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Home >> Mercedes Benz >> 2016 >> CLS400 4Matic >> Repair and Diagnosis >> Electrical >> Motors, Switches, Relays >> Electrical System - Body - 218 Chassis - 2 Of 5 >> Basic Knowledge >> Audio mode, function >> Audio mode, function - GF82.85-P-2030FQM

Audio mode, function - GF82.85-P-2030FQM

MODEL 218 as of model year 2015 

Fig 1: Audio Mode Block Diagram - Shown On Model 218
G10083336Courtesy of MERCEDES-BENZ USA

Shown on model 218 as of 1.9.14 

Function requirements, audio mode, general 

General information on the audio mode 

The audio mode consists of the following component functions:

Audio mode functions are selected using the following controls:

In vehicles without CODE 810 (Sound system) and CODE 811 (Advanced sound system) the audio equipment outputs the audio signals via the vehicle's speaker system. In vehicles with CODE 810 (Sound system) or CODE 811 (Advanced sound system), the audio equipment forwards the audio signals via MOST to the sound system amplifier control unit, which actuates the speaker system.

IMPORTANT More detailed information on the speaker system is available in the "Speaker output function" information.

Function sequence for volume/tone settings 

All volume and tone settings are performed using the audio equipment. This is performed either by the user or automatically by the audio unit. The volume and sound settings are shown on the audio/COMAND display. The sound settings can be changed with "Tone" and the system returned to the default settings in the system settings menu.

In vehicles with CODE 810 (Sound system) or CODE 811 (Advanced sound system), as well as the general sound settings (treble, bass and balance) the audio equipment has the additional Logic7 (surround sound) or surround sound (Bang&Olufsen) sound setting.

The volume and tone setting partial function is subdivided into the following subfunctions:

Function sequence for manual volume/sound settings 

The manual volume/tone setting function is subdivided into the following subfunctions:

IMPORTANT The desired settings in vehicles with CODE 810 (Sound system) or CODE 811 (Advanced sound system) are forwarded via MOST to the sound system amplifier control unit where they are processed. In vehicles without CODE 810 (Sound system) or CODE 811 (Advanced sound system) the selected settings are processed internally. Audio playback output via the speaker system is interrupted by pressing the Mute function button or using the relevant button on the audio equipment.

Function sequence for volume settings via right multifunction steering wheel button group 

The volume for the audio and video sources is increased or decreased by pressing the + and - buttons, selecting specific functions and volume control.

The control signals are forwarded to the audio equipment via the following route:

Function sequence for volume settings through the audio equipment 

Operating the control on the audio equipment increases or reduces the volume.

Function sequence for sound settings via audio/COMAND control panel 

The user can set the corresponding sound by selecting the "Sound" menu on the audio/COMAND control panel. The Audio/COMAND control panel control signals are sent via the telematics CAN to the audio equipment.

Function sequence for speed-dependent volume control (SDV [GAL]) 

The volume is adapted to the noise level in the vehicle interior using the speed-dependent volume control, which is defined by the vehicle speed. In order to make this adjustment, the instrument cluster transmits vehicle speed information to the audio equipment via the interior CAN.

In vehicles with CODE 810 (Sound system) or CODE 811 (Advanced sound system), the audio equipment forwards the vehicle speed information via MOST to the sound system amplifier control unit.

In accordance with this information the audio equipment or the sound system amplifier control unit raises the output level or lowers it. In vehicles with CODE 811 (Advanced sound system), the SDV [GAL] is additionally optimized by using the sound system microphone. The sound system amplifier control unit reads in the signals of the sound system microphone, evaluates the signals, and adjusts the volume of the audio signals to the interior or driving noises.

Function sequence for radio operation (FM, AM, HD radio) 

The antennas receive signals for the frequency bands FM (ultra-short wave) and AM (medium wave) and (not available in all national versions) short wave (SW)). The following useful signals relevant for the radio reception are modulated onto these signals:

The FM-1 signals are received by the audio equipment via the following route:

The FM-2 signals are received by the audio equipment via the following route:

The AM signals are received via direct lines from the audio equipment via the following route:

The radio mode function sequence consists of the following subfunctions:

AM tuner function sequence 

For the MW or SW frequency bands, the useful signals are broadcast using amplitude modulation (AM). The AM tuner integrated into the audio equipment demodulates these signals. In other words, it separates the useful signals (audible frequencies) from the carrier signal (inaudible).

IMPORTANT MODEL 218 as of model year 2015 with CODE 494 (US version)

MODEL 218 as of model year 2015 with CODE 498 (Japanese version)

Only MW frequencies are received in the AM frequency range.

Function sequence, FM twin tuner with multipath reception 

For the FM frequency band, the useful signals are broadcast using frequency modulation (FM).

The dual FM tuner integrated into the audio equipment demodulates these signals. In other words, it separates the useful signals (audible frequencies) from the carrier signal (inaudible). The audio equipment integrates the signals from the FM 1, AM, CL [ZV] and Keyless-Go antenna amplifier and the FM 2 and DAB antenna amplifier (model 218.3) or the rear window antenna amplifier 1 and the FM 2, DAB and TV antenna amplifier (model 218.9) into an optimized signal (phase diversity).

IMPORTANT For additional information such as the Weatherband (with CODE 494 (USA version) or the Vehicle Information and Communication System (VICS) FM multiplexer (with CODE 498 (Japan version)) an extra tuner function is integrated in the audio equipment.

Function sequence, RBDS (with CODE 494 (USA version)) or RDS (except CODE 494 (USA version), except CODE 498 (Japan version)) 

In addition to the radio program, many radio stations (FM) broadcast additional digital information such as the station name and traffic program identification. The additional digital information is evaluated by the audio equipment and shown on the Audio/COMAND display if the following preconditions are complied with:

Function sequence, HD radio (with CODE 494 (USA version)) 

The HD tuner integrated into the audio equipment decodes the digital signals. Additional information and services are shown on the Audio/COMAND display, e.g. Program Service Data, Artist Experience, traffic information.

Function sequence, digital radio (DAB) (with CODE 537 (Digital radio)) 

The tuner unit permits the reception of digital radio in DAB format. The stations are categorized into groups in DAB, so-called "Ensembles". Control of the DAB functions is accomplished via the audio equipment. The information or displays required for control are shown on the Audio/COMAND display. The tuner unit receives the DAB signals as DAB band III signals.

With model 218.3, the tuner unit receives the DAB signals via the following route:

With model 218.9, the tuner unit receives the DAB-1 signal via the following route:

With model 218.9, the tuner unit receives the DAB-2 signal via the following route:

The DAB signals are transmitted and made available by the audio unit via MOST.

The audio equipment transmits control signals via MOST to the tuner unit.

DAB dual tuner 

DAB is providing the following optimizations and extensions with the DAB double tuner:

Reception-specific switchover from DAB to FM 

The audio equipment transmits the FM station lists to the tuner unit. If a comparable FM station is found, it is requested by the tuner unit. If the DAB reception starts to deteriorate, a switch to the FM station of the audio device occurs. With the DAB twin tuner, reception-dependent changeover from DAB to FM is optimized for "Seamless Linking". The tuner unit compensates for the time offset between the digital and analog signals so that it is virtually impossible to hear the changeover. This requires that the audio equipment transmit the FM signals to the MOST when the DAB mode is active.

Function sequence, SDAR (with CODE 536 (SIRIUS satellite radio)) 

The tuner unit makes it possible to receive stations from the "Sirius satellite radio" provider. The SDAR system is controlled through the audio equipment and the control occurs via MOST. The information that is needed for operation and displays is output via the Audio/COMAND display and, if the appropriate setting has been made, also on the instrument cluster.

The Sirius satellite radio signal is broadcast 3 times to achieve multipath reception (using two satellites and one terrestrial transmitter). The multifunction antenna receives all three channels from the Sirius satellite radio (Sat 1, Sat 2, terrestrial station) and transmits these signals via a direct line to the tuner unit, which decodes the signals and transmits them via MOST to the audio equipment.

IMPORTANT The Real Time Traffic Data (RTTD) traffic information service is also available through SDAR. Details are given in the function description of the navigation mode.

Function sequence, multimedia connection unit 

External devices (e.g. USB sticks) can be connected to the multimedia connection unit via USB (Universal Serial Bus). The multimedia connection unit is connected to the audio equipment, from which it also receives the wake-up signal. When the media source is activated, the audio equipment outputs the audio signals for the connected devices via the speaker system or it forwards them via MOST to the sound system amplifier control unit (with CODE 810 (Sound system) or CODE 811 (Advanced sound system)).

IMPORTANT MODEL 218 as of model year 2015 with CODE 531 (COMAND APS)

In vehicles with the Cockpit Management and Data System (COMAND), the user interface of devices connected to the multimedia connection unit can be displayed and used on the Audio/COMAND display, if the device supports the MirrorLink standard (Terminal Mode).

Function sequence for DVD/CD audio 

The DVD/CD audio and video function can be used to play back audio CDs or audio DVDs (including MP3 format). User guidance for controlling DVD/CD functionality and displaying supplemental information is carried out via the audio/COMAND display.

The data exchange between the audio equipment and the audio/COMAND display takes place via the telematics CAN, but the audio equipment transmits image and video data to the audio/COMAND display via an LVDS line.

Additional function requirements for storing audio CDs on the COMAND controller unit (with CODE 531 (COMAND APS) and CODE 494 (USA version) or with CODE 498 (Japan version)) 

Function sequence, storing audio CDs on the COMAND controller unit (with CODE 531 (COMAND APS) and CODE 494 (USA version) or with CODE 498 (Japan version)) 

Audio CDs can be stored on the integrated hard disk of the COMAND controller unit and subsequently retrieved using the "Search" menu. The storage procedure is started during media operation by selecting "REC" in the "Media" menu bar. Only the entire audio CD can be stored on the hard disk. If the storage procedure is canceled prematurely (e.g. by selecting "Cancel"), no data is stored. Stored audio CDs can be retrieved using the "Search" menu in the "Media" menu bar. The individual tracks can also be retrieved using the general search function.

IMPORTANT Up to 12 audio CDs can be stored. When 12 audio CDs have been stored, an audio CD must be deleted before a new audio CD can be stored. In order to delete stored audio CDs, a stored audio CD must be played back. A stored audio CD can be selected for deletion using "Options" in the "Media" menu bar.

Function sequence for Bluetooth® audio 

The Bluetooth antenna enables the audio equipment to receive Bluetooth® audio signals from external devices. Bluetooth® audio is divided into the following subfunctions:

Search for devices and authorization 

The same options exist for the authorization of a Bluetooth® audio source as are available for telephony:

The device lists are set up the same for Bluetooth® audio and telephony. In the respective list, only those devices that support the corresponding Bluetooth® profile of the respective function are found or displayed during a search.

The Bluetooth® profiles Audio/Video Remote Control Profile (AVRCP) and Advanced Audio Distribution Profile (A2DP) are needed for Bluetooth® audio and the Hands-Free Profile (HFP) is needed for telephony. If a device supports both functions, it is shown in both lists following authorization.

Connection and reconnection 

An authorized device can be connected by means of selection in the corresponding list. If a device is connected that supports both HFP and AVRCP/A2DP, all profiles are connected. In this case the device is a telephone and the source of Bluetooth® audio at the same time.

On most devices, it is necessary to start the player on the telephone so that it can then be controlled via the audio equipment.

When starting, the audio equipment proceeds with the following strategy: First a check is performed as to whether an authorized telephone is inserted into the mobile phone cradle (with CODE 386 (Comfort telephony)). If this is the case, the audio equipment connects to the telephone and goes into the comfort telephony status. If no mobile phone cradle is present or no telephone inserted, the audio equipment searches for the last two telephones.

If one of the last two telephones is found, the audio equipment connects itself with this device. If this device also supports AVRCP/A2DP, these profiles are also connected.

If a device is connected that only supports HFP and a change to the Bluetooth® audio application is made, "No Bluetooth audio device connected" is shown on the audio equipment if corresponding audio sources are shown in the device list.

The "Connect last device" function bar enables the last used Bluetooth® audio source to be connected. However, the connection to the current telephone is interrupted here.

If a device is connected that only supports AVRCP/A2DP and a change to the telephone application is then made, the connection to the device is disconnected and the audio equipment begins the search for the last two telephones.

Metadata and display of information 

The display of information for Bluetooth® audio depends on the respective device used. If this unit supports AVRCP 1.0, "Audio streaming" is exclusively shown on the Audio/COMAND display and in the instrument cluster.

As of AVRCP 1.3, the track, album and artist are shown. In addition, the currently played time of the track can also be conveyed. Furthermore, there is the option of changing between the normal track sequence and shuffle.

IMPORTANT It is possible to jump to the next or the previous track using the left multifunction steering wheel button group.

IMPORTANT

Electrical function schematic for Digital Audio Broadcasting function MODEL 218 as of model year 2015 PE82.60-P-2057-97XAM
Electrical function diagram for audio mode, function MODEL 218 as of model year 2015 PE82.60-P-2058-97XAM
Electrical function schematic for SDAR function MODEL 218 as of model year 2015 PE82.60-P-2060-97XAM
Overview of system components, telematics   GF82.85-P-9999FQA 
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