Navigation Mode, Function - GF82.85-P-2012CE

MODEL 204.0/2 with CODE (511) Audio 50 APS with DVD changer as of model year 2009/YoM 08 

MODEL 204.0/2 with CODE (525) MB Audio 50 APS radio as of model year 2009/YoM 08 

MODEL 204.9 with CODE (511) Audio 50 APS with DVD changer 

MODEL 204.9 with CODE (525) MB Audio 50 APS radio 

Function requirements for navigation mode in general 

• Circuit 30g ON
• Signals available from at least 3 GPS satellites

Navigation mode, general 

The location of the vehicle, as well as the direction and distance to the destination are determined with the aid of the navigation system after entering the following information:

• Country
• Place
• Street
• House number
• Postal code
• Center
• Intersection
• Special destinations (Points of Interest (POI))

After the destination and street have been entered, the following computer models can be selected:

• Shortest route
• Dynamic route
• Quickest route

In addition, other route options can be selected:

• Avoid freeways
• Avoid toll roads
• Avoid tunnels
• Avoid ferries
• Avoid car trains
• Avoid toll sticker roads

In the Destination menu on the function bar and the From points of interest menu item, the submenus In destination area, Current position, Other location, Search using names and Search using telephone numbers are supported. After entering or calling up a destination location, route calculation starts.

The system can be activated or deactivated or the destination and street can be entered using the following components:

• Left multifunction steering wheel button group and right multifunction steering wheel button group
• Audio/COMAND control panel
• Operating panels on the radio with auto pilot system

The navigation system comprises the following subfunctions:

• Position finding and destination-oriented navigation 
• Route guidance through voice output 

The route is calculated in accordance with the options set. If observance of the options is not possible, then the options set are ignored for the sections in question and a message is displayed and signaled audibly.

The set options can be displayed and changed at any time. After the calculation, the route is displayed by arrow pictograms and there is an acoustic information output stating "the route is calculated".

If the vehicle is no longer moving on the pre-calculated route, then the route is recalculated. If the recalculated values are plausible for the navigation system, then the modified route is displayed.

Dynamic route guidance: An alternative route is offered under dynamic route guidance if there is a traffic jam or a road block on the calculated route.

The control signals from the left multifunction steering wheel button group and the right multifunction steering wheel button group are transmitted to the radio with auto pilot system in the following way:

• Direct line
• Steering wheel electronics
• Steering LIN
• Steering column module control unit
• Chassis CAN
• Instrument cluster
• Interior CAN

The control signals are transmitted via the telematics CAN to the radio with auto pilot system for entries via the Audio/COMAND control panel.

Control signals are processed within the device for direct entries via the control panel on the radio with auto pilot system.

The voice input, with code (511) Audio 50 APS with DVD changer, takes place via the hands-free system microphone. The spoken word is converted into an electrical signal via the hands-free system microphone and forwarded to the radio with auto pilot system via a direct line.

For the voice control (in particular entering a destination) of the navigation with code (511) Audio 50 APS with DVD changer, lists of names are also provided in the system.

The following lists are available for the voice control system:

• List of place names for selected towns on the data storage device
• Street name list for all towns/villages
• List of the relevant intersecting street
• Town center list

Position finding and destination-oriented navigation 

The position finding function and navigation consists of the following subfunctions:

D Function sequence for GPS position finding 

D Function sequence for basic position finding 

D Function sequence for destination-oriented navigation through voice output 

D Function sequence for dynamic route guidance 

GPS position finding function sequence 

The GPS is a satellite-based positioning system. It is available worldwide. The GPS satellites permanently transmit time and position data (longitude and latitude). GPS position finding is irretrievable after vehicle transport (e.g. by train or ferry or after towing). A new GPS position (after interruption of the satellite reception) can take several minutes (up to t = 20 minutes when the equipment is commissioned).

The accuracy of the position finding and the actual calculation is essentially based on the measurement of the runtimes of the signals transmitted synchronously by the various satellites. An important prerequisite is the synchronicity of the clocks of the satellites and the receiver. To this end the receiver is equipped with an automatic time correction, which in turn is made possible with the aid of the satellite signals.

Since GPS operates in the giga hertz (GHz) range (microwaves) and the signals are weak, reception interference can occur as a result of the following events:

• Atmospheric interference, e.g. inclement weather, water vapor, fog
• Multi-path reception due to signal reflections, e.g. from building walls
• Signal shadowing, e.g. in built-up areas and in tunnels, by high buildings, by trees

The GPS signals are received by the GPS receiver, which is integrated into the radio with auto pilot system, directly from the multifunction antenna. From the GPS signals, the radio with auto pilot system then calculates the current position of the vehicle (receiver). In addition, the vehicle's direction of travel is determined with the aid of the sequence of the locations calculated with GPS.

Basic position finding function sequence 

Basic position finding runs parallel to GPS position finding.

For basic position finding, the radio with auto pilot system requires the following information:

• Wheel speeds
• Distance traveled data
• Vehicle alignment (cardinal points)
• Direction of travel data (forwards or backwards)

The wheel speeds are recorded by the following components:

• Left front axle speed sensor
• Right front axle speed sensor

The signals from the rpm sensor are provided over the following route:

• Direct line
• Electronic Stability Program control unit
• Chassis CAN
• Front SAM control unit with fuse and relay module
• Interior CAN
• Radio with auto pilot system

Information on the vehicle direction is sensed and processed internally by the turn rate sensor (gyro sensor) in the radio with auto pilot system.

Information on direction of travel is provided in the following manner:

• Steering angle sensor (steering angle)
• Steering column module control unit
• Chassis CAN
• Front SAM control unit (also forward and backward)
• Interior CAN
• Radio with auto pilot system

Then, in the radio with auto pilot system, the instantaneous vehicle position (degree of longitude/latitude) is calculated from the travel distance covered and taking into consideration the vehicle orientation as well as the direction of travel.

This computation is performed approx. every t =1/s.

Location finding errors during position finding can occur by rolling backwards with c. 15 OFF (ignition switched off) or when a vehicle is transported. In both cases, the deviation is automatically corrected by the navigation processor integrated in the radio with auto pilot system.

The calibration following a tire replacement is performed automatically. Because of the tire abrasion, a constant recalibration of the tire circumference is required. It is carried out automatically and uses the difference between the calculated and actually traveled distance between turning points calculated with the aid of map-based position finding.

Function sequence for destination-oriented navigation through voice output 

The integrated navigation processor continuously compares the route calculation data with the position finding data and uses the data to deduce measures for further destination-oriented navigation. The route is calculated in accordance with the options set. If it should not be possible to adhere to the options, then the configured options are ignored for the stretch in question and a corresponding message is output visually as well as acoustically.

For vehicles with code (810) Sound system the voice output is sent over the Media Oriented System Transport (MOST), then amplified in the sound system amplifier control unit and forwarded over direct lines to the speaker system.

On vehicles without code (810) Sound system, the voice output takes place with direct lines via the radio with auto pilot system to the speaker system.

More detailed information on the speaker system is available in the "Speaker output function" document.

The signals for visual depiction of the route guidance (map navigation) are generated by the radio on cars with autopilot system and sent to the audio/COMAND display via the LVDS line. The radio with autopilot system sends the switch-on request to the audio/COMAND display via the telematics CAN.

Function sequence for dynamic route guidance 

The dynamic route guidance considers the current traffic situation. Information on the traffic situation is received by the radio data system (RDS) function or traffic message channel (TMC) via FM radio and transmitted by specially equipped radio station via FM. A suitable FM/RDS transmitter must be tuned in.

The FM receiver in the radio with auto pilot system receives the traffic messages from the following antenna amplifiers and relays them to the traffic data recorder in the radio with auto pilot system:

• Rear window FM antenna amplifier (model 204.9 except code (537) Digital radio, model 204.0/2)
• TV 1 and DAB Band III antenna amplifier (model 204.9 with code (537) Digital radio)
• FM, AM and CL antenna amplifier (model 204.0)
• Antenna amplifier 1, rear window (model 204.2/9)

In model 204.9, the rear window antenna amplifier 1 receives the FM signals from the rear spoiler antenna.

The traffic data recorder decodes the traffic information and forwards it internally to the navigation processor. The navigation processor makes the decision whether the route should be changed.

Route guidance through voice output 

The route guidance through voice output function is an assistance function that assists the driver without distracting him from the traffic. The navigation system's route guidance is supported primarily by voice output providing directions.

Additional voice messages take place at the start of the route calculation, when an intermediate destination is reached, or when the destination is reached. Voice is output with the selected system language.

A special note is given during voice output in the following cases:

• Destination lies in area where driving is not possible
• Destination lies in area where driving is only possible to a limited extent
• Route via ferry
• Route via toll road

The radio with auto pilot system combines, through the integrated navigation processor, the word segments into complete instructions or information during a voice output and generates low frequency (LF) signals.

When voice output is active the announcement volume can be adjusted using the following components:

• Using the rotary switch on the radio with auto pilot system
• Using the + and buttons for setting specific functions and volume control (S111s1)

	Electrical function diagram for navigation mode (APS), function		PE82.61-P-2054-97FAA
	Overview of system components, telematics		GF82.85-P-9999CE