Principles of Operation

PRINCIPLES OF OPERATION

The navigation module controls the operation and the interface between the user, the vehicle subsystems, and the external components. The navigation module communicates on the standard corporate protocol (SCP) network and can be diagnosed with a scan tool. A dedicated controller area network (CAN) bus is used for transmitting and receiving data between the navigation module and the audio unit to control the video screen display through the video interface circuits.

The vehicle navigation system guides the user to a pre-entered destination. A digital versatile disc (DVD) map stored in the navigation module sends route calculation data to the audio unit. The audio unit displays audibly and visually instructs the user of the maneuvers required to arrive at the destination entered.

A voice recognition system allows the user to interface with the system without using the touch screen. A microphone located in the rear view mirror provides a direct input to the navigation module.

The navigation system uses the global positioning system (GPS) antenna, vehicle speed, and other internal sensor information to accurately establish vehicle position. In order to calculate initial position, the GPS antenna tracks several available satellites simultaneously. The GPS antenna only receives data. It does not communicate with the satellites. A gyroscope, integral to the navigation module, monitors the pitch and yaw of the vehicle created during cornering or turning. A vehicle speed input from the powertrain control module (PCM) and a reverse input from the digital transmission range (TR) sensor through the SCP network are also used to detect vehicle speed and direction changes.