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

GF82.85-P-2030CAJ Audio Mode, Function
MODEL 207.3 /4
- with CODE (527) COMAND APS with single DVD drive (with navigation)
- with CODE (498) Japan version

Function requirements, audio mode, general
^ Circuit 30g ON

General information on the audio mode
Audio functions can be selected, activated and adjusted with the following components:
- Left multifunction steering wheel button group (S110) or right multifunction steering wheel button group (S111)
- Audio/COMAND control panel (A40/9)
- Buttons of the COMAND controller unit (A40/3)
- Voice control system (VCS [SBS])
In vehicles as of 1.7.2011, audio files can also be played back over a Universal Serial Bus (USB) stick connected via the USB electrical connector (X115).
On vehicles with code (810) Sound system the audio signals are sent by the COMAND controller unit over the Media Oriented System Transport (MOST) to the sound system amplifier control unit (N40/3) where they undergo final amplification.
On vehicles with code (810) Sound system, the audio signals are output by the COMAND controller unit over the MOST to the sound system amplifier control unit and from there, to the following speakers via direct lines:
- Left door tweeter (H4/1h1)
- Left door bass speaker (H4/1h2)
- Right door tweeter (H4/2h1)
- Right door bass speaker (H4/2h2)
- Left rear tweeter (H4/3h1)
- Left rear bass speaker (H4/3h2)
- Right rear tweeter (H4/4h1)
- Right rear bass speaker (H4/4h2)
- Center instrument panel speaker (H4/27)
- Rear shelf bass speaker (H4/29)
- Left rear surround speaker (H4/54)
- Right rear surround speaker (H4/57)
On vehicles without code (810) Sound system, the audio signals are output over direct lines by the COMAND controller unit to the following speakers:
- Left door tweeter
- Left door bass speaker
- Right door tweeter
- Right door bass speaker
- Left rear tweeter
- Left rear bass speaker
- Right rear tweeter
- Right rear bass speaker
The audio mode consists of the following component functions:
^ Function sequence for radio mode function (FM/AM)
^ Function sequence for audio DVD/CD
^ Function sequence for Music Register
^ Function sequence for media interface
^ Function sequence for Bluetooth(R) audio (as of 1.6.2010)

Function sequence for radio mode (FM/AM)
The antennas in the rear window (model 207.3) receive audio signals for the FM and AM (MW) radio frequency bands. The following useful signals relevant for the radio reception are modulated onto these signals:
- Music signals
- Speech signals
- Data signals (e.g. Vehicle Information and Communication System (VICS) signals on the current traffic information)
Model 207.3
The FM signals are routed from the antenna structures in the rear window over direct lines to the FM, AM and CL antenna amplifier (A2/18) and to the rear window antenna FM antenna amplifier (A2/19).
The AM signals are transmitted from the antenna structures in the rear window over direct lines to the FM, AM and CL antenna amplifier.
Model 207.4:
The FM signals are sent from the antenna structures in the windshield over direct lines to the FM, AM and CL antenna amplifier (A2/55) and to the TV 3, FM2 and DAB band III antenna amplifier (A2/54).
Reception of the AM signals takes place for model 207.4 via the AM soft top antenna (A2/111) with a closed soft top and via the rear side paneling AM antenna with an open soft top.
In model 207.4, the AM signals are sent on via the AM amplifier with selection switch (A104/2) by means of a direct line to the FM, AM and CL [ZV] antenna amplifier. The AM signals from the AM soft top antenna are also amplified by the AM amplifier (A104/1).
The antenna amplifiers filter the frequencies of the radio frequency bands out of the received signals and amplify them. The amplified signals are then sent via coaxial lines to the tuner integrated in the COMAND controller unit and demodulated.
The radio mode function comprises the following subfunctions:
^ Function sequence for FM reception
^ Function sequence for AM reception (MW)

Function sequence for FM reception
For the FM radio frequency band, the useful signals are transmitted using frequency modulation. These signals are demodulated by the FM tuner integrated into the COMAND controller unit. In other words, it also separates the useful signals (audible frequencies) from the carrier signal (inaudible).
VICS signals are demodulated by a separate FM tuner.

Function sequence for AM reception (MW)
For the MW radio frequency band, the useful signals are broadcast using amplitude modulation. To separate the useful signals (audible frequencies) from the carrier signal (inaudible), the AM tuner integrated into the COMAND controller unit demodulates the signals.

Function sequence for audio DVD/CD
A single DVD drive is integrated into the COMAND controller unit.
The audio DVD/CD function enables audio DVDs or audio CDs (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 (A40/8). The data exchange for controlling the DVD/CD function (e.g. track selection) between the COMAND controller unit and the Audio/COMAND display takes place via the telematics CAN (CAN A).
The signals for displaying supplemental information (e.g. track) and the menus are transmitted by the COMAND controller unit over a low voltage differential signaling (LVDS) line.

Function sequence for Music Register
The hard disk integrated into the COMAND controller unit can be used to save files (in MP3 format) and they can be called up again as and when required. Because of legal specifications it is not possible to copy MP3 files from an external source into the Music Register. 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, but actually created by the COMAND controller unit itself.

Function sequence for media interface
The audio signals and data of a connected, portable terminal (e.g. MP3 player) are sent over the following path to the COMAND controller unit:
- Adapter cable
- Media interface electrical connector (X18/70)
- Media interface control unit (N125/1)
- MOST
The "Media interface" menu item and the specific submenu item can be selected using one of the following controls:
- Buttons on COMAND controller unit
- Audio/COMAND control panel
- Left multifunction steering wheel button group and right multifunction steering wheel button group
Selection of the "Media interface" menu item as well as the specific submenu item ("Playlists", "Artists", "Albums", "Genres" or "Audio books") enables the audio data to be shown in the Audio/ COMAND display.
With the AUX audio source (via the media interface adapter cable (with code (518) Media interface) or via the AUX electrical connector (X39/45) (without code (518) Media interface)), "Standard" and "Boost" can be selected in the "Volume" menu. The input level can be increased by selecting "Boost".

Function sequence for Bluetooth(R) audio (as of 1.6.2010)
Via the Bluetooth antenna (A2/91), the COMAND controller unit can receive Bluetooth(R) audio signals from external devices.
Bluetooth(R) audio is divided into the following subfunctions:
^ Search for devices and authorization
^ Connection and reconnection
^ Meta data and display of information

Search for devices and authorization
The same options exist for the authorization of a Bluetooth(R) audio source as are available for telephony:
- Search via the device list or
- External authorization
The device lists are set up the same for Bluetooth(R) audio and telephony. In the respective list, only those devices that support the corresponding Bluetooth(R) profile of the respective function are found or displayed during a search.
During telephony, the hands-free profile (HFP) is used.
With Bluetooth(R) audio, the Audio/Video Remote Control Profile (AVRCP) and Advanced Audio Distribution Profile (A2DP) are used.
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(R) audio. On most devices, it is necessary to start the player on the telephone so that it can then be controlled via the COMAND controller unit.
When starting, the COMAND controller unit proceeds with the following strategy: First a check is performed as to whether an authorized telephone is inserted in the mobile phone cradle (A34/15) (with code (386) Comfort telephony).
If this is the case, the COMAND controller unit connects to the telephone and assumes the comfort telephony status.
If no mobile phone cradle is present or no telephone inserted, the COMAND controller unit searches for the last two telephones. If one of these devices is found, the COMAND controller 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(R) audio application, "No Bluetooth audio device connected" is shown on the Audio/COMAND display if the corresponding audio sources are shown in the device list.
With the comfort telephony status, the connected device is always treated as if it only supports HFP.
If no Bluetooth(R) audio source is shown in the device list, "No Bluetooth audio device authorized" is shown on the Audio/ COMAND display and the selection option "Connect last device" is not shown in the menu.
If a Bluetooth(R) audio source is shown in the device list, the last Bluetooth(R) audio source used can be connected via "Connect last device". However, the connection to the current telephone is interrupted here.
The search process with "Connect last device" can only be interrupted by changing to telephony. Otherwise, the search is continued in the background.
If a device is connected that only supports AVRCP/A2DP and a change to telephony is then made, the connection to the device is disconnected and the COMAND controller unit begins the search for the last two telephones.

Meta data and display of information
The display of information for Bluetooth(R) 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 (A1).
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.
It is possible to jump to the next or the previous track using the left multifunction steering wheel button group.
Notes on supported devices for Bluetooth(R) audio can be found under: http://www.mercedes-benz.com/connect