Mazda Mazda5 Owner's Manual page 214

Interior Comfort
Audio System
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.
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.
6-20
Reflected wave
Weak signal noise
In suburban areas, broadcast signals
become weak because of distance from
the transmitter. Reception in such fringe
areas is characterised by sound breakup.
Strong signal noise
This occurs very close to a transmitter
tower. The broadcast signals are
extremely strong, so the result is noise and
sound breakup at the radio receiver.
Station drift noise
When a vehicle reaches the area of two
strong stations broadcasting at similar
frequencies, the original station may be
temporarily lost and the second station
picked up. At this time there will be some
noise from this disturbance.
Station 1
88.1 MHz
Station 2
88.3 MHz