In the case of a moving emitter or a moving receiver, the received frequency is Doppler shifted fr(received)+ fe(emitted) by an amount Af which, apart from relativistic effects, is proportional to the radial velocity Vp dp/dt= p of the emitter with respect to the receiver 電 Principles of the Global Positioning System 2005-3-18(7 Af=? Example GPS mean velocity=3.9km/s Radial velocity=0; thus, No Doppler effect Max radial velocity =0.9km/s, GPS transmitted f=1. 5GHz Doppler frequency shift Af-? 4.5103Hz Phase change=4.5 cycle Principles of the Global Positioning System 20053-18(84 Principles of the Global Positioning System 2005-3-18 7 Principles of the Global Positioning System 2005-3-18 8 ∆f = ? Example: GPS mean velocity = 3.9km/s Radial velocity = 0; thus, No Doppler effect Max radial velocity = 0.9km/s, GPS transmitted f = 1.5GHz Doppler frequency shift ∆f= ? 4.5·103Hz Phase change = 4.5 cycle