Evaluation on the Multi-GNSS Precise Orbit and Clock Products

Transcription

1 Evaluation on the Multi-GNSS Precise Orbit and Clock Products Fei Guo 1, 2, Xingxing Li 3, Xiaohong Zhang 1, Jinling Wang 2 1 School of Geodesy and Geomatics, Wuhan University, China 2 School of Civil and Environment Engineering, UNSW, Australia 3 German Research Centre for Geosciences (GFZ), Potsdam, Germany fguo@whu.edu.cn 1

2 Contents 1.Background 2.Methods 3.Results 4.Conclusions 2

3 1 Background Multi-GNSS Constellations U.S.A. RUSSIA E.U. CHINA JAPAN INDIAN 3

4 1 Background Multi-GNSS Constellations Current: ~7 satellites in orbit Future: over 1 satellites in the sky 4

5 1 Background Multi-GNSS Network BeiDou Galileo QZSS 8 o N 4 o N o 4 o S 8 o S 18 o W 12 o W 6 o W o 6 o E 12 o E 18 o W As a minimum, all MGEX stations support tracking of GPS as well as at least one of the new Galileo, BeiDou or QZSS constellations. Figure 1. The distribution of MGEX stations (~12) and their 1 supported 1.5 2new 2.5 constellations 3 5

6 1 Background Multi-GNSS Products (precise orbits and clocks) com esm GRE GREC GRECJ GREC GRECJ Analysis Centers: gbm gfm grm qzf tum wum GE E EJ C GE Jan May Sep Jan May Sep Jan May Sep Jan May Date GC GREC E E GRE GJ GREC CODE ESA/ECOS GFZ CNES JAXA TUM WHU Figure 2. The availability of MGEX products provided by different ACs (by May 215) 6

7 1 Background Multi-GNSS Products (precise orbits and clocks) 7

8 2 Methods Comparisons between Analysis Centers (ACs) Satellite Laser Ranging (SLR) residuals Clock stability with Allan deviation Test period: 1 Jan May 215 Systems involved: GPS, GLONASS, Galileo, BeiDou, and QZSS 8

9 Radial [cm] Radial [cm] Cross [cm] Cross [cm] Along [cm] Along [cm] Orbit Comparisons GPS/GLONASS 3.1 Results (Orbit Quality) com esm gbm gfm grm qzf wum Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Date Fig. MGEX w.r.t. IGS (GPS) com esm gbm grm wum Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Date Fig. MGEX w.r.t. IGS (GLONASS) GPS: 1-2 cm (except for qzf ), GLONASS: 4-5 cm 9

10 Radial [cm] wum tum Cross [cm] grm gfm Along [cm] gbm esm Orbit Comparisons Galileo 3.1 Results (Orbit Quality) esm gbm gfm grm tum wum Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Date Fig. MGEX w.r.t. CODE (Galileo) E11 E12 E19 E2 E18 E14 Galileo PRN Fig. 3D RMS (Galileo) Galileo 3D RMS: ~15 cm 1

11 3.1 Results (Orbit Quality) Orbit Comparisons Galileo Tab. 3D RMS (Galileo) orbit comparisons amongst all ACs (units: cm) com esm gbm gfm grm tum wum com (32d) 21.5(134d) 9.9(364d) 23.(349d) 16.9(83d) 13.(181d) esm --- N/A* 11.2(15d) 18.1(13d) 14.(32d) 11.9(15d) gbm --- N/A 24.6(97d) 17.7(129d) N/A gfm (143d) 12.6(364d) 12.1(116d) grm (349d) N/A tum (181d) wum

12 MEO [m] IGSO [m] 3D RMS [m] GEO [m] Orbit Comparisons BeiDou 3.1 Results (Orbit Quality) Along-track Cross-track Radial com esm wum BeiDou PRN Fig. 3D RMS (BeiDou) PRN PRN PRN com esm wum Fig. MGEX w.r.t. GFZ (BeiDou) GEOs : 2-3 m IGSOs:.3-.4 m MEOs :.1-.2 m 12

13 3.1 Results (Orbit Quality) Orbit Comparisons BeiDou Tab. 3D RMS (BeiDou) orbit comparisons amongst all ACs (units: cm) com esm wum gbm GEO IGSO MEO GEO IGSO MEO GEO IGSO MEO GEO IGSO MEO com N/A N/A N/A esm wum gbm

14 Radial [cm] Cross [cm] Along [cm] Orbit Comparisons QZSS 3.1 Results (Orbit Quality) com esm qzf Jul Oct Jan Apr Jul Oct Jan Apr Date Fig. MGEX w.r.t. TUM (QZS-1) Tab. 3D RMS (QZS-1) orbit comparisons (units: cm) com esm qzf tum com --- N/A esm qzf tum --- QZS-1:.2-.4 m (except for esm ) 14

15 SLR residual [m] SLR residual [m] SLR Validation Galileo/BeiDou Results (Orbit Quality) C1: ±.289 m C8:.16 ±.77 m C1: -.71 ±.14 m C11: -.1 ±.128 m Sep/14 Oct/14 Nov/14 Dec/14 Jan/15 Feb/15 Mar/15 Apr/15 May/15 Date E11: -.33 ±.142 m E12: -.42 ±.115 m E19: -.39 ±.157 m Sep/14 Oct/14 Nov/14 Dec/14 Jan/15 Feb/15 Mar/15 Apr/15 May/15 Date Fig. SLR residuals (GFZ orbits) 15

16 SLR Validation Galileo/BeiDou 3.1 Results (Orbit Quality) Tab. Mean bias and standard deviation of SLR residuals (units: m) C1 C8 C1 C11 E11 E12 E19 com N/A -.35±.13.3± ± ± ± ±.19 gbm -.491± ± ± ± ± ± ±.157 grm N/A N/A N/A N/A -.17± ±.96.1±.17 wum -.418±.25.9±.62.36± ± ± ± ±.97 One has to keep in mind that the SLR validation primarily assesses the radial component whereas the largest errors occur in the along-track direction. 16

17 QZS [ns] Galileo [ns] GLONASS [ns] GPS [ns] Clock Comparisons 3.2 Results (Clock Quality) GPS/GLONASS/Galileo/QZSS.4.3 Wrt IGS Wrt IAC Wrt COD Wrt TUM 1.5 Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Date com esm gbm gfm grm qzf tum wum GPS: <.1 ns GLONASS:.2 ns Galileo: ~.3 ns QZS-1: ~.5 ns 17

18 Clock difference [ns] Clock Comparisons BeiDou 3.2 Results (Clock Quality).8.7 Wrt GFZ com esm wum GEOs :.4-.5 ns IGSOs:.2-.3 ns MEOs :.1-.2ns BeiDou PRN com esm wum gbm GEO IGSO MEO GEO IGSO MEO GEO IGSO MEO GEO IGSO MEO com N/A N/A N/A esm wum gbm

19 Clock Stability 3.2 Results (Clock Quality) GPS/QZSS (grouped according to the satellite generations) GPS IIA (G1:CAFS; Others:RAFS) G1 G4 G GPS IIR (RAFS) 1-12 G2 G11 G13 G14 G16 G19 G2 G21 G22 G23 G28 y ( ) RAFS clocks are superior to CAFS clocks; y ( ) GPS IIR-M (RAFS) [sec] G5 G7 G12 G15 G17 G29 G GPS IIF+QZS-1 (G24:CAFS;Others:RAFS) G24 G1 G3 G6 G G25 G26 G27 G3 J [sec] The new Block IIF clocks show the best performance, while the oldest Block IIA clocks show the worst stability. 19

20 Clock Stability 3.2 Results (Clock Quality) GLONASS (grouped according to the operational lifetime) y ( ) y ( ) GLONASS (life time:[12,44] months) R21 R18 R2 R3 R7 R8 R GLONASS (life time:[66,91] months) R1 R5 R6 R11 R13 R19 R [sec] 1-11 GLONASS (life time:[57,63] months) R9 R12 R16 R22 R23 R GLONASS (life time:[11,113] months) [sec] R1 R14 R15 R17 The newest clock: R21 (~1 year) The oldest clock: R17 (~9 years) Over trend: the older a CAFS clock, the larger is its Allan deviation. 2

21 Clock Stability 3.2 Results (Clock Quality) BeiDou/Galileo (grouped according to orbit types and clock types) y ( ) y ( ) BeiDou GEO (RAFS) C1 C2 C3 C4 C BeiDou MEO (RAFS) [sec] C11 C12 C BeiDou IGSO (RAFS) C6 C7 C8 C9 C Galileo (IOV/FOC, PHM/RAFS) [sec] E11: IOV PHM E12: IOV RAFS E19: IOV PHM E18: FOC PHM E14: FOC PHM BeiDou: GEO and IGSO clocks are on the same level; MEO clocks are competitive to GPS Block IIR (-M) RAFS clocks Galileo: PHM clocks have a better performance than RAFS 21

22 y ( ) Clock Stability 3.2 Results (Clock Quality) GPS/GLONASS/Galileo/BeiDou/QZSS (different ACs) G G G com --- gbm --- grm qzf G1 --- tum y ( ) R R R R y ( ) y ( ) E E E E C C C J [sec] [sec] [sec] [sec] The Allan deviations computed from different ACs agree well with each other 22

23 GREC [m] C [m] R [m] G [m] Kinematic PPP 3.3 Results (PPP validation) With different precise orbits and clocks East UTC [h] Solutions with different products agree well with each other; the poor performance of BeiDou PPP with com is related to the poor geometry due to the lack of BeiDou GEO satellites. North UTC [h] com esm gbm wum Up UTC [h] 23

24 Up [m] North [m] East [m] Kinematic PPP 3.3 Results (PPP validation) With different systems.4 G GR GC GRC GRCE UTC [h] 24

25 Static PPP 3.3 Results (PPP validation) Processing mode NS PDOP East/m North/m Up/m GPS-only GLONASS-only BeiDou-only GPS+BeiDou GPS+GLONASS GPS+GLONASS +BeiDou GPS+GLONASS +BeiDou +Galileo

26 4 Conclusions Orbit Comparisons In general, orbit comparisons show a consistency of about 1-2 cm for GPS, 4-5 cm for GLONASS, m for Galileo, and.2-.4 m for QZSS in terms of three dimensional (3D) root mean square (RMS). BeiDou orbit comparisons show that the IGSO and MEO orbit differences are mostly within.4 and.2 m, respectively. The GEO orbits, however, show the worst agreements with a few meters differences among ACs, particularly in along-track component. 26

27 4 Conclusions SLR Validation The SLR validation shows an orbit accuracy of 1-15 cm for Galileo (E11, E12, and E19), BeiDou IGSO (C8) and MEO (C1 and C11) satellites, whereas the SLR residuals of BeiDou GEO satellite (C1) show a systematic bias of about -.5 m together with a standard deviation of.3 m. However, One has to keep in mind that the SLR validation primarily assesses the radial component whereas the largest errors occur in the along-track. 27

28 4 Conclusions Clock Comparisons Clock comparisons show a consistency of.1 ns for GPS,.2 ns for GLONASS,.2-.3 ns for Galileo and BeiDou IGSOs,.1-.2 ns for BeiDou MEOs, and.4-.5 ns for BeiDou GEOs among ACs. Clock Stability Clock stability of onboard GNSS is highly dependent on the satellites generations, operational lifetime, orbit types, and frequency standards. PPP Tests Solutions with different products agree well with each other. PPP performance is benefit from the increasing Multi-GNSS. mm-cm for static PPP, 2-3 cm in horizontal and 6-8 cm vertically. 28

29 Thanks for your time 29