Cellular 9-1-1 GPS Location
| The GPS system consists of 24 earth-orbiting satellites. A chip embedded in the wireless phone receives signals from three or more satellites and calculates the location as described below. | ||
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| 1 | 2 | 3 |
| 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. |
