Dynamic Guidance (With Code [815] Dynamic Guidance)
Block diagram for COMAND navigation with dynamic guidance (code 815), illustrated with the following equipment:
- D network cellular telephone (D2B) (code 317)
- CD changer (code 819)
The parts marked are the components most significant for dynamic guidance
Dynamic guidance takes the present traffic situation into consideration. The COMAND navigation system can receive information on the traffic situation alternatively from the Traffic Center Service (TCS) or the Traffic Message Channel (TMC).
Traffic messages from Traffic Center Service (TCS)
The information on the current traffic situation is transmitted by a service provider at a fee in SMS (short message service) form via the cellular telephone network. The traffic data can only be transmitted when the service provider receives a corresponding request from the vehicle. The request is accomplished in one of the following manners:
- cyclically, every 15 minutes or
- once.
The current location of the vehicle is automatically transferred to the D network center in the information request to reduce the quantity of data. The service provider then transmits only the traffic messages relevant for a radius of approx. 75 km around the vehicle.
The vehicle telephone system receives the traffic messages and transfers them to the following equipment:
- on vehicles with D network cellular telephone (D2B) (code 317) via the CTEL interface (A34/4) and CAN COMAND bus to the traffic data memory (see block diagram) or,
- on vehicles with permanently installed telephone (code 316) via the D2B interface for permanently installed telephone (A59) and the CAN COMAND bus to the traffic data memory (not illustrated) or,
- on vehicles with TELE AID emergency call system (D2B) (code 347) via the TELE AID control module (A35/8) and the CAN COMAND bus to the traffic data memory (not illustrated).
NOTE: It is possible to use the telephone during TCS data interchange.
The traffic data memory is integrated into the COMAND operating, display and control module (A40/3).
Traffic messages from Traffic Message Channel (TMC)
The information on the current traffic situation is transmitted by a specially equipped radio station via FM radio in relation to the area and at no cost. For this purpose, it is necessary for the radio to return to an appropriate FM/RDS station.
The radio receives the traffic messages via the bottom left rear window antenna amplifier (A2/24) and transmits them to the traffic data memory via CAN COMAND bus (see block diagram).
Since there is no communication between the vehicle and radio station with TMC messages, the traffic data memory selects the traffic messages related to the section of highways on which the vehicle is driving momentarily as well as the surrounding area.
Evaluation of traffic information
The traffic data memory decodes the traffic information in both cases (TCS or TMC) and transfers it to the navigation processor (internally) on request. The decision whether to change the route is made by the navigation processor. Where applicable, a message is output on the vehicle loudspeakers that the route has been changed.
The traffic data memory requires a current "Location list" from the navigation processor for synchronization. Each section and distinguished point (e.g. freeway exit) in the mapped network of roads is clearly defined by a number in this list. This list is originally stored on the CD-ROM.
It is loaded into the traffic data memory automatically as required (e.g. after changing CD-ROM).
The traffic data information stored in the traffic data memory is erased automatically after half an hour, a maximum of 100 messages can be stored.
The traffic messages are decoded and indicated on the map with corresponding symbols. They can also be displayed as clear text. For this purpose, press the "Detour" button and then activate the "TRAFFIC-INFO" menu.
NOTE: It is possible to select the mode (TMC or TCS) with the menu "Navigation -> Settings -> Traffic information source".
Mixed operation with TMC and TCS is not possible.