Subaru 2009 Tribeca Owner's Manual page 181

You may experience problems in receiving
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XM satellite radio signals in the follow-
ing situations.
If you are driving northward in a coastal
area
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You will notice that the XM
radio antenna is fixed to the upper right
hand corner of your windscreen.
The signal comes from the south and may
not be able to reach the antenna in some
circumstances when you are driving north.
satellite
If you are driving in a tunnel or a
covered parking area
If you are driving beneath the top level
of a multi-level freeway
If you drive under a bridge
If you are driving next to a tall vehicle
(such as a truck or a bus) that blocks the
signal
If you are driving in a valley where the
surrounding hills or peaks block the signal
from the south
If you are driving on a mountain road
where the southern direction is blocked by
mountains
Audio
If you are driving in an area with tall
trees that block the signal (10 m or more),
for example on a road that goes through a
dense forest
The signal can become weak in some
areas that are not covered by the repeater
station network.
Please note that these may be other
unforeseen circumstances when there
are problems with the reception of XM
satellite radio signals.
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