Cadillac 2010 DTS Owner's Manual page 288

Cellular phone usage may cause interference
with the vehicle's radio. This interference may occur
when making or receiving phone calls, charging
the phone's battery, or simply having the phone on.
This interference causes an increased level of static
while listening to the radio. If static is received while
listening to the radio, unplug the cellular phone and
turn it off.
The AM-FM antenna is integrated with the rear window
defogger, located in the rear window. Make sure that the
inside surface of the rear window is not scratched and
that the lines on the glass are not damaged. If the
inside surface is damaged, it could interfere with radio
reception. For proper radio reception, the antenna
connector needs to be properly attached to the post
on the glass.
If a cellular telephone antenna needs to be attached to
the glass, make sure that the grid lines for the AM-FM
antenna are not damaged. There is enough space
between the grid lines to attach a cellular telephone
antenna without interfering with radio reception.
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The XM Satellite Radio antenna is located on the roof of
the vehicle. Keep the antenna clear of obstructions for
clear radio reception.
If the vehicle has a sunroof, the performance of the XM
system may be affected if the sunroof is open.