Mazda CX-9 2019, Owner'S Manual, Page: 477 / 696

FM characteristics
An FM broadcast range is usually about
40―50 km (25―30 miles) from the
source. Because of extra coding needed to
break the sound into 2 channels, stereo FM
has even less range than monaural
(non-stereo) FM.
FM Station
40—50km
(25—30 miles)
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.
AM wave
FM wave
FM wave
100—200 km (60—120 miles)
Ionosphere
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.
Reflected wave
Direct
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.
Interior Features
Appendix
5-87
CX-9_8HB2-EA-18G_Edition4_old 2019-3-15 13:53:31