Two Types Of Signals; Electrical Disturbances; Am Reception; Fm Reception - Chrysler 2008 Town & Country Owner's Manual

252 UNDERSTANDING YOUR INSTRUMENT PANEL

Two Types of Signals

There are two basic types of radio signals... AM or
Amplitude Modulation, in which the transmitted sound
causes the amplitude, or height, of the radio waves to
vary... and FM or Frequency Modulation, in which the
frequency of the wave is varied to carry the sound.

Electrical Disturbances

Radio waves may pick up electrical disturbances during
transmission. They mainly affect the wave amplitude,
and thus remain a part of the AM reception. They
interfere very little with the frequency variations that
carry the FM signal.

AM Reception

AM sound is based on wave amplitude, so AM reception
can be disrupted by such things as lightning, power lines
and neon signs.

FM Reception

Because FM transmission is based on frequency varia-
tions, interference that consists of amplitude variations
can be filtered out, leaving the reception relatively clear,
which is the major feature of FM radio.
NOTE: The radio, steering wheel radio controls (if
equipped), and 6 disc CD/DVD changer (if equipped)
will remain active for up to 90 seconds after the ignition
switch has been turned off, depending upon the acces-
sory delay setting. Opening a vehicle front door will
cancel this feature.