Satellite Orbit and Ephemeris Determination using Inter Satellite Links

Software DescriptionInter Satellite Links5 SOFTWARE DESCRIPTIONBased on the theory given in the preceding chapters, a software package has beenimplemented. The intention was to allow the analysis of arbitrary satellite constellations,ground networks, force models. The main features are given in Table 5-1.Function / ModuleDescriptionOrbit SimulationNumerical force model integrationForce Model • Earth's gravity as spherical harmonics expansion• Solar- Lunar- and major planets attraction• solid earth tides• air drag• solar radiation pressure• Vehicle Thrust (if commanded)Gravity Models • EGM-96 (360x360), WGS-84 (180x180)Planetary Ephemeris• JGM-1(70x70), JGM-2 (70x70), JGM-3(70x70)GEM-T1 (36x36), GEM-T2 (50x43), GEM-T3 (50x50)• GRIM4-S4 (66x66)JPL DE200 filesIntegration • 4 th order Runge-Kutta with automated step size controlNumber of SatellitesOrbit types• 8 th order Adams-Bashford-Moulton using fixed step sizeNot limitedArbitraryMain Output Precise ephemeris represented by a time series of state vectors (position /velocity)Orbit EstimationMeasurementsTypes • RangeThe orbit estimation from simulated measurements using differentialcorrections applied to the predicted trajectoryGenerated using geometry to "true trajectory", modified by introducingmeasurement errors• Range RateLink Types • Ground links• Inter satellite links (ISL)Errors Simulation • Free space attenuation• Ionospheric refraction• Tropospheric refraction• Random clock offsetPage 70R. Wolf