Navigation Computer
The navigation computer is located in the left hand rear corner of the luggage compartment. The navigation computer is a DVD based unit which allows for a greater capacity of data to be stored on the map disc when compared to previous CD based units. The navigation computer incorporates a GPS receiver, a Piezo gyro sensor and the voice recognition software and receives inputs from the ABS Unit and the GPS antenna..
The navigation computer contains a solid state piezo gyro which measures the motion of the vehicle around its vertical axis. The gyro operates on the principle known as the Coriolis force. The Coriolis force is the force that appears to accelerate a body moving away from its rotational axis against the direction of rotation of the axis.
Using the inputs from the ABS module, the GPS antenna and the gyro sensor, the computer calculates the vehicle's current position, direction and speed.
The navigation computer houses the DVD-ROM drive. The drive is used to read map data from region specific DVD's (1 DVD for each of the following regions: EU, US, Japan and Australia). A button, located adjacent to the DVD slot, is provided to eject the DVD from the unit. If the ignition is on, or the Entertainment System is in 1-hour mode, one press of the button will eject the DVD.
The GPS receiver receives information from between 1 and 8 satellites at any one time. This information is received from the GPS antenna. The built in GPS receiver is used for calculating the position (i.e. Latitude, longitude and height), direction and speed.
The navigation computer uses non-volatile memory to store settings and configuration information when it is powered down. This process takes place just before the computer turns off.
The navigation computer is connected to the TSD by a private CAN bus and a GVIF serial link. The GVIF serial link carries all video information from the navigation computer to the TSD. The CAN bus carries data and control instructions to and from the TSD.
Three connectors provide the interface between the navigation computer, the TSD and the GPS antenna and the VICS receiver. The TMC receiver is connected on the MOST ring.
For the Japanese market the navigation computer is a different component. Although it looks identical the software is specific to Japan market and the part number is different. The system also has extra components for the VICS system (a receiver and an antenna). The VICS system receiver allows the vehicle to receive information about traffic conditions from roadside transmitters and adjust the navigation instructions accordingly. The VICS information is received by both a radio link and an infra red link. For this reason the VICS beacon antenna is located on the inside of the windscreen.