Automotive navigation system
An automotive navigation system is a satellite navigation system designed for use in automobiles. Unlike other GPS systems, these use position data to locate the user on a road in the unit's map database. Using the road database, the unit can give directions to other locations along roads also in its database. Dead reckoning using distance data from sensors attached to the drivetrain and a gyroscope can be used for greater reliability, as GPS signal loss and/or multipath can occur due to urban canyons or tunnels.
Honda claims to have created the first navigation system starting in 1983, and culminating with general availability in the 1990 Acura Legend. This analog system used an accelerometer to judge location, as the GPS system was not yet generally available.
Navigation systems use a combination of:
- top view for the map
- top view for the map with the map rotating like the automobile
- bird's-eye view for the map or the next curve
- linear gauge for distance, which is redundant, if a rotating map is used
- numbers for distance
The road database is a vector map of some area of interest. Street names or numbers and house numbers are encoded as geographic coordinates so that the user can find some desired destination by street address. Points of interest will also be stored with their geographic coordinates.
Contents can be produced by the user base as their cars drive along existing streets and communicating via the internet, yielding a free and up to date map.
Formats are uniformly proprietary; there is no industry standard for satellite navigation maps. The map vendors Tele Atlas and NAVTEQ create the base map in a standard format GDF but each electronics manufacturer compiles it in an optimised format.
The road database may be stored in solid state read-only memory (ROM), optical media (CD or DVD), solid state flash memory, magnetic media (hard disk), or a combination. A common scheme is to have a base map permanently stored in ROM which can be augmented with detailed information for a region the user is interested in. A ROM is always programmed at the factory; the other media may be preprogrammed, or downloaded from a CD or DVD via a computer.
- Many systems can give information on nearby services such as restaurants, cash machines and gas stations.
- Some newer systems can not only give precise driving directions, they can also receive and display information on traffic congestion and suggest alternate routes. This may use either TMC, which delivers coded traffic information using Radio Data System or satellite radio, or an Internet link to a provider's server using technology such as GPRS through the user's mobile phone.
- The color LCD screens on some automotive navigation systems can also be used to display television broadcasts or DVD movies.
- A few systems integrate with mobile phones for handsfree talking and SMS messaging.
- GPS replaces the radio-dispatch of some taxicabs in Taiwan and Singapore. The location of every cab is known to the central dispatch computer, and when a cab is needed somewhere, the computer automatically selects the closest cab to answer the call. The system can also automate calls to the customer when the cab arrives and waits for the customer.
- Dynavix Mobile
- Garmin StreetPilot
- Hertz Neverlost
- Navman iCN series