Fade and drif t: As your vehicle moves away
from a station transmitter, the signals will
tend to fade and/or drif t.
Static and flutter: During signal interfer-
ence from buildings, large hills or due to
antenna position (usually in conjunction
with increased distance from the station
transmitter), static or flutter can be heard.
This can be reduced by adjusting the treble
control to reduce treble response.
Multipath reception: Because of the reflec-
tive characteristics of FM signals, direct and
reflected signals reach the receiver at the
same time. The signals may cancel each
other, resulting in momentary flutter or loss
of sound.
AM RADIO RECEPTION
AM signals, because of their low frequency,
can bend around objects and skip along
the ground. In addition, the signals can be
bounced off the ionosphere and bent back
to earth. Because of these characteristics,
AM signals are also subject to interference
as they travel from transmitter to receiver.Fading: Occurs while the vehicle is passing
through freeway underpasses or in areas
with many tall buildings. It can also occur
for several seconds during ionospheric tur-
bulence even in areas where no obstacles
exist.
Static: Caused by thunderstorms, electrical
power lines, electric signs and even traffic
lights.
AUDIO OPERATION PRECAUTIONS
MP3 or WMA terms
∙ MP3 — MP3 is short for Moving Pictures
Experts Group Audio Layer 3. MP3 is the
most well-known compressed digital
audio file format. This format allows for
near “CD quality” sound, but at a fraction
of the size of normal audio files. MP3
conversion of an audio track from CD-
ROM can reduce the file size by approxi-
mately a 10:1 ratio with virtually no per-
ceptible loss in quality. MP3
compression removes the redundant
and irrelevant parts of a sound signal
that the human ear doesn’t hear. ∙ WMA — Windows Media Audio (WMA)* is
a compressed audio format created by
Microsof t as an alternative to MP3. The
WMA codec offers greater file compres-
sion than the MP3 codec, enabling stor-
age of more digital audio tracks in the
same amount of space when com-
pared to MP3s at the same level of qual-
ity.
∙ Bit rate — Bit rate denotes the number of bits per second used by a digital mu-
sic file. The size and quality of a com-
pressed digital audio file is determined
by the bit rate used when encoding the
file.
∙ Sampling frequency — Sampling fre- quency is the rate at which the samples
of a signal are converted from analog to
digital (A/D conversion) per second.
∙ Multisession — Multisession is one of the methods for writing data to media.
Writing data once to the media is called
a single session, and writing more than
once is called a multisession.
4-24Monitor, climate, audio, phone and voice recognition systems
