Pioneer AVIC N4 Owner's Manual - Page 145

NAVI/AV Appendix Handling Large Errors 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. 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 vehicle. 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 antenna, GPS reception may be lost temporarily. • Do not cover the GPS antenna 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 antenna clear. ❒ 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 vehicle's actual position and the current location mark on the map may diverge considerably. Once GPS reception is restored, accuracy will be recovered. Vehicles that Cannot Obtain Speed Pulse Data In tunnels or enclosed parking garages ❒ The speed pulse data comes from the speed sensing circuit. The location of this speed sensing circuit depends on your vehicle model. In some cases, it is impossible to make a connection to it, and in such a case we recommend that the ND-PG1 speed pulse generator (sold separately) be used. Conditions Likely to Cause Noticeable Positioning Errors Under elevated roads or similar structures For various reasons such as the state of the road you are traveling on and the state of reception of the GPS signal, the actual position of your vehicle may differ from the position displayed on the map screen. • If you make a shallow turn. When driving among high buildings When driving through a dense forest or tall trees 143