Radio function - GF82.60-P-4109-04P

Processing key signals 

The controls on the radio (A2) are read in via the I/O ports of the microcontroller and made available to the central computer. Depending on the system function the button operations are further processed in the central computer or conveyed in the form of a data telegram to the system components (e.g. CD changer) involved via the Digital Data Bus (D2B) or interior CAN (CAN-B).

Display 

The display of the radio (A2) has 197 x 32 pixels. Texts are displayed in 3 lines.

After particular functions have been called up (e.g. navigation), the lowest line of the display shows variable marking for the row of buttons underneath it (multifunction buttons). This allows the system to be operated very conveniently with few buttons, as the function which is activated when the button is pressed is always displayed in plain text (e.g. SPRA, POS, DYN, UHR, etc.).

Audio signal output 

The audio signals from the various sources (CD, voice output for navigation, etc.) are processed by the radio (A2) and amplified before being output by the vehicle speakers.

With code (810) sound system the final amplification of the audio signals takes place through the sound amplifier (A2/13). For this purpose the audio source data (low-frequency signals) are transmitted to the Sound amplifier (A2/13) via separate lines.

All the data are transmitted via the D2B.

Audio mute 

An incoming telephone call activates the audio mute function (for this there is a separate signal input on the radio (A2)). When the audio mute function is active the current audio source (e.g. radio) is muted automatically.

Navigation processor, GPS control unit and gyrosensor 

The navigation processor is the central component of the navigation system.

It is integrated into the radio (A2) and from the incoming signals continuously calculates the location and, after the destination has been entered, calculates the route for navigation. The GPS receiver is integrated into the navigation processor. It evaluates the satellite signals coming from the GPS antenna (A2/23) and calculates from this the vehicle position in degrees of longitude and latitude.

Reception from at least 3 satellites is necessary for an exact GPS position calculation. A free view of the sky is required for this purpose.

The integrated gyrosensor continuously senses every change in direction of the vehicle. Evaluation of this data is accomplished by the navigation processor.

Calibration of the yaw rate sensor is not required.

DVD disk drive and DVD 

The DVD disk drive of the radio (A2) reads data from the inserted Navigation DVD and makes this available to the navigation processor via a data bus inside the device.

Audio CDs can also be played.

The following are located on the navigation DVD:

• Program data for the navigation processor
• Voice segments for the voice output
• Map data.

Within the DVD map area a distinction is made between digitized and non-digitized areas:

• Towns, cities, roads, intersections and their attributes (e.g. one- way streets, no turns etc.) are recorded in the digitized map area.
• The non-digitized areas include, for example, company and private grounds, farms, small housing estates, tracks across fields and the areas between the towns. No data is available here.

Diagnostic interface (K-line) and fault management of D2B components 

During operation, the system stores all occurring faults in the nonvolatile memory.

Fault management of the radio (A2) also includes the connected D2B components. For this purpose, each D2B component has its own DTC memory. The faults are transmitted from the corresponding components via the D2B to the radio (A2) and can then be read out via the diagnostic interface.