Overview
This document contains information on:
Radio mode function
Special features of FM radio mode
Special features of DAB radio mode
Transfer of additional information
General
In radio mode, radio signals are converted into audio signals. The audio signals are output over the speaker system. Radio mode is operated via the multimedia system's display and control elements.
Radio mode function
The antennas receive the electromagnetic waves of the radio signals. An antenna amplifier amplifies the signals and transmits these to multimedia system control. There, the signals are converted into audio signals by an integrated audio tuner and transmitted to the speaker system. This outputs the audio signals via the speaker.
Depending on the equipment installed, the following radio signals can be received and processed:
AM (amplitude modulation)
FM (frequency modulation)
DAB (digital radio (DAB))
HD radio (high-definition radio, North America)
SDARS (Satellite Digital Audio Radio Service)
Special features of FM radio mode
For FM radio mode, an FM twin tuner is integrated into the head unit. Thus the head unit uses the signals from both FM antennas simultaneously and calculates an optimized signal (phase diversity) from both signals.
The radio station search is carried out in the background via a third FM tuner.
Special features of DAB radio mode
The DAB tuner supports the extended audio codecs DAB+ and Digital Multimedia Broadcasting (DMB) audio, in addition to DAB, and so enables the reception of programs transmitted with these codecs.
The DAB tuner unit is designed as a diversity tuner and provides the following advantages:
Switching to the antenna with the better signal (reception diversity)
Almost inaudible switchover between various ensembles with identical program
Faster switchover to another Ensemble
Searching for available stations/ensembles and receiving the "Electronic Program Guide" program index in the background
If a radio station is available as an FM station as well as a DAB station, then there will be a switchover to the FM station if the DAB reception deteriorates. Switchover to reception of the FM station only occurs after checking and ensuring a better signal reception. In this case, multimedia system control compensates the time offset between the digital and analog signal. This makes the switchover almost inaudible ("seamless linking").
Transfer of additional information
As well as radio programs, many radio stations also broadcast additional information such as the station name, type of program and traffic message channel recognition. Multimedia system control evaluates this information and displays it.
Depending on the equipment installed, the following additional information can be received and processed:
RDS (Radio data system)
RBDS (Radio Broadcast Data System) (North America)
VICS (Vehicle Information and Communication System) (Japan)