2007 Mazda MAZDA3 Owner's Manual - Page 203

Mazda3_8V66-EA-06F_Edition2 Page202 Friday, May 26 2006 10:54 AM Black plate (202,1) Interior Comfort Audio System Signals from an FM transmitter are similar to beams of light because they do not bend around corners, but they do reflect. Unlike AM signals, FM signals cannot travel beyond the horizon. Therefore, FM stations cannot be received at the great distances possible with AM reception. Ionosphere FM wave FM wave 100-200 km (60-120 miles) AM wave Flutter/Skip noise Signals from an FM transmitter move in straight lines and become weak in valleys between tall buildings, mountains, and other obstacles. When a vehicle passes through such an area, the reception conditions may change suddenly, resulting in annoying noise. Atmospheric conditions can also affect FM reception. High humidity will cause poor reception. However, cloudy days may provide better reception than clear days. Multipath noise Since FM signals can be reflected by obstructions, it is possible to receive both the direct signal and the reflected signal at the same time. This causes a slight delay in reception and may be heard as a broken sound or a distortion. This problem may also be encountered when in close proximity to the transmitter. Weak signal noise In suburban areas, broadcast signals become weak because of distance from the transmitter. Reception in such fringe areas is characterized by sound breakup. Reflected wave Direct 6-18 Form No.8V66-EA-06F