Sensitivities Satellites move at about 1 km/sec. therefore an error of 1 msec in time results in 1 m satellite position(and therefore in range estimate and receiver position) For pseudo-range positioning, 1 msec errors OK. For phase positioning(1 mm), times needed to 1 usec (1 usec is about 300 m of range Pseudorange accuracy of a few meters in fine 04/01/02 12.540Lec14 Light-time-iteration To compute theoretical range two basic methods used (a" Doppler shift corrections" ie Account for rate o change of range during propagation time used ght-time-iteration "Method most commonly Light time iteration Basic process is to compute range using simple Cartesian geometry but with position of receiver at receive time and position of transmitter at transmit time 04/01/02 2.540Lec1404/01/02 12.540 Lec 14 7 Sensitivities position (and therefore in range estimate and receiver position). OK. For phase positioning (1 mm), times needed to 1 µsec. µsec is about 300 m of range. Pseudorange accuracy of a few meters in fine). 04/01/02 12.540 Lec 14 8 “Light-time-iteration” methods used – (a) “Doppler shift corrections” ie. Account for rate of change of range during propagation time – (b) “Light-time-iteration” Method most commonly used. compute range using simple Cartesian geometry but with position of receiver at receive time and position of transmitter at transmit time. • Satellites move at about 1km/sec, therefore an error of 1 msec in time results in 1 m satellite • For pseudo-range positioning, 1 msec errors • (1 • To compute theoretical range; two basic • Light time iteration: Basic process is to