GF82.61-P-2003FQ Navigation, Function

GF82.61-P-2003FQ Navigation, Function
MODEL 218
- with CODE (511) Audio 50 APS with DVD changer
- with CODE (525) MB Audio 50 APS radio

Function requirements, general
^ Circuit 30g ON
^ Signals from at least three Global Positioning System (GPS) satellites present
^ Country group loaded

Navigation, general
The navigation system enables the position of the vehicle to be determined, along with its direction and distance to the destination once the following information has been entered into the "Destination" submenu:
- Country
- Place name
- Road
- Intersection or house number (depending on the availability of the data)
- Town center
- ZIP code
- Point(s) of Interest (POI))
Apart from this, the auto pilot system (APS) also allows the route from the vehicle's location to the chosen destination to be navigated.
Navigation is conducted in the form of a 2D-map display on the Audio/COMAND display (A40/8) as well as verbally over the vehicle's speaker system.
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.
The set criteria and options can be displayed and changed at any time. After a successful route calculation, the route is displayed by arrow pictograms and a verbal message stating "the route is calculated" is issued.
If the vehicle is no longer moving on the precalculated route, the route is recalculated. If the recalculated values are plausible for the navigation system, then the modified route is displayed.
The radio with auto pilot system (A2/56) is operated using the following controls or systems:
- Control buttons on the radio with auto pilot system
- Audio/COMAND control panel (A40/9)
- Left multifunction steering wheel button group (S110) and right multifunction steering wheel button group (S111)
- Voice control system (VCS [SBS]) (with code (511) Audio 50 APS with DVD changer)
Entries using the control buttons on the radio with auto pilot system are processed internally.
The control signals for the multifunction steering wheel button groups are read in by the radio with auto pilot system as follows:
- Steering wheel electronics (N135)
- Steering LIN (LIN E1)
- Steering column tube module control unit (N80)
- Chassis CAN (CAN E)
- Instrument cluster (A1)
- Interior CAN (CAN B)
The control signals for the Audio/COMAND control panel are read in by the radio with auto pilot system over the telematics CAN (CAN A).
Control signals through the VCS [SBS] are recorded by the hands- free system microphone (A67b1), which is read in directly by the radio with auto pilot system.

Navigation, function sequence
The information for reaching the destination (route guidance) is calculated via the navigation system integrated into the radio with auto pilot system using the data entered.
To this end, the navigation system is equipped with the following functions, which are described in the following subfunctions:
^ Position finding, function
^ Destination-oriented navigation, function

Position finding, function
The position finding function consists of the following subfunctions:
^ Function sequence for GPS position finding
^ Function sequence for basic position finding

Function sequence for GPS position finding
GPS is a satellite-based positioning system, which is available on a global basis. 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, 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 faults, e.g. inclement weather (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 or trees
The GPS signals are received by the GPS receiver, which is integrated into the radio with auto pilot system (A28/11), 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. At the same time, the positioning data is compared against the map data on the navigation system DVD.
On vehicles without code (511) Audio 50 APS with DVD changer it is therefore not possible to play music data media in the DVD drive when the navigation system is active.
On vehicles with code (511) Audio 50 APS with DVD changer the navigation DVD is inserted into changer slot no. 6. The user thus has five free changer slots to enable DVD data media to be played for audio entertainment purposes.

Basic position finding function sequence
The basic position finding runs at the same time as the GPS position finding process and is a requirement for a reliable navigation if the GPS signal drops out, for example while driving through a tunnel.
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 speed/wheel rotation direction is recorded by the following components:
- Left front axle rpm sensor (L6/1)
- Right front axle rpm sensor (L6/2)
The signals from the rpm sensor are provided over the following route:
- Direct line
- Electronic Stability Program control unit (N30/4) (without code (233) DISTRONIC PLUS except model 218.374) or Premium Electronic Stability Program control unit (N30/7) (with code (233) DISTRONIC PLUS or model 218.374)
- Chassis CAN
- Front SAM control unit with fuse and relay module (N10/1)
- 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. Direction of travel information is provided in the following manner:
- Steering angle sensor (N49) (steering angle)
- Steering column tube module control unit
- Chassis CAN
- Front SAM control unit
- 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 conducted at an interval of approx. t =1 s.
Location finding errors during position finding can occur by rolling backwards with circuit 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.

Destination-oriented navigation, function
The route guidance partial function is comprised of the following subfunctions:
^ Function sequence for destination-oriented navigation through voice output
^ Function sequence for dynamic route guidance

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 following stretches can be excluded from the route calculation in the Mode submenu of the Navi menu:
- "Avoid freeways"
- "Avoid toll roads"
- "Avoid tunnels"
- "Avoid ferries"
- "Avoid car trains"
- "Avoid toll sticker roads"
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.
The set criteria and options can be displayed and changed at any time.
After a successful route calculation, the route is displayed by arrow pictograms and there is an acoustic message output stating "the route is calculated".
On vehicles without code (810) Sound system, voice output for navigation is output via the following speakers:
- Left front door speaker (H4/1)
- Left front door tweeter (H4/1h1)
- Right front door speaker (H4/2)
- Right front door tweeter (H4/2h1)
On vehicles with code (810) Sound system, the radio with auto pilot system transmits the audio signals via the Media Oriented System Transport (MOST) to the sound system amplifier control unit (N40/3), which amplifies and outputs them over the following speakers:
- Center instrument panel speaker (H4/27)
- Left front door sound system bass speaker (H4/64)
- Right front door sound system bass speaker (H4/65)
- Left front door sound system tweeter (H4/68)
- Right front door sound system tweeter (H4/69)
- Left front door sound system midrange speaker (H4/72)
- Right front door sound system midrange speaker (H4/73)
The navigation system voice output takes place depending on the selected system language.
The signals for visually displaying the destination-oriented navigation (map navigation) are generated by the radio with auto pilot system and displayed on the Audio/COMAND display or the instrument cluster accordingly.
The radio with auto pilot system sends corresponding information over the telematics CAN to the Audio/COMAND display as well as over the interior CAN to the instrument cluster.

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.
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:
- FM 1, AM, CL and KEYLESS-GO antenna amplifier (A2/18)
- Antenna amplifier FM 2 and DAB (A2/19)
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.