BMW serie 3 sedan 2000 Manual Do Utilizador

164

Radio reception

Safety belt tensioner

AM radio provides reception across a
considerable distance because the
broadcast signals not only travel along
the ground as surface waves, but they
are also reflected from the ionosphere
as atmospheric waves.
Frequency-modulation (FM) provides
substantially better sound quality than
AM. However, because FM transmis-
sions rely on line-of-sight broadcast
waves, their effective reception range is
limited.

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The limitations inherent to radio recep-
tion in a moving vehicle have been min-
imized by a number of innovative sys-
tem designs:

The "Radio Data System" (RDS) makes
sure that, for broadcast stations send-
ing on several frequencies, the radio
automatically tunes to the frequency
with the best reception quality.

The Diversity Antenna system employs
several FM antennas integrated within
the rear window to provide three sepa-
rate sources for receiving broadcast
waves. An integral processor automati-
cally selects the antenna with the best
FM reception quality at any given time.
The selection of the antenna takes
place within milliseconds, and is there-
fore not noticed by the radio listener.

The safety belt tensioner responds to
severe collisions by tightening the belts
to ensure that occupants remain firmly
positioned in their seats. A gas-pressure
system retracts the buckle assembly
to tension the shoulder and lap belts
within fractions of a second. This re-
duces the tendency to slide under the
lap belt.

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