Navigation Systems: Notes

The navigation systems used on BMW vehicles have been in use since the E38 in 1997.

There have been various versions which have been carried over into other models as well. These navigation systems are possible due to the available Global Positioning System technology.

The BMW Navigation system operates in conjunction with the Global Positioning System (GPS). Utilization of the GPS improves the accuracy and provides redundancy for the Navigation system which also incorporates a dead reckoning system. The GPS was designed by the US Government in the 1970s for military purposes. In recent years it has been made available for civilian use.

There are 24 satellites equally divided among six geosynchronous orbits that are positioned 11,000 miles out in space. Each satellite continuously emits a radio signal. The signals contain short information messages including:

• The exact time the message was broadcast.
• Current latitude and longitude positions relative to the geosynchronous orbit.

A GPS receiver device on earth receives these signals from the satellites and determines its own location by:

• Comparing its internal clock signal with the satellites. This determines the distance from the satellites location.
• Through triangulation computation, the receiver module calculates its own longitude and latitude position. This is only possible when it receives a minimum of three satellite signals.
  Fig 2: Identifying GPS Receiver Device

  Courtesy of BMW OF NORTH AMERICA, INC.

In a sense, GPS can be compared to navigation methods used by sailing ship navigators years ago. They used a sextant to plot the changing locations of known stars to determine their own position. This, in conjunction with compass navigation, proved an accurate method of sailing across the seas.

The BMW navigation system is based on the CARiN(tm) system developed by Philips Electronics. (CARiN(tm) = Car Information and Navigation System.)

The BMW Navigation system is a CD driven, on board, active route mapping computer. The driver can enter a destination through the On Board monitor and the navigation system will select a mapped route, from the current location, to the destination.

The route maps are stored digitally on a navigational database CD that is installed in a dedicated CD drive in the navigation computer.

The U.S. is currently divided into 7 mapped CD database areas ranging from:

• Area 1 - California and Nevada, through
• Area 7 - Covering the South Eastern States.

In addition to the digitized route maps, other information such as hotels, restaurants, service stations, dealerships, points of interest and local sight-seeing attractions along with their addresses are stored on the database CD.

The map CDs are currently being updated twice a year. As the updates occur, more streets and roads will be added. In addition, more local information will be added with regards to businesses, hotels, motels, local attractions, etc.