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

Model 172.4 

up to model year 2017 

G13848178Courtesy of MERCEDES-BENZ USA

Shown on model 172.4 

Function requirements, audio mode, general 

General information on the audio mode 

The functions in the audio mode are selected using the following controls:

Menu guidance and the display of additional information are carried out over the Audio/COMAND display. The Audio/COMAND display is switched on over the telematics CAN from the COMAND controller unit. The picture signals are received by the audio/COMAND display over the LVDS line from the COMAND controller unit.

The audio signals are forwarded and issued as follows:

The audio mode consists of the following component functions:

IMPORTANT Model 172.4

up to model year 2017

with code 518 (Media interface)

Further audio applications are also available that are described elsewhere.

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 tone 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 Model 172.4 up to 11/29/13

up to model year 2015

except code 518 (Media interface)

With the AUX audio source (over the AUX connection electrical connector), the "Volume" menu can be used to select between the default volume and a raised input level.

On vehicles with CODE 810 (Sound system), the audio equipment is not only equipped with the general tone settings (treble, bass and balance), but also with additional tone settings.

IMPORTANT The tone settings can be carried out separately for each audio source. The volume can be adjusted separately for the traffic information service and navigation announcements.

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 audio output through the speaker system can be interrupted using the right multifunction steering wheel button group or the corresponding button on the COMAND controller unit (mute function).

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

The right multifunction steering wheel button group can be used to increase or reduce the volume for the audio or video sources.

The control signals are forwarded by the steering wheel electronics over the following path:

Steering LIN →

Steering column tube module control unit →

Chassis CAN →

Instrument cluster →

Interior CAN →

Audio unit

Function sequence for volume settings through the audio equipment 

Operating the control on the audio equipment 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 transmitted 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, defined by the vehicle speed, using the speed-dependent volume control. To this end, the instrument cluster sends information on vehicle speed over the interior CAN to the audio equipment, which forwards the information in vehicles with code 810 (Sound system) over the 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.

Function sequence for radio mode (FM/AM) 

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

The FM-1 signals are received via direct lines via the following route:

Windshield antenna →

FM, AM and CL [ZV] antenna amplifier →

Audio unit

The FM-2 signals are received via direct lines via the following route:

Windshield antenna →

FM 2, DAB and TV antenna amplifier →

FM/TMC antenna splitter (with code 508 (Navigation box preinstallation) or with code 509 (Navigation box)) →

Audio unit

The AM signals are received when the Vario roof is closed through direct lines over the following path:

Rear window antenna →

AM antenna amplifier →

Rear shelf with selection switch antenna amplifier →

FM, AM and CL [ZV] antenna amplifier →

Audio unit

The AM signals are received when the Vario roof is open through direct lines over the following path:

Rear shelf antenna →

Rear shelf with selection switch antenna amplifier →

FM, AM and CL [ZV] antenna amplifier →

Audio unit

The rear shelf antenna amplifier with selection switch reads in the status of the antenna switchover limit switch, and switches over in the event of a status change to the AM antenna amplifier or the rear shelf antenna.

The radio mode function sequence consists of the following subfunctions:

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

For the MW, LW and SW radio 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 172.4

up to model year 2017

with code 494 (US version)

Model 172.4

up to model year 2017

with code 498 (Japanese version)

Only MW frequencies are received in the AM frequency range.

Function sequence for FM double tuner with multipath reception (FM) 

For the FM radio frequency band, the useful signals are broadcast using frequency modulation (FM). These signals are demodulated by the FM tuner integrated into the COMAND controller unit. In other words, it separates the useful signals (audible frequencies) from the carrier signal (inaudible). The COMAND controller unit integrates the useful signals from the FM, AM and CL antenna amplifier, and the FM 2, DAB and TV antenna amplifier to form an optimized signal (phase diversity).

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)) 

Apart from the normal radio program, many radio stations (FM) transmit additional digital information such as station names, program type (PTY) (e.g. pop, culture, etc.) and traffic program identification.

This information is evaluated by the audio equipment and shown on the Audio/COMAND display if the following preconditions are complied with:

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

The Digital Audio Broadcasting control unit allows reception of digital radio in the 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.

DAB signals are received as DAB-Band-III signals via direct lines over the following path:

Windshield antenna →

FM 2, DAB and TV antenna amplifier →

Digital Audio Broadcasting control unit

The DAB signals are transmitted and made available by the audio unit via MOST. The audio equipment 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. The audio equipment 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 audio unit's FM station, whereby the Digital Audio Broadcasting control unit adjusts the time lag between the digital and the analog signal. In this way the switchover is almost inaudible ("Seamless Linking").

DAB dual tuner 

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 satellite digital audio radio (SDAR) control unit permits the reception of stations from the provider "Sirius satellite radio". The SDAR system is controlled through the audio equipment and the control occurs via 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 transmitter). The multifunction antenna receives all three channels of the Sirius satellite radio (Sat 1, Sat 2, terrestrial stations) and transmits these signals via a direct line to the satellite digital audio radio (SDAR) control unit. The satellite digital audio radio (SDAR) control unit receives and decodes the signals and transmits them via MOST to the audio unit.

Function sequence for connections in stowage compartment (telephone compartment) under armrest 

External devices (e.g. Walkman, USB stick) can be connected to the AUX connection electrical connector (except code 518 (Media interface), up to 29.11.2013) and the USB electrical connector. The electrical connectors are connected to the audio equipment via direct line. If the "AUX" menu or the "USB storage" menu is activated, the audio equipment outputs the audio data of the connected devices over the speaker system or forwards it via the MOST to the sound system amplifier controller unit (with CODE 810 (Sound system)).

In the "USB storage" menu, user guidance is provided via the Audio/COMAND display. The audio equipment generates the display information and transmits it to the Audio/COMAND display via an LVDS line. The control signals are sent by the audio equipment over the USB electrical connector to the external device.

The "Aux" menu is operated from the external device (except the volume and tone settings).

Function sequence for DVD/CD audio 

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

The audio equipment generates the display information and transmits it to the Audio/COMAND display via an LVDS line.

Function sequence for Music Register (with CODE 512 (COMAND APS with DVD changer) or with CODE 527 (COMAND APS with single DVD drive (with navigation))) 

Files in MP3 format on a CD/DVD, a USB memory stick or a Secure Digital (SD) card can be stored on the hard disk integrated in the audio equipment and then retrieved as required.

IMPORTANT Model 172.4

up to model year 2017

with code 498 (Japanese version)

Due to legal regulations, it is not possible to copy MP3 files to the Music Register. Instead of this, in the "Disc" menu one can use "REC" to store music tracks from an audio CD as 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 equipment itself.

Function sequence for Bluetooth® audio 

The Bluetooth® antenna allows 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.

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 telephone so that it can then be controlled via the audio equipment.

When starting, the audio equipment proceeds with the following strategy:

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 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, only "Audio streaming" is 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. 

  Electrical function schematic for Digital Audio Broadcasting function Model 172.4 up to model year 2017 with code 537 (Digital radio (DAB)) PE82.60-P-2057-97TAA
  Electrical function diagram for audio mode function   PE82.60-P-2058-97TAA
  Electrical function schematic for SDAR function Model 172.4 up to model year 2017 with code 536 (SIRIUS satellite radio) PE82.60-P-2060-97TAA
  Overview of system components, telematics   GF82.85-P-9999RD 
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