2013 SUBARU LEGACY navigation

184 Navigation
Further Information
Accuracy & error calculation
Regarding Precision Accuracy
Since the GPS satellites are controlled by the US Depar tment of Defense
they do have a very high level of accuracy, however a multipath due to
reflections from buildings and so on could cause errors to occur.
Regarding the Properties of the GPS Electro-
Magnetic Waves and Signal Reception
If there are any obstacles between the GPS antenna and the GPS
satellite, electromagnetic-waves cannot be received from the satellite.
It is also impossible to use GPS posi tioning in the following locations as
at least three simultaneous electr omagnetic-waves are necessary to
take measurements.
Also, if there are any obstacles around the GPS antenna,
electromagnetic-waves cannot be received from the satellite.
• In tunnels • If the immediate area is enclosed by
large objects such as skyscrapers

Navigation 185
Further Information
NOTE•Because the GPS satellite is in orbit around the earth, the reception status for
the electromagnetic waves changes depend ing on their position at that point
in time, even if your vehicle is in th e same place. Also, electromagnetic-waves
from satellites near the horizon can be easily influenced by surrounding
obstacles.
• At times, satellites under the control of the US Department of Defence will
intentionally drop positioning accuracy.
Regarding Errors in Current Position Display
The system displays the vehicle current position based on GPS
information and data from various sensors and road maps. However,
when the radiowave signals from GPS satellites are weak or when
signals are received only from two sate llites or less, errors may occur in
the position. Modifying or adjusting the system will not prevent these
errors.
• In underground buil dings and indoor
parking lots • In places with a lot of overgrown
trees and so on
• Under elevated roads • Roads at the base of cliffs and caves

186 Navigation
Further Information
Regarding Vehicle Position Detection
Correction Using Map Matching
Map matching is a method of comparing information on the current
position acquired by GPS and so on, with the road driven up to that
point, and correcting the current po sition based on the most likely
road.
This unit uses information on th e current position combined with
independent navigation and satellite navigation and matches it to the
shape of the road to create the correction.
However, as it cannot avoid the error margins at the current position,
the current position may shift away from the actual position even when
correcting using map matching.
Also, the vehicle marker may shift if the map data and the shape of the
road being driven on differ.
NOTE
Because it takes a short time for operations to stabilize just after turning on the
unit, the vehicle mark may not immediately match the vehicle as it moves. After
driving for a while, operations stabilize, and the marker should match the actual
driving position.
Regarding the Accuracy of the Current Position
and Route Navigation
As in the following images, an accura te display of the current position
or route navigation may not be pr ovided, however this is not an
indication of a malfunction in the un it, but is due to road conditions or
driving conditions.
Actual Vehicle Swept Path
Vehicle swept path acquired from each sensor
Corrected using map matching on the screen
• Shows the current position on roads
running in parallel. • Shows the current position on the
other road when there is a narrow
fork in the road.
• Shows the current position on the road ahead or behi nd when turning
right or left. • Shows the current position when
traveling up a steep hill.

Navigation 187
Further Information
• Shows the current position if the road continues to curve around on
itself in the same direction. • Shows the current position after a
sudden change in lanes.
• Shows the current position when the
vehicle is on a parking garage
turntable and the ACC is off. • Shows the current position when
driving on snowy roads where the
vehicle may slip easily, or when
driving with snow chains.• Shows the current position in the last confirmed position before moving
when using another means of
transport, such as a ferry, until the
GPS can determine the new position.• It actually navigates through roads
that cannot be driven (no entry and
so on).
• Shows the current position when reversing.

188 Navigation
Further Information
Regarding Roads and Place Name Data
Because road and place names may change after the map data has
been created, there may be times when road and place names do not
match.
When no information is available in the map data, function such as
display of road names, searching for facilities, and route guidance
cannot be used.
When maps are created, land surv eys are conducted and information
about roads improvement and opening is collected to provide the
most accurate information possible. However, modifications in roads,
place names and facilities may be carried out at any time.
Consequently, we cannot guarantee that map data contains no errors
in road positions, configuration and names, or in facility names.
The navigation system includes a func tion to read out names of roads,
intersections, and so on during guidance.
Depending on the selected language , names read out by the system
may not be exactly accurate due to missing information in map data.
Regarding Route Navigation
• It may deviate from the route
navigation when there is a turn at an
intersection etc., and a mistake in the
voice navigation. • When searching for the route, it may
take the long way around.
• The route may need you to make a U- turn during navigation. • When driving on a straight road,
information may be displayed
indicating that you should go
straight ahead.( When the
intersection shape is not clear and so
on.)
In six tenthsof a mile,
right turm.

Navigation 189
Further Information
•Performing a new search while tr aveling at high speeds may take
some time.
• The route may not change even af ter performing another search.
• When isolated locations or road s with no surrounding available
information are set as the current position/destination, you may not
be able to search for a route.
• A route may not be displayed when the current position is close to
the destination.
• Even if you select toll roads as a priority, the route may not guide you
through a toll road.
In a similar way, toll roads may be displayed even if you prioritize
other roads over toll roads.
( When it is possible to select a toll road or a normal road to create
the route, priority is given to the user's toll road preference - use toll
roads, or avoid toll roads.)
• The navigation may not indicate that
the road curves at an intersection. • The navigation may guide you back
to a waypoint if you search for the
route again after passing the
waypoint and are heading to your
destination.
• Many place names may be displayed when navigating a district. • Always drive by following the actual
traffic regulations.
• When searching for a route, it may not be displayed quick enough for the next left or right turn.
Transit point
Search
reinitiated
Route
search
complete

190 Navigation
Further Information