To accurately determine the three coordinates of the current position in space, the car must receive signals from at least four satellites.
If the vehicle is in motion, the specified information changes continuously. The navigation system computer determines which satellites are in view and calculates their relative position. Using this information, the computer compensates for deviations in the position of the satellites, which improves the accuracy of the vehicle's positioning.
The signals used by the GPS system are called precision positioning signals (Precision positioning signal - PPS).
PPS Positioning Accuracy:
- 22 meters horizontally
- 27.7 meters in height
- Time determination error is 200 nanoseconds
The navigation system receives information from satellites via the GPS antenna. Based on the GPS signals received from the satellites, the navigation system computer calculates the position of the vehicle. After the driver enters a destination, the navigation system computer calculates the route based on the driver's preset preferences or «default», embedded in the computer.
The navigation system receives GPS information (global positioning system) from satellites via the GPS antenna. Based on the GPS signals received from the satellites, the navigation system computer calculates the position of the vehicle. After the driver enters the desired destination, the navigation system computer calculates the route based on the preferences preset by the driver or on the settings «default», embedded in the computer.
The navigation system is activated by pressing the soft key on the touch screen.
Navigation mode is initiated when the driver enters a destination. This can be done in the following ways:
- Address entry using the touch screen.
- Postcode entry.
- Select a previous destination.
- Selecting a location of interest from the map disk database.
- Selecting a starting point.
- Select a memorized location.
After the driver enters the destination, the system suggests the driver a route, «scrolling» on the screen a map of the area and giving verbal instructions. The shape and scale of the map output on the screen may change.
In addition to the navigation system, there are two other systems that provide additional information to the navigation system and the driver. Namely:
- Road services messaging channel (TMC) - only for Europe.
- System for receiving messages from infrared and radio transmitters installed along the road (VICS) - Japan only.
Traffic channel (TMS)
Data transmitted by the traffic channel (TMC), are now broadcast in many European countries.
TMC is one of the functions of the Radio Data System (RDS), which operates on the FM band (frequency modulation). The system transmits real-time traffic and weather reports. TMC information is received using a conventional FM antenna.
The data is received and decoded by the TMC receiver and sent to the navigation system, which forwards it further through its interface. TMC messages can be filtered in the navigation computer so that only messages relevant to the current trip are displayed. This allows the navigation system to correct the route in time and offer the driver an alternative route to avoid trouble. The map displays all TMC events, not just those related to the route you have plotted.
TMC traffic information systems comply with global standards adopted by:
- road data collection organizations
- information service providers
- broadcasters
- car/receiver manufacturers
All TMC radios use the same list of event codes, but local databases (on the roadmap disc) may additionally contain country-specific codes for strategic European roads.
System for receiving messages from infrared and radio transmitters installed along the road (VICS)
System for receiving messages from infrared and radio transmitters installed along the road (VICS) operates in Japan.
The VICS system sends information to the navigation computer to notify the driver of the vehicle about the traffic situation in the area and, if necessary, calculate alternative routes. Information is transmitted to the navigation system through three channels:
1. RF transmissions
Radio frequency transmission is usually carried out from transmitters («radio beacons»), installed along roads, mainly on highways. Information is transmitted as follows:
- traffic density
- Driving time to the next intersection
- Road conditions in neighboring areas and the possibility of exiting the motorway
- traffic accidents
- Speed Limit
- Lane change rules
- Tire change points
- Parking affordability and availability of parking areas on motorways
2. Infrared transmission.
Data transmitted in the infrared range is received by the infrared antenna located at the top of the instrument panel. Infra-red broadcasts are broadcast by radio beacons installed along the main roads. The following information is transmitted:
- Traffic density and driving time
- traffic accidents
- accidents
- Traffic restrictions due to road works
- Possibility of parking
3. FM broadcasts (frequency modulation).
FM broadcasts (frequency modulation) received by FM antenna; broadcasting is carried out within the framework of the RDS system in the FM band.
The following information is transmitted:
- Traffic density and driving time (covers a large area)
- Traffic accidents, road works, speed limits, lane change rules (covers a large area)
- Information about parking availability
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