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  1. 1. INTRODUCTIONTraditional methods of surveying and navigation resort to tedious field andastronomical observation for deriving positional and directional information.Diverse field conditions, seasonal variation and many unavoidablecircumstances always bias the traditional field approach. However, due to rapidadvancement in electronic systems, every aspect of human life is affected to agreat deal. Field of surveying and navigation is tremendously benefited throughelectronic devices. Many of the critical situations in surveying/navigation arenow easily and precisely solved in short time.The NAVSTAR Global Positioning System (GPS) is a satellite-based radio-positioning and time transfer system designed, financed, deployed, and operatedby the U.S. Department of Defence. GPS has also demonstrated a significantbenefit to the civilian community who are applying GPS to a rapidly expandingnumber of applications. What attracts us to GPS is:  The relatively high positioning accuracies, from tens of metres down to the millimetre level.  The capability of determining velocity and time, to an accuracy commensurate with position.  The signals are available to users anywhere on the globe: in the air, on the ground, or at sea.  It is a positioning system with no user charges that simply requires the use of relatively low cost hardware.  It is an all-weather system, available 24 hours a day.  The position information is in three dimensions, that is, vertical as well as horizontal information is provided.The number of civilian users is already significantly greater than that of themilitary users. However, for the time being the U.S. military still operatesseveral "levers" with which they control the performance of GPS . Nevertheless,despite the handicap of GPS being a military system there continues to betremendous product innovation within the civilian sector, and it is ironic thatthis innovative drive is partly directed to developing technology and proceduresto overcome some of the constraints to GPS performance which have beenapplied by the systems military operators.
  2. 2. HISTORY OF GPSSince the beginning of time, mankind has been trying to figure out a dependableway to know where they were, and to guide them to where they wanted to goand get back again. Seamen followed the coastline to keep them from gettinglost. They discovered, when they sailed out into the open sea, that they coulduse the position of the stars to chart their courses.Major developments in early navigation were the compass and the sextant. Theneedle of the compass always points north. So even if they didnt knew wherethey were, at least they knew in what direction they were travelling. The sextantmeasures the exact angles of stars, the moon and the sun above the horizon bythe use of adjustable mirrors. Early sextants could only measure the latitude andsailors were still not able to work out their longitude.As this was determined to be a serious enough problem, in the seventeenthcentury, Great Britain formed a group of well-known scientists called the Boardof Longitude. They offered a substantial cash reward to any person who couldfind a way of working out the longitude of a ship within thirty nautical miles. In1761, a man named John Harrison developed a timepiece called a chronometer.This invention lost or gained only about one second a day. Sextants andchronometers were used together to provide travellers with their latitude andlongitude.Radio-based navigation systems were developed in the early twentieth century,and were used in World War II. As this technology advanced, both ships andairplanes used ground-based radio-navigation systems. The disadvantage ofusing a system that uses ground generated radio waves is that a choice has tomade between a high-frequency system that is accurate, but does not cover awide area, and a low-frequency system that covers a wide area, but is not veryaccurate.When Sputnik was launched into space by Russia on October 4th, 1957 itbecame known that "artificial stars" could be used for navigation. The eveningafter the launch researchers of the Massachusetts Institute of Technologydetermined the orbit of the Russian satellite by noting that the Sputniks radiosignals increased as it approached and decreased as it left. So the fact that asatellites position could be tracked from the ground was the first step inrecognizing that a subjects whereabouts on the ground could be determinedusing radio signals from the satellite.
  3. 3. The U.S. Navy experimented with satellite navigation. In the mid-sixties therewas the Transit System that was developed for submarines carrying Polarisnuclear missiles. This system has six satellites that circled the earth in polarorbits. In measuring the Doppler shift of the radio signals the submarines couldlocate its position within fifteen minutes.The Global Positioning System, now commonly known GPS was designed andbuilt and is operated and maintained by the U.S. Department of Defence. It usedto be known as the Navstar Global Positioning System and was firstbrainstormed at the Pentagon in 1973 as they were looking for a satellite systemthat was error-proof. In 1978 the first operational GPS satellite was launched.By the mid-1990s the system was fully operational with 24 satellites.This incredible new technology was made possible by a combination ofscientific and engineering advances, particularly development of the worldsmost accurate timepieces: atomic clocks that are precise to within a billionth ofa second. The clocks were created by physicists seeking answers to questionsabout the nature of the universe, with no conception that their technology wouldsome day lead to a global system of navigation. Today, GPS is saving lives,helping society in countless other ways, and generating 100,000 jobs in a multi-billion-dollar industry. GPS SATELLITE SYSTEMThe 24 satellites that make up the GPS space segment are orbiting the earthabout 12,000 miles above us. They are constantly moving, making twocomplete orbits in less than 24 hours. These satellites are travelling at speeds ofroughly 7,000 miles an hour.GPS satellites are powered by solar energy. They have backup batteries onboardto keep them running in the event of a solar eclipse, when theres no solarpower. Small rocket boosters on each satellite keep them flying in the correctpath.Here are some other interesting facts about the GPS satellites (also calledNAVSTAR, the official U.S. Department of Defence name for GPS):o The first GPS satellite was launched in 1978.o A full constellation of 24 satellites was achieved in 1994.o Each satellite is built to last about 10 years. Replacements are constantly being built and launched into orbit.
  4. 4. o A GPS satellite weighs approximately 2,000 pounds and is about 17 feet across with the solar panels extended.o Transmitter power is only 50 watts or less. A GPS SATELLITE SYSTEM  The United States Department of Defense developed the system, officially named NAVSTAR GPS (Navigation Signal Timing and Ranging Global Positioning System), and launched the first experimental satellite in 1978. FIRST SATELLITE LAUNCHED BY NAVSTAR
  5. 5. WORKING OF GPSGPS satellites circle the earth twice a day in a very precise orbit and transmitsignal information to earth. GPS receivers take this information and usetriangulation to calculate the users exact location. Essentially, the GPS receivercompares the time a signal was transmitted by a satellite with the time it wasreceived. The time difference tells the GPS receiver how far away the satelliteis. Now, with distance measurements from a few more satellites, the receivercan determine the users position and display it on the units electronic map.A GPS receiver must be locked on to the signal of at least three satellites tocalculate a 2D position (latitude and longitude) and track movement. With fouror more satellites in view, the receiver can determine the users 3D position(latitude, longitude and altitude). Once the users position has been determined,the GPS unit can calculate other information, such as speed, bearing, track, tripdistance, distance to destination, sunrise and sunset time and more.  The following points provide a summary of the technology at work:  The control segment constantly monitors the GPS constellation and uploads information to satellites to provide maximum user accuracy.  The GPS receiver collects information from the GPS satellites that are in view.  The GPS receiver accounts for errors.  The GPS receiver determines your current location, velocity, and time.  The GPS receiver can calculate other information, such as bearing, track, trip distance, distance to destination, sunrise and sunset time, and so on.  The GPS receiver displays the applicable information on the screen.
  6. 6. SEGMENTS OF GPSThe GPS system consists of three segments:-Space SegmentThe Space Segment consists of the constellation of spacecraft and the signalsbroadcast by them which allow users to determine position, velocity and time.  Receive and store data transmitted by the Control Segment stations.  Maintain accurate time by means of several onboard atomic clocks.  Transmit information and signals to users on two L-band frequencies.  Provide a stable platform and orbit for the L-band transmitters.  The particular satellite that is sending the information.  Where that satellite should be at any given time (the precise location of the satellite is called ephemeris data).  Whether or not the satellite is working properly.  The date and time that the satellite sent the signal.  Comprises of a nominal network of 24 GPS satellites in orbit around the globe.  Nominal orbit height of 20,200 Km.  Initial 24Hr operational capability was declared on 8 December, 1993.  Full 24 Hr operational capability was declared after testing on 17 July, 1995.  Selective Availability signal degradation was removed in May, 2000.Control SegmentThe Control Segment is the ground facilities carrying out the task of satellitetracking, orbit computations, telemetry and supervision necessary for the dailycontrol of the space segment. The control segment is responsible for constantlymonitoring satellite health, signal integrity and orbital configuration from theground. The control segment includes the following sections:-  Master control station  Monitor stations  Ground antennas
  7. 7. The Control Segment consists of facilities necessary for satellite healthmonitoring, telemetry, tracking, command and control, satellite orbit and clockdata computations, and data linking. There are five ground facility stations:Hawaii, Colorado Springs, Ascension Island, Diego Garcia and Kwajalein. Allare owned and operated by the U.S. Department of Defence and perform thefollowing functions:  All five stations are Monitor Stations, equipped with GPS receivers to track the satellites. The resultant tracking data is sent to the Master Control Station.  Colorado Springs is the Master Control Station (MCS), where the tracking data are processed in order to compute the satellite ephemerides and satellite clock corrections. It is also the station that initiates all operations of the space segment, such as spacecraft manoeuvring, signal encryption, satellite clock-keeping, etc.  Three of the stations (Ascension Is., Diego Garcia, and Kwajalein) are Upload Stations allowing for the uplink of data to the satellites. The data includes the orbit and clock correction information transmitted within the navigation message, as well as command telemetry from the MCS.User SegmentThe User Segment is the entire spectrum of applications equipment andcomputational techniques that are available to the users. The GPS user segmentconsists of GPS receiver. The receiver collects and processes signals from theGPS satellites that are in view and then uses that information to determine anddisplay your location, speed, time, and so on. Your GPS receiver does nottransmit any information back to the satellites. Overall operation of the Controland Space Segments is the responsibility of the U.S. Air Force SpaceCommand, Second Space Wing, Satellite Control Squadron at the Falcon AirForce Base, Colorado. This is the part of the GPS system with which we aremost concerned -- the space and control segments being largely transparent tothe operations of the navigation function.• Applications,• Equipment• Positioning strategies.
  8. 8. GPS –NowadaysTodays GPS receivers are extremely accurate, thanks to their parallel multi-channel design. Garmins 12 parallel channel receivers are quick to lock ontosatellites when first turned on and they maintain strong locks, even in densefoliage or urban settings with tall buildings. Certain atmospheric factors andother sources of error can affect the accuracy of GPS receivers. Todays GPSreceivers are extremely accurate, thanks to their parallel multi-channel design.Garmins 12 parallel channel receivers are quick to lock onto satellites whenfirst turned on and they maintain strong locks, even in dense foliage or urbansettings with tall buildings. Certain atmospheric factors and other sources oferror can affect the accuracy of GPS receivers.  GPS has become a vital global utility, indispensable for modern navigation on land, sea, and air around the world, as well as an important tool for map-making and land surveying.  GPS also provides an extremely precise time reference, required for telecommunications and some scientific research, including the study of earthquakes.  GPS receivers can also gauge altitude and speed with a very high degree of accuracy.
  9. 9. APPLICATIONS OF GPS MILITARYGPS allows accurate targeting of various military weapons includingcruise missiles and precision-guided munitions, as well as improvedcommand and control of forces through improved location awareness.The satellites also carry nuclear detonation detectors, which form amajor portion of the United States Nuclear Detonation DetectionSystem. Civilian GPS receivers are required to have limits on thevelocities and altitudes at which they will report coordinates. AVIATIONAircraft pilots use GPS technology for en route navigation and airportapproaches. Satellite navigation provides accurate aircraft locationanywhere on or near the earth. A number of attempts were made toproduce a true powered aircraft. However the majority of these effortswere doomed to failure, being designed by ill-informed amateurs whodid not have a full understanding of the problems being discussed byLilienthal and Chanute.
  10. 10. NAVIGATORSNavigation applications are the most famous GPS applications. Thelatest releases of those applications allow users to have muchadvanced features and facilities.DeLorme Street Atlas 2010: This is software that enables users to dothings like trip planning, GPS navigation and mapping. This wasmuch harder to learn how to work with it with the software. It is saidthat the latest edition has removed that complexity and made it easyfor the users to use.Gramin nRoute: This is free software that enables laptop users tomake their work easy with the GPS maps. However, users mustalready have a MapSource product running on your computer fornRoute to work.In addition to those Microsoft AutoRoute and Streetsand Tips are some of the other famous applications. TRACKINGA tracking applications are not that much popular as the navigationapplications. But, so many people take uses of them. It enables usersto find a location of any object that is tagged with a system.Top Grossing Apps on iTunes: iPhone users can have this facilitythrough the iTune store. This made the iPhone look much smart in itswords.LOC i MOBILE Apps for tracking people: This enables iPhone usersto track people in a particular place at a particular time.
  11. 11. GPS Tracking Lite v2.0 is taking the nation by storm: GPS Trackingv2.0 by Locimobile is their biggest update to date application and itincludes much advanced features than the others. AGRICULTUREGPS Machine Guidance is used for tractors and other largeagricultural machines via auto steer or a visual aid displayed on ascreen, which is extremely useful for controlled traffic and row cropoperations and when spraying. As well as guidance, GPS used inharvesters with yield monitors can provide a yield map of the paddockbeing harvested. FUTURE OF GPS APPLICATIONSThere can be several further implementations also as this GPS hasbecome widely available. This can be used to provide a solution forthe deforestation. The green plant density of a certain area can becalculated or estimated. With a comparison and analyze, thedeforestation rate can be calculate and can ask the officials to paytheir attention on those areas.Cultivation also can be helped with this Global Positioning System.The empty lands can be explored and let the people to cultivate onthose areas is something that can help the people to improve theirproduction and the right place for the right product will be availablethrough this system.The functioning of the currently available GPS is at a very low level.This can be developed with advanced features that could be able tofind the areas where marijuana cultivated likewise. The camerasshould be much more sensitive to identify such objects. The researchthings will be easy if that kind of facility can be established. Theapplication developers will have much advanced API for theirdevelopment that can give a greater outcome.
  12. 12. ADVANTAGES OF GPSThere are many advantages of having a GPS system:Ease of NavigationA GPS device is extremely handy. When you are hiking, you can deviate from apath without worrying about how you will find your way back. When you aredriving, GPS-based navigation systems can provide you with turn-by-turndirections, a helpful feature in a strange town.Search Nearby AreaSome GPS systems allow you to search the local area for nearby amenities, suchas hotels, restaurants and gas stations. This is extremely helpful in somesituations. For example, if you are driving cross-country and realize there is aproblem with your car, you can search for nearby auto mechanics and select onethat is along your route. Your GPS system will show you exactly how to getthere.Water NavigationGPS devices are perfect for water navigation. Since there are no landmarks inlarge bodies of water, boaters in the past had to use a compass and a map todetermine if they were on the right heading, with somewhat imprecise results.But the advent of GPS systems allowed boaters to figure out their exact positionon the map. In situations where underwater hazards are a problem, GPS devicesallow boaters to steer around hidden dangers.Other Advantages are:-1. A GPS system comes with a "panic" button. When this button is pressed anoperator at the GPS carrier can listen in on the conversation and either help youout or alert the authorities. This will keep you safe in case of accidents or hijacks.2. Your car will never loose your car at a football match or mall. The GPSservice will track the car for you and send its lights flashing.3. If your vehicle is ever stolen the GPS system will track the vehicle and theauthorities will be able to get it back in no time.
  13. 13. 4. A GPS system in a car, boat, plane or haversack will ensure that you arenever lost.5. A GPS system streamlines supply chains and truck movements. The systemcan track goods at any point of time and accurately predict when goods willreach their destination.6. GPS systems are used to detect structural problems in buildings and roadsand to predict disasters like earthquakes and so on. The scientific applications ofa GPS system are many.7. A GPS system can be used to locate a missing person, pet or family. Thedevice is quite small and is like a watch or button on a collar.8. A GPS is a great exercise monitor and will help you keep track of your speedand so on.9. If you are using a GPS device then you can be found easily if you arein danger or in accident.10. GPS device is small enough to get plugged into your car’s cigarette lighter.
  14. 14. DISADVANTAGESESSENTIAL MAP READING SKILLSCreating GPS technology that is readily available; our younger generation islosing the essential ability to read maps. With any computer devise, all can haveproblems that may cause the devise to malfunction or break. If you are someonewho relies heavily on a devise that tells you which route to take and it happensto malfunction, you may not a map available as an alternative. Modern GPStechnology is again dulling general knowledge that everyone should know andbe capable of understanding.RELYING ON TECHNOLOGYAs mentioned above, some people may rely on their devise too often. Turningtheir navigation system on each time they get into the car, even to go to a localstore. Use your sense, your sensibility and your knowledge contained in the bestcomputer of your brain instead of the GPS in your car.LOSING INDEPENDENCE AND TRUST ISSUESThis would be important for subcontractors and truck drivers whose companyhas installed GPS devises in the vehicles. Now you have Big Brother watchingat all times, no longer can you use the company vehicle for personal chores andreasons. In the modern era of high fuel costs and the expense of maintainingvehicle and truck fleets, using a company vehicle for personal reasons is nolonger considered okay.WAYS TO STOP SATELLITE SIGNALSModern technology always has its downfalls. One of these is the intelligenceused to stop satellite signals. A company that uses a fleet of vehicles with GPStechnology installed may find their employees going to certain extents to avoiddetection on their maps. I have heard tales of a simple aluminium can beingplaced over the antennae, that will disable the GPS system from being able totrack positions and routes. Please look into this when considering GPStechnology for your fleet vehicles.
  15. 15. COMPUTER TECHNOLOGY AND YOUAlthough many of us have great electronic devices in our homes and cars, dowe really use them to the best of their ability? Do you even like the technologyyou have at your disposal? Consider your GPS devise and its capabilities, areyou going to make use of downloading music and some DVD capabilities? Doyou know how to spell street names accurately to enter into you GPS system?Making a slight error in spelling may have you going around in circles. Thenyou will blame the devise, not yourself. This therefore becomes an extremelyuseless devise that may have cost you a lot of money, and some anger andfrustration.ELECTRONIC WAVES AND YOUR HEALTHWeve all heard how microwaves can be dangerous to your health. We hearstories or mobile phones and their continuing use causing cancer for those whouse them often. A GPS devise is another form of technology that utilizesinvisible satellite and electro-waves that could also prove to be bad for ourhealth.Consider the mobile phone, the GPS satellite in your car, the portable DVDplayer playing for the kids. How many electro-magnetic waves are bouncingaround your car?SATELLITE DETECTIONGPS makes use of satellite technology, bouncing waves from your devise to thesatellite detecting signals to operate. When one of these satellites ismalfunctioning, your GPS may have issues picking up signals. You need toconsider connection times, response times and how often the system ismaintained and repaired. Just like mobile phone coverage, GPS relies onperformance of the coverage to function.EXPENSEYou will also need to consider the expense of purchasing a GPS system. Fleetcompanies could claim them on their business tax, but individuals may not.These are expensive devices, ranging from a couple of hundred to manyhundred dollars. Is really vital you have this new devise?So although it has many advantages, it too has disadvantages to you as anindividual and society in general. Those disadvantages above are just some ofthe darker sides to popular GPS technology.
  16. 16. CONCLUSIONThe technology of the Global Positioning System is allowing forhuge changes in society. The applications using GPS areconstantly growing. The cost of the receivers is dropping whileat the same time the accuracy of the system is improving. Thisaffects everyone with things such as faster Internet speed andsafer plane landings.Initially developed for military use, GPS is now part ofeveryday life; used in mobile phones, in-car navigation andsearch and rescue equipment to mention just a few. But there isa wide variety of equipment and techniques that can be used forsurveying.GPS was rapidly adapted for surveying, as it can give a position(Latitude, Longitude and Height) directly, without the need tomeasure angles and distances between intermediate points.Survey control could now be established almost anywhere and itwas only necessary to have a clear view of the sky so the signalfrom the GPS satellites could be received clearly.GPS is similar in some ways to the Trilateration and EDMexcept that the known positions are now the GPS satellites (andtheir orbits) 20,000 km in space. The equipment andcalculations are extremely complex, but for the user the processis generally very simple.The GPS receivers used for surveying are generally morecomplex and expensive than those used in everyday life. Theyuse the two frequencies broadcast by the GPS satellites and theyuse the physical characteristic of the GPS signal (the phase) andsophisticated calculation methods to greatly improve theaccuracy of the positions obtained. These receivers usually havea separate high-quality antenna.
  18. 18. CERTIFICATEThis is to certify that this seminar has been conducted by Kajal Singh on thetopic “GPS TECHNOLOGY” under the graceful guidance of Mr.Dilip Sharma,as a mandatory part for the completion of their course Bachelor of Technologyin the branch Information and Technology (session 2011-2012). SIGNATURE:-