Radio Reception - GMC Sierra Denali 2009 Owner's Manual

Radio Reception

Frequency interference and static can occur during
normal radio reception if items such as cell phone
chargers, vehicle convenience accessories, and external
electronic devices are plugged into the accessory
power outlet. If there is interference or static, unplug the
item from the accessory power outlet.
AM
The range for most AM stations is greater than for FM,
especially at night. The longer range can cause
station frequencies to interfere with each other. For
better radio reception, most AM radio stations boost the
power levels during the day, and then reduce these
levels during the night. Static can also occur when things
like storms and power lines interfere with radio
reception. When this happens, try reducing the treble on
the radio.
3-128
FM Stereo
FM signals only reach about 10 to 40 miles (16 to 65 km).
Although the radio has a built-in electronic circuit that
automatically works to reduce interference, some static
can occur, especially around tall buildings or hills,
causing the sound to fade in and out.
XM™ Satellite Radio Service
XM Satellite Radio Service gives digital radio reception
from coast-to-coast in the 48 contiguous United States,
and in Canada. Just as with FM, tall buildings or hills can
interfere with satellite radio signals, causing the sound to
fade in and out. In addition, traveling or standing under
heavy foliage, bridges, garages, or tunnels may cause
loss of the XM signal for a period of time.