Page 408 - Understanding Automotive Electronics
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FUTURE AUTOMOTIVE ELECTRONIC SYSTEMS 11
Figure 11.20
Automotive GPS
Navigation System
FPO
give the time of transmission. The distance to any satellite is known by the
relationship
R i = ct i – )
(
t r
where
R is the distance to any satellite
i
c is the speed of light
t is the time that the clock pulse is transmitted from satellite to car
i
t is the time that the car receives the pulses
r
The measurement of the propagation time from satellite to receiver (t – t )
i r
requires highly accurate (and expensive) clocks in both the satellite and the car.
Position is determined (in three dimensions and time) by solving four
equations involving the range to four satellites. In GPS service, an accuracy of
UNDERSTANDING AUTOMOTIVE ELECTRONICS 395
