GF82.85-D-2012H Navigation Mode, Function
GF82.85-D-2012H Navigation Mode, Function
- with CODE (EN4) COMAND with TMC interface
- with CODE (EN8) Sound 50 APS radio
A1 Instrument cluster
A2/18 Antenna amplifier
N80 MRM control unit
N87/1 Radio/radio with navigation
S110 Right multifunction steering wheel button group
S111 Left multifunction steering wheel button group
The navigation system can be activated by pressing the "NAV" button on the radio/radio with navigation. The location of the vehicle, as well as the direction and distance to the destination (after entering the destination) are determined with the aid of the navigation system.
The digital map data for navigating to a destination (destination-oriented navigation) is read and calculated by the navigation processor integrated in the radio/radio with navigation from the navigation DVD inserted in the DVD drive. The processed map data is output over the LCD (liquid crystal display) color display of the radio/radio with navigation.
If the navigation DVD is not inserted, the message "Please insert navigation DVD" appears on the LCD color display. The purpose of this note is to ensure that the user inserts the correct DVD.
Destination entry
The user can enter the destination (menu-assisted) using the radio/ radio with navigation. This destination entry is then processed by the integrated navigation processor.
Dynamic supplementation
The dynamic supplementation is active during manual input of the destination. While entering a destination the letters which are still missing are completed from an existing list. The supplemented characters have a black background. Deleting can be accomplished character by character. The predictive speller refers to the entry of the destination and street during destination-oriented navigation. The "Special Destinations" menu is supplemented by the "Bypassing other Locations" and "National Destinations" submenus. The "National Destinations" menu is subdivided into an additional submenu.
Position finding
The radio/radio with navigation continuously calculates the location of the vehicle with the aid of the following procedures:
- Global positioning system (GPS) position finding
- Basic location finding (dead reckoning)
- Map-based position finding
The integrated navigation processor calculates the most probable position by continuously comparing the results returned by these 3 methods.
Route calculation
The route is calculated in the navigation processor of the radio/radio with navigation after destination input or automatically after a deviation from the proposed route. With the dynamic destination- oriented navigation system, the route is calculated automatically including traffic information, either free of charge via the traffic message channel (TMC) or via an external provider by telephone, which is subject to a fee. The calculated route is stored in the navigation processor.
Continuous position finding
Continuous location finding means that the current position of the vehicle is calculated. This function is active when the transmitter key is in position 1 (terminal 15R on), and is carried out by the navigation processor, which is integrated in the radio/radio with navigation. During the switch-on phase (software is loaded), only the basic position finding (composite positioning) is available. After the transmitter key has been turned to position 0 (terminal 15R OFF), all important localizing parameters are stored for the duration of the run- on time (approx. 30 min).
The radio/radio with navigation then goes into sleep mode. In sleep mode, the navigation data remains stored for a maximum of t = 72 h.
Following the final destination-oriented navigation execution (destination reached), the position map is displayed again. The radio/radio with navigation switches off after t = 1 minute.
Manual entry of vehicle location
It is possible to enter the location manually on the radio/radio with navigation in the "Navigation" menu. This may be useful in the following cases:
- Following transport of the vehicle (e.g. ferry or train)
- if no GPS reception is available at the start of the journey.
Basic location finding (dead reckoning)
Basic location finding (dead reckoning) is the basic function of continuous location finding. It is carried out continuously by the navigation processor of the radio/radio with navigation with the ignition switched on (terminal 15 ON) and is independent of the DVD map. The current position is stored after the ignition is switched off (terminal 15 OFF).
The following information is calculated with the aid of basic position finding (composite positioning):
- Distance travelled
- Direction of motion (forward or reverse).
- Vehicle orientation
Distance traveled
The integral navigation processor of the radio/radio with navigation receives the wheel speed signals from the ESP control unit (N30/4) via the Controller Area Network bus class C (engine compartment) (CAN-C). The evaluation of the wheel speed signals shows the distance traveled.
Direction of travel
The signal for backing up, which is transferred by the EZS control unit (N73) via the Controller Area Network bus class B (interior) (CAN-B), allows the navigation processor of the radio/radio with navigation to recognize the direction of motion (forward or backward).
Vehicle orientation
The navigation processor of the radio/radio with navigation calculates the orientation (compass direction) of the vehicle from the data of the yaw rate sensor (gyro sensor) and the sequence of the positions calculated using the GPS.
Position finding errors during basic position finding (composite positioning)
Rolling backwards without the transmission being shifted into reverse gear is evaluated as moving forwards and can lead to temporary errors in location finding. Rolling when the ignition is switched off or transporting the vehicle can also distort the position finding. In both cases, when the GPS data is received, the deviation is automatically corrected by the navigation processor of the radio/radio with navigation.
The driving direction signal (forwards, backwards) is generated by the wheel speed sensors. This makes possible an exact recording of the distance traveled.
Calibration
Wheel calibration is necessary following a tire change.
To do this, the difference in the calculated mileage and the mileage actually covered between 2 turnoff points is used to automatically recalibrate the tire circumference (necessary due to tire wear).
The input of tire size and the coding, whether new tires (depth of tread approx. 5 to 10 mm) or worn tires (depth of tread approx. 3 to 5 mm) have been fitted, is necessary for this. The entry is made via STAR DIAGNOSIS or directly at the radio/radio with navigation. A special calibration drive is not required.
GPS position finding
GPS position finding is irreplaceable for journeys outside the digitized map area and after vehicle transport (e.g. train or ferry journeys and towing). A new GPS position (after interruption of the satellite reception) can take several minutes (up to 20 minutes when the equipment is first set up).
GPS position finding, function
The navigation processor in the radio/radio with navigation calculates the vehicle location and the accuracy of the position finding from the satellite signals received and amplified by the GPS antenna integrated in the antenna amplifier (A2/18). The actual calculation is based on the measurement of the transmission times of the signals transmitted synchronously by the various satellites. Here, an important prerequisite is that the satellite and receiver clocks are synchronized.
For this purpose, the receiver has an automatic time correction feature which again is possible with the aid of the satellite signals. When the navigation processor determines that basic location finding is less precise than GPS location finding, the currently calculated position is corrected with the aid of the GPS data.
In addition, the vehicle's course of travel is determined with the aid of the sequence of the locations calculated with GPS.
Possible interference when receiving GPS signals
Since GPS operates in the gigahertz (GHz) range (microwave) and the signals are weak, reception interference can occur as the result of:
- atmospheric interference,
e.g. bad weather, water vapor, fog
- Multiple reception due to reflection of the signals,
e.g. from walls of buildings
- Signal shading,
e.g. in built-up areas, tunnels, through high buildings, through trees
GPS reception therefore necessitates a clear view of the sky.
Positioning accuracy is approx. 10 m.
The position of the vehicle is constantly tracked on the DVD map by the navigation processor of the radio/radio with navigation. In the event of deviations in the course traveled from the calculated route, the position coordinates of the basic location finding (dead reckoning) are corrected.
Map-based position finding is only available in the digitized area of the DVD map. By comparison with the calculated position of the vehicle with the DVD map, the deviation can be recognized and corrected automatically.
After entry of the destination on the radio/radio with navigation, the integrated navigation processor calculates and continually updates the route. This can only be calculated within the digitalized map areas. The calculated route is the prerequisite of the destination guidance system.
The navigation processor calculates the route with the aid of the DVD map data, the destination entered, and the current position. For the calculation it takes into account roads and their attributes read from the DVD map, such as one-way streets, turn prohibitions, road classes etc. (where available).
Here, it is possible for the user to indicate how the route should be calculated:
- Fastest route
- Shortest route
- Dynamic route
- Own selection
When the user selects "dynamic route", traffic messages received via two-way radio (ultra-short waves (FM) or network provider) are stored with the aid of a traffic data recorder integrated in the radio/ radio with navigation and automatically taken into consideration when the route is calculated. The route is then calculated with the optimum time, in a manner similar to the "Fastest route" option. Notification that the route has been recalculated taking traffic messages into consideration, is provided.
Under "Own selection", the following stretches can be blocked from the route calculation:
- FREEWAY
- FERRY
- TOLL
- Tunnel
The toll roads are marked in color on the map.
Following the calculation of the route, the navigation processor generates a list of roads and junctions to be driven along. This route list is used for destination guidance. It may also be displayed by calling up the "Information" menu.
Route updating
When the driver deviates from the calculated route, a new route list is calculated by the navigation processor. When doing so, the current position and the direction of travel are taken into consideration. The message "New Route" appears on the display of the radio/radio with navigation and "NEW RTE" appears in the instrument cluster.
Trips outside the digitized map area
If the vehicle leaves the digitized DVD map area (e.g. driving into a multilevel car park), then no route can be calculated or updated. The message "OFF ROAD" appears on the display of the radio/radio with navigation. Upon leaving the map boundaries (e.g. foreign country), the message "OFF MAP" appears. Destinations which lie outside of the digitalized map area cannot be taken into consideration on calculation of the route.
Bypassing traffic tailbacks through the "Detour" function
After a tailback message via traffic radio and before the route section concerned is reached, a route calculation can be arranged which bypasses the tailback.
To do this, the user must press the "Bypass" button and enter the following data:
- The length of the traffic jam, including the distance to the start of the traffic jam
- The corresponding stretch must be blocked within the detailed route list.
Digitized DVD map area
1 Vehicle position within the digitized DVD map
Non digitized DVD map areas
2 Vehicle position within the DVD map limits, but outside the digitized map area ("OFF ROAD", company grounds, track across a field)
3 Vehicle position outside the DVD map limits ("OFF MAP")
Destination guidance, function
Destination guidance is the generation and output of driving recommendations, in order to guide the driver to the desired destination. The prerequisites of destination guidance include:
- Constant location finding is active and takes place automatically.
- Destination was entered
- The route has been calculated.
The navigation processor of the radio/radio with navigation continuously compares the route calculation data with the data of the continuous position finding.
The measures for further route guidance are derived from this. Depending on the position of the vehicle, a distinction can be made between 2 destination-oriented navigation modes:
- Destination-oriented navigation within the digitized DVD map area
- Destination-oriented navigation in non-digitized DVD map area
During trips within the digitized map area, the following information, calculated by the navigation processor of the radio/radio with navigation, is available to the user:
- The current position and route of the vehicle on a digital map
- Route list
- Distance from the destination and likely time up to arrival
- Direction recommendation
- Direction indication arrow
- Name of the road currently being traveled along
- Name of the road to turn into
- Distance from the next junction (specified in units of length or as a bar graph)
For destination guidance, 3 illustration modes are possible:
- with map
- with map and symbol display before turn-off points
- with symbol display (guide symbols)
The scale of the map can be changed in stages (50 m/cm to 500 km/cm on the screen). Moreover, it is possible to select whether the map is aligned in the direction of travel (forward) or facing North.
When traveling outside the digitized map area (e.g. company sites, multi-level car parks, field tracks etc.), but still within the DVD map boundaries, the navigation processor of the radio/radio with navigation switches over to "destination-oriented navigation in the non digitized map area". Appearing on the display of the radio/radio with navigation is the message:
- "OFF ROAD"
In addition, if the vehicle is outside the DVD map limits (outside the country), the following message appears:
- "OFF MAP"
When entering the OFF-ROAD mode, the street map is opened and a route information is displayed.
In both cases, only basic position finding (dead reckoning) with correction by GPS data takes place.
Limited destination guidance takes place while only specifying:
- Distance to the destination as the crow flies
- direction to destination (as arrow).
After reentering the digitized map area, the system automatically continues with "Destination guidance in digitized map area". The GPS position is used to help determine the roads on which the vehicle could be located. During this process a slight delay in the route guidance may result.
In the event of the message "OFF MAP", comprehensive destination-oriented navigation can be continued after loading a corresponding abroad DVD.
Dynamic route guidance
The current traffic situation is taken into consideration in the dynamic route guidance. The navigation system in the radio/radio with navigation can receive the information on the traffic situation either via the Traffic Center Service (TCS) or via the traffic message channel (TMC).
The services from the TCS are offered by an external provider and an application is to be sent to the provider for use.
Traffic messages via TCS
Information on the current traffic situation is transmitted by a service provider for a fee in the form of a short message service (SMS) message via the telephone network.
During the TCS data transfer, operation of the telephone is possible. The traffic data recorder is integrated in the radio/ radio with navigation. The traffic data are only transmitted when the service provider receives a corresponding request from the vehicle.
The request is made either cyclically every 15 min. or once. In order to reduce the data volume, the current location of the vehicle is automatically sent to the network provider when the information request is posted. The service provider then transmits only traffic messages at within a radius of approx. 75 km around the vehicle.
Traffic messages via TMC
Information on the current traffic situation is broadcast at no cost regionally by specially equipped radio stations via ultra-short wave (FM). For this purpose, it is necessary for an appropriate FM RDS radio station to be tuned in. The radio tuner receives the traffic messages and forwards them to the traffic data recorder. Since no communication is accomplished between the vehicle and broadcasting corporation with TMC messages, the traffic data recorder selects the traffic messages related to the route on which the vehicle is presently driving as well as the surrounding area.
If the traffic message channel transmission signal is weak, the system searches in the background for an alternative station via station search.
Traffic information analysis
In both cases (TCS or TMC) the traffic data recorder decodes the traffic information and forwards it to the navigation processor when requested. The navigation processor makes the decision whether the route should be changed. If necessary, a message that the route should be changed is output via the vehicle speaker.
For synchronization the traffic data recorder requires a current "location list" from the navigation processor. Each stretch of road and each striking feature (e.g. expressway exit) of the road network detected is clearly defined by means of a number. The "Location list" is stored on the DVD. If required (e.g. changing the DVD) it is automatically loaded into the traffic data recorder. The traffic information stored in the traffic data recorder is automatically deleted after 30 min. A maximum of 100 messages can be stored.
The decoded traffic messages are marked on the map using suitable symbols. They can also be displayed as clear text. For this purpose press button "Detour" and then active menu "TRAFFIC-INFO.
The "Navigation - Settings - Traffic Information" menu can be used to select the mode (TMC or TCS). A mixed operation of TMC and TCS is not possible.
Traffic jams are marked during navigation on and next to the route on the map.
