subject: Portable Gps Are Completely Effective [print this page] Portable systems for cars is the cheaper option for those who can't afford to buy those fancy cars with integrated GPS systems. But they are not in any way less effective.
The clever thing is, that they know what your location is in terms of other places. When you first know where you are supposedly, and where you wish to go, then a whole bunch of possible uses for automobile GPS systems suddenly becomes open to you for your travels.
This is so that it can effectively know where you are, both horizontally and vertically on the surface of the Earth. The electronics for this are fairly well established these days since the US military developed the GPS system for its own use.
A position for the automotive GPS system in your car is not much good without a map of the area, so that the device knows where it is in regards to other places.
Each place where the road or highway changes direction or forks, must have an absolute co-ordinate associated with it. The smaller the distance between these points, the better and more accurate the map inside the unit will be.
Once the position with regards to other places is determined, the unit needs in order to output the information in a fashion that is immediately understandable to the driver. This is done through a small flat screen during the unit's construction and sometimes also via text-to-speech spoken output through a loudspeaker.
An output that is clear, and easily understood is essential, but so too is an input, so the start and destination of the journey may be entered into the automotive GPS system. The main ways it's done this way, is through a touch screen interface, using buttons and text boxes to describe your destination.
Manufacturers add value and make models different, by building into their systems other inputs or outputs, extra features, better more accurate maps, quicker acquisition of satellite positional fixes, landmarks, etc.
