| A
Chip-equipped
phone measures the amount of time it takes for a satellite's radio signal
to reach the phone.
Since the speed of radio signals is known, the
distance from the satellite can be calculated. |
The phone then measures the
time for a second satellite's signal to reach the phone.
The phone is at one of the two points where the
first and second circle overlap. |
When the phone can receive a
signal from three or more satellites the location becomes precise.
The location must then be transmitted to the 9-1-1
center and displayed on a map so the Dispatcher can determine the proper
responders. |
