When we were 200 miles west of Albuquerque, we decided we wanted Mexican food. I found plenty of restaurants in the database, but it lists only the name, phone number and address, not whether the food is any good. So I used the database to find a hotel and used our mobile phone to ask the concierge to recommend a good Mexican restaurant. I located that restaurant on Magellan and called to make sure it'd be open. I was told it'd serve us as long as we arrived by 10 p.m.
All commercial systems use a combination of three technologies.
The car is equipped with such a receiver. The computer in the car is equipped with a detailed digital map of a given area, its size dependent upon population density. Every street, address, business, park, hospital, driveway, and more is entered on a changeable drive on the computer. At present about six drives are required to map the United States. Using a combination of all of these technologies, the car's navigation system can pinpoint its location, follow itself as the vehicle moves and give directions to a preprogrammed destination.