2007 Dodge Durango Owner's Manual - Page 196

196 INSTRUMENT PANEL AND CONTROLS 5. To exit, press any button/knob or wait approximately 5 seconds. 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 operation and natural phenomena, which might lead you to believe your sound system is malfunctioning. To help you understand and save you concern about these "apparent" malfunctions, you must understand a point or two about the transmission and reception of radio signals. 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.