All About Radio Frequencies - Ford Thunderbird Owner's Manual

To minimize these conditions, a stereo/mono
blend circuit has been incorporated into this
system. This feature automatically switches a
weak stereo signal to a clearer monaural signal,
which improves the quality of reception.
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

The Federal Communications Commission (FCC)
and the Canadian Radio Telecommunications
Commission (CRTC) establish the frequencies
that AM and FM radio stations may use for
their broadcasts. The allowable frequencies are,
AM: 530, 540...1600, 1610 kHz in 10 kHz steps;
FM: 87.9, 88.1...107.7, 107.9 MHz in 0.2 MHz
steps.
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