GPS And How It Works
Author: Chris Simons
Source: articleage.com
GPS stands for Global Positioning System, a satellite navigation system with twenty-four satellites in orbit. These satellites were launched by the Department of Defense United States for military purposes, and were called NAVSTAR. The first satellite was launched in 1978 and the twenty-fourth and last satellite was finally in place in 1994. In 1980 NAVSTAR was made available to the general public for commercial use. GPS works 24 hours a day any time. The satellites orbit the earth twice a day in a specific orbit is about 12,000 miles above us. In orbit, the satellites travel as fast as 7,000 kilometers per hour. As they orbit, which transmit information to receivers on the ground. Recipients using this information to calculate the user's location. This is calculated by determining the difference between the time that the transfer was made when the recipient receives. This is used to calculate the distance and position shown on the receiver. For a receiver to calculate the latitude and longitude is the position of receiving information from three satellites. To calculate the latitude, longitude and altitude of a receiver must be able to receive information from four or more satellites. After GPS position is known you can tell the user with information on speed, distance traveled, distance to a desired destination, times of sunrise and sunset, taking and other information. While in orbit, satellites are powered by solar energy. They also have backup batteries that are used in the case of non-solar energy as an eclipse. Energy is used to power small rockets on the satellites that keep them in the correct orbit. At any time, only about 50 watts or less is used to transmit information. The satellites are designed to last about ten years, and the Department of Defense is constantly making and launching replacement satellites. Each satellite is about 2,000 pounds and seventeen feet across when the solar panels are out. GPS receivers are generally accurate to 15 meters. Apart from investing in a receiver that no expenses or any other equipment necessary to access the GPS signal. If you need precise readings, the differential global positioning system (DGPS), which provide an accuracy of three to five meters. The U.S. Coast Guard operates the most popular DGPS. Two power signals are transmitted and are labeled L1 and L2. The L1 frequency is used for civil purposes. These signals are relatively low power signals and travel line of sight, so you can go through clouds, glass and plastic, but not solid objects like buildings or mountains. In each satellite transmission sends three types of information, the pseudorandom code, ephemeris data and almanac data. The pseudo-code is a code identifying the satellite of the information is sent. Ephemeris tells the receiver that the satellite should be at any time of day, and almanac data submitted information on the status of the satellite, the date and time. The almanac data is the part that is essential to determine the user's location. Chris Simons is a prolific freelance writer. You are welcome to visit http://gps.theconsumerguide.net for more information on GPS units and monitoring systems.