sat nav SUBARU BRZ 2013 1.G Navigation Manual

Navigation 181
Further Information
Display Connection Status Information
You can check the connection between the unit and the
vehicle, such as GPS information, parking signals and so on.
Display Connection Status Information
1Press .
2To u c h .
• If is not displayed, touch .
3To u c h ( S y s t e m C h e c k ) .
• Displays the connection status information screen.
<Connection status information screen>
Info
Info
System Check
Information Content
GPS information Displays the number of GPS satellites currently
sending information.
Parking signal On When the parking brake is applied.
Off When the parking brake is not applied.
Reverse signal On When shifting into reverse. Off When shifting into another gear.

182 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 183
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
To pinpoint the current position, th e unit uses information from GPS
satellite electromagnetic waves. If any of these contain errors, the
current position may not match the actual position.
• 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

184 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.