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With map matching
Without map matching
Positioning errors are kept to a minimum
by combining GPS, dead reckoning and
map matching. However, in some
situations, these functions may not work
properly, and the error may become
bigger.
•
GPS positioning is disabled if signals
cannot be received from more than two
GPS satellites.
•
In some driving conditions, signals from
GPS satellites may not reach your vehicle.
In this case, it is impossible for the system
to use GPS positioning.
In tunnels or enclosed parking garages
Under elevated roads or similar
structures
When driving among high buildings
When driving through a dense forest
or tall trees
•
If a car phone or mobile phone is used
near the GPS aerial, GPS reception may
be lost temporarily.
Handling large errors
When positioning by GPS is
impossible