J. Astron. Space Sci. 18(2), 129 136 (2001) GPS,,,, PRECISE ORBIT DETERMINATION OF GPS SATELLITES FOR REAL TIME APPLICATIONS Hyung-Chul Lim, Pil-Ho Park, Jong-Uk Park, Jung-Ho Cho, Yong-Won Ahn GPS Research Group, Korea Astronomy Observatory E-mail: hclim@kao.re.kr (Received September 20, 2001; Accepted October 20, 2001) GPS (Global Positioning System) (Earth Orientation Parameter, EOP) כ. כ, GPS כ EOP כ. IGS (International GPS Service) 3, 15 (UTC) IGU (IGS Ultra Rapid Product). IGU 48 EOP, 24 24 כ. URP (Ultra Rapid Product). 32 IGS 48 URP, IGS EOP. ABSTRACT The accuracy of GPS applications is heavily dependent on the satellite ephemeris and earth orientation parameter. Specially applications like as the real time monitoring of troposphere and ionosphere require real time or predicted ephemeris and earth orientation parameter with very high quality. IGS is producing IGS ultra rapid product called IGU for real time applications which includes the information of ephemeris and earth orientation. IGU is being made available twice everyday at 3:00 and 15:00 UTC and covers 48 hours. The first 24 hours of it are based on actual GPS observations and the second 24 hours extrapolated. We will construct the processing strategy for yielding ultra rapid product and demonstrate the propriety through producing it using 48 hours data of 32 stations. Key words: IGS, IGU, Ultra Rapid Product corresponding author 129
130 LIM et al. 1. IGS. IGP IGU IGR IGF 17 13 1 2 260cm 71cm 25cm 5cm <5cm http://igscb.jpl.nasa.gov/components/prods.html. IGP Springer & Hugentobler (2001). 1. GPS., GPS GPS (Springer & Hugentobler 2001). EOP כ כ כ. GPS. EOP IGS, כ. 1 IGS 48 EOP. IGS 1990 IGP (IGS Predicted Product). IGP 48 EOP, 12 36 כ. IGP EOP כ כ. 1999 La Jolla IGS URP (Springer & Hugentobler 2001). 1999 10 GFZ (GeoForschungsZentrum Potsdam) URP, IGS 2000 5 5 (Analysis Centers, ACs) URP IGU. IGS GPS IGU IGF (IGS Final Product) IGR (IGS Rapid Product). IGF IGR 24 EOP. IGS ACs 1. IGU IGS GPS 1 IGS, ACs 2 URP IGS. IGS 2 55, 14 55 UTC כ 48 IGU. ACs URP 24 Fitting, 24. IGU (Zenith Path Delay) 7mm 1mm (Springer & Hugentobler 2001).
GPS SATELLITES FOR REAL TIME APPLICATIONS 131 NYA1 45 KOKB FAIR YELL DRAO ALGO NLIB GOLD MDO1 BRMU ONSA WSRT WTZR VILL MATE MAS1 BAHR KIT3 LHAS IRKT SHAO TSKB GUAM 0 KOUR FORT MALI AREQ -45 SANT OHIG KERG DAV1 Station used in this processing Station not used in this processing -90 0 90 PERT TIDB AUCK MAC1 MCM4 1. URP GPS. GPS, Bernese, Gipsy-Oasis. EOP כ URP IGU. URP. URP Bernese ACs EOP. 2. GPS (Gurtner et al. 1989). 200 IGS GPS IGS 36, 1 5,000km.,. RINEX (Receiver INdependent EXchange) URP 48 RINEX, כ כ RINEX ( 2). URP. 1. RINEX, IGS 36 24 24., RINEX L1/L2. 2. כ URP IGU EOP
132 LIM et al. Day 178.. Day 182 Day 183 Day 184 Day 185 Day 186 Obs. Data (5days) Obs. Data (2days) Station Coordinates Ultra Rapid Product Ultra Rapid Product (Priori Orbit &EOP).כ 2. Ultra Rapid Product 2.. Measurement Models Orbit Models Estimated Parameters Reference Frame RHC phase rotation correction, Ground ant. phase center calibrations, Troposphere delay, Plate motions, Tidal displacements, Earth rotation, Satellite center of mass correction, Relativity corrections Geopotential(degree 12 and order 12), Sun and moon gravity, Solar radiation pressure and Y-bias, Tidal forces, Relativity Station coordinates, Satellite clock bias, Orbital parameters, Troposphere, Integer ambiguity, Earth orientation parameters J2000 (inertial), ITRF97 (terrstrial), TDT (terrestrial dynamic time). 24 כ EOP, 24 כ Fitting כ. 3. IGR URP 5 ITRF (International Terrestrial Reference Frame) IGS SINEX (Software INdependent EXchange). 4. RINEX, L1 L2 L3 Outlier Cycle slip. 5.. 36 1,000km QIF (Quasi-Ionosphere-Free)., 2,000km QIF (Hugentobler et al. 2001). 6., כ,,. 7. EOP 48 URP. URP EOP. (variation equation) Collocation method (Hugentobler et al. 2001). 2 URP,. כ.
GPS SATELLITES FOR REAL TIME APPLICATIONS 133 3.. Fitting Prediction RMS (cm) Median (cm) RMS (cm) ROCK (T20) 76 134 161 ROCK (T20 Scaled) 72 119 151 JPL Model (Scaled) 10 45 58 ECOM 5 17 22 ) Scaled: Direct solar radiation Y-bias.,, כ. GPS ROCK (Fliegel et al. 1992). 1994 CODE (Center for Orbit Determination in Europe) 9 ECOM (Extended CODE Orbit Model) (Beutler et al. 1994). 3 ROCK 7 Fitting 2 (Springer 1999). (Montenbruck & Gill 2000). 1 2 0, 12 (UTC) radial, along-track (Springer et al. 1999). (Stochastic Orbit Parameter) כ,. כ. (x, y, z) 5mm. 1mm cm, 5mm URP IGF. 3. 2001 7 3 4 48 URP EOP. 36 IGS 32 GPS. 2001 7 2 3 32 IGS. 10 60 RINEX. כ 2000 7 2 IGU, EOP CODE., כ IGS IGS01P27 SINEX. IGS EOP 15 24 URP EOP. 3 1 (Block IIA), 2 (Block II), 3 (Block I), 13 (Block IIR) IGF. IGU IGR. 4
" s ç 134 LIM et al.! ) * ' ( % & 9 : ; ; < = >? @ A B C D E F G H I J K L M N O P +, -. / 0 1 2 3 4 5 6 7 8 r qp no m z { x y v w } ~ ƒ ˆ # $ k l t u f [ \ ] ^ _ g h ` a b c d e i j Q R S T U V W X Y Z «ª ± ² ³ µ ¹ º» ¼ ½ ¾ À â áà Þß Ý Û Ü ê ë å æ è é ã ä ì í î ï ð ñ ò ó ô õ ö ø ù ú Ÿ š œ ž Š Œ Ž Ö Ë Ì Í Î Ï Ø Ð Ñ Ò Ó Ô Õ Ù Ú Á Â Ã Ä Å Æ Ç È É Ê 3. URP (dr IGF ). 4. URP. Fitting Part (cm) Prediction Part (cm) Total (cm) IGR IGU כ IGR IGU כ IGR IGU כ 1 7.0 9.8 11.3 6.9 17.4 30.0 7.0 13.6 20.7 2 5.8 5.7 19.2 6.0 24.4 36.3 5.9 15.1 27.8 3 2.3 10.5 13.9 2.9 16.4 24.6 2.6 13.4 19.2 13 7.1 7.0 8.5 6.0 19.6 19.9 6.5 13.3 14.2 Fitting (24 ) (24 ) (48 ) IGF. IGR 24 Fitting כ., EOP IGF EOP IGU, IGR 5. URP Fitting 2 IGU. 13 IGU 1.5. Fitting 2 כ Fitting, (Propagation). URP 48 IGF 20cm GPS., EOP x, y כ IGU UT1-UTC כ. GPS EOP VLBI (Very Long Baseline Interferometry) SLR (Satellite Laser
GPS SATELLITES FOR REAL TIME APPLICATIONS 135 5. URP EOP. כ IGU IGR x pole y pole t x pole y pole t x pole y pole t (10 6 ) (10 6 ) (µsec) (10 6 ) (10 6 ) (µsec) (10 6 ) (10 6 ) (µsec) 7.3.Oh -40-610 7.7-233 -86-1.5 115-6 -2.9 7.4.Oh -130-421 13.0 472 419 1.1 72 1-3.8 t UT1-UTC Ranging). UT1-UTC 1 µsec GPS 2mm. UT1-UTC 2.6cm. 7 3, 4 x, y 5cm. 4. URP EOP. IGF 20cm. IGU 70cm IGP., EOP. URP GPS. URP 3. 5 ACs IGS. CPU Sun Ultra 2 (200MHz, 256MB) 1 כ. כ., URP כ. Beutler, G., Brockmann, E., Gurtner, W., Hugentobler, U., Mervart, L., & Rothacher, M. 1994, J. Geodesy, 19, 367 Fliegel, H. F., Gallini, T. E., & Swift, E. R. 1992, J. Geophys. Res., 97(B1), 559 Gurtner, W., Beutler, G., & Rothacher, M. 1989, Proceedings 5th International Geodetic Symposium on Satellite Positioning, 1, 362 Hugentobler, U., Schaer, S., & Fridez, P. 2001, Bernese GPS Software Version 4.2 (Berne: Univ. Berne Press), pp.136-246 Montenbruck, O., & Gill., E. 2000, Satellite Orbits(Berlin: Springer), 112 Springer, T. A. 1999, PhD Thesis, University of Berne
136 LIM et al. Springer, T. A., Beutler, G., & Rothacher, M. 1999, J. Geodesy, 73, 147 Springer, T. A., & Hugentobler, U. 2001, Phys. Chem. Earth (A), 26, 623