Global Positioning System - Research Paper Example

GLOBAL POSITIONING SYSTEM (GPS) Initially, people navigated only through the usage of tress, mountains, or leaving trails of stones, that is, they used landmarks. This method worked within one specific area and was heavily influenced by the environmental factors such as natural disasters. In order to travel across the ocean, a process known as the dead reckoning was used. This method applied a magnetic compass and needed the computation of how speedy the boat was traveling. Both these measurement tools used complex processes and were rudimentary and inaccurate. Afterwards, people started using stars as guidelines to travel across the ocean. The stars come out different from different positions on Earth so evaluating the stars gave sailors the basic course to follow. Celestial navigation was the main method of navigation for over a hundreds of years. The process of triangulation, which is the measurement of angles between stars, was a lengthy and difficult task. The amount of accuracy was restricted. The users or receivers of the ground-based navigation systems introduced in the 20th century worked out how further away they are from the transmitting tower, whose position is known. When numerous towers are utilized, the position can be identified. Even though, this process of navigation was a large improvement, but it still had its difficulties. During the 1970s, the military used numerous navigational systems, such as LORAN (acronym for Long Range Radio Navigation), VOR (acronym for VHF Omni-directional Radio) and OMEGA. There was a strong need for more precise navigational devices which would function continuously, irrespective of day or night or weather conditions (Frequently Asked Questions about GPS 2007). The Department of Defense ultimately created a Joint Program Office (JPO), which strengthened the developments of the Global Positioning System (GPS). The first GPS satellite was initiated in 1974, and was confirmed completely operational in 1994. They were and still are designed and built by Rockwell International, Boeing and Lockheed-Martin. The GPS was initially founded on and run with 24 satellites. NAVSTAR (Navigation System for Timing and Ranging) is the actual name of GPS, but is generally referred to as GPS (History of NAVSTAR GPS 2007). The satellite constellation is handled by the United States Air Force 50th Space Wing. The maintenance cost of the system is approximately US$750 million per year, which includes the changing of satellites which are growing old, and research and development. In spite of these costs, GPS is free for the general public as a public good. GPS is being increasingly used assist to navigation globally, and is a valuable tool for map-making, land surveying, commerce, and scientific uses. It also offers accurate time reference applied in many tasks including scientific analysis of earthquakes, and synchronization of telecommunications networks. A GPS receiver computes its position by measuring the distance between itself and three or more GPS satellites. As the signal travels at the speed of light, therefore, the time delay between the transmission and reception of each GPS microwave signal gives the distance to each satellite. These signals also bear information regarding the satellites' position and general system health which are known as almanac and ephemeris data. By analyzing the position and distance from at least three satellites, the recipient can estimate its position by means of trilateration. Receivers normally do not have entirely exact clocks and so they track one or more added satellites, using their atomic clocks to fix the receiver's own clock error. The operation of GPS is divided into three segments. The space segment constitutes of the 24 Block II NAVSTAR satellites that transmit specifically timed pulses of code and orbital data (User Segment 2007). The control segment assists monitors the satellites with monitoring stations to find their exact orbit and any clock errors and hence correct the satellites own data if necessary. Finally the user segment consists of all of the receivers located on the ground, or in airplanes, or in ships. GPS satellites transmit on two L-Band frequencies: 1.57542 GHz (L1) and 1.22760 GHz (L2). The L1 signal is adjusted by two codes - the P-code (precise) and the C/A-code (coarse acquisition). The L2 carrier contains only P-code, which is encrypted. However there are some civilian receivers which have the ability of using the L1 P-code without decoding it (Pearce 1997). The P-code is encrypted for use only by approved military users. The encryption is known as anti-spoofing with the purpose of stopping enemies from sending out bogus signals to trick any military weapons or vehicles. The C/A code is the regular freely accessible service for non-military users. It is less precise and easier to jam. It uses only one frequency and so cannot recompense for ionospheric delay. The world’s foremost innovators in the GPS technology are the Trimble Navigation Ltd. Trimble not only provides advanced GPS components but its also offers other locating technologies as well as wireless communications and software to generate entire customer solutions. It also provides its customers with functions including surveying, automobile navigation, machine guidance, asset tracking, wireless platforms, and telecommunications infrastructure. Other numerous renowned companies have also made use of the GPS like the ESRI, Pitney Bowes MapInfo, 3S Navigation, @Road (A Trimble Company) and many more. The GPS has proved very valuable for the U.S. military forces. The system enabled them to perform numerous actions in the Operation Desert Storm. The systems were held by the soldiers on the ground and were attached to numerous vehicles and aircraft instrument panels. The GPS has become increasingly significant for nearly all military operations and weapons systems. Furthermore, it is also used on satellites to get hold of highly precise orbit data and to control spacecraft orientation. Even though, GPS was developed to meet the military needs but new methods of usage for the civilians have also evolved. It is helping to save lives and property of individuals around the world. A lot of emergency services like the police, fire or paramedics make use of GPS to determine the vehicle’s location to enable the fastest possible reaction in life-or-death situations. Furthermore, aircrafts which are equipped with the GPS technology can pinpoint the location of any forest fire so immediate action can be taken. The use of the GPS technology is extensive in the surveying, mapping and construction companies. Also managers at different companies make use of GPS-equipped cellular phones to trace their employees (GPS/Tracking 2009). One of the fastest-growing uses of GPS is the vehicle tracking system. The public transportation systems, fleet vehicles, courier services and delivery trucks which are GPS-enabled can be located and monitored at all times for both efficiency and driver safety. Another application of GPS is in the automobile industry where the manufacturers offer their customers moving-map displays which are operated by GPS receivers and can even be detached. Numerous rental car companies use GPS-equipped vehicles that provide directions to drivers on display screens and through synthesized voice instructions. Further usage of GPS can be seen from the GPS-equipped balloons which scrutinize holes in the ozone layer. It also helps in keeping a close check over major oil spills so that cleanup operations take place immediately. Furthermore, archaeologists, biologists, and explorers use the system to situate ancient ruins, migrating animal herds, and endangered species such as manatees, snow leopards, and giant pandas. The advantages of a Global Positioning System are that the intervisibility between the stations is not required and as GPS uses radio frequencies to transmit the signals, the system is completely independent of the weather conditions. If similar field and data reduction methods are utilized, location precision is principally a function of inter-station distance. Furthermore, because of the generally homogeneous accuracy of GPS surveying, geodetic network planning in the classical sense is no longer relevant. The points are positioned where required and are not required to be located at uniformly distributed areas. Also, because of the two above-mentioned advantages of non-requirement of intervisibility and following a traditional networking design, GPS allows a more proficient, flexible and less time consuming locating system. It can also be used around-the-clock and provides three-dimensional information. Lastly, high accuracies can be achieved with relatively little effort, unlike conventional terrestrial techniques. The GPS instrumentation, and to some extent the data processing software, is similar whether accuracies at the 1 part in 104 or 1 part in 106 level are sought. The disadvantages of GPS are that high efficiency always has its price. Proficient use of GPS needs that transmission durations between stations are severed to match the savings in on-site time. The requirement of GPS is that there is no barrier to the signals; therefore, it cannot be used underground. Because GPS surveys can be optimized to suit the specific needs of the particular survey, these may not be helpful for other applications in the same locality. GPS coordinates are provided in the earth-centered, earth-fixed coordinate system defined by the GPS satellite ephemeredes so the results might have to be altered into a local geodetic system before usage. Moreover, the ethical considerations also have to be kept in mind when tracking the employees as this kind of service may violate the employee’s privacy rights. Though, for all its technological advantages, there are numerous of vital variations between the GPS surveying technology and that of traditional methods. To resolve these differences and to make certain that GPS will balance other technologies an important level of post-processing of GPS results is essential (Pearce 1997). But the hope for greater than before acceptance of GPS satellite surveying is extremely good, especially as the price of GPS drops and newer high efficiency methods are evolved. There have also been extraordinary enhancements of GPS of precision and constant stream of data every second. Also, the increase in the number of satellites has a greatly reduced error. GPS is an ever growing system that proposes enhanced precision all the time. New systems which have combined the American NAVSTAR system and the Russian Glonass system indicates that there are a total of 48 satellites available and overall provide improved accuracy than GPS alone (. Though there is a benefit of higher stability that might be interrupted from buildings and terrain otherwise. The technology of the Global Positioning System is making huge changes in the society that have never been before seen. The applications which make use of GPS are constantly and increasingly growing. The cost of the receivers is dropping while at the same time the precision of the system is enhancing. It is bringing home the consumers degree of unmatched knowledge and insight to any outdoor endeavor. Other advances in GPS technology also includes improved situational precision and more consistent computations. The adding of civilian passwords and civilian frequencies has been developed to exclusively meet the requirements of civilian users with slight to no military application. WORKS CITED “Frequently Asked Questions about GPS.” beagle software. 01 February 2007. 7 May 2009 . “GPS/Tracking.” Directions Magazine: All Things Location. 2009. 7 May 2009 “History of NAVSTAR GPS.” kowoma.de. 19 April 2007. 7 May 2009 Pearce, Corin, G. The Differential Global Positioning System. 1997. 7 May 2009 “User Segment.” kowoma.de. 19 April 2007. 7 May 2009. Read More