Radio General Information; Radio Broadcast Signals; Two Types Of Signals; Electrical Disturbances - Jeep Automobile Owner's Manual

194 UNDERSTANDING YOUR INSTRUMENT PANEL
To set the variance: Turn the ignition ON and set the
display to "Compass/Temperature." Press the C/T but-
ton approximately 5 seconds. The last variance zone
number will be displayed. Press and hold the STEP
button for 1 second to select the new variance zone and
press the RESET button to resume normal operation.

RADIO GENERAL INFORMATION

Radio Broadcast Signals

Your new radio will provide excellent reception under
most operating conditions. Like any system, however, car
radios have performance limitations, due to mobile op-
eration and natural phenomena, which might lead you to
believe your sound system is malfunctioning. To help
you understand and save you concern about these "ap-
parent" malfunctions, you must understand a point or
two about the transmission and reception of radio sig-
nals.

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.