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Melaha 2004

Melaha 2004. A Half-Century of Global Satellite Navigation Systems: 1965 - 2015 Dave Wells Tuesday 13 April 2004. Outline. Evolutionary background The past (1965-1994) - predates operational GPS The present (1994-2004) - the first age of GPS

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Melaha 2004

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  1. Melaha 2004 A Half-Century of Global Satellite Navigation Systems:1965 - 2015Dave WellsTuesday 13 April 2004 50 years of GNSS

  2. Outline • Evolutionary background • The past (1965-1994) - predates operational GPS • The present (1994-2004) - the first age of GPS • The future (2004-2015) - GPS modernized, and other GNSS systems operational 50 years of GNSS

  3. Evolutionary background • Enabling technology • Microelectronics & computers • Position determination • Radiopositioning • Earth-orbiting satellites 50 years of GNSS

  4. BIO Metrology: Reg Gilbert Clive Mason Andrew Bennett Introduced in 1965 BIO bought s/n 132 & 198 in 1966 World’s first Minicomputer (less than $25,000) 4096 12-bit word 1.5 µsec core memory Only I/O device - 10 cps teletype Storage medium - punched paper tape Programming language - PAL III 50,000 sold before PDP-11 arrived in 1970 1966 DEC PDP-8 Computer 50 years of GNSS

  5. Gordon Moore, Intel co-founder Logic density increase 50 years of GNSS

  6. Computer memory • 40 year trend • Memory cost cut in half every 20 months • Memory capacity doubled every 24 months • Memory (and computer) size cut in half every 36 months • PDP-8 vs this laptop (12-inch Mac Titanium) • Laptop has 150,000 times more memory • (others have 350,000 times more) • Laptop memory is 1,500 times faster • (others are 5,000 times faster) • PDP-8 memory cost 25,000,000 times more (per bit) • PDP-8 core memory occupied 3,000 times more space 50 years of GNSS

  7. Radiopositioning • First developed during WW II • Three modes: hyperbolic (range-differencing) • two-way (active) ranging • one-way (passive) ranging (“rho-rho”) • Three ways to identify reference stations: • frequency diversity • time-sharing • code-diversity • Two signal types: continuous-wave (CW) and pulsed 50 years of GNSS

  8. Hyperbolic Requires minimum of n+1 base stations for n-dimensional coordinate solution Solve for coordinates. Cancel clock offset by measuring range differences. Passive ranging Requires minimum of n+1 base stations for n-dimensional coordinate solution Solve for coordinates and clock offset Hyperbolic vs Passive ranging The two methods are mathematically equivalent. Each algorithm can be transformed rigorously into the other 50 years of GNSS

  9. sv1 sv2 Rx1 Rx2 1980 - Double differencingeliminates clock noise • F = r + dr + c(dt-dT)+ lN - I + T + emf+ ef • DD[F] = (F11- F12) - (F21 - F22) • DD[c(dt-dT)] = 0 50 years of GNSS

  10. Loran-C coverage in 1980 50 years of GNSS

  11. LORAN-C Hyperbolic LOP / SOP (also used in “rho-rho” mode) Time-shared and coded transmitter ID Pulse envelope containing continuous wave signal (pulse-matching and cycle-matching) Multipath issue (skywave) GPS Passive ranging LOP / SOP Coded transmitter ID Coded modulation on continuous wave carrier Multipath issue (nearby reflections) LORAN-C vs GPS 50 years of GNSS

  12. Omega network 50 years of GNSS

  13. OMEGA: First global radiopositioning system Hyperbolic LOP / SOP Time-shared transmitter ID Continuous-wave signal Multiple frequencies for widelaning method of cycle ambiguity resolution GPS Passive ranging LOP / SOP Coded transmitter ID Continuous wave carrier PLUS coded modulation Multiple frequencies permit widelaning method of cycle ambiguity resolution OMEGA vs GPS 50 years of GNSS

  14. Hyperbolic system evolution Wells & Grant 2003 50 years of GNSS

  15. The Past (1965 - 1994) Evolution of satellite positioning Navy Navigation Satellite System (Transit) Concept in 1957, Operational in 1964 Publicly available in 1967 Passive ranging (“rho-rho”) Concept in 1957 Timation I launched in 1967 Global Positioning System Concept in 1970 First satellites launched in 1978 50 years of GNSS

  16. Shelltech: Alex Hittel Jan Kouba Bedford Institute: Dave Dalby Bob Reiniger Magnavox: Tom Stansell ITT: Paul Rodgers ITT Transit receiver s/n 4 purchased by Shelltech First trials on board “Miss Juanita” ITT s/n 5 and Magnavox s/n 4 purchased by BIO 1967 Transit receivers No software or processor supplied Used PDP-8s Wrote NNSS position fix in PAL III 50 years of GNSS

  17. Control Data Corp: Bob Lillestrand Denmark: Eigel Knuth First geodetic control points in northern Greenland Arrows show displacement from previous (astro-geodetic) control Added 10,000 km2 to area of Greenland 1968 Project NORD 50 years of GNSS

  18. UNB: Ed Krakiwsky Don Thomson Geodetic Survey Div: Jan Kouba et al Worked out methodology to use Transit for geodetic control 1973 - 1977 Geodetic Survey established new control across Canada 1970-73 Doppler Control 50 years of GNSS

  19. Univ Washington: Pat Martin Alan Thorndike “Gillespie” Arctic Ice Dynamics Joint Experiment Attempt to determine role of arctic ice in global weather Ice strain measured by Transit compared with stress-strain models 1975 AIDJEX 50 years of GNSS

  20. Natural Resources Canada: Hans Weber Joe Popelar Jan Kouba Lomonosov Ridge Experiment Is it oceanic or continental in origin? 1979 LOREX 50 years of GNSS

  21. 16 x 250-ton LAPES drops in 7 days Navigation centre LOREX • Camp building • Transit • antenna 50 years of GNSS

  22. Between 3 April and 25 May, the Arctic wind blew all three camps across the ridge Speed varied from 100 to 1000 m/hr One camp came within 12 km of the Pole LOREX 50 years of GNSS

  23. “postulate the limit of this evolution: a cheap “wrist locator” giving instantaneous positions to an accuracy of 1 mm.” . . . “One day, perhaps 100 years from now, the wrist locator will exist” Petr Vanicek Adam Chrzanowski Angus Hamilton Richard Langley John McLaughlin Brad Nickerson 1983 A prediction 50 years of GNSS

  24. 1999 Prediction fulfilled 6 January 1999 - 84 years early!! (but not yet 1 mm accuracy) 50 years of GNSS

  25. Norm Beck Demitris Delikaraoglou Alfred Kleusberg Ed Krakiwsky Gerard Lachapelle Richard Langley Mete Nakiboglu Klaus-Peter Schwarz Jim Tranquilla Petr Vanicek Authors designed book over 1986 Easter Weekend First printing December 1986 Sold 12,252 copies in 12 years Reprinted as UNB TR in 1999 1985 Guide to GPS Ranked in top 2% of Amazon’s 13,000,000 titles!! News flash: free digital copy at http://plan.geomatics.ucalgary.ca/special_publications.html 50 years of GNSS

  26. GEODAS database history • Cumulative • content . • 1960 < 2% • 14% • 1980 40% 50 years of GNSS

  27. GEODAS positioning allocation Mayer et al 2002 50 years of GNSS

  28. The Present (1994 - 2004) • GPS operational • Multiple modes of using GPS • GNSS = GPS + GLONASS + GALILEO + . . . • Numerous (unexpected) GNSS applications 50 years of GNSS

  29. Number of active satellites 50 years of GNSS

  30. GLONASS satellites 1982-2004 80 launched 10 operating Median lifetime 2.3 yrs 50 years of GNSS

  31. GPS satellites 1978-2004 48 launched 29 operating Median lifetime 10.5 yrs 50 years of GNSS

  32. Watch List Clock meets spec watch list dead unused in use Wheel functional watch list dead launch date SVN (PRN) Clock* Wheel 1 2 3 4 1 2 3 4 * II/IIA = Rb, Rb, Cs, Cs IIR = Rb, Rb, Rb Diagonal Line = Unhealthy PLANE A B C D E F 39A(09) 06/93 56R(16) 1/03 24A (24) 07/91 36A (06) 03/94 41R (14) 11/00 51R (20) 05/00 1 SLOT 25A (25)02/92 30A(30) 9/96 33A (03) 03/96 46R (11)10/99 26A (26)07/92 47R(22)12/03 2 43R(13) 07/97 44R(28) 07/00 40A (10) 07/96 38A (08) 11/97 45R (21) 03/03 31A (31) 03/93 3 54R (18) 01/01 35A (05) 08/93 27A (27) 09/92 32A (01) 11/92 34A (04) 10/93 37A (07) 05/93 4 23A (23) 11/90 29A (29) 12/92 13 (02) 06/89 15 (15) 10/90 5 17 (17)12/89 6 GPS Space and Control Clock and Reaction Wheel Performance Status (1 January 2004) 50 years of GNSS

  33. Many modes of GNSS 50 years of GNSS

  34. GNSS augmentation overlays • Purpose: improve accuracy & reliability • “Overlay” = system augmentation = ground station network, & satellites for communications & possibly additional LOPs • Late 1980’s - Geodetic GPS “overlay” - IGS network • Early 1990’s - Marine GPS “overlays” - Starfix, Skyfix, et al & IALA marine beacons • Late 1990’s - Land GPS “overlays” - Omnistar, Landstar • Early 2000’s - SBAS: Space-based augmentation systems - WAAS/LAAS, EGNOS, MSAS • - RTG / C-NAV, Starfix HP / Starfix GSS / Skyfix XP • 2007 - 2015 - new GNSS systems (interoperable?) - GPS modernization, Galileo, QZSS, Beidou 50 years of GNSS

  35. Three overlay strategies • Corrections in observation space • 1. Single baseline service (e.g. IALA) • Limited coverage surrounding each base station • 2. Network (multi-baseline) service (e.g. Starfix HP) • Extended coverage (within network) • Corrections in state-space (orbits and clocks) • 3. Point positioning (actually network state-space) service (e.g. RTG) • Global solution and coverage (may be less accurate than network, within network coverage) 50 years of GNSS

  36. 50 years of GNSS

  37. 50 years of GNSS

  38. 50 years of GNSS

  39. 50 years of GNSS

  40. 139 sites planned 200% land coverage 95% submetre uncertainty 99.9% availability eNDGPS network will provide 3 services 1. Single freq low rate(0.8 - 3 m, 95%) 2. Dual freq low rate (0.8 m, 95%) 3. Dual freq high rate(0.1 - 0.3 m, 95%) 50 years of GNSS

  41. New commercial services • Starfix GSS / SkyFix XP / C-NAV • State-Space solution (broadcast Orbit and Clock corrections) • Use JPL Reference Network and Data Stream • Valid Globally • Must apply Orbits & Clocks corrections, and account for Earth Tide, Ocean Loading, and Satellite Phase Windup etc… • Starfix HP • Measurement correction solution • Available only within service network regions (e.g. 750 km from nearest base station) • Higher Vertical Accuracy 50 years of GNSS

  42. JPL reference network 30 Reference Stations 50 years of GNSS

  43. 85 Reference Stations HP service availability 50 HP Stations World Wide 50 years of GNSS

  44. C-NAV Results Sunil Bisnath, 2002 50 years of GNSS

  45. SKYFIX XP Results Sunil Bisnath, 2002 50 years of GNSS

  46. STARFIX-HP Results Sunil Bisnath, 2002 50 years of GNSS

  47. OTF = on the fly resolution • Search all compatible sets of integers.Faster and easier if • Low noise code (narrow correlators 1992) • Dual frequency (overcome anti-spoofing 1988) • Many satellites (full constellation 1993) 50 years of GNSS

  48. Widelaning today • Obtain beat signal between L1 & L2 • fo = 1.023 MHz • lfo = c = 299,792,458 m/s = 293.0522561 m/c fo 1,023,000 c/s • L1 = 1540 fo = 1575.42 MHz • lL1 = lfo / 1540 = 19.03 . . cm • L2 = 1200 fo = 1227.60 MHz • lL2 = lfo / 1200 = 24.42 . . cm • L1 - L2 = 340 fo • l(L1-L2) = lfo / 340 = 86.19 . . cm 50 years of GNSS

  49. Widelaning after L5 • Using L2 & L5 • L5 = 1150 fo = 1176.45 MHz • lL5 = lfo / 1150 = 25.48 . . cm • L2 – L5 = 50 fo • l(L2 –L5) = lfo / 50 = 5.861 . . m • Impact • Under best conditions, code-DGPS uncertainty is about 1 m. • Not good enough for direct single-epoch L1-L2 widelane ambiguity resolution (86 cm wavelength). • No problem using L2 - L5 (5.9 metre wavelength). 50 years of GNSS

  50. GPS tide concept 50 years of GNSS

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