Sienna FWD V6-3.3L (3MZ-FE) (2006)
1. The service areas of AM and FM broadcasts are vastly different. Sometimes an AM broadcast can be received very clearly but an FM
stereo cannot. FM stereo has the smallest service area, and is prone to pick up static and other types of interference such as noise.
c. Radio reception problems
HINT: In addition to static, other problems such as "phasing", "multipath", and "fade out" exist. These problems are not caused by electrical
noise, but by the radio signal propagation method itself.
1. Phasing
AM broadcasts are susceptible to electrical interference and another kind of interference called phasing. Occurring only at night, phasing is
the interference created when a vehicle receives 2 radio wave signals from the same transmitter. One signal is reflected off the ionosphere
and the other signal is received directly from the transmitter.
2. Multipath
Multipath is a type of interference created when a vehicle receives 2 radio wave signals from the same transmitter. One signal is reflected
off buildings or mountains and the other signal is received directly from the transmitter.
3. Fade out
Fade out is caused by objects (buildings, mountains, and other large obstacles) that deflect away part of a signal, resulting in a weaker
signal when the object is between the transmitter and vehicle. High frequency radio waves, such as FM broadcasts, are easily deflected by
obstructions. Low frequency radio waves, such as AM broadcasts, are much more difficult to deflect.