How Do Automobile Navigation Systems Work?

Identification

The automobile navigation system is a fairly new technology that found its beginnings toward the end of the 1990s. Through the use of radio waves, space satellites and GPS receivers, a car is able to receive directions to a destination based on its current location. GPS, or global positioning systems, lie at the heart of this technology. These systems rely on a network of 27 satellites, each weighing 3,000 to 4,000 pounds, that orbit the Earth on a continuous basis. Through the use of radio signals, these satellites communicate directional information through a map interface located inside the car. The first car manufacturer to come out with a navigation system was General Motors. Since then, Ford, BMW and Lexus have also incorporated this technology into their manufacturing process. In addition to purchasing a car that comes with a navigation system, these systems can be installed in your car as well.

Function

Once an automobile's navigation system is enabled, its GPS receiver sends a signal out to nearby orbiting satellites. These satellites orbit the Earth according to a pattern which ensures that a minimum of four satellites are accessible from any one point on Earth. The GPS signal is what lets the satellites know to start tracking, or locating, that particular device. These transmissions are carried by radio waves that travel back and forth between the satellites and the car's antenna. Radio waves are used to determine the car's location by tracking how far the waves have to travel to reach the car. It takes a total of four satellites to narrow down an exact location. They do this through a process of elimination called trilateration, in which three of the four make approximations on where the signal originated, while the fourth satellite compiles this data and pinpoints an exact location.

Features

The user interface for an automobile navigation system can vary by design, but typically includes a display monitor and onscreen keyboard. Additional features like voice activation, Internet access and cell phone capabilities are also available in the more sophisticated models. The monitor setup displays map data that's been transmitted from the satellite's database. These maps are derived from real-world survey data compiled by government sources. The driver uses the onscreen keyboard to enter destination information. Once the satellites determine the car's location, mapping data is displayed on the screen. As of late, a newer navigational technology, called Differential GPS, has been developed to make up for certain inaccuracies apparent within the original system. Inaccuracies can come in the form of incorrect map data caused by poor radio signal transmissions. Systems equipped with Differential GPS have the added support of ground stations set up to ensure that accurate signal transmissions take place.

Resources

• Car GPS Reviews
• Differential GPS