Introduction
Global positioning system (G.P.S.) & its role in advanced transportation projects is inseparable is become a synonym. We people, whenever like to talk or take a project that will automate the management and operations of vehicles & giving real-time information to users, that will lead to cost-effective & satisfied service to customers/passengers, and then planners and other decision-making authorities will not find any other effective tool to select except G.P.S.
What is GPS?
GPS, which stands for Global Positioning System, is the only system today able to show you your exact position on the Earth anytime, in any weather, anywhere. Ground stations, located worldwide, continuously monitor them. The satellites transmit signals that can be detected by anyone with a GPS receiver. Using the receiver, you can determine your location with great precision. GPS is one of history’s most exciting and revolutionary developments, and new uses for it are constantly being discovered.
GPS Elements
GPS has 3 parts: the space segment, the user segment, and the control segment. The space segment consists of 24 satellites, each in its own orbit 11,000 nautical miles above the Earth. The user segment consists of receivers, which you can hold in your hand or mount in your car. The control segment consists of ground stations (five of them, located around the world) that make sure the satellites are working properly. The GPS satellites each take 12 hours to orbit the Earth. Satellites are equipped with very precise clocks that keep accurate time to within three nanoseconds - that’s 0.000000003, or three billionths, of a second. This precision timing is important because the receiver must determine exactly how long it takes for signals to travel from each GPS satellite. To help you understand the GPS system, let’s take the three parts of the system - the satellites, the receivers, and the ground control - and discuss them in more detail.
Satellites in Space
The first GPS satellite was launched in 1978. The first 10 satellites were developmental satellites, called Block I. From 1989 to 1993, 23 production satellites, called Block II, were launched. The launch of the 24th satellite in 1994 completed the system.
Ground Control Stations and Receivers
Ground Control Stations
The GPS control, or ground, segment consists of unmanned monitor stations located around the world (Hawaii and Kwajalein in the Pacific Ocean; Diego Garcia in the Indian Ocean; Ascension Island in the Atlantic Ocean; and Colorado Springs, Colorado); a master ground station at Schriever (Falcon) Air Force Base in Colorado Springs, Colorado; and four large ground antenna stations that broadcast signals to the satellites. The stations also track and monitor the GPS satellites.
Receivers
GPS receivers can be hand carried or installed on aircraft, ships, tanks, submarines, cars, and trucks. These receivers detect, decode, and process GPS satellite signals. The typical hand-held receiver is about the size of a cellular telephone, and the newer models are even smaller weighed only 28 ounces.
How GPS Works
So you can more easily understand some of the scientific principles that make GPS work, let’s discuss the basic features of the system. The principle behind GPS is the measurement of distance (or “rangeâ€) between the receiver and the satellites. The satellites also tell us exactly where they are in their orbits above the Earth. It works something like this: If we know our exact distance from a satellite in space, we know we are somewhere on the surface of an imaginary sphere with radius equal to the distance to the satellite radius. If we know our exact distance from two satellites, we know that we are located somewhere on the line where the two spheres intersect. And, if we take a third measurement, there are only two possible points where we could be located. One of these is usually impossible, and the GPS receivers have mathematical methods of eliminating the impossible location.
Global positioning system (G.P.S.) & its role in advanced transportation projects is inseparable is become a synonym. We people, whenever like to talk or take a project that will automate the management and operations of vehicles & giving real-time information to users, that will lead to cost-effective & satisfied service to customers/passengers, and then planners and other decision-making authorities will not find any other effective tool to select except G.P.S.
What is GPS?
GPS, which stands for Global Positioning System, is the only system today able to show you your exact position on the Earth anytime, in any weather, anywhere. Ground stations, located worldwide, continuously monitor them. The satellites transmit signals that can be detected by anyone with a GPS receiver. Using the receiver, you can determine your location with great precision. GPS is one of history’s most exciting and revolutionary developments, and new uses for it are constantly being discovered.
GPS Elements
GPS has 3 parts: the space segment, the user segment, and the control segment. The space segment consists of 24 satellites, each in its own orbit 11,000 nautical miles above the Earth. The user segment consists of receivers, which you can hold in your hand or mount in your car. The control segment consists of ground stations (five of them, located around the world) that make sure the satellites are working properly. The GPS satellites each take 12 hours to orbit the Earth. Satellites are equipped with very precise clocks that keep accurate time to within three nanoseconds - that’s 0.000000003, or three billionths, of a second. This precision timing is important because the receiver must determine exactly how long it takes for signals to travel from each GPS satellite. To help you understand the GPS system, let’s take the three parts of the system - the satellites, the receivers, and the ground control - and discuss them in more detail.
Satellites in Space
The first GPS satellite was launched in 1978. The first 10 satellites were developmental satellites, called Block I. From 1989 to 1993, 23 production satellites, called Block II, were launched. The launch of the 24th satellite in 1994 completed the system.
Ground Control Stations and Receivers
Ground Control Stations
The GPS control, or ground, segment consists of unmanned monitor stations located around the world (Hawaii and Kwajalein in the Pacific Ocean; Diego Garcia in the Indian Ocean; Ascension Island in the Atlantic Ocean; and Colorado Springs, Colorado); a master ground station at Schriever (Falcon) Air Force Base in Colorado Springs, Colorado; and four large ground antenna stations that broadcast signals to the satellites. The stations also track and monitor the GPS satellites.
Receivers
GPS receivers can be hand carried or installed on aircraft, ships, tanks, submarines, cars, and trucks. These receivers detect, decode, and process GPS satellite signals. The typical hand-held receiver is about the size of a cellular telephone, and the newer models are even smaller weighed only 28 ounces.
How GPS Works
So you can more easily understand some of the scientific principles that make GPS work, let’s discuss the basic features of the system. The principle behind GPS is the measurement of distance (or “rangeâ€) between the receiver and the satellites. The satellites also tell us exactly where they are in their orbits above the Earth. It works something like this: If we know our exact distance from a satellite in space, we know we are somewhere on the surface of an imaginary sphere with radius equal to the distance to the satellite radius. If we know our exact distance from two satellites, we know that we are located somewhere on the line where the two spheres intersect. And, if we take a third measurement, there are only two possible points where we could be located. One of these is usually impossible, and the GPS receivers have mathematical methods of eliminating the impossible location.
