Technical Impact of Multiple GNSS on Applications

Transkript

1 Technical Impact of Multiple GNSS on Applications Professor Gethin Wyn oberts Dr. Lawrence Lau Dr. Craig Hancock University of Nottingham 1 of 23

2 Overview Discrepancy among the GNSS eference Frames Discrepancy among the GNSS eference Time Systems Impact on the Mainstream Applications (i.e., SPP) Impact on the Land/Engineering Surveying Applications (i.e., TK including NTK) Impact on the Standalone/emote Precise Positioning Applications (i.e., Precise Point Positioning - PPP) Summary and Discussion 2 of 23

3 Discrepancy between ITF and GNSS reference frames Discrepancy between ITF2000 and WGS84 (G1150): two reference frames are essentially identical with differences being statistically insignificant for most applications (NGA, 2003), ~1-2cm (Slater, J.A. - NGIA) -> WGS84(G1674): sub-cm? Diff. ITF2000/ITF2005 < diff. ITF2000/WGS84 Discrepancy between ITF2005 and GTF: sub-mm Discrepancy between ITF2000 and PZ90.02 (introduced 20 Sept 2007): No rotation, dx:-36cm, dy: 8 cm, dz:18cm (Ørpen, 2008) Discrepancy between ITF2000 and CGCS 2000: +/- 3 cm or less (Cheng, et. al.,2009)? US National Geospatial Intelligence Agency (NGA), Addendum to NIMA T : Implementation of the World Geodetic System 1984 (WGS 84) eference Frame G1150, O. Ørpen (Fugro Seastar), GNSS Status, Havbunnskartlegging og Inspeksjon, Geilo 6-8 Feb CHENG P., et. al. (Chinese Academy of Surveying and Mapping), China Geodetic Coordinate System 2000, Eighteenth United Nations egional Cartographic Conference for Asia and the Pacific Bangkok, October of 23

4 GNSS eference Time Systems GGTO specified requirement of 5 ns, 2 sigma over 24 hour (Hahn & Powers, 2005) > too challenging Error of determining GLONASS Time/GPS Time is no more than 20 ns (IT) GPS Time & Beidou Time (BDT) -> GBTO: 20 ns or better? J. Hahn & E. Powers, 2005, Implementation of the GPS to Galileo Time Offset (GGTO), in Proceedings of the 2005 Joint IEEE International Frequency Control Symposium and Precise Time and Time Interval (PTTI) Systems and Applications Meeting, August 2005, Vancouver, Canada (IEEE 05CH37664C), pp ussian Institute of adionavigation and Time (IT), Complementarity of GNSS egarding System Time Scales, 4 of 23

5 Single Point Positioning (SPP) - Mass Market applications T0 GPST (X,Y,Z) WGS84 Transit time T t (X,Y,Z) WGS84 5 of 23

6 Single Point Positioning/Navigation solution ( S1 ) ( S1 ) ( S1 X X ) Y Y Z Z c S1 S1 S1 ( S 2 ) ( S 2 ) ( S 2 ) X X Y Y Z Z c S 2 S 2 S 2 X Y Ax = ( S 3 ) ( S 3 ) ( S 3 X X ) l Y Y Z Z = c Z S 3 S 3 S 3 t M M M M ( Sn ) ( Sn ) ( Sn X X ) Y Y Z Z c Sn Sn Sn l = P ( + ( δt δt ) c + I + T + ε ) X n k k k k k k i i i i i 1, i 6 of 23

7 Single Point Positioning (SPP) - Mass Market applications T0 GST (X,Y,Z) GT F T0 GPST (X,Y,Z) WGS84 Transit time T t (X,Y,Z) WGS84 (X,Y,Z) GT F 7 of 23

8 k k k k k k P = + ( δt δt ) c + I + T + ε1, Single Point Positioning (SPP) - Mass Market applications A x = G 1 G 1 G 1 ( X X ) ( Y Y ) ( Z Z ) i i i i i i c 0 0 G 1 G 1 G 1 M M M M M M G n G n G n ( X X ) ( Y Y ) ( Z Z ) c 0 0 G n G n G n E 1 E 1 E 1 X ( X X ) ( Y Y ) ( Z Z ) 0 c 0 Y E 1 E 1 E 1 Z M M M M M M E n E n E n t, G ( X X ) ( Y Y ) ( Z Z ) 0 c 0 t, E E n E n E n t, B B 1 B 1 B 1 ( X X ) ( Y Y ) ( Z Z ) 0 0 c B 1 B 1 B 1 M M M M M M One freq. B n B n B n ( X X ) ( Y Y ) ( Z Z ) only!, 0 0 c B n B n B n more.. 8 of 23

9 Single Point Positioning (SPP) - Mass Market applications GNSS time offsets Can be aligned by applying the broadcast GxTO Estimate in user level GNSS reference frames Can be neglected (ecommended!!) Can be mitigated by applying given transformation parameters Satellite coordinates User position 9 of 23

10 k k k k k k l = Pi ( i + ( δti δt ) c + Ii + Ti + ε1, i ) Single Point Positioning (SPP) - Mass Market applications A x = G 1 G 1 G 1 ( X X ) ( Y Y ) ( Z Z ) c 0 0 G 1 G 1 G 1 M M M M M M G n G n G n ( X X ) ( Y Y ) ( Z Z ) c 0 0 G n G n G n E 1 E 1 E 1 X ( X X ) ( Y Y ) ( Z Z ) 0 c 0 Y E 1 E 1 E 1 Z M M M M M M E n E n E n t, G ( X X ) ( Y Y ) ( Z Z ) 0 c 0 t, E E n E n E n t, B B 1 B 1 B 1 ( X X ) ( Y Y ) ( Z Z ) 0 0 c B 1 B 1 B 1 Use User GxTO estimates M M M M M M B n B n B n ( X X ) ( Y Y ) ( Z Z ) IFB/ICB? 0 0 c B n B n B n 10 of 23

11 elative Positioning - Land/Engineering surveying T0 GPST (X,Y,Z) WGS84 t rov, GPST t ref, GPST t t ref, GPST rov, GPST (X,Y,Z) ref,wgs84 (X,Y,Z) rov,wgs84 11 of 23

12 elative Positioning - Land/Engineering surveying 1 GNSS, 3 Freq. Φ = I + T + λ N + ε kl kl kl kl kl kl 1, ij ij ij ij 1 1, ij 1, ij Φ = ( f / f ) I + T + λ N + ε kl kl 2 kl kl kl kl 2, ij ij 1 2 ij ij 2 2, ij 2, ij Φ = ( f / f ) I + T + λ N + ε kl kl 2 kl kl kl kl 5, ij ij 1 5 ij ij 5 5, ij 5, ij Medium/Short baselines Φ = + λ N + ε kl kl kl kl 1, ij ij 1 1, ij 1, ij Φ = + λ N + ε kl kl kl kl 2, ij ij 2 2, ij 2, ij Φ = + λ N + ε kl kl kl kl 5, ij ij 5 5, ij 5, ij l = Φ ( + λ N + ε ) kl kl kl kl 1, ij ij 1 1, ij 1, ij 12 of 23

13 elative Positioning - Land/Engineering surveying T0 GST T0 GPST (X,Y,Z) GTF (X,Y,Z) WGS84 t ref, GPST t ref, GST t rov, GST t rov, GPST (X,Y,Z) ref,wgs84? (X,Y,Z) rov,wgs84? 13 of 23

14 elative Positioning - Land/Engineering surveying T0 GST T0 GST T0 GPST T0 GPST (X,Y,Z) GTF (X,Y,Z) GTF (X,Y,Z) WGS84 t ref, GST t rov, GST (X,Y,Z) WGS84 t rov, GST t ref, GPST t rov, GPST t ref, GPST t ref, GST t rov, GPST l = Φ ( + λ N + ε ) kl kl kl kl 1, ij ij 1 1, ij 1, ij Single difference + models (X,Y,Z) ref,wgs84? (X,Y,Z) rov,wgs84? 14 of 23

15 elative Positioning - Land/Engineering surveying ( ) ( ) ( ) ( ) ( ) ( ) G2 G1 G2 G1 G2 G1 X X X X Y Y Y Y Z Z Z Z λ L 0 0 L 0 G2 G1 G2 G1 G2 G1 M M M 0 O 0 M O M M O M X Gn G1 Gn G1 Gn G1 ( X X ) ( X X ) ( Y Y ) ( Y Y ) ( Z Z ) ( Z Z ) Y 0 0 λ 0 L 0 0 L 0 Gn G1 Gn G1 Gn G1 Z G2G1 E2 E1 E2 E1 E2 E1 ( X X ) ( X X ) ( Y Y ) ( Y Y ) ( Z Z ) ( Z Z ) N 0 L 0 λ L 0 E2 E1 E2 E1 E2 E1 M GnG 1 N Ax = M M M M O M 0 O 0 M O M E2E1 N En E1 En E1 En E1 ( X X ) ( X X ) ( Y Y ) ( Y Y ) ( Z Z ) ( Z Z ) 0 L λ 0 L 0 M En E1 En E1 En E1 EnE 1 N B2 B1 B2 B1 B2 B1 ( X X ) ( X X ) ( Y Y ) ( Y Y ) ( Z Z ) ( Z Z 2 1 ) B B N 0 L 0 0 L 0 λ 0 0 B2 B1 B2 B1 B2 B1 M BnB 1 M M M M O M M O M 0 O 0 N Bn B1 Bn B1 Bn B1 ( X X ) ( X X ) ( Y Y ) ( Y Y ) ( Z Z ) ( Z Z ) 0 L 0 0 L λ Bn B1 Bn B1 Bn B1 15 of 23

16 elative Positioning - Land/Engineering surveying ef. station over e.g., 10 cm/year Intraplate earthquake and other local deformation such as subsidence and landslides!! 16 of 23

17 elative Positioning - Land/Engineering surveying over VS NTK stations e.g., 10 cm/year Intraplate earthquake and other local deformation such as subsidence and landslides!! 17 of 23

18 Precise Point Positioning (PPP) Standalone/remote precise positioning applications + Precise ephemeris T0 GPST? (X,Y,Z) ITF T t + High-precision carrier-phase data (X,Y,Z) ITF 18 of 23

19 Precise Point Positioning (PPP) Standalone/remote precise positioning applications P = + ( δt δt ) c + I + T + ε Φ k k ( k ) k k k k i = i + δti δt c Ii + Ti + λni + εi, Φ k k k k k k i i i i i i, P Iono-free f c t MF ZTD P k k k P = i + δ i + + εi, P i = 0 f = + cδt + MF ZTD + λn + ε Φ = Φ Iono-free k k k k i i i i, Φ i 0 19 of 23

20 ( ) ( ) ( ) G1 G1 G1 X X Y Y Z Z Precise Point Positioning (PPP) Standalone/remote G1 precise positioning applications Phase P c 0 MF λl L 0 G G G M M M M M M 0 O 0 M O M Gn Gn Gn ( X X ) ( Y Y ) ( Z Z ) Gn c 0 MF 0 0 λl 1 0 L 0 Gn Gn Gn E1 E1 E1 X ( X X ) ( Y Y ) ( Z Z ) E1 0 c MF L λl Y E E E Z M M M M M M M O M 0 O 0 t, G En En En ( X X ) ( Y Y ) ( Z Z ) En t, E 0 c MF En En En L λl 1 ZTD Ax = = l G1 G1 G1 G1 ( X X ) ( Y Y ) ( Z Z ) N G1 c 0 MF G1 G1 G1 L L M Gn M M M M M M M O M M O M N E1 Gn Gn Gn ( X X ) ( Y Y ) ( Z Z ) N Gn c 0 MF 0 L 0 0 L 0 Gn Gn Gn M En E1 E1 E1 N ( X X ) ( Y Y ) ( Z Z ) E1 0 c MF E1 E1 E1 L L M M M M M M M O M M O M En En En ( X X ) ( Y Y ) ( Z Z ) En 0 c MF En En En L L 20 of 23

21 Precise Point Positioning (PPP) Standalone/remote precise positioning applications Site displacement effects Solid Earth tides Ocean loading Sub-daily Earth otation Parameters (i.e. Pole position Xp, Yp and UT1-UTC) Satellite attitude effects Satellite antenna offset Phase wind-up correction IFB/ICB 21 of 23

22 Summary and Discussion Transform all GNSS reference frames to a reference frame Align all GNSS reference time to a reference time Multiple GNSS Benefits and esiduals SPP eference frames eference time elative positioning eference frames eference time PPP eference frames eference time 22 of 23

23 END Thank you for your attention 23 of 23

24 Local Datum Difference to Local Datum depends on the time of synchronization with ITF or other GNSS reference frames Tectonic movement of the corresponding plate Preferably there is a set of transformation parameters between the national datum and the selected GNSS reference frame 24 of 23