GF82.60-P-2001RA Radio Operation Function
GF82.60-P-2001RA Radio Operation Function
- with CODE (352) COMAND operating and display system
- except CODE (491) USA version
- except CODE (498) Japan version
The COMAND module can be switched "ON" and OFF with the ON button. It is possible to switch over to the basic radio menu at any time from any menu of another unit with the "AM/FM button" on the COMAND, operating, display and control module (A40/3).
Radio reception, function
All radio frequency signals required for radio reception are distributed on the antennas installed in the vehicle as follows:
AM: One antenna in the rear window antenna amplifier module (A2/12) and one antenna in the rear shelf antenna amplifier (A2/67).
The rear window and/or rear shelf"AM antennas are connected depending on the position of the roof . During operation of the roof, interference may occur when the information "Roof intermediate position" is received. When the information "Roof intermediate position" is present, the radio is switched to MUTE in the AM mode.
Required information for switchover includes: "Roof open", "Intermediate position" and "Roof closed". This information can be read out on the CAN-B bus.
In order to retain the compatibility of the radio to other series, this information is transmitted over the antenna control cable of the radio.
The following intermediate voltages are available:
^ Antenna amplifier On:
Roof on U St > UBS x 0.8
^ Antenna amplifier On:
Roof to 0.6 * U BS > USt > 0.4 x U BS
^ Antenna amplifier Off:
USt > 0.2 x UBS
USt= Control voltage
UBS= Battery voltage
On the models without the information "Roof closed " the intermediate voltage has no effect.
FM: 4 antennae in the front screen which in each case are connected to the left antenna amplifier module (A2/64) and right antenna amplifier module (A2/65).
The music, voice and/or data signals are superimposed on the radio frequency signals. The antenna amplifier modules filter the frequencies from the radio frequency bands out of the radio frequency signals received and amplify the former.
The amplified signals are then relayed from the antenna amplifier modules to the radio receiver (integrated into the COMAND operating, display and control module (A40/3)) via a coaxial cable (AM, FM). The radio receiver demodulates the high frequency signals, i.e. it separates the useful information (audible frequencies) from the carrier signal (inaudible).
The demodulated audio signals are amplified and converted into sound signals by the vehicle loudspeakers.
FM antenna diversity, function
For this purpose, the system automatically switches over between the FM antennae depending on the reception. This function is accomplished by the left antenna amplifier module (A2/64) and right antenna amplifier module (A2/65) .
The radio tuner of the COMAND operating, display and control unit (A40/3) merely generates the IF signal (Intermediate Frequency), which serves the antenna booster as a reference for switching the FM antenna.
Two receivers RDS-EON system, with automatic frequency control (AF), traffic announcement (TA, traffic information) and REG function (regional function)
A second (integrated) radio receiver generates a list of the FM stations received, automatically when the COMAND module is switched on; this list is continuously updated during operation.
This list appears, sorted alphabetically, when the "FM station list" menu is called up. The stations which are displayed can be activated via selection and confirmation.
The station list is only available when the RDS function is activated.
If reception interference occurs while driving, the COMAND module attempts to receive the selected station on an alternative frequency with the aid of the second receiver and switch over accordingly reception is better.
Certain radio channel programs are subdivided into regional programs at certain transmission times. Since the COMAND module automatically changes to an alternative station frequency as described above when reception interference occurs, the regional program may also be changed. If this is not desired, the "Regional program" entry can be activated under the "FM settings" menu.
Radio Data System (RDS) function
In addition, to the radio program, many radio stations (FM) transmit additional information such as the station name, type of program (PTY), culture, sport, pop, etc. and traffic radio recognition.
This information is evaluated by COMAND, and is displayed on the screen if:
^ an RDS transmitter is set and
^ the RDS function is activated
The COMAND system's radio component additionally provides:
^ A station list of the currently most powerful FM transmitters in RDS mode
^ An automatic memory for the most powerful transmitters for MW/LW updated in qualitative sequence to autostore
^ A program type selection "PTY" (culture, sport, pop etc.) for FM stations in RDS mode
^ Multipath optimized reception system
^ FM background receiver for dynamic list administration
^ FM stereo concept with multipath and field strength dependent mono and stereo transmission
^ Multipath and field strength-dependent high-cut
^ Last station memory
^ Background traffic radio
Possibilities for tuning stations:
^ Automatic station search with scan function (the stations of a waveband are played for 8 seconds)
^ Station search at multifunction steering wheel
^ Manual station search
^ Station selection with station list
^ Station selection with number buttons
^ Station selection via frequency input (e. g. 92.2 MHz)
^ station selection from the memory (10 stations per waveband)
