
02/05/03 12.540 Lec 01 11 Topics • Mathematic models in GPS positioning purposes 02/05/03 12.540 Lec 01 12 Topics • (Unavco) – Basic theory of contributions that need be to included for millimeter level global – Use of differenced data – Combinations of observables for different Methods of processing GPS data – Available software – Available data (International GPS service, IGS; University consortium – Cycle slip detection and repair – Relationship between satellite based and conventional geodetic systems (revisit since this is an important topic) 6
Topics Applications and examples from GPS Tectonic motions and continuous time series Earth rotation variations: measurement and oraIn Kinematic GPS; aircraft and moving hicles Atmospheric delay studies 12540Lec01 Text books No specific text books are required for this course The books below cover the geodetic and engineering aspects of GPS B. Hofmann-Wellenhof, H. Lichtenegger, and J. Collins. GPS Theory and Practice, Springer-Verlag, Wein, New York,Pp.326,1992. Parkinson, B. W.,J. Spilker, P. Axelrad and P. Enge Global positioning System: Theory and Applications, 793 pp, Am. Inst Aeronaut. Astronaut, Washington D 02/5/03 2540Lec01
02/05/03 12.540 Lec 01 13 Topics • series origin ; vehicles 02/05/03 12.540 Lec 01 14 Text books • course. • – GPS Theory and Practice, York, pp. 326, 1992. – Global Positioning System: Theory and Applications, C., 1996. Applications and examples from GPS – Tectonic motions and continuous time – Earth rotation variations; measurement and – Kinematic GPS aircraft and moving – Atmospheric delay studies No specific text books are required for this The books below cover the geodetic and engineering aspects of GPS B. Hofmann-Wellenhof, H. Lichtenegger, and J. Collins, Springer-Verlag, Wein, New Parkinson, B. W., J. Spilker, P. Axelrad and P. Enge, 793 pp., Am. Inst. Aeronaut. Astronaut., Washington D. 7
Other reference material Most of the reference material for the course will be posted as links on the web page Some web sites to explore http://www.navcen.uscg.gov http://www.unavco.ucar.edu/ http:/www.scign.org 12540Lec01 Homeworks The theme of the homeworks will for you to write a program for GPs data analysis. The program will read GPS data and satellite information in RINEX format Programming will be required: Most students use Matlab and some use fortran or c 02/5/03 2540Lec01
Other reference material • Most of the reference material for the course will be posted as links on the web page • Some web sites to explore: – http://www.navcen.uscg.gov – http://www.unavco.ucar.edu/ – http://www.scign.org 02/05/03 12.540 Lec 01 15 Homeworks • The theme of the homeworks will for you to write a program for GPS data analysis. The program will read GPS data and satellite information in RINEX format • Programming will be required: Most students use Matlab and some use fortran or C 02/05/03 12.540 Lec 01 16 8
Coordinate systems Suggested reading Herring, T. A, Geodetic Applications of GPS, Proceedings of the IEEE,87,1,92-110.1999 Questions to ponder Why do we need a coordinate system What properties should it have How were coordinates defined before space based geodetic systems were available 12540Lec01 17 Coordinate systems More questions Does the Earth's gravity field play a role in coordinate systems? How does this type of system relate to space based systems? What is needed to define a coordinate system and how are they " realized(i.e implemented) 02/5/03 2540Lec01
02/05/03 12.540 Lec 01 17 Coordinate systems • – Herring, T. A., Geodetic Applications of GPS, Proceedings of the IEEE, 87, . • – Why do we need a coordinate system – What properties should it have – 02/05/03 12.540 Lec 01 18 Coordinate systems • More questions: implemented) Suggested reading: 1, 92–110, 1999 Questions to ponder How were coordinates defined before space based geodetic systems were available – Does the Earth’s gravity field play a role in coordinate systems? – How does this type of system relate to space based systems? – What is needed to define a coordinate system and how are they “realized” (i.e. 9