Design

Design

Control module




The audio module (AUD) is an amplifier which is connected to the MOST network. It has the following functions:
- to carry the sound signal transmitted on the MOST network out to the directly connected loudspeakers and to the headsets as analogue signals
- to carry voice messages from the microphone, which is directly connected to the audio module (AUD), to the MOST network
- to transmit requests from the headset panel, which is directly connected to the audio module (AUD), to the relevant control modules on the MOST network to change to the next or the previous track or to change the sound source.
If a subwoofer module (SUB) is installed on the MOST network, the audio module (AUD) can process the incoming signal and transmit it to the subwoofer module (SUB).
There are three versions of the audio module (AUD):
Performance
- Has an output of 25 W per channel. The control module has 4 channels, giving a total output of 100 W.
High Performance
- Has an output of 40 W per channel. The control module has 4 channels, giving a total output of 160 W. There are two versions, one with four headset sockets and one without any headset sockets. These sockets can run headsets with a minimum impedance of 8 ohms.
Premium Sound
- Has an output of 70 W per channel plus an output of 25 W for the channel for the centrally-mounted loudspeaker. The control module has four channels plus the channel for the centrally-mounted loudspeaker. This gives a total output of 305 W. The Premium Sound Audio Module (AUD) has four headset sockets. These sockets can run headsets with a minimum impedance of 8 ohms.
Each version of the audio module (AUD) has a different number of loudspeakers and different loudspeaker models.
All versions of the audio module (AUD) have a microphone input. This is used by the phone module (PHM) for phone calls (handsfree) for example.

Functions in the audio module (AUD)
The audio module (AUD) can run a number of different functions, but these functions can also be activated by other nodes. An example of these functions is lowering and increasing the volume. The signal comes from the infotainment control module (ICM), but it is the audio module (AUD) that actually changes the volume. The functions are described below.

Functions in the audio module (AUD):
1. Adjustable volume, raises and lowers the volume
2. Adjustable bass, raises and lowers the bass level
3. Adjustable treble, raises and lowers the treble level
4. System generated sound signals, assists other nodes in the system with single sound signals generated in the control module, for example alarm signals for the reverse (reverse) warning function
5. Limiter, the limiter function in the control module does not permit an increase in the power output level if this leads to a fall in sound quality
6. Mixing, mixing allows numerous different sound types to be mixed. In this case, the different sound types are foreground noise, background noise and system generated sound signals. An example of this is where a CD is playing (background noise) and the carphone rings (foreground noise). The ringing signal will be heard through the loudspeakers while the volume of the music drops at the same time
7. Digital bass speaker output, the control module transmits sound signals to the bass speakers via the MOST network. The signal is processed in the audio module (AUD) before it is transmitted on the MOST network to the subwoofer module (SUB)
8. Bass compensation, the bass from the control module is compensated or modified depending on the volume level and the speed of the car. If the vehicle speed and volume level changes, the bass compensation is also changed
9. Treble compensation, the treble in the control module is compensated or modified depending on how the volume is changed. If the volume changes, the treble compensation also changes
10. Equalizer setting, sound compensation, there are different settings for the sound from the audio module (AUD). This compensates for factors such as the location of the loudspeakers and the layout of the car interior
11. Dolby ProLogic II, a surround decoder for sound reproduction.
There are two types of sound, foreground sound and background sound. The sounds which are foreground and background are listed below.

Foreground sound
- telephone calls
- carphone settings (setting the ring signal)
- navigation
- system generated sound from the audio module (AUD) (different types of alarm sound)
- traffic messages.

Background sound
- analogue radio, AM/FM
- digital radio, DAB
- CD player
- MD player.
The functions in the different versions of the audio module (AUD) are:

Performance
1. adjustable volume
2. adjustable bass level
3. adjustable treble level
4. system generated sound signals
5. limiter.

High Performance
1. adjustable volume
2. adjustable bass level
3. adjustable treble level
4. system generated sound signals
5. limiter
6. mixing
7. digital bass speaker output
8. bass compensation
9. treble compensation
10. equalizer.

Premium Sound
1. adjustable volume
2. adjustable bass level
3. adjustable treble level
4. system generated sound signals
5. limiter
6. mixing
7. digital bass speaker output
8. bass compensation
9. treble compensation
10. equalizer
11. DPL2 - Dolby ProLogic II.

Loudspeakers




Two pairs of loudspeakers and one centre loudspeaker can be installed in the car.
The two pairs of loudspeakers are:
- front loudspeakers in the front doors
- rear loudspeakers in the rear doors.
The centre loudspeaker is positioned in the middle of the dashboard.
In some versions of the audio module (AUD), a treble speaker can be connected to the front and rear speakers. The treble speakers for the front loudspeakers are positioned in the front door at the same height as the door mirrors. For the rear loudspeakers, the treble speakers are positioned in the D-post.
The three audio module (AUD) versions have different loudspeaker arrangements:

Performance
- one pair of front bass speakers
- one pair of rear loudspeakers.
Each loudspeaker consists of a transducer for the entire frequency range. There are no treble speakers connected to this version.

High Performance
- a pair of front bass / mid-range loudspeakers with treble speakers
- a rear pair of loudspeakers (coaxial*) with treble speakers.
The front treble speakers are electrically connected to the same signal cable as the front loudspeakers. The rear treble speakers are electrically connected to the rear loudspeakers.

Premium Sound
- a front pair of 3-way loudspeakers (consisting of a pair of 2-way loudspeakers with treble speakers)
- a rear pair of loudspeakers (coaxial*) with treble speakers.
- a centrally-mounted loudspeaker in the dashboard.
The front treble speakers are electrically connected to the same signal cable as the front loudspeakers. The rear treble speakers are electrically connected to the rear loudspeakers.
*Consists of one bass and one treble transducer integrated in the same unit.






Headset panel




Depending on the version of the audio module (AUD), two headset panels can be installed. The panels have two headset sockets each giving a total of four headset sockets.
Each headset socket has a SEL. button which is used to select the sound source, such as CD player, MD player and radio.
Each headset output also has buttons to select the previous and next track or one of the pre-programmed radio channels. The buttons are internally connected to a resistor stage. When the buttons are pressed, different voltages levels are produced. These voltages are interpreted by the control module as three different selections. When any of the buttons are pressed, this data is transmitted to the audio module (AUD). The module then transmits the data via MOST network to the infotainment module (ICM). The infotainment control module (ICM) then changes the track or sound source.
Each headset socket has a volume control which can be used to change the sound level in the headset. The headset panels are in the left and right-hand C-posts.
If a sound source, which has already been selected via the infotainment control module (ICM), is selected the track or radio channel for this sound source cannot be changed via the headset output. There is no difference in priority between the headset outputs. This means that the radio channel or track can be changed via the headset output for a sound source which is being used by another headset output. All headset outputs with the same sound source then change radio channel or track.
The signals to the headset sockets and the buttons on the headset panel are directly connected to the audio module (AUD).

Microphone




All versions of the audio module (AUD) have a microphone which is directly connected to the control module. The microphone is installed in the rear view mirror.
The microphone is used for functions such as handsfree in the phone module (PHM).