Precise Orbit Determination of Global Navigation Satellite System of ...

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Chapter 5 Perturbation Models of IGSO,GEO and MEO Satellites Orbits Difference (meter) Difference (meter) 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 dx dy dz 0 24 48 72 96 120 Tim e (hour) 144 168 192 216 240 Figure 5-11 The Effect of Geopotential Perturbation Sectorial and Tesseral Terms, 6≤ n ≤10, 1≤ m ≤n 0.2 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 -0.2 dx dy dz 0 24 48 72 96 120 Tim e (hour) 144 168 192 216 240 Figure 5-12 The Effect of Geopotential Perturbation Sectorial and Tesseral Terms, 7≤ n ≤10, 1≤ m ≤n Figure 5-1 shows total effects of geopotential perturbation with degree and order from 2 to 10 (2≤n ≤10, 0≤ m≤n). Figure 5-2 to Figure 5-6 show effects of geopotential perturbation of zonal terms (J2 to J6 ). Figure 5-7 to Figure 5-12 illustrate the effects of geopotential perturbation of sectorial and tesseral parts. Comparing Figure 5- 1 with Figure 5-2 it can be seen that there are almost same change phases and periods in these two figures, which means that in total geopotential perturbation, zonal term J2 plays a major role (see Fig. 5-2). Interesting is that the even order terms have the same change phases and periods as the total perturbation effects, odd order terms have reverse phases that act as reducing the effects of the even order terms. From Table 5-1 and Table 5-2 and Figure 5-12, it can be found that the geopotential model whose degree and order are more than 6 has an effect of max. 3 cm on IGSO satellite after ten days, thus the effect of geopotential model with degree more than 6 may be neglected in the satellite dynamic model if the accuracy of orbit determination to be within one meter is required. Also from Figure 5-7 and Figure 5-8 there are some resonant phenomenon existing. According to Blitzer (1966), the coefficients of geopotential C22, S22 are resonant terms for 24 hour satellite. The resonant term means that if the force frequency is equal to the natural frequency of the satellite orbital motion, a dynamical resonance occurs. In other words, the influence of geopotential perturbations from these two coefficients on 24-hour satellite like GEO and IGSO are significantly increased. Figure 5-13 shows the effects of these two resonant terms on IGSO satellite. Although there are other resonant terms, for example, C31 S31, C32, S32, C33, S33, C41, S41, C42, S42, etc., but compared to C22,S22, the effects from these terms are very small. 50
Chapter 5 Perturbation Models of IGSO,GEO and MEO Satellites Orbits Difference (kilometer) 30 20 10 0 -10 -20 -30 dx dy dz 0 24 48 72 96 120 Tim e (hour) 144 168 192 216 240 Figure 5-13 The Effect of Geopotential Perturbation Model C 22,S 22 5.1.3.2 Geopotential Influence on GEO Satellite The following results are for geostationary (GEO) satellites. A GEO orbit is one where the orbit has the same period as IGSO satellite (24 hour), but remains at a fixed point in the sky at all times and stationary over a single point on the Earth's surface. Obviously, a GEO satellite is a special case of IGSO satellite with inclination of orbit i=0. The effects of geopotential on GEO satellite orbit are shown in Table 5-3 and Table 5-4. Table 5-3 The Effect of Geopotential Perturbation on Geostationary Satellite Orbit (Zonal Part ) (Satellite Parameters: a=42164.174km, λ=20°, i=0°) Perturbation Force Acceleration Orbit Errors (m) (m/sec 2 ) One Day Ten Days J2 8×10 -6 19.7 (km) 196 (km) J3 3×10 -9 0.00 0.02 J4 3×10 -10 0.84 8.42 J5 7×10 -12 0.00 0.00 J6 3×10 -12 0.01 0.07 J7 3×10 -13 0.00 0.00 J8 3×10 -14 0.00 0.01 J9 3×10 -15 0.00 0.00 J10 9×10 -16 0.00 0.00 51
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PRECISE ORBIT DETERMINATION OF GLOB
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Summary GNSS-2 (Global Navigation S
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3.2.2.1 Principle..................
Page 8 and 9: 9.3.3 The Effect of Distribution of
Page 10 and 11: Chapter 1 Introduction 1.2 Developm
Page 12 and 13: Chapter 2 Observations of Orbit Det
Page 26 and 27: Chapter 3 Orbit Tracking System and
Page 40 and 41: Chapter 4 Major Error Sources of Sa
Page 52 and 53: Chapter 5 Perturbation Models of IG
Page 74 and 75: Chapter 6 Algorithms of Orbit Deter
Page 94 and 95: Chapter 7 Orbit Determination Using
Page 104 and 105: Chapter 8 Geostationary Orbit Deter
Page 106 and 107: Chapter 8 Geostationary Orbit Deter
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Chapter 8 Geostationary Orbit Deter
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Chapter 9 Software and Simulation R
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Conclusion 144
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References Carpino M. (1995): SAEG
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References Klobuchar, J. A.(1996):
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References Traquilla, J. M. and J.
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Acknowledgments 152
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