All About Radio Frequencies - Ford 1996 Escort Manual

Several sources of static are normal conditions
on AM frequencies. These can be caused by
power lines, electric fences, traffic lights and
thunderstorms.
Another reception phenomenon is Strong Signal
Capture and Overload. This can occur when
listening to a weak station and when passing
another broadcast tower. The close station may
capture the more distant station, although the
displayed frequency does not change. While
passing the tower, the station may switch back
and forth a few times before returning to the
original station.
When several broadcast towers are present
(common in metropolitan areas) several stations
may overload the receiver, resulting in
considerable station changing, mixing and
distortion.
Automatic gain control circuitry for both AM
and FM bands has been incorporated into this
system to reduce strong signal capture and
overload.

All About Radio Frequencies

Not all frequencies will be assigned to a given
area. This radio will tune to each of these
frequencies using manual tune and no fine
tuning is necessary as radio stations may not use
other frequencies.
Some FM radio stations advertise a
"rounded-off" frequency which is not the
frequency they actually broadcast on. For
example, a radio station that is assigned a
frequency of 98.7 MHz may call itself "Radio 99"
even though 99.0 MHz is not an allowable FM
broadcast frequency.
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