Saab 2000 9-3, Руководство пользователя

Страница: 108 / 236

108 Saab 9-3 Audio System
Cross-modulation
When the radio is tuned to a weak transmit-
ter in the vicinity of a stronger one, the car’s
antennas will receive signals from both.
Such interference is apparent when the
unwanted broadcast can be heard faintly in
the background.
Radio waves, FM/AM
FM radio waves radiate in straight lines from
the transmitter. Because such waves do not
follow the curvature of the Earth, their
strength becomes weaker the further they
travel. That is why a large number of trans-
mitters are needed to provide good recep-
tion.
AM waves, on the other hand, are reflected
off the ionosphere, thus greatly extending
their range.
Sources of AM interference
AM reception is prone to interference, e.g.
from electrical systems on other vehicles,
high-tension power lines and lightning.
IB980
IB388
AM FM
IB981