GPS or Global Positioning System is a
network of orbiting satellites that send precise details of their position in
space back to earth. The signals are obtained by GPS receivers, such as
navigation devices and are used to calculate the exact position, speed and time
at the vehicles location.
GPS is well-known for its military uses and was first developed by the US to aid in its global intelligence efforts at the height of the Cold War.
Ever since the early 1980s, however, the GPS has been freely available to anyone with a GPS receiver. Airlines, shipping companies, trucking firms, and drivers everywhere use the GPS system to track vehicles, follow the best route to get them from A to B in the shortest possible time.
The very first GPS system was developed in the 1960s to allow ships in the US Navy to navigate the oceans more accurately. The first system had five satellites and allowed ships to check their location once every hour. Today, portable Navigation device devices can give drivers their precise location to within a few meters, which is accurate enough to navigate roadways. Military applications have much higher precision so that a location can be pinpointed within a few centimeters.
The US NAVSTAR Global Positioning System (GPS) is the only fully operational Global Navigation Satellite System (GNSS) currently providing positioning data with global coverage. The European Union is currently developing its own GPS known as the Galileo positioning system, which will be operational by 2013. China has a local system it may expand globally, while Russia is currently restoring its GLONASS system.
GPS has answers five questions simultaneously:
"Where am I?"
"Where am I going?"
"Where are you?"
"What's the best way to get there?
"When will I get there?"
GPS is the only system today that can show your exact position on the Earth anytime, in any weather, no matter where you are!
Like so many other high-tech developments, GPS was designed by the U. S. military. The concept started in the late '60s but the first satellite wasn't launched until February 1978. In 1989 the Magellan Corp. introduced the first hand-held GPS receiver. In 1992 GPS was used in Operation Desert Storm. On March 1996 the President decided to make GPS free for civilian users.
GPS has three 'segments':
The space segment now consists of 28 satellites, each in its own orbit about 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.
At first, the military did not want to let civilians use GPS, fearing that smugglers, terrorists, or hostile forces would use it. Finally, bowing to pressure from the companies that built the equipment, The Defense Department made GPS available for non-military purposes, with some restrictions. On May 1, 2000, President Clinton lifted the restrictions, and announced that the option to degrade civil GPS signals during emergencies would be phased out by 2010. The federal government is committed to providing GPS technology for peaceful uses on a worldwide basis, free of charge.
How does GPS work?
The GPS is owned and operated by the U.S. Department of Defense but is available for general use around the world. Briefly, here's how it works:
a)On the world 21 GPS satellites and three spare satellites are in orbit at 10,600 miles above the Earth. The satellites are spaced so that from any point on Earth, four satellites will be above the horizon.
b)Each satellite contains a computer, an atomic clock, and a radio. With an understanding of its own orbit and the clock, it continually broadcasts its changing position and time. (Once a day, each satellite checks its own sense of time and position with a ground station and makes any minor correction.)
c)On the ground, any GPS receiver contains a computer that "triangulates" its own position by getting bearings from three of the four satellites. The result is provided in the form of a geographic position - longitude and latitude - to, for most receivers, within 100 meters.
d)If the receiver is also equipped with a display screen that shows a map, the position can be shown on the map.
If a fourth satellite can be received, the receiver/computer can figure out the altitude as well as the geographic position.
If you are moving, your receiver may also be able to calculate your speed and direction of travel and give you estimated times of arrival to specified destinations.
Advantages of GPS:
1)GPS is extremely easy to navigate as it tells you to the direction for each turns you take or you have to take to reach to your destination.
2)GPS works in all weather so you need not to worry of the climate as in other navigating devices.
3)The GPS costs you very low in comparison other navigation systems.
4)The most attractive feature of this system is its100% coverage on the planet.
5)It also helps you to search the nearby restaurants, hotels and gas stations and is very useful for a new place.
6)Due to its low cost, it is very easy to integrate into other technologies like cell phone.
7)The system is updated regularly by the US government and hence is very advance.
8)This is the best navigating system in water as in larger water bodies we are often misled due to lack of proper directions.
Disadvantages of GPS:
1)Sometimes the GPS may fail due to certain reasons and in that case you need to carry a backup map and directions.
2)If you are using GPS on a battery operated device, there may be a battery failure and you may need a external power supply which is not always possible.
3)Sometimes the GPS signals are not accurate due to some obstacles to the signals such as buildings, trees and sometimes by extreme atmospheric conditions such as geomagnetic storms.
Note: The Global Positioning System (GPS) tells you where you are on Earth. nowdays this technology uses millions of people in the world