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Audio Mode, Function - GF82.85-P-2030RF

Model 205 

up to model year 2019 

Model 253 (except 253.99) 

up to model year 2020 

G12941375Courtesy of MERCEDES-BENZ USA

Shown on model 205.0/1/2/3, 253 

G12941376Courtesy of MERCEDES-BENZ USA

Shown: model 205.4 

Function requirements, audio mode, general 

General information on the audio mode 

The head unit is activated via the "ON" button in the left lower control panel (manual transmission) or in the right lower control panel (automatic transmission) (except code U78 (AMG Sport exhaust system)). In vehicles with code U78 (AMG Sport exhaust system), the head unit can be switched ON/OFF by pressing the volume adjustment button in the right lower control panel. The left lower control panel (manual transmission) or the right lower control panel (automatic transmission) transmits the "ON" button or volume adjustment button signal via the LCP-LIN, Audio/COMAND control panel and telematics CAN to the head unit. The menu for radio reception or for the media sources can be called up using the upper control panel control unit.

The menu contents are generated by the head unit and shown on the Audio/COMAND display. The head unit transmits an ON signal to the Audio/COMAND via the telematics CAN. The head unit transmits the image data to the Audio/COMAND via the LVDS line.

The audio mode functions can be selected, activated and set with the Audio/COMAND controller of the Audio/COMAND control panel. The "Back" button supports navigation in the menus. The Audio/COMAND control panel sends the control signals via telematics CAN to the head unit.

The audio mode functions can be operated with the touchpad (up to 31.05.2015 with code 531 (COMAND APS), with code 522 (Radio Audio 20), from 01.06.2015 with code 448 (Touchpad), with code 498 (Japan version) or code 494 (USA version)). The touchpad sends the operation signals over the telematics CAN to the head unit.

The audio mode functions can be selected, activated and set with the left multifunction steering wheel button group and the right multifunction steering wheel button group. The steering wheel electronics reads the control signals directly. The steering column tube module control unit reads them via the steering LIN and transmits them to the instrument cluster via chassis FlexRay, the electronic ignition lock control unit and user interface CAN. The instrument cluster transmits the control signals of the multifunction steering wheel button group to the head unit via the user interface CAN.

In vehicles with CODE 531 (COMAND APS), the audio mode functions can be operated with the voice control system. The voice commands are converted into electric signals by the hands-free system microphone and forwarded to the head unit.

In vehicles except CODE 810 (Sound system), the head unit outputs the audio signals over the vehicle's speaker system in accordance with the volume and tone settings.

In vehicles with CODE 810 (Sound system), the head unit forwards the audio signals and the volume and tone settings via the MOST to the sound system amplifier control unit, which actuates the speaker system.

The audio mode consists of the following component functions:

Volume and tone settings 

All volume and tone settings are selected using the head unit. This is done either by the user or automatically by the head unit. The sound settings are shown on the Audio/COMAND display. The sound settings can be changed individually for applications with the "Sound" menu and the system returned to the default settings via the system settings. In vehicles with CODE 810 (Sound system)), the head unit has additional tone settings.

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

Manual volume and tone settings 

Manually volume and tone settings can be selected as follows:

IMPORTANT The audio output via the speaker system is interrupted by actuating the mute function button (S111s6) in the right multifunction steering wheel button group.

SDV 

The volume is adapted to the noise situation in the vehicle interior with the help of the speed-dependent volume control. The noise level in the vehicle interior is determined via the vehicle speed, whereby the assignment depends on the respective body variant. The instrument cluster transmits the vehicle speed data to the head unit via the user interface CAN. Depending on this information, the head unit and sound system sound system amplifier (with code 810 (Sound system)) raises or lowers the output level.

In vehicles with code 810 (Sound system), SDV is additionally optimized through the use of the hands-free system microphone. The sound system amplifier control unit (with code 810 (Sound system)) receives the signals from the hands-free system microphone from the head unit via MOST, evaluates the signals and adjusts the volume of the audio signals according to the interior compartment/driving noise.

Radio mode (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:

Vehicles with code 494 (USA version) or code 460 (Canada version) are equipped for reception of HD radio. In HD radio, digital signals are sent over the radio frequencies along with the analog signals. This makes audio signals available in better reception quality, and additional information and services can also be received and used. These signals are processed by the audio tuner integrated in the head unit.

On model 205.0/3, the head unit receives the FM-1 and FM-2 signals or the HD radio signals via the rear window antenna and the FM1, AM, CL [ZV] and KEYLESS-GO antenna amplifier and the FM 2 and DAB band III antenna amplifier.

On model 205.2, 253 the head unit receives the FM-1 signals or the HD radio signals via the rear spoiler antenna and the FM1, AM, CL [ZV] and KEYLESS-GO antenna amplifier.

On model 205.2, 253 the head unit receives the FM-2 signals or the HD radio signals via the rear spoiler antenna and the FM 2, DAB and TV 1 antenna amplifier.

With model 205.4, the head unit receives the FM-1 and FM-2 signals or the HD radio signals via the windshield antenna, the antenna amplifier FM 1, AM, CL [ZV] and KEYLESS-GO and the antenna amplifier FM 2, DAB and TV 1.

On model 205.0/1/3, the head unit receives the AM signals via the rear window antenna and the FM1, AM, CL [ZV] and KEYLESS-GO antenna amplifier.

On model 205.2, 253 the head unit receives the AM signals via the rear spoiler antenna and the FM1, AM, CL [ZV] and KEYLESS-GO antenna amplifier.

On model 205.4 with closed soft top, the head unit receives the AM signals via the soft top AM antenna, AM amplifier, AM amplifier with changeover switch and FM 1, AM, CL [ZV] and KEYLESS-GO antenna amplifier.

On model 205.4 with open soft top, the head unit receives the AM signals via the left rear passenger compartment side trim antenna, AM amplifier with changeover switch and FM 1, AM, CL [ZV] and KEYLESS-GO antenna amplifier.

Radio mode involves the following components:

AM tuner 

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

IMPORTANT Only MW frequencies are received in the AM frequency range.

Dual FM tuner with multipath reception (FM) 

For the FM radio frequency band, the useful signals are broadcast using frequency modulation (FM). The FM twin tuner integrated into the head unit demodulates these signals. In other words, it separates the useful signals (audible frequencies) from the carrier signal (inaudible). The head unit integrates the useful signals from the FM 1, AM, CL [ZV] and KEYLESS-GO antenna amplifier and from the FM 2 and DAB band III antenna amplifier (model 205.0/3, 253.3) or FM 2, DAB and TV 1 antenna amplifier (model 205.2/4, 253.9) into an optimized signal (phase diversity).

IMPORTANT An additional tuner function is integrated into the head unit for additional information e.g. Weather Band or Vehicle Information and Communication System (VICS) FM multiplexer.

RBDS (with code 494 (USA version) or code 460 (Canada version)) or RDS (except code 494 (USA version), except code 460 (Canada version) and except code 498 (Japan version)) 

In addition to the radio program, many radio stations (FM) also broadcast additional digital information such as station name, type of program and traffic message channel recognition. This information is evaluated by the head unit and shown on the Audio/COMAND display, if an RDS or RBDS station is tuned and the RDS or RBDS function is activated.

HD radio (with code 494 (USA version) or code 460 (Canada version)) 

The audio tuner integrated in the head unit decodes the digital signals. Additional information and services are shown on the Audio/COMAND display, e.g. program service data, artist experience, traffic information.

DVD, CD audio (with code 522 (Radio Audio 20) or with code 531 (COMAND APS)) 

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

Secure Digital (SD) memory card (with code 355 (Preinstallation for navigation retrofit), with code 357 (Map navigation) or with code 531 (COMAND APS)) 

The memory card reader is integrated into the multimedia connection unit. The head unit reads in the signals of the multimedia connection unit. Audio data stored on an SD card can be shown on the Audio/COMAND display by activating the "Memory Card" media source and played back by the head unit.

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

Storage of audio CDs on the head 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 head 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.

Additional function requirements for USB electrical connector 1 or USB electrical connector 2 (except code 355 (Pre-installation for navigation retrofit), except code 357 (Map navigation) and except code 531 (COMAND APS)) 

USB electrical connector 1 or USB electrical connector 2 (except code 355 (Pre-installation for navigation retrofit), except code 357 (Map navigation) and except code 531 (COMAND APS)) 

External devices (e.g. audio equipment, universal serial bus (USB) memory sticks, iPods and MTP devices) can be connected to USB electrical connector 1 or USB electrical connector 2. The electrical connectors are connected to the head unit via a direct line.

IMPORTANT Three adapter cables are enclosed for connecting the external devices.

IMPORTANT The universal serial bus (USB) connections are integrated in the multimedia connection unit.

When a device is connected to a USB electrical connector, the head unit switches to the new media source. The head unit outputs the audio signals of the connected devices via the speaker system or forwards them via the MOST to the sound system amplifier control unit (with CODE 810 (Sound system)). User guidance is carried out via the Audio/COMAND display. The head unit generates the display information and transmits it to the Audio/COMAND display via an LVDS line.

Metadata is stored in the connected device in addition to the actual media files. This metadata is compiled by the head unit in a memory, the media database. It is then possible to search for the relevant metadata in the media database. Metadata includes, for example, the title, artist, composer, album, genre, audio book, podcast, file identifier, file type (audio or video). The head unit permanently saves the meta data of up to three devices. When one of these devices is reconnected, the metadata is updated. As soon as a fourth device is connected, the oldest metadata record is overwritten.

When playing pieces of music, the corresponding cover art is shown on the Audio/COMAND display if the cover art in question is stored in the portable terminal (e.g. iPod). The maximum file size for processing cover art is 5 MB. The head unit adjusts the resolution to 240x240 pixels, 16 bit colors and converts the file to JPG format. When searching for albums or pieces of music on the connected device, the corresponding cover art is also shown on the Audio/COMAND display.

DAB (with code 537 (Digital radio (DAB))) 

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

To ensure reception diversity (selection of the best signal), the tuner unit receives two DAB Band III signals.

On model 205.0/1/3, 253.3, the tuner unit receives the DAB band III signals via the rear window antenna and FM 2 and DAB band III antenna amplifier and the TV 1 and DAB band III antenna amplifier.

IMPORTANT TV signals are also received via the TV 1 and DAB band III antenna amplifier The tuner unit separates the signals internally via an integrated antenna splitter.

On model 205.2, 253.9, the tuner unit receives the first DAB band III signal via the rear window antenna and the FM 2, DAB and TV 1 antenna amplifier.

With model 205.4, the tuner unit receives the first DAB Band III signal via the windshield antenna and antenna amplifier FM 2, DAB and TV 1.

With model 205.2/4, the tuner unit receives the second DAB Band III signal via the windshield antenna and antenna amplifier TV 2 and DAB Band III and antenna splitter TV and DAB (with code 865 (TV tuner)).

IMPORTANT TV signals are also received via the FM 2, DAB and TV 1 antenna amplifier. The tuner unit separates the signals internally via an integrated antenna splitter.

The tuner unit transmits the DAB signals via MOST to the head unit and receives the FM station lists from there. If a comparable FM station is found, it is requested by the tuner unit. The head unit provides the FM audio signals on the MOST when the DAB mode is active. If the DAB reception worsens, a switch is made to the head unit's FM station, whereby the tuner unit adjusts the time lag between the digital and the analog signal. This makes the switchover almost inaudible ("seamless linking").

The tuner unit is designed as a multi-tuner and thus offers the following advantages:

SDARS (with code 536 (SIRIUS satellite radio)) 

The tuner unit makes it possible to receive stations from the "Sirius satellite radio" provider. The SDARS system control takes place through the head unit and is realized via MOST. The information or displays required for control are output via the audio/COMAND display and also in the instrument cluster.

To achieve multipath reception the Sirius satellite radio signal is broadcast 3 times (using two satellites and one terrestrial transmitter). All three channels of the SIRIUS satellite radio (Sat 1, Sat 2, terrestrial station) are received by the SDARS antenna.

The SDAR antenna transmits the signals via a direct line to the tuner unit, which receives and decodes the signals. The tuner unit transmits the decoded signals to the head unit via MOST.

IMPORTANT SDARS also broadcasts real-time traffic data (RTTD), which includes accident and traffic jam messages and traffic flow information. Real-time traffic data is made available to the navigation module of the head unit via MOST.

Additional function requirements for Bluetooth® Audio 

Bluetooth® Audio 

The Bluetooth® antenna allows the head unit to receive Bluetooth® audio signals from external devices. Bluetooth® audio is divided into the following additional information:

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 hands-free profile (HFP). If a device supports both functions, it appears in both lists after 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 device so that it can then be controlled via the head unit.

When starting, the head unit proceeds with the following strategy:

A check is first performed to determine whether an authorized telephone module with Bluetooth® (SAP profile) (A34/1) (with code 379 (telephone module with Bluetooth® (SAP profile))) is connected to the mobile phone contact plate (X237/1). If this is the case, the head unit connects to the telephone module with Bluetooth® (SAP) and is in telephony status, with code 379 (Telephone module with Bluetooth® (SAP)).

If no authorized telephone module with Bluetooth® (SAP profile) (with code 379 (Telephone module with Bluetooth® (SAP profile))) is present, it is checked whether there is an authorized telephone in the mobile phone cradle (A34/15) (with code 386 (Comfort telephony), accessories, in model 205 up to 30.11.2015) or in the universal smartphone cradle (A34/17) (with code 386 (Comfort telephony), in model 205 as of 01.12.2015 or in model 253 as of 01.06.2015). If this is the case, the head unit connects to the telephone and assumes the comfort telephony status.

If no mobile phone cradle is present or no telephone inserted, the head unit searches for the last two telephones. If one of these devices is found, the head unit connects to this device. If this telephone also supports AVRCP/A2DP, these profiles are also connected. If a device is connected that only supports HFP and a switch takes place to the "Bluetooth® Audio" application, the head unit displays "No Bluetooth audio device connected" if appropriate 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 head unit 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 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 scroll forward and backward button (S110s1).

IMPORTANT Notes on supported devices for Bluetooth® Audio can be found under the appropriate webpage:

  Electrical function schematic for Digital Audio Broadcasting function Model 205 up to model year 2019 with code 537 (Digital radio (DAB)) Model 253 (except 253.99) up to model year 2020 with code 537 (Digital radio (DAB)) PE82.60-P-2057-97FBA
  Electrical function diagram for audio mode function   PE82.60-P-2058-97FBA
  Electrical function schematic for SDARS function Model 205 up to model year 2019 with code 536 (SIRIUS satellite radio) Model 253 (except 253.99) up to model year 2020 with code 536 (SIRIUS satellite radio) PE82.60-P-2066-97FBA
  Overview of system components, telematics   GF82.85-P-9999RF 
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