The Global Positioning system (Gps) is a satellite-based pilotage system owned and industrialized by the United States branch of Defense. It is officially named Navstar (Navigation Satellite Timing And Ranging) Gps. while the 1980s, the United States government made the Gps ready for group use for free. It can be used from in any place in the world and is operational 24 hours a day. The Gps consists of three segments: space, control and user.
Transmission Problems
The space segment includes a network of 24 Gps satellites that is managed by the United States Air Force. The satellites are spaced so that at least four satellites will be above the horizon from any point on Earth. These satellites are enough to settle the location of a Gps receiver in any place on earth. They orbit the earth every 12 hours at an altitude of about 12,000 miles. They tour at speeds exceeding 7,000 miles an hour.
The control segment consists of a devotee control station, monitor stations and ground antennas. Monitor stations track the orbits of the satellites and this data is sent to the devotee control station. The devotee control center normally uses the ground antennas to send updated orbital path facts to every one of the satellites.
The user segment consists of the Gps receiver. The receiver has an antenna that allows it to obtain the signals sent from the satellites. A receiver can have between 12 and 20 channels. The amount of channels indicates how many satellites it can monitor simultaneously.
Here's how all these segments work together. Each Gps satellite contains a computer, atomic clocks and a radio. Each satellite constantly broadcasts its current time and current location. All of the satellites broadcast their facts at the same time. A Gps receiver can calculate its exact position by determining the length between itself and three or more satellites. The time between a signal transmission and reception will allow the receiver to settle the length to each satellite. When the receiver gets the length measurements from three or more satellites, the exact location of the receiver can be determined. This process is known as triangulation. If the receiver can display a map, its position can be shown on the map. The position can be considered within 10 to 100 meters. If you have extra military-approved equipment, the position can be considered within 1 meter. In addition, the clock in a receiver is not as definite as the atomic clocks in the satellites. This is why receivers track one or more supplementary satellites to definite any clock errors.
A Gps receiver can calculate its two-dimensional position (latitude and longitude), if it acquires signals from at least three Gps satellites. A Gps receiver can calculate its three-dimensional position (latitude, longitude and elevation), if it acquires signals from four or more Gps satellites. The receiver can not only settle its exact location; it can also settle speed, direction of travel, length to destination, estimated arrival times and more.
If you want to ensure the top accuracy, a Gps receiver should have a clear line of sight (unobstructed view) of the Gps satellites. This means that it should be used in the outdoors. A Gps receiver will not work indoors, hidden or underwater. Buildings, overpasses, forested areas, or electronic interference can shield the receiver from a satellite. This can weaken the signal from the satellite and cause the receiver to give unreliable readings. other problem that may occur is multipath interference. Multipath interference occurs when a signal from a satellite to a receiver is delayed because it was forced to bounce off of tall buildings or large rock surfaces.
