Topics Satellite motions How are satellite orbits described and how do the satellites move What forces effect the motions of satellites What do gps satellite motions look like and what are the main perturbations to the orbits Where do you obtain GPS satellite orbits 12540Lec01 Topics GPS observables GPS signal structure and its uniqueness Pseudo-range measurements Carrier phase measurements Initial phase ambiguities Effects of GPS security: Selective availability (SA)and antispoofing(AS) Data formats(RINEX) 02/5/03 2540Lec0102/05/03 12.540 Lec 01 7 Topics • orbits 02/05/03 12.540 Lec 01 8 Topics • GPS observables Satellite motions – How are satellite orbits described and how do the satellites move – What forces effect the motions of satellites – What do GPS satellite motions look like and what are the main perturbations to the – Where do you obtain GPS satellite orbits – GPS signal structure and its uniqueness – Pseudo-range measurements – Carrier phase measurements – Initial phase ambiguities – Effects of GPS security: Selective availability (SA) and antispoofing (AS) – Data formats (RINEX) 4