Contents 1. Introduction 4 2. Principle of Radio Navigation 5 3. GPS Ephemeris Parameter 8 4. GPS Errors 10 4.1 Ionospheric Error 11 4.2 Troposphere Error 12 4.3 Satellite Clock Error 13 5. Simulation & GPS Toolbox 14 5.1 Calculation of satellite position 20 5.1.1 Mfile Simulation- SV_Ephemeris_Mode