In contrast to previous models, the radio is provided as standard in the E39. In line with design and ergonomic objectives to reduce the total number of display and operating elements in the centre console of the E39, a radio has been designed whose primary functions (volume, station selection buttons, station search, source selection etc.) are operated via the multi-information display (MID) or the operating unit of the integrated radio information system (IRIS). The volume and search function can also be operated via a multi-function steering wheel, this status is then additionally indicated in the text display of the instrument cluster (with IKE).
The following types of radios are offered for the E39:
Trade name of radio |
Operating unit |
BMW-internal designation |
|---|---|---|
BMW reverse RDS |
BMW designation |
C32 |
BMW Business RDS |
IRIS or MID |
C33 |
BMW Business CD RDS |
IRIS or MID |
CD33 |
BMW Professional RDS |
MID |
C34 |
BMW on-board monitor radio |
On-board monitor |
C23 |
An anti-theft security code (radio code) is no longer necessary for the radios C33, CD33, C34 and C23 since these radios can only be operated in conjunction with IRIS, MID or on-board monitor. Since the radio set and operating unit of the C32 form one unit, this radio is protected by a code function (activated after disconnecting and reconnecting to power supply).
The IRIS operating unit contains the operating and display elements for:
The push-button information on the IRIS is transferred in the form of an I-bus/K-bus telegram to the relevant control unit:
In turn, these control units send text information via the I-bus/K-bus which is then shown in the IRIS display.
The MID is used as soon as further optional extras in addition to the functions which can be operated by the IRIS are installed in the vehicle.
Depending on the scope of equipment, the MID contains the operating and display elements for:
The components are linked via the I-bus/K-bus. The push-button information on the MID is transferred in the form of an I-bus/K-bus telegram to the relevant control unit. In turn, the control unit sends text information via the I-bus/K-bus which is then shown in the MID display.
In contrast to a home radio, a car radio is constantly subjected to changing reception conditions. At one point reception is excellent, however, reception may be very poor after just a short distance has been covered. Reception can be best checked by driving in a circle. In this way, the rear window aerial is pointed in all directions.
One aerial each for the AM (amplitude modulation) and FM (frequency modulation) bands is integrated in the rear window. The received signal is amplified by the aerial amplifier and is transferred via a high frequency line (HF line) directly into the radio.
In the aerial diversity optional extra, one aerial is connected for the AM band and three separate aerials for the FM range. The three FM signals received are switched in the diversity amplifier through to the radio cyclically via the RF line. The radio sends a feedback signal relating to the quality of the received aerial signal (the intermediate frequency signal) to the aerial diversity system. The aerial diversity system decides which of the three aerials has the best reception quality at present and switches this aerial through to the radio until the next measuring cycle is carried out. The aerial (FM1) arranged vertically in the rear window is used in the case of interference in the intermediate frequency signal.
Three speaker systems are offered irrespective of the type of radio. In contrast to the Active and Top HiFi systems, in which an amplifier is interconnected, the speakers are connected directly to the radio in the stereo system.
Speakers as for stereo (same parts), additionally:
Due to different connector assignments than for stereo, the tweeter is not operated by means of the diplexer integrated in the front speaker but rather it is driven as all loudspeakers directly by the active amplifier.
Number of speakers and locations same as Active HiFi, but in superior quality and additionally: