In contrast to previous models, the radio is provided as standard in the E38. In line with design and ergonomic objectives to reduce the total number of display and operating elements in the centre console of the E38, a radio has been designed where the primary functions (volume, station selection buttons, station search, source selection etc.) are operated via the multi-information display. The volume and search function can also be operated using the multi-function steering wheel; this status is then additionally indicated in the text display of the instrument cluster.
The series standard radio is equipped in the same way as today's ”BMW BUSINESS RDS” with a few additional functions. Alongside improvements in the AUTO-BEST frequency search, the RDS system has been extended to include EON (Enhanced Other Network). EON enables traffic information announcements to be overlaid within a broadcasting network on all stations of this network (e.g. traffic information announcements from Radio 2 when Radio 1 is set). In addition, the Business has been extended to include functions such short wave or Autostore (permits automatic storage of the six best stations at the push of one button).
In the same way as today's BMW BUSINESS RDS, the E38 series standard radio also offers a connection option for a CD changer and the aerial diversity system. For the series-standard stereo system, the Active HiFi system already known from the E32 is offered as an optional extra.
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 antenna 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 antenna 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.
Two loudspeaker systems are offered for the radio. In contrast to the Active HiFi system, in which an amplifier is interconnected, the speakers are connected directly to the radio.
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.