What is Global Positioning System ?? Where it is used?? How much will it cost ?? Who all can get it ??

Answer 1

Hi Golmol,
Hope this helps

Go to GOOGLE
Type in wikipedia.com
Type in global positioning in the search bar

There is all kinds of info there. Too much to post here.
Good Luck

Answer 2

GPS is a Space-Based Geographical Positioning Satellite.
It transmits data to the Receiver(In your Car,Boat,Ship,Aircraft).
The accuracy of such systems is determined by How many of these 12 Satellites you can receive!
So, it will not work fully when Underground,inside some buildings and limited coverage in Mountainous areas!.
Anyone can purchase a GPS Receiver,and it it Free to use the Satellites!

Answer 3

It is a system used to triangulate your position on earth using satellites and units on the ground which you can carry around. The gps units have atomic clocks that measure the distance between the satellite and reciever. They measure the signal with time to determine how long it took to get from the satellite to the reciever. Lets say the reciever gets the first signal and it says it took 5.08098080809 seconds to reach the reciever which is exactly 2000.34585859 miles (hypothetical example) from the satellite to the ground. That gives it somewhat of an idea where it is on the earth. If it gets a signal from another satellite that says it is 2300.32478237490723 miles away it narrows it down further. The third one says it is 2005.646464646 miles away - the third one is necessary to narrow it down further to "triangulate" it. If you think of it like this it may help. Get three strings about 4 feet long (doesn't have to be 4 feet, I am just using that as an example). Tie one end of each to a different stationary object in a room or have 3 people to each hold one end of the strings. Next tie a paper clip to the opposite end of string one. Keeping the string tight you will notice that you can swing that paper clip in a circle but you have some limitation where you can go since your string is only 4 feet long. This gives you an idea of where the paper clip location should be. Next tie the second string to the paper clip. Keeping the strings tight, you can now only move the paper clip in a line between the two and it is narrowing down the location of the paper clip to a higher level of accuracy. Now tie the third to it. If you keep all the strings tight there is only one place in which that paper clip can be. The more satellites you add the more accurate it is. This is how GPS works. The atomic clocks all have a distance figured and when you compare them against each other there can only be one place which the point exists. As for where it is used, how much it will cost, and who can get it - that depends. Some people use recreational grade ones for navigating in their vehicle or marking points on a lake for fishing, some cities use mapping grade gps to collect points for their sanitary sewer or water distribution maps, and some land surveyors use survey grade gps to mark out survey points and benchmarks. The cost goes up considerably with the accuracy that you wish to achieve. The recreational grade ones are only accurate to a few meters and cost about $300 to $800, the mapping grade ones can get sub foot accuracy and cost approximately $5000 to $6000, and survey grade gps units can get accuracy of less than 1/100th or a foot and cost $50,000 to $60,000. I have used all three of them extensively - I have a Lowrance "Hunt" gps in my pickup, a Trimble ProXH gps at my current job which I collect points for city maps, and at my old job I used a Topcon RTK (real time kinetic) which is survey grade. Look up each of these for more information on accuracy and cost since I am approximating and they should give you more information as well. As far as who can get it - anybody can get it. There was a time when the American government kept it to itself and used "selective availability" to limit who could have it but they have released their hold on it and now anyone can get it - they just need to buy the reciever. Each work right out of the box. There is alot more to it like multipath correction and DGPS signals which increase accuracy but there is just too much of that to type. Yahoo search multipath correction and Digital Global Position System if you want to learn more.

Answer 4

Global Positioning System (GPS) are widely used in all types of aircraft, ships of all types, cars, and also on heavy machinery as well as cars. Their are many varieties of types and prices. Hand held GPS are used as portable devices, and are more economical in my opinion. Its a tracking device that use satilites all over the globe, accurate to about three feet in todays technology. " Use them on Fishing vessels," and you can use them to track your way to bring you back. Its a must have for people that are unfamiliar with outdoors such as hiking, etc.

Answer 5

Hi
what's a good question and what nice answers.

in addition to above answers, GPS price depends on its precision , now aday you can buy one by less than 100$
http://www.gpsnow.com/
but +/- 1m in plan and +/-3m in z.

GPS is not useful every were, for example in ROAD/RAILWAY projects and for cartography purposes , specially in areas where GEOID is not studied, elevations are not reliable.

have look and search on the web

regards, and good luck

Answer 6

The Global Positioning System (GPS), is currently the only fully-functional satellite navigation system. More than two dozen GPS satellites are in medium Earth orbit, transmitting signals allowing GPS receivers to determine the receiver's location, speed and direction.

Since the first experimental satellite was launched in 1978, GPS has become an indispensable aid to navigation around the world, and an important tool for map-making and land surveying. GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.

Developed by the United States Department of Defense, it is officially named NAVSTAR GPS (Navigation Satellite Timing And Ranging Global Positioning System). The satellite constellation is managed by the United States Air Force 50th Space Wing. Although the cost of maintaining the system is approximately US$400 million per year, including the replacement of aging satellites, GPS is free for civilian use as a public good.
A GPS receiver calculates its position by measuring the distance between itself and three or more GPS satellites. Measuring the time delay between transmission and reception of each GPS radio signal gives the distance to each satellite, since the signal travels at a known speed. The signals also carry information about the satellites' location. By determining the position of, and distance to, at least three satellites, the receiver can compute its position using trilateration. Receivers typically do not have perfectly accurate clocks and therefore track one or more additional satellites to correct the receiver's clock error.

System segmentation
The current GPS consists of three major segments. These are the space segment (SS), a control segment (CS), and a user segment (US).

Space segment
The space segment (SS) is composed of the orbiting GPS satellites, or Space Vehicles (SV) in GPS parlance. The GPS design calls for 24 SVs to be distributed equally among six circular orbital planes.[3] The orbital planes are centered on the Earth, not rotating with respect to the distant stars.[4] The six planes have approximately 55° inclination (tilt relative to Earth's equator) and are separated by 60° right ascension of the ascending node (angle along the equator from a reference point to the orbit's intersection).

Orbiting at an altitude of approximately 20,200 kilometers (12,600 miles or 10,900 nautical miles; orbital radius of 26,600 km (16,500 mi or 14,400 NM)), each SV makes two complete orbits each sidereal day, so it passes over the same location on Earth once each day. The orbits are arranged so that at least six satellites are always within line of sight from almost anywhere on Earth.

As of January 2007, there are 29 actively broadcasting satellites in the GPS constellation. The additional satellites improve the precision of GPS receiver calculations by providing redundant measurements. With the increased number of satellites, the constellation was changed to a nonuniform arrangement. Such an arrangement was shown to improve reliability and availability of the system, relative to a uniform system, when multiple satellites fail.

Control segment
The flight paths of the satellites are tracked by US Air Force monitoring stations in Hawaii, Kwajalein, Ascension Island, Diego Garcia, and Colorado Springs, Colorado, along with monitor stations operated by the National Geospatial-Intelligence Agency (NGA). The tracking information is sent to the Air Force Space Command's master control station at Schriever Air Force Base, Colorado Springs, Colorado, which is operated by the 2d Space Operations Squadron (2 SOPS) of the United States Air Force (USAF). 2 SOPS contacts each GPS satellite regularly with a navigational update (using the ground antennas at Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs). These updates synchronize the atomic clocks on board the satellites to within one microsecond and adjust the ephemeris of each satellite's internal orbital model. The updates are created by a Kalman Filter which uses inputs from the ground monitoring stations, space weather information, and other various inputs.

User segment
The user's GPS receiver is the user segment (US) of the GPS system. In general, GPS receivers are composed of an antenna, tuned to the frequencies transmitted by the satellites, receiver-processors, and a highly-stable clock (often a crystal oscillator). They may also include a display for providing location and speed information to the user. A receiver is often described by its number of channels: this signifies how many satellites it can monitor simultaneously. Originally limited to four or five, this has progressively increased over the years so that, as of 2006, receivers typically have between twelve and twenty channels.

GPS receivers may include an input for differential corrections, using the RTCM SC-104 format. This is typically in the form of a RS-232 port at 4,800 bps speed. Data is actually sent at a much lower rate, which limits the accuracy of the signal sent using RTCM. Receivers with internal DGPS receivers can outperform those using external RTCM data. As of 2006, even low-cost units commonly include WAAS receivers.

Many GPS receivers can relay position data to a PC or other device using the NMEA 0183 protocol. NMEA 2000 is a newer and less widely adopted protocol. Both are proprietary and controlled by the US-based National Marine Electronics Association. References to the NMEA protocols have been compiled from public records, allowing open source tools like gpsd to read the protocol without violating intellectual property laws. Other proprietary protocols exist as well, such as the SiRF protocol. Receivers can interface with other devices using methods including a serial connection, USB or Bluetooth.

GPS satellites broadcast three different types of data in the primary navigation signal. The first is the almanac which sends coarse time information along with status information about the satellites. The second is the ephemeris, which contains orbital information that allows the receiver to calculate the position of the satellite. This data is included in the 37,500 bit Navigation Message, which takes 12.5 minutes to send at 50 bps.

The satellites also broadcast two forms of clock information, the Coarse / Acquisition code, or C/A which is freely available to the public, and the restricted Precise code, or P-code, usually reserved for military applications. The C/A code is a 1,023 bit long pseudo-random code broadcast at 1.023 MHz, repeating every millisecond. Each satellite sends a distinct C/A code, which allows it to be uniquely identified. The P-code is a similar code broadcast at 10.23 MHz, but it repeats only once a week. In normal operation, the so-called "anti-spoofing mode", the P code is first encrypted into the Y-code, or P(Y), which can only be decrypted by units with a valid decryption key. Frequencies used by GPS include:

L1 (1575.42 MHz) - Mix of Navigation Message, coarse-acquisition (C/A) code and encrypted precision P(Y) code.
L2 (1227.60 MHz) - P(Y) code, plus the new L2C code on the Block IIR-M and newer satellites.
L3 (1381.05 MHz) - Used by the Defense Support Program to signal detection of missile launches, nuclear detonations, and other high-energy infrared events.
L4 (1379.913 MHz) - Being studied for additional ionospheric correction.
L5 (1176.45 MHz) - Proposed for use as a civilian safety-of-life (SoL) signal (see GPS modernization). This frequency falls into an internationally protected range for aeronautical navigation, promising little or no interference under all circumstances. The first Block IIF satellite that would provide this signal is set to be launched in 2008.