Propagation · Basics Signal, tagged with time from satellite clock transmitte About 66 msec(20,000 km) later the signal arrives at gPs receiver satellite has moved about 66 m during the time it takes signal to propagate to recelver Time the signal is received is given by clock in recelver ference between transmit time and receive time is pseudorange During the propagation, signal passes through the ionosphere (10-100 m of delay phase advance and neutral atmosphere(2 o m depending on elevation angle) 04/01/02 12.540Lec14 Propagation To determine an accurate position from range data. we need to account for all these propagation effects and time offsets In later lectures examine ionospheric and atmospheric delays, and effects near antenna Basic clock treatment in GPs True time of reception of signal needed True time of transmission needed (afo af1 from broadcast ephemeris initially OK Position of satellite when signal transmitted 04/01/02 2.540Lec1404/01/02 12.540 Lec 14 3 Propagation i – transmitted. – at GPS receiver. Satellite has moved about 66 m during the time it takes signal to propagate to receiver. – receiver. Difference between transmit time and receive time is pseudorange. – and neutral atmosphere (2.3-30 m depending on elevation angle). 04/01/02 12.540 Lec 14 4 Propagation data, we need to account for all these propagation effects and time offsets. atmospheric delays, and effects near antenna. – – broadcast ephemeris initially OK) – • Bas cs: Signal, tagged with time from satellite clock, About 66 msec (20,000 km) later the signal arrives Time the signal is received is given by clock in During the propagation, signal passes through the ionosphere (10-100 m of delay, phase advance), • To determine an accurate position from range • In later lectures, examine ionospheric and • Basic clock treatment in GPS True time of reception of signal needed True time of transmission needed (af0, af1 from Position of satellite when signal transmitted