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

MODEL 204.0 /2 as of model year 2009 /YoM 08 

MODEL 204.3/ 9 

Fig 1: Audio Mode Function Diagram
G07532288Courtesy of MERCEDES-BENZ USA

Function requirements 

IMPORTANT Audio functions are selected using the following controls:

General 

The audio mode consists of the following component functions:

Function sequence for volume and sound settings 

All volume and sound settings are performed using the audio unit. 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.

IMPORTANT The "Volume" allows selection of the settings "Standard" or "Boost" for the AUX audio source (via Media interface adapter cable (with code (518) Media interface) or via AUX electrical connector). The input level can be increased by selecting "Boost".

On vehicles with code (810) Sound system the audio equipment also has an additional Logic 7 tone setting (surround sound).

IMPORTANT The sound settings can be set separately for each audio and video source. The volume can be adjusted separately for the traffic information service and navigation announcements.

The audio signals are output over the speaker system.

The volume and sound settings function is subdivided into the following subfunctions:

D Function sequence for manual volume and sound settings 

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

Function sequence for manual volume and sound settings 

The manual volume and sound settings are subdivided into the following subfunctions:

D Function sequence for volume settings through the audio unit 

D Function sequence for sound settings via audio/COMAND control panel 

IMPORTANT The selected settings are relayed on vehicles with code (810) Sound system via MOST to the sound system amplifier control unit where they are then processed. On vehicles except code (810) Sound-system, the settings are processed by the audio equipment. Audio emitted through the speaker system is interrupted by actuating the Mute button (S111s6) or using the corresponding function key on the audio unit.

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

Pressing the + and - button for setting specific functions and volume control (S111s1) enables the volume for audio and video source to be increased or reduced.

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

Function sequence for volume settings through the audio unit 

Operating the rotary switch on the audio unit enables the volume to be raised or lowered for the audio or video sources.

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 over the telematics CAN to the audio unit.

IMPORTANT With code (510) Audio 20 including CD changer or with code (523) Radio MB Audio 20, the menu "Tone" can be activated on the audio equipment. Settings are performed with the audio/COMAND control panel.

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

The volume is adapted to the noise level in the vehicle interior with the aid of the speed-dependent volume control defined by the vehicle speed. To do this, the instrument cluster transmits information on vehicle speed via the interior CAN to the audio unit (without code (810) Sound system) or via MOST to the sound system amplifier control unit (with code (810) Sound system). In accordance with this information the audio unit or the sound system amplifier control unit raises the output level or lowers it.

Function sequence for radio mode (FM/AM) 

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

The FM and AM signals are received over direct lines from the audio unit in the following manner:

The radio mode function sequence consists of the following subfunctions:

IMPORTANT The function sequence for receiving traffic data for vehicles with code (498) Japan version (over the Vehicle Information and Communication System (VICS)) is described in the document "Navigation mode, function".

Function sequence for AM tuner (MW, LW, SW) 

For the MW and LW radio frequency bands, the useful signals are broadcast using amplitude modulation (AM). The AM tuner integrated into the audio unit demodulates these signals. This means that the AM tuner integrated into the audio equipment separates the audio signals (audible frequencies) from the carrier signal (not audible).

IMPORTANT On vehicles with code (498) Japan version or code (494) USA version, only MW frequencies can be received in the AM frequency range.

Function sequence for FM double tuner with multi-path reception (FM), except code (498) Japan version 

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

The dual FM tuner integrated into the audio unit demodulates these signals. In other words, it separates the useful signals (audible frequencies) from the carrier signal (inaudible).

The audio equipment also provides for reception-dependent switchover between the antenna amplifiers for the FM-1- and FM-2-signal.

Function sequence for FM double tuner with multi-path reception (UHW), with code (498) Japan version 

The double FM tuner integrated into the audio equipment separates the audio signals (audible frequencies) from the carrier signal (not audible).

The FM, AM and CL antenna amplifiers are used for Vehicle Information and Communication System (VICS) signals (traffic messages) and the FM 2 and DAB antenna amplifiers for FM radio signals. Reception-dependent switchover is not accomplished.

Function sequence for Radio Broadcast Data system (RBDS) (with code (494) USA version) or Radio Data System (RDS) (except code (494) USA version, except code (498) Japan version) 

In addition to the radio program, many radio stations (FM) also transmit additional digital information. Additional digital information (e.g. station name, program model - pop, culture, etc. - and traffic information recognition) is evaluated by the audio equipment and displayed on the audio/COMAND display when the following conditions are satisfied:

Function sequence for High-Definiton (HD) Radio mode (as of 1.6.2010 with code (494) USA version and code (512) COMAND APS incl. DVD changer, Code (528) COMAND incl. DVD changer) 

The HD radio function improves the audio quality using digital technology:

The HD radio function is implemented in the COMAND controller unit. The integrated HD tuner is a combined AM/FM/Weatherband (WB) receiver with HD radio function. The HD tuner in the COMAND control unit demodulates the analog AM and FM signals with the two integrated double tuners and decodes the digital AM And FM signals with the integrated HD radio decoder chips. The weatherband feature allows reception of US weatherband signals.

The HD radio function also allows additional reception of digital carrier waves for analog AM/FM programs, which are also broadcast by the stations. The stations also broadcast other audio channels and data with the digital carriers. This supplements the program with up to two audio channels per frequency (e.g. foreign language program from National Public Radio (NPR)) and supplemental information (e.g. title, artist).

Additional transmission of digital carriers is designated as "On Channel", the digital station is tuned to the same frequency as the analog station.

The digital transmission process in the FM and AM band is known as "in-band".

In contrast to the satellite digital audio radio (satellite radio) (SDAR) function (with code (536) SIRIUS satellite radio) regional stations and programs are received by the HD radio function and no fees will be charged.

Function sequence for Digital Audio Broadcasting (DAB) (with code (537) Digital radio) 

The Digital Audio Broadcasting control unit permits the reception of stations in the Digital Audio Broadcasting (Digital Radio) (DAB) format. The stations are categorized into groups in DAB, so-called "Ensembles". Control of the DAB functions is accomplished via the audio unit. The information or displays required for control are shown on the Audio/COMAND display.

The DAB band III signals are used for large area broadcasting and contain mostly stations with a large range or national stations. The DAB L band signals are used for local broadcasts and contain mostly conurbation stations.

The Digital Audio Broadcasting control unit receives the DAB signals over direct lines:

IMPORTANT On vehicles as of 1.12.2010 only DAB-Band-III signals are processed and the multifunction antenna is not longer required for DAs.

The DAB signals are sent and made available by the audio unit over MOST.

Reception-dependent switchover of DAs to FM (as of 1.6.2009) 

The audio unit transmits the FM station lists to the Digital Audio Broadcasting control unit. If a comparable FM station is found, it is requested by the Digital Audio Broadcasting control unit. If the DAB reception starts to deteriorate the system switches over to the FM station being received by the audio equipment.

As of 1.3.2011 (except model 204.9) reception-dependent switchover of DAS to FM has been optimized for "Seamless Linking". The digital audio broadcasting control unit compensates for the time offset between the digital and analog signals so that it is virtually impossible to hear the switchover. This requires that the audio equipment send the FM signals to the MOST when the DAB mode is active.

DAB double tuner (as of 1.3.2011, except model 204.9) 

As of 1.3.2011 the Digital Audio Broadcasting control unit is designed as a dual tuner and provides not only the known functions but also the following optimizations and extensions:

Function sequence for Satellite Digital Audio Radio (satellite radio) (SDAR) (with code (536) SIRIUS satellite radio) 

The corresponding SDAR control unit enables "Sirius Satellite Radio" provider channels to be received. The SDAR system is controlled through the audio unit and the control occurs over MOST. The information or displays required for control are output via the Audio/COMAND display and also in the instrument cluster. The Sirius satellite radio signal is broadcast 3 times to achieve a diversity of channels (using two satellites and one terrestrial station). The multifunction antenna receives all three channels (Sat 1, Sat 2, terrestrial station) and sends these signals via a direct line to the corresponding SDAR control unit.

The SDAR control unit receives and decodes the signals and transmits them to the audio equipment unit via MOST.

IMPORTANT On vehicles as of 1.6.2010 (On vehicles with code (512) COMAND APS incl. DVD changer already as of 1.6.2009) the Real Time Traffic Data service (RTTD) is also available via SCAR. Details are given in the function description of the navigation 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. Data exchange between the audio unit and the Audio/COMAND display takes place via the telematics CAN.

Function sequence for music register (with code (527) COMAND APS with single DVD drive (with navigation) or with code (512) COMAND APS with DVD changer) 

The hard disk integrated into the audio unit enables files in MP3 format to be stored from CD/DVD, USB memory stick or a Secure Digital (SD) card and then called as required.

IMPORTANT For vehicles with code (498) Japan version, MP3 files may not be copied to the music register due to legal specifications. Instead of this, in the "Disc" menu one can use "REC" to store music tracks from an audio CD as an MP3 file on the COMAND controller unit's hard disk ("rip"). The MP3 files in the music register are not imported in this instance, but generated by the audio unit itself.

Function sequence for Bluetooth® Audio (as of 1.3.2011, except model 204.9) 

The Bluetooth antenna enables the audio unit 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. With Bluetooth® audio these are Audio Video Remote Control Profiles (AVRCP) and Advanced Audio Distribution Profiles (A2DP), and for telephony it is the Handsfree Profile (HFP). 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. That means that the device is now a telephone and at the same time a source for Bluetooth® audio. On most devices, it is necessary to start the player on the telephone so that it can then be controlled via the audio unit.

When starting, the audio unit 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).

Where this is the case, the audio unit connects to the telephone and goes into the comfort telephony status.

If a mobile phone cradle is present, however, phone not plugged in, an inquiry is displayed after 2 minutes whether the system is to switchover to basic telephony. If answered with "No" the system remains in the comfort telephony status.

If no mobile phone cradle is present or no telephone inserted, the audio unit searches for the last two telephones. If one of these devices is found, the audio unit connects to this device. If this device also supports AVRCP/A2DP, these profiles are also connected.

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

IMPORTANT The same applies when a telephone is connected in the comfort telephony status.

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.

IMPORTANT The search process with "Connect last device" can only be interrupted by changing to telephony. Otherwise, the search is continued in the background.

When corresponding audio sources are not present in the device list, "No Bluetooth audio device authorized" is displayed and the selection possibility "Connect last device" is suppressed.

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 unit begins the search for the last two telephones.

Meta data and display of information 

The display of information for Bluetooth® audio depends on the respective device used. If this 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 Notes on supported devices for Bluetooth® audio can be found under: http://www.mercedes-benz.com/connect 

REFER TO SYSTEM WIRING DIAGRAMS Electrical function diagram for audio mode, function Model 204.0/2 as of model year 2012/model refinement package 11
Model 204.3		 PE82.60-P-2058-97FAB
Model 204.0/2 up to model year 2012/model refinement package 11
Model 204.9		 PE82.60-P-2058-97FAA
REFER TO SYSTEM WIRING DIAGRAMS Electrical function diagram for Digital Audio Broadcasting, function Model 204.0/2 with code (537) Digital radio as of model year 2012/model refinement package 11
Model 204.3 with code (537) Digital radio		 PE82.60-P-2057-97FAB
Model 204.0/2 with code (537) Digital radio up to model year 2012/model refinement package 11
Model 204.9 with code (537) Digital radio as of model year 2010 /YoM 09		 PE82.60-P-2057-97FAA
REFER TO SYSTEM WIRING DIAGRAMS Electrical function schematic for SDAR function Model 204.0 with code (536) SIRIUS satellite radio as of model year 2012/model refinement package 11
Model 204.3 with code (536) SIRIUS satellite radio		 PE82.60-P-2060-97FAB
Model 204.0 with code (536) SIRIUS satellite radio up to model year 2012/model refinement package 11
Model 204.9 with code (536) SIRIUS satellite radio		 PE82.60-P-2060-97FAA
  Overview of system components, telematics   GF82.85-P-9999CE 
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