28 Navigation Functions
Map Data
The map data may contain wrong or missing
characters, incorrect locations etc.
Position Measurement
When Accurate Position
Measurement Is Not Possible
Radio signals from GPS satellites cannot be
received in locations such as in tunnels, indoor
parking garages, locations surrounded by high
buildings, mountains or trees, under freeways
and elevated train lines. In such cases, the
position measurement uses autonomous
navigation based on the gyro sensor and
speed sensor, so accurate measurement of
your car's location may become impossible.
Measurement Error
When radio signals cannot be received from
GPS satellites, measurement error occurs
easily and the location of your car may not be
displayed correctly.
If you keep on driving, when it becomes
possible to receive radio signals from GPS
satellites, the error in the current location will
be automatically corrected.Reasons Why the Location of Your
Car Is Not Displayed Correctly
• When a freeway and general road are near
each other
• When driving roads laid out in a grid
• When driving on a mountain road with a
sharp slope
• When turning left or right after having driven
a long while on a straight road
• Immediately after the engine is switched ON
• When driving at slow speed, for example on
a congested road or in a parking lot (Because
some cars do not output a vehicle speed
signal when driving too slow)
• When traveling with chains on the tires
• When the vehicle was turned on a turntable
or the like
• When driving through a fork in the road with
a small angle between the two branches
• After the vehicle has been moved by ferry or
the like
• When driving in a multi-level parking garage
or on a spiral road
• When zig-zagging on a wide road
• When a tire has been replaced with the
emergency spare
• When driving on snow, sand, or other
slippery road
3D Position Measurement
When effective radio signals for which
positional precision can be expected can be
received from four or more GPS satellites, the
3D position of latitude, longitude, and altitude
can be calculated.
“GPS Information”(P143)
2D Position Measurement
When effective radio signals for which
positional precision can be expected can be
received from three or more GPS satellites
but not enough for 3D position measurement,
the altitude is assumed to have remained
the same since the last time it could be
measured and only the 2D of latitude and
longitude can be calculated. In this case, the
positional precision is less than for 3D position
measurement.
“GPS Information” (P143)
Non-measurable Position
When effective radio signals from GPS
satellites for which positional precision can be
expected can not be received, the position is
not measured.
“GPS Information”(P143)
