RTI Unit

The RTI unit calculates the position of the car and the route a chosen destination, decodes traffic bulletins etc. The unit then transmits information to the display based on these calculations. If the voice message has been selected the RTI system sends the voice guide to the audio system via a separate bus which is not part of CAN.

The RTI system includes a position sensor which gives an absolute value through GPS and a gyro which senses the vehicles relative position and angle.

The calculated position is compared with data stored on the CD ROM discs located in the CD changer. The current map and vehicle position are displayed on the system display screen. The TMC radio signal or the FM Multiplex radio signal (depending on market) is supplied via the RTI antenna unit which decodes the signal. The information is then displayed on the screen in the form of symbols.

GPS data is adjusted with dead reckoning and map alignment which means that when the car turns the information from car position on the GPS is aligned to the map information to what the road network looks like. Faulty indication from the GPS can mean that the cars position is outside the road network or on a parallel road for short periods of time until map adjustment occurs.

Depending on the market the receiver for the TMC or FM-MPX is used for traffic information.