The last 25 years - GPS to multi-gnss: from a military tool to the most widely used civilian positioning solution

Transcription

1 1 The last 25 years - GPS to multi-gnss: from a military tool to the most widely used civilian positioning solution B. Hofmann-Wellenhof Institute of Geodesy / Navigation, Graz University of Technology

2 2 Satellite Navigation History October 4, 1957: Soviet Union launched Sputnik, the first satellite U.S. scientists computed its orbit from Doppler shifts B. Hofmann-Wellenhof, TU Graz

3 3 Satellite Navigation History October 4, 1957: Soviet Union launched Sputnik, the first satellite U.S. scientists computed its orbit from Doppler shifts Inversion of this principle: Use of known orbits to determine the position of a receiver 1967: U.S. Navy navigational satellite system (NNSS) Transit fully operational B. Hofmann-Wellenhof, TU Graz

4 4 Transit System architecture Control segment Tracking stations Computing center Source: Space segment Source: public domain Circular, polar orbits Height: 1075 km (low-earth orbit, LEO) Period: 107 minutes B. Hofmann-Wellenhof, TU Graz

5 5 Transit Signal structure Two stable carrier waves at 150 MHz and 400 MHz Modulation of timing marks and navigation data on the carriers Observables: Doppler shift of the satellite signals due to the orbital motion of the satellites (high Doppler shift due to fast radial motion in low-earth orbits) B. Hofmann-Wellenhof, TU Graz

6 6 Satellite Navigation History October 4, 1957: Soviet Union launched Sputnik, the first satellite U.S. scientists computed its orbit from Doppler shifts Inversion of this principle: Use of known orbits to determine the position of a receiver 1967: U.S. Navy navigational satellite system (NNSS) Transit fully operational USA: GPS - fully operational since 1995 Soviet Union (Russia): GLONASS - fully operational in 1996 B. Hofmann-Wellenhof, TU Graz

7 7 Satellite Navigation History and future October 4, 1957: Soviet Union launched Sputnik, the first satellite U.S. scientists computed its orbit from Doppler shifts Inversion of this principle: Use of known orbits to determine the position of a receiver 1967: U.S. Navy navigational satellite system (NNSS) Transit fully operational USA: GPS - fully operational since 1995 Soviet Union (Russia): GLONASS - fully operational in 1996 China: Beidou - fully operational by 2020 (or earlier) Europe: Galileo - fully operational by 2020/22 More? B. Hofmann-Wellenhof, TU Graz

8 8 GPS Definition given by Wooden (1985) reads: The Navstar Global Positioning System (GPS) is an all-weather, space-based navigation system under development by the Department of Defense (DoD) to satisfy the requirements for the military forces to accurately determine their position, velocity, and time in a common reference system, anywhere on or near the Earth on a continuous basis. Goals primarily dedicated to military users civilian use was the first productive application of GPS (Macrometer receiver) B. Hofmann-Wellenhof, TU Graz

9 9 GPS - denial of accuracy and access B. Hofmann-Wellenhof, TU Graz

10 10 GPS effect of SA SA effect of truncating the orbital information shown for the radial orbit error SA effect of dithering the satellite clock shown for the pseudorange residuals B. Hofmann-Wellenhof, TU Graz III. Control Segment

11 11 GPS SA off (a miracle?) Termination of SA on May 2, 2000, 04:00 UTC (Station: Graz/Lustbühel) B. Hofmann-Wellenhof, TU Graz

12 12 GLONASS vs GPS GLONASS Parameter GPS 24 Number of Satellites 24 3 Orbital Planes º Inclination 55º 19,100 km Orbit Altitude 20,233 km MHz MHz FDMA 8 day ground repeat RF Frequency Ground Tracks L1:1575 MHz L2: 1227 MHz CDMA Ground repeat 4 mins earlier each day 511 kbits/sec C/A Code 1023 kbits/sec 5.11 MHz P Code MHz P,V,T Ephemeris Keplerian Keplerian Almanac Keplerian T. Moore, The University of Nottingham

13 13 GPS modernisation GPS IIA GPS II R / IIR-M GPS IIF GPS III Standard Service Single frequency (L1) Coarse acquisition code navigation Precise Service Y-Code (L1Y & L2Y) IIA/IIR capabilities plus 2nd civil signal (L2C) M-Code (L1M & L2M) IIR-M capability plus 3rd civil signal (L5) 12 year design life Backward compatible 4th civil signal (L1C) Increased accuracy Increased integrity Legacy Control System Architecture Evolution Plan (AEP) Next Generation Control Segment (OCX) T. Moore, The University of Nottingham

14 14 GLONASS modernisation GLONASS GLONASS-M 2003 onwards GLONASS-K 2011 onwards GLONASS-KM Life-time 4.5 ys Life-time 7 years 2 nd civil signal Design & Development phase Life-time >10 yrs 3 rd civil signal (L3) Requirement definition CDMA T. Moore, The University of Nottingham

15 15 History of GLONASS constellation T. Moore, The University of Nottingham

16 16 BeiDou or Compass Originally BeiDou military system Ultimately global civil / mil capability Medium Earth Orbits (21,550km) First satellite launched in Satellites (15 operational, 4 in comm.) 7 MEO, 5 GEO, 7 IGSO Compass - 1. Operational 2012 Regional, passive positioning. 12 SVs, 5 GEO, 3 IGSO, 4 MEO China & nearby areas. Compass 2. Operational 2020 Global, passive positioning. 27 MEO, 5 GEO, 3 IGSO (35 SVs) T. Moore, The University of Nottingham

17 17 Global Navigation Satellite Systems (GNSS): Air transport needs GNSS GNSS for road transport GNSS for precision agriculture Selling GNSS-based security and defence Maritime navigation with satellites for stars Keeping transport fleets up and running Power to the cities GNSS for finance In 2009, 6-7% of EU GDP, or about EUR 800 billion, depended either directly or indirectly on satellite navigation applications B. Hofmann-Wellenhof, TU Graz

18 18 Galileo implementation steps Full Operational Capability All services, 30 satellites 2020/2022 Initial Operational Capability Early Services for OS, SAR, PRS 18 satellites 2014/2015 In-Orbit Validation 4 IOV satellites plus ground segment 2011/2012 Galileo System Testbed v2 2 initial test satellites 2005, 2008 Galileo System Testbed v1 Validation of critical algorithms 2003 B. Hofmann-Wellenhof

19 19 Soyuz Launch Site - CSG Kourou G. Hein, ESA

20 20 GNSS today and tomorrow Global Regional Augmentierung GPS QZSS WAAS EGNOS GLONASS IRNSS MSAS GAGAN Galileo COMPASS SDCM MASS GINS (?) G. Hein, ESA

21 21 GNSS is there any need for it? PDOP GPS versus GPS/GNSS User at 30 degree latitude, mask angle 30 degrees. 3 Frequency operation. GPS/GNSS in blue J. Spilker, Stanford University

22 22 GNSS the more satellites the better? G. Hein, ESA

23 23 GNSS GPS GLONASS Galileo BeiDou/COMPASS EGNOS, WAAS, MSAS, GAGAN, SDCM, etc. QZSS P. Berglez, TeleConsult Austria GmbH