The automatic vehicle location (AVL) component determines the precise location of each tow truck. This information is automatically transmitted to the CHP center in Vallejo for processing and is displayed on a computerized map of the Bay Area. The display system uses icons, or symbols, which change color to show the status of each vehicle. By using color, the dispatcher knows whether a truck is assisting a motorist or is available to answer calls. The AVL system also provides information on each truck's direction and speed.
The vehicle position capability relies on the global positioning system (GPS), a satellite system deployed by the U.S. government for defense purposes. The GPS is designed to provide precise time and position information to land-based, sea-based and airborne platforms. Each FSP vehicle is equipped with a receiver that receives signals from a number of GPS satellites. The vehicle's location is determined by processing these signals.