Pioneer F900BT Owner's Manual - Page 164

Appendix Appendix Map matching As mentioned, the positioning systems used by this navigation system are susceptible to certain errors. Their calculations may, on occasion, place you in a location on the map where no road exists. In this situation, the processing system understands that vehicles travel only on roads, and can correct your position by adjusting it to a nearby road. This is called map matching. When 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. With map matching In tunnels or enclosed parking garages Under elevated roads or similar structures Without map matching 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 driving among high buildings When driving through a dense forest or tall trees ! 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. p 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. 164 En