100 NavigationGeneral Information(10) The vehicle's mark could deviate from its actual position after
the tires have been replaced.
(11) While driving on a public road, if an expressway that is under construction travels over the public road, the position mark of
the vehicle may be indicated on a different road.
(12) If other electronic devices are installed on the instrument panel ,
these devices may adversely affe ct the GPS signal communica-
tion and the position of the ve hicle may not be indicated cor-
rectly.■ How the vehicle position is detectedDetecting the vehicle's position through the GPSGPS stands for "Global Positioning Sy stem", which is a system used for
detecting an object's position through the use of satellites of the U.S.
Department of Defense.
Radiowave signals from three or more satellites are received by the
navigation system, which utilizes th e principle of triangulation to
detect the position at which the radiowave signals are received.
When the navigation unit is receiving the GPS radiowave signals, a
"GPS" mark will appear on the map screen.
Detecting the vehicle's position through self-contained naviga-tionSelf-contained navigation is a system that detects the vehicle's posi -
tion by calculating the vehicle's driven distance and turning angle
though the use of various types of sensors that are mounted on the
vehicle. Through the use of self-contained navigation, the vehicle's pos
ition
can be detected even in an area where the GPS radiowave signals
cannot be received.
Making corrections to the detection of the vehicle's position
through map matching
• In map matching, the position information resulting from the
detection of the vehicle's position and the locus of the travel of
the vehicle up to the present are constantly compared to the
shape of the roads on the map in order to correct the vehicle's
position mark to the most appropriate road.
• If the vehicle is driven on a road whose actual shape differs from
its map data, the vehicle's position mark on the map could devi-
ate from its actual position.
Occasionally, the correction of th e vehicle's position mark to the
actual road on the map can be observed, particularly after the
vehicle has turned at an intersection or has exited from a parking
area.
■ Accuracy of the route guidanceThe conditions listed below do not indicate a malfunction.
(1) The guidance might prompt the driver to drive straight even
though the vehicle is being driven on a straight road.
(2) The directional guidance could display multiple place name s.
(3) If the vehicle makes a turn at an intersection before the guid ed
route, the wrong type of voice guidance could be outputted.
(4) The guidance might not be ou tputted while the vehicle is mak-
ing a turn at an intersection.
(5) The system might not be able to search for the proper route .
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