Handling Large Errors - Pioneer AVG-VDP1 Mode D'emploi

Appendix
Additional Information
How do GPS and dead
reckoning work together?
For maximum accuracy, this unit continually
compares GPS data with your estimated posi-
tion as calculated from the data of 3D Hybrid
Sensor. However, if only the data from the 3D
Hybrid Sensor is available for a long period,
positioning errors are gradually compounded
until the estimated position becomes unreli-
able. For this reason, whenever GPS signals
are available, they are matched with the data
of the 3D Hybrid Sensor and used to correct it
for improved accuracy.
To ensure maximum accuracy, the dead reck-
oning system learns with experience. By com-
paring the position it estimates with your
actual position as obtained using GPS, it can
correct for various types of error, such as tire
wear and the rolling motion of your vehicle. As
you drive, the dead reckoning system gradu-
ally gathers more data, learns more, and the
accuracy of its estimates gradually increases.
! If you use chains on your wheels for winter
driving or put on the spare wheel, errors
may suddenly increase because of differ-
ence in wheel diameter. The system detects
the fact that the tire diameter has changed,
and automatically replaces the value for
calculating distance.

Handling large errors

Positioning errors are kept to a minimum by
combining GPS and dead reckoning. However,
in some situations, these functions may not
work properly, and the error may become big-
ger.
32
En
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.
 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
! 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.
Note
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 vehicles actual position may not
be displayed properly. Once GPS reception is re-
stored, accuracy will be recovered.