33 1 Vol. 33, No. 1 2015 2 PROGRESS IN ASTRONOMY Feb., 2015 doi: 10.3969/j.issn.1000-8349.2015.01.07 BDS 1,2 1 1 3 3 3 1,2 3 1 (1. 200030 2. 100049 3. 100094) BDS BDS ( ICD ) DOP GEO BDS 50% 60% P173 A 1 (GNSS) (BDS) BDS 2014-05-27 2014-06-03 (11203059 41204023) (13-01-07) (14DZ2276100) hxg@shao.ac.cn
1 BDS 123 2013 2020 GNSS GNSS BDS [1] [2] BDS (GEO) (IGSO) (MEO) GEO MEO BDS BDS ICD (Interface Control Document) [2] [2, 3] GPS WAAS (Wide Area Augmentation System) [4] BDS GNSS BDS 2 2.1 i j P j i = X sat X rcv + c( t i t j ) + ε orb + ε satclk + t Iono + t Trop + t cor + ε j i. (1) P j i X sat X rcv t i t j ε orb ε satclk t Iono t Trop t cor ε j i (1)
124 33 pcor j = (ε orb + ε satclk ), (2) pcor j j 2.2 (2) (dr, dt, dn) i ε orb = a i dr + b i dt + c i dn (a i, b i, c i ) [5,10] GEO G5 (60 E) G4 (160 E) 1 R, T, N 1 1 (a) GEO4 (b) GEO5 01 02 03 04 05 T N IGSO
1 BDS 125 1 GEO 4 GEO 5 R 0.002 0.005 T 0.050 0.060 N 0.070 0.080 2.3 WAAS BDS 2 2 [6] T AS = 1 2 (R A R S ) + 1 2 [(τ A T + τs R ) (τs T + τa R )] + 1 ion (τas τsa ion ) + 2 1 tro (τas τsa tro ) + 1 2 2 (τ AS G τsa) G + 1 2 (τ AS τ SA ), (3) T AS R A R B τ A T τ S T τ A R τ S R ion ion τ AS τ SA
126 33 τ AS tro tro τ SA τ AS G τ SA G τ AS τ SA 1 ns [3,7] kalman [4] ε satclk n n Clk sta = (ρ(o) ρ (C) ). (4) n ρ (C) ρ (O) (dx i j dy i j dz i j) ρ i(o) j ρ i(c) j = A dx i j dy i j dz i j dr i = A RT N dt i, (5) dn i A i j 2.4 1 ns [5] [2] BDS DOP DOP (5) Q RT Ni = (A T RT Ni P i A RT Ni ) 1 RDOP i = Q RT Ni1,1, T DOP i = Q RT Ni2,2, NDOP i = Q RT Ni3,3. (6) 10 BDS 2 2 34 R 4.3 T 26.6 N 19.5 3 GNSS BDS
1 BDS 127 2 SatID RDOP T DOP NDOP P DOP SatID RDOP T DOP NDOP P DOP GEO1 2.2 17.3 15.2 23.1 IGSO6 4.2 31.2 17.9 36.2 GEO3 2.1 18.2 11.8 21.8 IGSO7 4.1 30.5 18.0 35.6 GEO4 6.9 38.4 36.7 53.6 IGSO8 4.0 29.4 16.8 34.1 GEO5 4.2 28.0 19.6 34.5 IGSO9 4.2 30.8 17.0 35.4 MEO11 7.5 22.3 29.3 37.6 IGSO10 3.8 28.4 16.4 33.0 MEO12 4.6 18.3 16.1 24.8 Mean 4.3 26.6 19.5 33.6 BDS (24MEO+3GEO+3IGSO) 3 cowell MEO MEO IGSO GEO 20 50 MEO 3 IGSO GEO 0 5 4 5 6 3 BDS 4
128 33 5 6 0.002 m [8] 0.01 m 4 DOP UERE [9] = DOP UERE UDRE 4.1 DOP MEO IGSO GEO R T N 24 h RMS 3 RMS = mean 2 + std 2 mean std 3 20 MEO IGSO GEO 50% R T 10% R N
1 BDS 129 3 MEO-06 MEO-10 IGSO-28 IGSO-30 IGSO-25 IGSO-26 DOP (COV ) RDOP T DOP NDOP P DOP R/T R/N T/N 2.456 14.094 9.911 17.404 0.796 0.725 0.355 / 1.248 5.317 6.076 8.169 0.702 0.630 0.354 1.946 11.860 9.483 15.308 0.842 0.504 0.273 / 2.282 5.994 5.478 8.434 0.640 0.432 0.249 1.536 15.776 12.438 20.148 0.723 0.655 0.313 / 1.195 7.341 6.322 9.761 0.701 0.464 0.230 1.205 14.189 12.475 18.931 0.655 0.695 0.267 / 1.150 7.026 6.337 9.531 0.616 0.509 0.222 2.364 19.452 12.296 23.133 0.942 0.695 0.466 / 0.880 7.470 5.353 9.232 0.840 0.439 0.146 1.812 17.744 11.129 21.023 0.964 0.307 0.183 / 0.722 6.543 4.953 8.238 0.884 0.268 0.132 20% T N 20% 1 MEO 1 GEO 1 IGSO P DOP 7 7 (a) 6 MEO (b) 26 GEO (c) 28 IGSO SG SS DOP MEO IGSO 7 / P DOP DOP
130 33 8 1 MEO / R 4 cm T 18 cm N 11 cm R 1 cm T 4 cm N 5 cm 8 MEO (a) (b) / 4.2 UDRE UERE (UERE) (UDRE) [2] 3 1 2 (dx i j dyj i dzj) i 3 (dx i j dyj i dzj) i ( 4) ( ) ( ) 2 3 UDRE UERE 9 10 UERE UDRE 1 1 UDRE 2 2 UDRE 3 3 UDRE UDRE UDRE UDRE
1 BDS 131 9 UDRE UERE 10 UDRE UERE 5 BDS BDS GEO/IGSO DOP
132 33 (dx i j dyj i dzj) i T N 20 30 R 4 BDS MEO IGSO GEO 50% R T 10% R N 20% T N 20% UDRE 60% [1] www.beidou.gov.cn, 2014 [2] Cao Y L, Hu X G, et al. Sci China Phys Mech Astron, 2012, 55: 1307 [3] Zhou S S, Cao Y L, et al. Sci China Phys Mech Astron, 2012, 55: 2290 [4] Yeou-Jyh Tsai. Dissertation. Stanford: Stanford University, 1999: 175 [5],,. GPS ( ). :, 2004: 97 [6],., 2004, 22(3): 219 [7] Zhou S S, Hu X G, Wu B, et al. Sci China Phys Mech Astron, 2011, 54: 1089 [8] Karl S, Zeta AI, Peter S, et al. ION GPS 2001. Utah: ION, 2001: 2334 [9] Jiao W H, Ding Q, Li J W, et al. Sci China Phys Mech Astron, 2011, 41: 521 [10] Cai C L, Li X H, Wu H T. Sci China Ser G-Phys Mech Astron, 2009, 52: 310 The Method for Real-time Wide Area Differential Corrections of BDS with Inter Satellite Links CAO Yue-ling 1,2, HU Xiao-gong 1, ZHOU Shan-shi 1, LIU Li 3, WU Xiao-li 3, SU Ran-ran 3, CHANG Zhi-qiao 3, HE Feng 3, WU Bin 1 (1. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China; 2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China; 3. Beijing Global Information Application and Development Center, Beijing 100094, China) Abstract: Real-time wide area differential corrections ensure BDS authorized users with high-accuracy navigation service. A new method for introducing time synchronization observations for the correction estimation is introduced, the performance of two approaches with one- or four-dimensional correction parameters are compared. Results show that for
1 BDS 133 one-dimensional approach, the correction accuracy will decrease when the orbital errors are large. Therefore it is not suitable for the situations such as quickly orbit determination recovery after satellite failure or maneuver. While for four-dimensional approach, the stability and precision of ephemeris and satellite clock parameters are seriously affected by the limited regional monitoring network. Considering that the Inter satellite links will be setup to support auto-navigation for the global BDS system, the separation of orbital and satellite clock errors is discussed with inter satellite links. Simulation processing results show that the orbital errors in ephemeris may be effectively solved with inter satellite link observations, and propagation error may be reduced by 50%. Compared with one-dimensional approach, the performance of four-dimensional approach is also improved by 60% in the area lacked monitor stations. Key words: equivalent satellite clock error; separation of orbital and clock error; inter satellite links; DOP; UDRE