Navigation System: Description and Operation

System Description




The navigation system periodically calculates the vehicle's current
position according to the following three signals: Travel distance of
the vehicle as determined by the vehicle speed sensor, turning angle
of the vehicle as determined by the gyroscope (angular velocity sensor),
and the direction of vehicle travel as determined by the GPS
antenna (GPS information).

The current position of the vehicle is then identified by comparing the
calculated vehicle position with map data read from the map DVD-ROM,
which is stored in the DVD-ROM drive (map-matching), and indicated on the screen with a current-location mark.




By comparing the vehicle position detection results found by the
GPS and by map-matching, more accurate vehicle position data can
be used.

The current vehicle position will be calculated by detecting the distance
the vehicle moved from the previous calculation point and its
direction.

TRAVEL DISTANCE
Travel distance calculations are based on the vehicle speed sensor input signal. Therefore, the calculation may become incorrect as the tires wear down. To prevent this, an automatic distance fine adjustment function
has been adopted.

TRAVEL DIRECTION




Change in the travel direction of the vehicle is calculated by a gyroscope (angular velocity sensor) and a GPS antenna (GPS information). As the gyroscope and GPS antenna have both merit and demerit, input signals 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 manually.

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 currently 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 direction 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)




GPS (Global Positioning System) has been developed and controlled 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 dimensions
(latitude/longitude/altitude) according to the time lag of the radio waves received from four or more GPS satellites (three-dimensional 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 calculated previously by using radio waves from four or more GPS satellites (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.

COMPONENT DESCRIPTION




NAVI Control Unit
- The gyro (angular speed sensor) and the DVD-ROM drive are built-in units that control the navigation functions.
- Signals are received from the gyro, the vehicle speed sensor, and the GPS antenna. Vehicle location is determined by combining this data with the data contained in the DVD-ROM map. Locational information is shown on LCD(liquid crystal display) screen.




DVD-ROM Drive
Maps, traffic control regulations, and other pertinent information can
be easily read from the DVD-ROM disc.

Map DVD-ROM
- The map DVD-ROM has maps, traffic control regulations, and other pertinent information.
- To improve DVD-ROM map matching and route determination functions, the DVD-ROM uses an exclusive Nissan format. Therefore, the use of a DVD-ROM provided by other manufacturers cannot be used.

Gyro (Angular Speed Sensor)
- The oscillator gyro sensor is used to detect changes in vehicle steering angle.
- The gyro is built into the NAVI control unit.

BIRD VIEW(TM)
The BIRD VIEW(TM) provides a detailed and easily seen display of road conditions covering the vehicle's immediate to distant area.




- MAP DISPLAY




- BIRD VIEW(TM)




Description
- Display area: Trapezoidal representation showing approximate distances (Wn, D, and Wd).
- Ten horizontal grid lines indicate display width while six vertical grid lines indicate display depth and direction.
- Drawing line area shows open space, depth, and immediate front area. Each area is to a scale of approximately 5:6:25.
- Pushing the "ZOOM IN" button during operation displays the scale change and the view point height on the left side of the screen.
The height of the view point increases or decreases when "ZOOM" or "WIDE" is selected with the joystick.




MAP DISPLAY
Function of each icon is as follows:
1. Azimuth indication.
2. Position marker.
- The tip of the arrow shows the current position. The shaft of the arrow indicates the direction in which the vehicle is traveling.

3. GPS reception signal (indicates current reception conditions).
4. Distance display (shows the distance in a reduced scale).

FUNCTION OF NAVI SWITCH

Display with Pushed "DEST" Switch




- Easy Mode




- Expert Mode




Display with Pushed "ROUTE" Switch




- Easy Mode




- Expert Mode












Display with Pushed "SETTING" Switch
The function of each icon is as shown:








Display with Pushed "INFO" Switch
NAVI control unit is communicating combination meter.
1. Push "INFO" switch to display vehicle information display.

NOTE: If a warning signal is received by NAVI at this time, NAVI control unit displays warning message on screen.

2. Select "Trip Computer", "Fuel Economy" or "Maintenance".




Clock Setting
How To Perform Navigation Setting
1. Start the engine.
2. Push "SETTING" switch.
3. Select "CLOCK".
- GPS time can be changed to offset time.
- Daylight Savings Time can be set.
- Time zone can be set.




Display Setting
How To Perform Navigation Setting
1. Start the engine.
2. Push "SETTING" switch.
3. Select "Display".
- Brightness, contrast, or map background setting can be changed.
- Display sleep mode ON/OFF can be switched.
- Display sleep mode timer can be set.




Language Setting
How To Perform Navigation Setting
1. Start the engine.
2. Push "SETTING" switch.
3. Select "Language".
- Language setting can be switched.
- Unit setting can be changed.




Navigation Setting
How To Perform Navigation Setting
1. Start the engine.
2. Push "SETTING" switch.
3. Select "Navigation".

Application Items:

Application Items




"VIEW" MODE
1. Select "Bird view(TM)" or "Plan view" icon.
- To open the map screen display with Bird View(TM), select "Bird View(TM)".
- To open the map screen display with Plan View, select "Plan View".




"HEADING" MODE
- To display North up, select "North up".
- To display the car heading up, select "Heading up".




"NEARBY DISPLAY ICONS" MODE
- Select an icon to display on the map screen.




"SAVE CURRENT LOCATION" MODE
- The current vehicle location can be registered in "Address Book".

NOTE: "Address Book" can store 50 items max.

"ADJUST CURRENT LOCATION" MODE




1. Select an icon"right" or "left" to calibrate the heading direction.
(Arrow marks will rotate corresponding to the calibration key.)




2. Select "Set". Then the vehicle mark will be matched to the arrow mark.




"AUTO RE-ROUTE" MODE
- To Perform the auto re-route of route, select "On".
- Not to perform the auto re-route of route, select "Off".




"AVOID AREA SETTING" MODE
- Areas to avoid can be registered.




"BUTTON TONE/BEEP RESPONSE" MODE
- If beep is required, select "On".
- If no beep is required, select "Off".




"CLEAR MEMORY" MODE
- To delete all the stored places in "Address Book", "Avoid Area" and "Previous Dest", select "Yes".




"EDIT ADDRESS BOOK" MODE
- Edit the items registered in Address Book.




"GPS INFORMATION" MODE
- Latitude, longitude, altitude, astrometric state, and satellite location are displayed as GPS information.

NOTE: Altitude is displayed only in three-dimensional status.




"QUICK STOP CUSTOMER SETTING" MODE
- Select a category for the "Quick Stop" menu.




"SET AVERAGE SPEED" MODE
- Set the average vehicle speed to calibrate the estimated journey time for the destination.
- Set three items; "Freeway", "Main Roads", and "Ordinary Roads".




"TRACKING" MODE
- To leave no trail on the map, select "Off".
- To leave a trail in the map, select "On".

NOTE: When a trail display is turned OFF, trail data is erased from the memory.




GUIDE VOLUME SETTING

Description
Following voice guidance setting can be changed.

Activation/Deactivation Setting
- The voice prompt can be turned on/off by Pushing the "Guidance Volume" button.

Voice Volume Setting
- Volume of the voice can be controlled by bending the joystick to left/right.




TRIP COMPUTER INFORMATION
- Elapsed time, Driving distance and Average speed are displayed as Trip Computer information.




FUEL ECONOMY INFORMATION
- Average Fuel Economy, Distance to Empty, Fuel Economy are displayed as Fuel Economy information.




- Select "Fuel Economy Record". The average fuel consumption history will be displayed in graph along with the average for the previous Reset - to - Reset period.




MAINTENANCE INFORMATION
- Engine Oil and Oil Filter are displayed as Maintenance information.

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WARNING INDICATIONS
When combination meter receives warning signal from some control units or sensors, then combination meter warning lamp is illuminated.
Then combination meter sends warning signal to NAVI control unit to display warning indications on the screen.