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An automotive navigation system is a satellite navigation system designed for use in automobiles. It typically uses a GPS navigation device to acquire 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, a gyroscope and an accelerometer can be used for greater reliability, as GPS signal loss and/or multipath can occur due to urban canyons or tunnels.

Visualization

Navigation systems may (or may not) use a combination of any of the following:

* 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
* schematic pictograms
* voice prompts
Contents

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 (see map database management).

Points of interest (waypoints) will also be stored with their geographic coordinates. Point of interest specialties include speed cameras, fuel stations, public parking, and “parked here” (or “you parked here”).

Contents can be produced by the user base as their cars drive along existing streets (Wi-Fi) and communicating via the internet, yielding a free and up-to-date map.
Map Formats

Formats are almost uniformly proprietary; there is no industry standard for satellite navigation maps, although Navteq are currently trying to address this with S-Dal (see below).

The map vendors Tele Atlas and NAVTEQ create the base map in a standard format GDF, but each electronics manufacturer compiles it in an optimized, usually proprietary format. GDF is not a CD standard for car navigation systems. GDF is used and converted onto the CD-ROM in the internal format of the navigation system.
Media

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 that 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, downloaded from a CD or DVD via a computer or wireless connection (bluetooth, Wi-Fi), or directly used utilizing a card reader.

Some navigation device makers provide free map updates for their customers. These updates are often obtained from the vendor’s website, which is accessed by connecting the navigation device to a PC.
Real-time Data

Main article: Integration of traffic data with navigation systems

Some newer systems can not only give precise driving directions, they can also receive and display information on traffic congestion and suggest alternate routes. These may use either TMC, which delivers coded traffic information using radio RDS, or by GPRS/3G data transmission via mobile phones.

One key type of real-time data is Traffic information, which includes:

* Real-time data about free/full parkings;
* Nearest public transport lines and prices, to go to a destination, when there is a jam.

Other real-time data includes weather broadcasting, etc.
Integration and Other Functions

* The color LCD screens on some automotive navigation systems can also be used to display television broadcasts or DVD movies.
* A few systems integrate (or communicate) with mobile phones for hands-free talking and SMS messaging (i.e., using Bluetooth or Wi-Fi).
* Automotive navigation systems can include personal information management for meetings, which can be combined with a traffic and public transport information system.
Safety Features

Vehicles produced by Subaru and Lexus, as well as Lexus’ parent company, Toyota, lock out many of the features when the vehicle is in motion. The manufacturers claim this is a safety feature to avoid the driver being distracted. Many users have complained that passengers are not able to enter destinations while in motion, even though it is safe to do so. Additionally, drivers have complained that it is often more dangerous to pull off a highway and stop than it would be to enter a destination into the system. An explicit acknowledgment that the operator of the navigation system is acting only as navigator and not as driver has been proposed as an option.[citation needed] This would relieve the car manufacturer of legal liabilities[citation needed] and restore full functionality.[citation needed]
GPS vs Speed Camera Accuracy

In July 2007, an Australian man successfully overturned a speeding conviction after evidence from a GPS navigational track proved that he did not exceed the speed limit.
Portable GPS

This type of GPS navigation device is not permanently integrated into the vehicle, having only a simple bracket to mount the device on the surface of the dashboard and powered via the car cigarette lighter. This class of GPS unit does not require professional installation and can typically be used as handheld device, too.

Benefits of this type of GPS unit include low cost as well as the ability to move them easily to other vehicles. Their portability means they are easily stolen if left inside the vehicle but cannot be stolen if the driver takes it with him when he gets out. Furthermore, not having a compass, accelerometer or inputs from the vehicle’s speed sensors, means that they cannot navigate as accurately by dead reckoning as some built-in devices when there’s no GPS signal. More modern portable devices such as the TomTom 920, have an inbuilt accelerometer to try to address this.

A portable automotive navigation system kit generally includes:

* Mini-USB sync cable
* AC adaptor
* Car charger
* Car mount kit
* Pouch
* Wrist band
* External antenna (optional by model)
* Stylus
* Battery pack
* Document kit
* SD card with preload map (sometimes capable of shuffling MP3 playlists)
* Companion CD-ROM
* Navigation software CD-ROM

All information from

http://en.wikipedia.org/wiki/Automotive_navigation_system