GF82.61-P-2010GQA Position Finding and Destination-Oriented Navigation, Function

GF82.61-P-2010GQA Position Finding And Destination-oriented Navigation, Function
- with CODE (525) MB Audio 50 APS radio
- with CODE (511) Audio 50 APS with DVD changer


Function requirements
^ Status "Circuit 30 ON"
^ The Auto pilot system (APS) is operating properly
^ No fault on global positioning system (GPS) antenna system
^ Signals are available from at least 3 GPS satellites.
^ Proper communication with ESP control unit (N47-5)
^ Destination has been entered
^ the route has been calculated.

General
The position finding and destination-oriented navigation function is divided into the following subareas:
^ General information on GPS position finding
^ Function sequence for GPS position finding
^ General information on basic position finding
^ Basic position finding function sequence
^ Recalibration
^ General information on route calculation
^ Function sequence for destination-oriented navigation through voice output
^ General information on dynamic route guidance
^ Function sequence for dynamic route guidance

Operating instructions
Operation takes place using the control buttons of the radio and navigation unit (A2/56).

During an active voice output the volume of the announcement can be adjusted by the following components:
- Using the rotary switch on the radio and navigation unit
- With the + and
- buttons, for selecting specific functions and volume control (S111s1) in the right multifunction steering wheel button group (S111)

General information on GPS position finding
The GPS is a satellite-based positioning system. It is available worldwide. The GPS satellites permanently transmit time an 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 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.

Function sequence for GPS position finding
The GPS signals are received by the GPS receiver that is integrated into the radio and navigation unit directly from the GPS antenna (A2/93a6). The GPS signals are used by the radio and navigation unit to calculate the current vehicle position (receiver). In addition, the vehicle's direction of travel is determined with the aid of the sequence of the locations calculated with GPS.

Possible problems in GPS signal reception
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 blocking, e.g. in built-over areas and in tunnels, through high-rise buildings, trees

General information on basic position finding
Basic position finding runs parallel to GPS position finding. The radio and navigation unit requires the following data for basic position finding:
- Wheel speed signals
- Distance traveled data
- Vehicle alignment (cardinal points)
- Direction of travel data (forwards or backwards)

Basic position finding function sequence
The radio and navigation unit requires signals from the following components for basic position finding:
- Left front rpm sensor (L6/1), right front rpm sensor (L6/2), left rear rpm sensor (L6/3), right rear rpm sensor (L6/4), for recording the wheel speed signals in the ESP control unit
- The turn rate sensor (gyro sensor), integrated into the radio and navigation unit, to determine the vehicle alignment (cardinal points)
- Central gateway control unit (N93), for capturing data on direction of travel
- Steering angle sensor (N49), for recording the steering angle signal

The radio and navigation unit receives the wheel speed signals from the listed rpm sensors via the following route:
- Direct line
- ESP control unit
- Engine compartment CAN
- Central gateway control unit
- Interior CAN

The data of the turn rate sensor (gyro sensor) integrated into the radio and navigation unit are internally forwarded in the radio and navigation unit. The direction of travel data (forward or backward) is transferred to the radio and navigation unit by the central gateway control unit via the interior CAN.

After this the radio and navigation unit uses the distance traveled, the vehicle alignment and the direction of travel to calculate the current vehicle position (degree of longitude and degree of latitude).
The radio and navigation unit receives the steering angle signal from the steering angle sensor via the following route:
- Steering column tube module (N80)
- Engine compartment CAN
- Central gateway control unit
- Interior CAN

Calculation of the basic position finding takes approx. 1/s.

Error during position finding
Backward rolling with "circuit 15 OFF" (ignition switched off), any transport of the vehicle as well as driving in multi-level car parks or underground garages with circular entrances or exits can falsify the basic position finding. In such an event, the deviation is then automatically corrected by the navigation processor integrated into the radio and navigation unit.

Recalibration
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 2 turning points calculated with the aid of map-based position finding.

General information on route calculation
Under "Own selection", the following stretches can be excluded from the route calculation:
- Freeway
- Toll road
- Roads requiring toll stickers
- Ferries and vehicle transport
- Tunnels

Route calculation is accomplished using the options set to the best possible extent. 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 criteria and options can be displayed and changed at any time. After a successful calculation, the route is displayed by arrow pictograms and there is an acoustic information output stating "the route is calculated".

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 voice output for destination-oriented navigation is sent to the Media Oriented System Transport (MOST) and then amplified in the amplifier for sound system (N40/3), with code (810) Sound system.
The audio signals reach the following speakers via direct lines:
- Left rear door speaker (H4/3)
- Right rear door speaker (H4/4)
- Left front door speaker (H4/5)
- Right front door speaker (H4/6)
- Center cockpit speaker (centerfill) (H4/27)
- Left front door tweeter (H4/33)
- Right front door tweeter (H4/34)
- Left rear door tweeter (H4/35)
- Right rear door tweeter (H4/36)
- Left rear surround speaker (H4/54)
- Right rear surround speaker (H4/57)

The audio signal for the subwoofer (H4/29) travels from the radio and navigation unit to the amplifier for the sound system via MOST and from there, via direct lines to the subwoofer amplifier (N40/9) and then to the subwoofer speaker.

In vehicles without code (810) Sound system, the voice output is performed via the radio and navigation unit using direct lines over the following speakers:
- Left rear door speaker
- Right rear door speaker
- Left front door speaker
- Right front door speaker
- Left front door tweeter
- Right front door tweeter
- Left rear door tweeter
- Right rear door tweeter

The signals for visually displaying the destination-oriented navigation (map navigation) are generated by the radio and navigation unit and shown internally via the display on the radio and navigation unit.


General information on dynamic route guidance
The current traffic situation is taken into consideration in the dynamic route guidance. The incoming information on the traffic situation can be received by the radio data system/Traffic Message Channel (RDS/TMC) function via FM radio. The information on the current traffic situation is emitted by a specially equipped broadcasting corporation on an area-related basis via FM. A suitable FM/RDS transmitter must be tuned in. The traffic data recorder decodes the traffic information and forwards it internally to the navigation processor upon request. The navigation processor makes the decision whether the route should be changed.

Function sequence for dynamic route guidance
The FM receiver in the radio and navigation unit receives the traffic messages from the FM rear window antenna amplifier (A2/19) and forwards them to the roof antenna module (A2/93). From there the traffic messages are forwarded to the traffic data recorder in the radio and navigation unit. The traffic messages are stored in the traffic data recorder of the radio and navigation unit and made available for the integrated navigation processor. The voice output for dynamic route guidance is sent to the MOST and then amplified in the amplifier for sound system, with code (810) Sound system.

The audio signal reaches the speaker system via direct lines.
- Left rear door speaker
- Right rear door speaker
- Left front door speaker
- Right front door speaker
- Center cockpit speaker (centerfill)
- Left front door tweeter
- Right front door tweeter
- Left rear door tweeter
- Right rear door tweeter
- Left rear surround speaker
- Right rear surround speaker

The audio signal for the subwoofer speaker travels via MOST from the radio and navigation unit to the sound system amplifier and from there, via the subwoofer amplifier along direct lines to the subwoofer speaker.

In vehicles without code (810) Sound system, the voice output is processed and amplified within the radio and navigation unit. The audio signal reaches the speaker system via direct lines.
- Left rear door speaker
- Right rear door speaker
- Left front door speaker
- Right front door speaker
- Left front door tweeter
- Right front door tweeter
- Left rear door tweeter
- Right rear door tweeter