Nissan Altima L32. Instruction — part 66
AV-256
< FUNCTION DIAGNOSIS >
[BOSE AUDIO WITH NAVIGATION]
NAVIGATION SYSTEM (SEDAN)
from them are prioritized in each situation. However, this order of priority may change in accordance with more
detailed travel conditions so that the travel direction is detected more accurately.
MAP–MATCHING
Map–matching is a function that repositions the vehicle on the road
map when a new location is judged to be the most accurate. This is
done by comparing the current vehicle position, calculated by the
method described in the position detection principle, with the road
map data around the vehicle, read from the map DVD-ROM stored in
the DVD-ROM drive.
Therefore, the vehicle position may not be corrected after the vehicle
is driven over a certain distance or time in which GPS information is
hard to receive. In this case, the current-location mark on the display
must be corrected instructionly.
CAUTION:
The road map data is based on data stored in the map DVD-
ROM.
• In map-matching, alternative routes to reach the destination will be
shown and prioritized, after the road on which the vehicle is cur-
rently driven has been judged and the current-location mark has
been repositioned.
If there is an error in distance and/or direction, the alternative
routes will be shown in different order of priority, and the wrong
road can be avoided.
If two roads are running in parallel, they are of the same priority.
Therefore, the current-location mark may appear on either of them
alternately, depending on maneuvering of the steering wheel and
configuration of the road.
• Map-matching does not function correctly when the road on which
the vehicle is driving is new and not recorded in the map DVD-
ROM, or when the road pattern stored in the map data and the
actual road pattern are different due to repair.
When driving on a road not present in the map, the map-matching
function may find another road and position the current-location
mark on it. Then, when the correct road is detected, the current-
location mark may leap to it.
• Effective range for comparing the vehicle position and travel direc-
tion calculated by the distance and direction with the road data
read from the map DVD-ROM is limited. Therefore, when there is
an excessive gap between the current vehicle position and the
position on the map, correction by map-matching is not possible.
GPS (GLOBAL POSITIONING SYSTEM)
Type
Advantage
Disadvantage
Gyroscope (angular velocity sensor)
• Can detect the vehicle's turning angle quite
accurately.
• Direction errors may accumulate when the ve-
hicle is driven for long distances without stop-
ping.
GPS antenna (GPS information)
• Can detect the vehicle's travel direction
(North/South/East/West).
• Correct direction cannot be detected when the
vehicle speed is low.
SEL685V
SEL686V
SKIA0613E
AV
NAVIGATION SYSTEM (SEDAN)
AV-257
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[BOSE AUDIO WITH NAVIGATION]
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GPS (Global Positioning System) has been developed and con-
trolled by the US Department of Defense. The system utilizes GPS
satellite (NAVSTAR), sending out radio waves while flying on an orbit
around the earth at the height of approx. 21,000 km (13,000 miles).
The GPS receiver calculates the vehicle's position in three dimen-
sions (latitude/longitude/altitude) according to the time lag of the
radio waves received from four or more GPS satellites (three-dimen-
sional positioning). If radio waves were received only from three
GPS satellites, the GPS receiver calculates the vehicle's position in
two dimensions (latitude/longitude), utilizing the altitude data calcu-
lated previously by using radio waves from four or more GPS satel-
lites (two-dimensional positioning).
Accuracy of the GPS will deteriorate under the following conditions.
• In two-dimensional positioning, the GPS accuracy will deteriorate when the altitude of the vehicle position
changes.
• There may be an error of approximately 10 m (30 ft.) in position detected by three-dimensional positioning,
which is more accurate than two-dimensional positioning. The accuracy can be even lower depending on the
arrangement of the GPS satellites utilized for the positioning.
• Position detection is not possible when the vehicle is in an area where radio waves from the GPS satellite do
not reach, such as in a tunnel, parking lot in a building, and under an elevated highway. Radio waves from
the GPS satellites may not be received when some object is located over the GPS antenna.
• Position correction by GPS is not available while the vehicle is stopped.
SEL526V
AV-258
< FUNCTION DIAGNOSIS >
[BOSE AUDIO WITH NAVIGATION]
NAVIGATION SYSTEM (SEDAN)
Component Parts Location
INFOID:0000000004206538
AV
NAVIGATION SYSTEM (SEDAN)
AV-259
< FUNCTION DIAGNOSIS >
[BOSE AUDIO WITH NAVIGATION]
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