AIR CONDITIONING AND AUDIO
11 4FM reception tips
A vehicle is not an ideal place to listen to a radio. Because
it moves, reception conditions are constantly changing.
Buildings, terrain, signal distance and noise from other
vehicles are all working against good reception. Some
conditions of FM may appear to be problems when they are
not. The following characteristics are completely normal for
a given reception area, and they do not indicate any problem
with the radio itself.
Fading and drifting:
FM range is limited to about 40 km (25 miles), except for
some high power stations.
If a vehicle is moving away from the desired station's
transmitter, the signal will tend to fade and/or drift. This
phenomenon is more noticeable with FM than with AM,
and is accompanied by distortion.
Fading and drifting can be minimized to a certain degree
by careful attention to fine tuning, or you should retune
the radio to another stronger station.
Static and fluttering:
When the line±of±sight link between a transmitter and
vehicle is blocked by large buildings or the like, the radio
sound may be accompanied by static or fluttering
because of the characteristics of FM. In a similar effect,
a fluttering noise is sometimes heard when driving along
a tree±lined road.This static and fluttering can be reduced by adjusting the
tone control for greater bass response until the
disturbance has passed.
Multipath:
Because of the reflecting characteristics of FM, direct
and reflected signals may reach the antenna at the same
time (multipath) and cancel each other out. As a vehicle
moves through these electronic dead spots, the listener
may hear a momentary flutter or loss of reception.
Station swapping:
When two FM stations are close to each other, and an
electronic dead spot, such as static or multipath area,
interrupts the original signal, sometimes the stronger
second signal will be selected automatically until the
original one returns. This swapping can also occur as
you drive away from the selected station and approach
another station with a stronger signal.
