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General information about your radio
Signal transmission
FM signals do not follow the earth surface
nor are they reflected by the upper atmo-
sphere. For this reason, FM broadcasts cannot
be received over long distances. AM signals
follow the earth's surface and are reflected by
the upper atmosphere. For this reason, AM
broadcasts can be received over longer dis-
tances.
7
FM
AM
25 to 40 mile radius
100 mile radius
(40 to 64 km)
(160 km)
Weak reception (fading)
Because of the limited range of FM signals
and the way FM waves transmit, you may
experience weak or fading FM reception.
When the broadcast is blocked by mountains
or similar obstructions, reception can be dis-
turbed.
7-16
Comfort controls
Reflection
The reason why one can hear FM but not AM
in parking garages, under bridges etc., is that
FM signals, unlike AM signals, are reflected
by solid objects such as buildings, etc.
Because FM signals are easily reflected by
buildings, this can also cause reception dis-
turbances.
The direct signal from the broadcast station
reaches the antenna slightly before the
reflected signal. This time difference may
cause some reception disturbance or flutter.
This problem occurs primarily in urban areas.
Cross modulation
If one listens to a weak station and is in the
vicinity of another strong station, both sta-
tions might be received simultaneously.
FM stereo reception
Stereo reception requires a high quality
broadcast signal. This means that types of
disturbances mentioned previously become
more marked and the reception range is
somewhat diminished during stereo recep-
tion.
Causes of disturbances
FM reception is affected by the electrical sys-
tems of vehicles in the vicinity, especially
those without an electronic noise suppression
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