Your car needs GPS navigation
As a driver, you don’t need to know the road in some city, and you can drive everywhere without labyrinths, and may be you even familiar with the city like a people who live in the city for years. You know what I am saying about, that is GPS, a famous system for traffic, military, and even scientific research. And there is a GPS Navigation in your car.
GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and use triangulation to calculate the user's exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map.
A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position (latitude and longitude) and track movement. With four or more satellites in view, the receiver can determine the user's 3D position (latitude, longitude and altitude). Once the user's position has been determined, the GPS unit can calculate other information, such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time and more.
Today's GPS receivers are extremely accurate, thanks to their parallel multi-channel design. Garmin's 12 parallel channel receivers are quick to lock onto satellites when first turned on and they maintain strong locks, even in dense foliage or urban settings with tall buildings. Certain atmospheric factors and other sources of error can affect the accuracy of GPS receivers. Garmin GPS receivers are accurate to within 15 meters on average.
I like to go for a trip, or travel to other city to enjoy myself, so I have a GPS in my car. That makes the trip very simple; there are no troubles at all. If you want a simple trip like me, go to buy GPS navigation. Online shops sell this equipment at a pretty low price, and the quality is good enough. So I think 3.5 inch screen GPS navigation is great.
Internet reference: http://www8.garmin.com/aboutGPS/
Editor: Kim