Pioneer DVD Navigation Unit AVIC-80DVD - Manual (Page 167)

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Appendix
Handling Large Errors
Positioning errors are kept to a minimum by combining GPS, Dead Reckoning, and map matching. How-
ever, in some situations, these functions may not work properly, and the error may become bigger.
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When the positioning by GPS is impossible
• If signals cannot be received from more than two GPS satellites, GPS positioning does not take place.
• In some driving conditions, signals from GPS satellites may not reach your car. In this case, it is
impossible for the system to use GPS positioning.
• If a car phone or cellular phone is used near the GPS aerial, GPS reception may be lost temporarily.
• Do not cover the GPS aerial with spray paint or car wax, because this may block the reception of GPS
signals. Snow buildup can also degrade the signals, so keep the aerial clear.
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If, for any reason, GPS signals cannot be received, learning and error correction are not
possible. If GPS positioning has been operating for only a short time, your car’s actual
position and the current location mark on the map may diverge considerably. Once GPS
reception is restored, accuracy will be recovered.
In tunnels or enclosed parking garages Under elevated roads or similar
When driving among high buildings When driving through a dense forest or tall trees