Radio/navigation unit, component description

D82.85-0002-04

N87/1 Radio/radio with navigation

Location

The radio/radio with navigation is installed in the center console.

Task

The radio/radio with navigation controls the following systems:

 Audio system (radio, audio CD)

 Navigation system

 Telephone system (with code (EH3) Universal preinstallation for networked portable CTEL)

Design

Integrated in the radio/radio with navigation are:

 Display

 CD drive

 Operating unit for controlling the audio, navigation and telematics functions

 Audio amplifier

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 Central computer

 Navigation processor

Function

The buttons for the control panel on the radio/radio with navigation are read in and relayed to the central computer. The keys pressed are further processed in the central computer and transmitted to the other system components via the Media Oriented System Transport (MOST) or the Controller Area Network bus class B (interior) (CAN-B) in the form of a Controller Area Network (databus/CAN bus) (CAN) message. If the ON button on the rotary pushbutton is pressed the radio/radio with navigation switches on. The volume for the set audio source is regulated at the rotary switch. The function keys switch over to the audio source desired by the user.

Three fixed contrast settings can be retrieved for better perception of the display information of the radio/radio with navigation.

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CD drive

Data can be read from the navigation CD or an audio CD can be played using the integrated CD drive.

Navigation CD

The following are on the navigation CD:

 Program data for execution in navigation processor

 Voice data for voice output

 Map data.

Navigation processor and GPS control unit.

The navigation processor is integrated into the radio/radio with navigation and calculates the location of the vehicle from the incoming antenna signals and the vehicle's route after the destination has been entered. The navigation processor evaluates the satellite signals coming from the antenna amplifier (A2/18) and uses them to calculate the position of the vehicle.

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Signals from at least 4 satellites are required for the first position calculation. Signals from 3 satellites are subsequently sufficient. If these conditions for position calculation are not met, only the number of satellites appears on the display.

Yaw rate sensor

The yaw rate sensor determines the direction changes of the vehicle. It is installed in the navigation processor. Calibration is not required.

The traffic data memory

The traffic data recorder is located in the radio/radio with navigation. The received data is stored for a maximum of 30 minutes, also during the "run-on time" (up to 100 messages). The traffic data recorder decodes the messages and sends them on internally to the navigation processor as required.

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For synchronization the traffic data recorder requires a current "location list" from the navigation processor. The monitory points required for checking the road network (e.g. freeway exit) are defined by unambiguous numbers in the "location list". The "location list" is stored on the navigation CD. It is loaded automatically into the traffic data recorder by the navigation processor as required.