1. Technical Seminar An Overview of Positioning Systems and Technologies Chandraraj Naidu L USN: 1RN07IT012 Dept. of Instrumentation Technology RNS Institute of Technology

2. Overview  Introduction to Positioning and Navigation  A Brief History : Evolution of GPS  The Global Navigation Satellite System (GNSS)  The Global Positioning System (GPS)  Basic Concept  Structure  Signals & Messages  Policy and Restrictions  Accuracy Enhancement  Applications  IRNSS and GAGAN

3. Brief History Evolution of the GPS  First Satellite Navigation Systems Transit Timation  Ground based system Omega  DNSS, Navstar-GPS  Military and Civilian Usage policies  Selective Availability and its deactivation  Free Availability across the world  Nearly 60 satellites so far into space  33 currently in orbit

4. Global Navigation Satellite System  Autonomous geo-spatial positioning with global coverage  Allows small electronic receivers to determine their location (longitude, latitude, and altitude) to within a few meters  Receivers calculate the precise time as well as position  Precision in the delivery of weapons to targets  Troops can be directed and locate themselves easily  US GPS and Russian GLONASS only two fully operational GNSS  Upcoming GNSS: European Union – Galileo (by 2014) China – Compass (by 2020)

5. Global Navigation Satellite System  Global coverage achieved by constellation of 20–30 Medium Earth Orbit satellites on several orbital planes  Operator of a GNSS has the ability to degrade / eliminate services over any territory it desires  Classification: GNSS-I GNSS-II Regional Systems  GNSS Augmentation Systems  GNSS Basic Components  Satellite constellation in space  Satellite control unit on Earth  Receiver unit with the user

6. GPS Satellite GLONASS Satellite IRNSS Satellite

7. Global Positioning System Basic Concept  Receiver calculates own position with respect to at least 3 satellites  Satellites provide continually updated almanac  Satellite continually transmits messages that include The time the message was transmitted Precise orbital information (the ephemeris) The general system health & orbits of all GPS satellites  Trilateration used to compute distance  Final position in terms of latitude, longitude and altitude  Devices can derive direction and speed information  Data can be processed to be placed on a pre-loaded map  Minimum of 4 satellites used for accurate computations

8. GPS Concept

9. Global Positioning System Structure  Three major segments  Space Segment  Control Segment  User Segment  Space Segment ‐27 to 32 satellites in medium Earth orbit ‐6 planes with 4 satellites each ‐Approx. altitude 20,000 km ‐Additional satellites improve precision of GPS calculations ‐Constellation in non-uniform arrangement ‐Improves reliability and availability

10. GPS Satellite GPS Satellite Constellation

11. GPS Satellites: Past, Present & Future

12. Global Positioning System Structure  Control Segment  The control segment is composed of : ‐Master Control Station ‐Alternate Master Control Station ‐4 dedicated Ground Antennas ‐6 dedicated Monitor Stations  Stations in constant communication with satellites  Updates synchronize the atomic clocks on board  Also adjust the ephemeris of each satellite's internal orbital model  Satellites marked unhealthy, for orbital corrections

13. Garmin Standalone GPS Receiver Advanced GPS Receiver Component Forms a section of a larger system that uses GPS receiver system

14. Global Positioning System Structure  User Segment  Hundreds of thousands of US & allied military users ‐Secure GPS Precise Positioning Service  Tens of millions of civil, commercial and scientific users ‐Standard Positioning Service  GPS receivers are composed of: antenna, tuned to frequencies transmitted by satellites receiver-processors highly stable clock  Channels: signifies number of satellites monitored simultaneously  DGPS module - enhances accuracy

15. The GPS Panel used in Aircraft Navigation A highly evolved Vehicular GPS Navigator Movement and Directions tracked on a map on a full color screen

16. Global Positioning System Signals and Messages  Satellite continuously broadcasts navigation message at 50 bits/sec  Complete message is composed of 30-second frames  Each frame further subdivided into 5 sub-frames  Each sub-frame contains 10 words of 30 bits  1 st part of message encodes week number & time within the week  2 nd part of message (ephemeris) provides precise orbit for satellite  Last part (almanac) contains coarse orbit & status info for all satellites  All satellites broadcast at the same frequencies using CDMA  Two types: (C/A) and (P)  All satellites broadcast at the same two frequencies L1 and L2

17. Global Positioning System Policy and Usage Restrictions  GPS is owned & operated by US Government Department of Defense  When introduced was meant exclusively for the US Defense Forces  Initially there was Selective Availability concept for civil use  Year 2000: Selective Availability turned off  Two services:  Standard Positioning Service  Precise Positioning Service

18. Global Positioning System Accuracy Enhancement  Analysis of errors in the information by GPS  Integrating external information into the calculation process  Augmentation systems, DGPS, AGPS etc.  Precise monitoring and measurement of existing GPS signals  GPS Time

19. Illustration of GPS usage in Warfare

20. Applications Military Use  High Precision Navigation  Target Tracking  Missile Technology  Nuclear Weapon Detection

21. Illustration of GPS usage in Warfare

22. Applications Civilian Use  Navigation & Tracking  Map-Making  Emergency Services  Surveying  Tectonics  Geo-fencing  Geo-tagging

23. GPS integrated into Smartphones Cellular phones today come with a built-in GPS receiver antenna Software applications enhance it by using maps, direction finding and 3D imaging Geo-Tagging A digital camera fitted with the GPS device, records a position (latitude, longitude) for every photograph.

24. Geo-Tracking using Ankle Monitor Programmable to alert if the wearer crosses a predefined boundary, law enforcement gets sophisticated Civil Engineering’s New Tools The standard surveying equipment are quickly revolutionizing with advent of automation and the GPS

25. The Indian Regional Navigational Satellite System  Autonomous Regional Satellite Navigation System  Under development by Indian Space Research Organization (ISRO)  Counters GPS unavailability under hostile situations  Approved in 2006; Expected Project completion in 2014  7 satellites; of which 3 in geo-stationary orbit  Both Standard Positioning Service and a Precision Service  Absolute position accuracy of better than 20 meters  Service availability all through India, and within a region extending approximately 2,000 km around it

26. The IRNSS service extends to a large area, including & surrounding the Indian Sub-continent

27. GPS Aided Geo-Augmented Navigation  Implementation of regional Satellite Based Augmentation System  Execution by Airports Authority of India and ISRO  Operational phase of GAGAN likely to be completed by May 2011  Improve accuracy of a GNSS receiver by providing reference signals  Provide navigation system for all phases of flight over the Indian airspace and in the adjoining areas  Eight crucial reference stations; Master control center at Bangalore  Compatible with other SBAS systems (WAAS, EGNOS etc.)  Flight Management System based on GAGAN  Will manage climb, descent and engine performance profiles

28. This seminar is based on an IEEE paper titled, “An Overview of Positioning Systems and Technologies” by A Waadt ; G H Bruck ; P Jung of Lehrstuhl fur Kommunikations Tech. Univ., Germany Published in November 2009 Other references include: IEEE paper on, “Evolution of the Global Navigation Satellite System (GNSS)” by C J Hegarty ; E Chatre ; of MITRE Corp., USA Published in December 2008 A PowerPoint Presentation titled, “IRNSS and GAGAN” presented at COSPAR, Montreal, by A Bhaskaranarayana of ISRO gps.gov : The official website of the Global Positioning System nasa.gov : NASA, USA, official website isro.org : ISRO, India, official website