INTRODUCTION

PAGE

CERTIFICATE

This is to certify that Mr. Avinash Kumar Mishra, a student of B.Tech.(Electronics & communication Engineering) 7th semester has submitted his Seminar report entitled Adaptive Missile Guidance Using GPS under our guidance. Supervisor: Mr. Mehtab Singh Mr. Yogendra Kr Katiyar

(Assistant Professor) HOD(ECE) i AKNOWLEDGEMENTThis is an great opportunity to express my heartfelt words for the people who were part of this seminar in numerous ways, people who gave me wishful and helpful support right from beginning of the seminar.

I am thankful to seminar incharge Mr. Mehtab singh for giving me guidelines to make the seminar successful.

I want to give sincere thanks to the HOD of the Department, Mr. Yogendra Kr. Katiyar for his valuable support & co-operation.Yours Sincerely,

(Avinash Kumar Mishra) ii ABSTRACTIn the modern day theatre of combat, the need to be able to strike at targets that are on

the opposite side of the globe has strongly presented itself. This had led to the

development of various types of guided missiles. These guided missiles are self guiding

weapon sin tended to maximize damage to the target while minimizing collateral damage

. The buzzword in modern day combat is fire and forget. GPS guided missiles, using

the exceptional navigational and surveying abilities of GPS, after being launched, could

deliver a warhead to any part of the globe via the interface pof the onboard computer in

the missile with the GPS satellite system.

Under this principle many modern day laser weapons were designed. Laser guided

missiles use a laser of a certain frequency bandwidth to acquire their target. GPS/inertial weapons are oblivious to the effects of weather, allowing a target to be engaged at the

time of the attacker's choosing. GPS allows accurate targeting of various military

weapons including ICBMs, cruise missiles and precision-guided munitions. Artillery

projectiles with embedded GPS receivers able to withstand accelerations of 12,000 G

have been developed for use in 155mm. GPS signals can also be affected by multipath

issues, where the radio signals reflect off surrounding terrain; buildings, canyon walls,

hard ground , etc. These delayed signals can cause inaccuracy. A variety of techniques,

most notably narrow correlator spacing, have been developed to mitigate multipath errors.

Multipath effects are much less severe in moving vehicles. When the GPS antenna is

moving, the false solutions using reflected signals quickly fail to converge and only the

direct signals result in stable solutions... In summary, GPS-INS guided weapons are not

affected by harsh weather conditions or restricted by a wire, nor do they leave the gunner

vulnerable for attack. GPS guided weapons with their technological advances over

previous, are the superior weapon of choice in modern day warfare. iiiLIST OF FIGURES: Page no.

1.1. Concept of missile Guidance 01

1.2. Missile guidance using radar signal 03

1.3. Missile guidance using wire 04

1.4. Missile guidance using laser 05

1.5. GPS satellite 10

1.6. Ground monitor station 15

1.7. Segment of GPS 17

1.8. Working of DGPS 18

1.9. Satellite guided weapons 21 iv

CONTENTS1. CERTIFICATE i 2. Acknowledgment ii3. ABSTRACT iii4. LIST OF FIGURES iv

5. INTRODUCTION 15.1 CONCEPT OF MISSILE GUIDANCE 15.2 TYPES OF MISSILE GUIDANCE 26. INTRODUCTION TO GPS 66.1. MEANING OF GPS 67.2. ELEMENTS OF GPS 87.2 WORKING OF DGPS 187.3 WORKING OF INERTIAL NAVIGATION SYSTEM 198. ROLE OF SATELLITE IN MISSILE

GUIDANCE 208.1. SATELLITE GUIDED WEAPONS 208.2. MISSILE GUIDANCE USING GPS 229. APPLICATIONS 236 DEVELOPMENT 257 CONCLUSION 288 REFERENCES 29 INTRODUCTION1). Introduction to missile guidance :

Guided missile systems have evolved at a tremendous rate over the past four decades, and recent breakthroughs in technology ensure that smart warheads will have an increasing role in maintaining our military superiority. On ethical grounds, one prays that each warhead deployed during a sortie will strike only its intended target, and that innocent civilians will not be harmed by a misfire. From a tactical standpoint, our military desires weaponry that is reliable and effective, inflicting maximal damage on valid military targets and ensuring our capacity for lighting fast strikes with pinpoint accuracy. Guided missile systems help fulfill all of these demands.

1.1). Concept of missile guidance :Missile guidance concerns the method by which the missile receives its commands to move along a certain path to reach a target. On some missiles, these commands are generated internally by the missile computer autopilot. On others, the commands are transmitted to the missile by some external source. Fig 1.1 concept of missile guidance The missile sensor or seeker, on the other hand, is a component within a missile that generates data fed into the missile computer. This data is processed by the computer and used to generate guidance commands. Sensor types commonly used today include infrared, radar, and the global positioning system. 1

Based on the relative position between the missile and the target at any given point in flight, the computer autopilot sends commands to the control surfaces to adjust the missile's course.

1.2). Types of missile guidance :

Many of the early guidance systems used in missiles where based on gyroscope models. Many of these models used magnets in their gyroscope to increase the sensitivity of the navigational array. In modern day warfare, the inertial measurements of the missiles are also controlled by a gyroscope in one form or another ,but the method by which missile approaches the target bears a technical edge. On the battlefield of today, guided missiles are guided to or acquire their targets by using: Radar signal

Wires

Lasers (or)

Most recently GPS1.2.1)Missile guidance using radar signal:Many machines used in battle, such as tanks, planes, etc. and targets, such as buildings, hangers, launch pads, etc. have a specific signature when a radar wave is reflected off of it. Guided missiles that use radar signatures to acquire their targ ets are programmed with the specific signature to home in on. Once the missile is launched, it then uses its onboard navigational array to home in on the preprogrammed radar signature. Most radar guided missiles are very successful in acquiring their targets, however, these missiles need a source to pump out radar signals so that they can acquire their target. The major problem with these missiles in todays battlefield is that the countermeasures used against these missiles work on the same principles that these missiles operate under. The countermeasures home in on the radar signal source and destroy the antenna array,

2

Fig1.2: missile guidance using radar signal 3which essential shuts down the radar source, and hence the radar guided missiles cannot acquire their targets.

1.2.2). Missile guidance using wires :

Wire guided missiles do not see the target. Once the missile is launched, the missile proceeds in a linear direction from the launch vehicle. Miles of small, fine wire are wound in the tail section of the missile and unwind as the missile travels to the target. Along this wire, the gunner sends navigational signals directing the missile to the target. If for some reason the wire breaks, the missile will never acquire the target. Wire guided missiles carry no instrument array that would allow them to acquire a target. One strong downside to wire guided missiles is the fact that the vehicle from which the missile is fired must stay out in the open to guide the missile to its target. This leaves the launch vehicle vulnerable to attack, which on the ba ttlefield one wants to avoid at all costs.

Fig1.3: missile guidance using wire. 41.2.3). Missile guidance using lasers :

In modern day weaponry the buzzword is fire and forget. Under this principle many modern day laser weapons were designed. Laser guided missile use a laser of a certain frequency bandwidth to acquire their target. The gunner sights the target using a laser; this is called painting the target. When the missile is launched it uses its onboard instrumentation to look for the heat signature created by the laser on the target. Once the missile locates the heat signature, the target is acquired, and the missile will home in on the target even if the target is moving. Despite the much publicized success of laser guided missiles, laser guided weapons are no good in the rain or in weather conditions where there is sufficient cloud cover. To overcome the shortcomings of laser guided missiles presented in unsuitable atmospheric conditions and radar guided missiles entered GPS as a method of navigating the missile to the target. So, before going to GPS guided missile we will have an introduction to GPS.

Fig1.4: missile guidance using laser. 5 INTRODUCTION TO GPS: 2.1). What is meant by GPS ?

GPS, which stands for Global Positioning System, is the only system today able to show us our exact position on the Earth anytime, in any weather, anywhere. GPS satellites, 24 in all, orbit at 11,000 nautical miles above the Earth. 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. The GPS project was developed in 1973 to overcome the limitations of previous navigation systems, integrating ideas from several predecessors, including a number of classified engineering

design studies from the 1960s. GPS was created and realized by the U.S. Department of Defense (DoD) and was originally run with 24 satellites. It became fully operational in 1994. Bradford Parkinson, Roger L. Easton, and Ivan A. Getting are credited with inventing it. Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS system and implement the next generation of GPS III satellites and Next Generation Operational Control System (OCX). Announcements from Vice President Al Gore and the White House in 1998 initiated these changes. In 2000, the U.S. Congress authorized the modernization effort, GPS III.

In addition to GPS, other systems are in use or under development. The Russian Global Navigation Satellite System (GLONASS) was developed contemporaneously with GPS, but suffered from incomplete coverage of the globe until the mid-2000s. 6The design of GPS is based partly on similar ground-based radio-navigation systems, such as LORAN and the Decca Navigator, developed in the early 1940s and used during World War II.The first satellite navigation system, Transit, used by the United States Navy, was first successfully tested in 1960. It used a constellation of five satellites and could provide a navigational fix approximately once per hour. In 1967, the U.S. Navy developed the Timation satellite that proved the ability to place accurate clocks in space, a technology required by GPS. In the 1970s, the ground-based Omega Navigation System, based on phase comparison of signal transmission from pairs of stations, became the first

world wide radio navigation system. Limitations of these systems drove the need for a more universal navigation solution with greater accuracy. While there were wide needs for accurate navigation in military and civilian sectors, almost none of those was seen as justification for the billions of dollars it would cost in research, development, eployment, and operation for a constellation of navigation satellites. During the Cold War arms race, the nuclear threat to the existence of the United States was the one need that did justify this cost in the view of the United States Congress. This deterrent effect is why GPS was funded. It is also the reason for the ultra secrecy at that time. The nuclear triad consisted of the United States Navy's submarine-launched ballistic missiles (SLBMs)

along with United States Air Force (USAF) strategic bombers and intercontinental ballistic missiles (ICBMs). Considered vital to the nuclear deterrence posture, accurate 7determination of the SLBM launch position was a force multiplier.

Precise navigation would enable United States submarines to get an accurate fix of their positions before they launched their SLBMs. The USAF, with two thirds of the nuclear triad, also had requirements for a more accurate and reliable navigation system. The Navy and Air Force were developing their own technologies in parallel to solve what was essentially the same problem. To increase the survivability of ICBMs,

there was a proposal to use mobile launch platforms (such as Russian SS-24 and SS-25) and so the need to fix the launch position had similarity to the SLBM situation.

In 1960, the Air Force proposed a radio-navigation system called MOSAIC (MObile

System for Accurate ICBM Control) that was essentially a 3-D LORAN. A follow-on study, Project 57, was worked in 1963 and it was "in this study that the GPS concept was born". That same year, the concept was pursued as Project 621B, which had "many of the attributes that you now see in GPS" and promised increased accuracy for Air Force bombers as well as ICBMs. Updates from the Navy Transit system were too slow for the high speeds of Air Force operation. The Naval Research Laboratory continued advancements with their Timation (Time Navigation) satellites, first launched in 1967, and with the third one in 1974 carrying the first atomic clock into orbit.2.2).Elements of GPS:GPS has three parts: the space segment, the user segment, and the control segment.

(a)Space segment: The space segment (SS) is composed of the orbiting GPS satellites, or Space Vehicles (SV) in GPS parlance. The GPS design originally called for 24 SVs, eight 8each in three approximately circular orbits, but this was modified to six orbital planes with four satellites each. The six orbit 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). The orbital period is one-half a sidereal day, i.e., 11 hours and 58 minutes so that the satellites pass over the same locations or almost the same locations every day. The orbits are arranged so that at least six satellites are always within line of sight from almost

everywhere on Earth's surface. The result of this objective is that the four satellites are not evenly spaced (90 degrees) apart within each orbit. In general terms, the angular difference between satellites in each orbit is 30, 105, 120, and 105 degrees apart which sum to 360 degrees. Orbiting at an altitude of approximately 20,200 km (12,600 mi); orbital radius of approximately

26,600 km (16,500 mi), each SV makes two complete orbits each sidereal day, repeating The same ground track each day. This was very helpful during development because even with only four satellites, correct alignment means all four are visible from one spot for a few hours each day. For military operations, the ground track repeat can be used to ensure good coverage in combat zones.

As of December 2012,[63] there are 32 satellites in the GPS constellation. The additional satellite improve the precision of GPS receiver calculations by providing redundant measurements. 9availability of the system, relative to a uniform system, when multiple satellites fail.[64] About nine satellites are visible from any point on the ground at any one time (see animation at right), ensuring considerable redundancy over the minimum four satellites needed for a position.

Fig2.1: A visual example of a 24 satellite GPS constellation in motion with the Earth rotating. Notice how the number of satellites in view from a given point on the Earth's surface, in this example at 45N, changes with time.

Fig2.2: Artist's conception of GPS Block II-F satellite in Earth orbit.

10

Fig2.3: Vehicles using gps for getting map to go through. 11(b)control segment:The control segment is composed of1. a master control station (MCS), 2. an alternate master control station,

3. four dedicated ground antennas and

4. six dedicated monitor stations.

The MCS can also access U.S. Air Force Satellite Control Network (AFSCN) ground antennas (for additional command and control capability) and NGA (National Geospatial-Intelligence Agency) monitor stations. The flight paths of the satellites are tracked by dedicated U.S. Air Force monitoring stations in Hawaii, Kwajalein Atoll, Ascension Island, Diego Garcia, Colorado Springs, Colorado and Cape Canaveral, along with shared NGA monitor stations operated in England, Argentina, Ecuador, Bahrain, Australia and Washington DC.[65] The tracking information is sent to the Air Force Space Command MCS at Schriever Air Force Base 25 km (16 mi) ESE of Colorado Springs, which is operated by the 2nd Space Operations Squadron (2 SOPS) of the U.S. Air Force.

Then 2 SOPS contacts each GPS satellite regularly with a navigational update using dedicated or shared (AFSCN) ground antennas (GPS dedicated ground antennas are located at Kwajalein, Ascension Island, Diego Garcia, and Cape Canaveral). These updates synchronize the atomic clocks on board the satellites to within a few nanoseconds of each other, and adjust the ephemeris of each satellite's internal orbital model. The updates are created by a Kalman filter that uses inputs from the ground monitoring stations, space weather information, and various other inputs.[66] Satellite maneuvers are 12not precise by GPS standards. So to change the orbit of a satellite, the satellite must be marked unhealthy, so receivers will not use it in their calculation. Then the maneuver can be carried out, and the resulting orbit tracked from the ground. Then the new ephemeris is uploaded and the satellite marked healthy again. The Operation Control Segment (OCS) currently serves as the control segment of record. It provides the operational capability that supports global GPS users and keeps the GPS system operational and performing within specification. OCS successfully replaced the legacy 1970s-era mainframe computer at Schriever Air Force Base in September 2007. After installation, the

system helped enable upgrades and provide a foundation for a new security architecture that supported the U.S. armed forces. OCS will continue to be the ground control system of record until the new segment, Next Generation GPS Operation Control System (OCX), is fully developed and functional. The new capabilities provided by OCX will be the cornerstone for revolutionizing GPS's mission capabilities, and enabling Air Force Space Command to greatly enhance GPS operational services to U.S. combat forces, civil partners and myriad domestic and international users.

The GPS OCX program also will reduce cost, schedule and technical risk. It is designed to provide 50% sustainment cost savings through efficient software architecture and Performance-Based Logistics. In addition, GPS OCX expected to cost millions less than the cost to upgrade OCS while providing four times the capability.

The GPS OCX program represents a critical part of GPS modernization and provides significant information assurance improvements over the current GPS OCS program.

13OCX will have the ability to control and manage GPS legacy satellites as well as the next generation of GPS III satellites, while enabling the full array of military signals.

Built on a flexible architecture that can rapidly adapt to the changing needs of today's and future GPS users allowing immediate access to GPS data and constellations status through secure, accurate and reliable information.

Empowers the warfighter with more secure, actionable and predictive information to enhance situational awareness. Enables new modernized signals (L1C, L2C, and L5) and has M-code capability, which the legacy system is unable to do.

Provides significant information assurance improvements over the current program including detecting and preventing cyber attacks, while isolating, containing and operating during such attacks. Supports higher volume near real-time command and control capabilities and abilities.

On September 14, 2011,the U.S. Air Force announced the completion of GPS OCX Preliminary Design Review and confirmed that the OCX program is ready for the next phase of development.

The GPS OCX program has achieved major milestones and is on track to support the GPS IIIA launch in May 2014. 14

Fig2.4: Ground monitor station used from 1984 to 2007, on display at the Air Force Space & Missile Museum.current GPS OCS program. OCX will have the ability to control and manage GPS legacy satellites as well as the next generation of GPS III satellites, while enabling

the full array of military signals.

Built on a flexible architecture that can rapidly adapt to the changing needs of today's and future GPS users allowing immediate access to

GPS data and constellations status through secure, accurate and reliable information.

Empowers the war fighter with more secure, actionable and predictive information to enhance situational awareness. Enables new modernized

signals (L1C, L2C, and L5) and has M-code capability, which the legacy system is unable to do.

Provides significant information assurance improvements over the current program including detecting and preventing cyber attacks, while isolating, containing and operating during such attacks.

Supports higher volume near real-time command and control capabilities and abilities. 15On September 14, 2011,[69] the U.S. Air Force announced the completion of GPS OCX Preliminary Design Review and confirmed that the OCX program is ready for the next phase of development.

The GPS OCX program has achieved major milestones and is on track to support the GPS IIIA launch in May 2014.(c)User segment:The user segment is composed of hundreds of thousands of U.S. and allied military users of the secure GPS Precise Positioning Service, and tens of millions of civil, commercial and scientific users of the Standard Positioning Service. 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 that, as of 2007, receivers typically have between 12 and 20 channels.[b] GPS receivers may include an input for differential corrections, using the RTCM SC-104 format. This is typically in the form of an RS-232 port at 4,800 bit/s speed. Data is actually sent at a much lower rate, which limits the accuracy of the signal sent using RTCM.[citation needed] Receivers with internal DGPS receivers can outperform those using external RTCM data.[citation needed] As of 2006, even low-cost units commonly include Wide Area Augmentation System (WAAS) receivers.

16Many GPS receivers can relay position data to a PC or other device using the NMEA 0183 protocol. Although this protocol is officially defined by the National Marine Electronics Association (NMEA),[70] references to this protocol 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 and MTK protocols. Receivers can interface with other devices using methods including a serial connection, USB or Bluetooth.

Fig2.5 :segment of GPS

172.3.1). Working of DGPS :

1.) Technique called differential correction can yield accuracies within 1 -5 meters,

or even better, with advanced equipment.

2.) Differential correction requires a second GPS receiver, a base station, collecting data at a stationary position on a precisely known point (typically it is a surveyed benchmark).

3.) Because physical location of base station is known, a correction factor can be computed by comparing known location with GPS location determined by using satellites.

4.) Differential correction process takes this correction factor and applies it to GPS data

collected by the GPS receiver in the field. -- Differential correction eliminates

most of the errors. Fig2.5: working of dgps 183.1). Working Of inertial Navigation system:

Inertial navigation relies on devices onboard the missile that senses its motion and acceleration in different directions. These devices are called gyroscopes and accelerometer.

Fig 3.1. Mechanical, fiber optic, and ring laser gyroscopes

The purpose of a gyroscope is to measure angular rotation, and a number of different

Methods to do so have been devised. A classic mechanical gyroscope senses the stability of a mass rotating on gimbals. More recent ring laser gyros and fiber optic gyros are based on the interference between laser beams. Current advances in Micro-Electro-Mechanical Systems (MEMS) offer the potential to develop gyroscopes that are very small and inexpensive While gyroscopes measure angular motion, accelerometers measure linear motion. The accelerations from these devices are translated into electrical signals for processing by the missile computer autopilot. When a gyroscope and an accelerometer are combined into a single device along with a control mechanism, it is called an inertial measurement unit (IMU) or inertial navigation system(INS).

19

Fig.3.2. Inertial navigation concept

The INS uses these two devices to sense motion relative to a point of origin Inertial navigation works by telling the missile where it is at the time of launch and how it should move in terms of both distance and rotation over the course of its flight. The missile computer uses signals from the INS to measure these motions and insure that the missile travels along its proper - programmed path. Inertial navigation systems are widel y used on all kinds of aerospace vehicles, including weapons, military aircraft, commercial airliners, and spacecraft. Many missiles uses inertial methods for guidance including

AMRAAM ,storm shadow and tomahawk.

ROLE OF SATELLITE IN MISSILE GUIDANCE :

4.1). Satellite guided weapons: The problem of poor visibility does not affect satellite-guided weapons such as JDAM (Joint Direct Attack Munitions) , which uses satellite navigation systems, specifically the GPS system. This offers improved accuracy compared to laser systems, and can operate in all weather conditions, without any need for ground support. Because it is possible to jam GPS, the bomb reverts to inertial navigation in the event of losing the GPS signal. Inertial navigation is significantly less accurate; JDAM achieves a CEP of 13 m under GPS guidance, but

20typically only 30 m under inertial guidance. Further, the inertial guidance CEP increases as the dropping altitude increases, while the GPS CEP does not.The precision of these weapons is dependent both on the precision of the measurement system used for location

determination and the precision in setting the coordinates of the target. The latter critically depends on intelligence information, not all of which is accurate. However, if the targeting information is accurate, satellite-guided weapons are significantly more likely to achieve a successful strike in any given weather conditions than any other type of precision guided munition .

Fig4.1: Satellite guided weapons. 214.2 MISSILE GUIDANCE USING GPS :

The central idea behind the design of DGPS/GPS/inertial guided weapons is that of using a 3-axis gyro/accelerometer package as an inertial reference for the weapon's autopilot, and correcting the accumulated drift error in the inertial package by using GPS PPS/P-code. Such weapons are designated as "accurate" munitions as they will offer CEPs (Circular Error Probable) of the order of the accuracy of GPS P -code signals, typically about 40ft. Fig.4.2. Global Positioning System used in ranging navigation guidance .

The next incremental step is then to update the weapon before launch with a DGPS derived position estimate, which will allow it to correct its GPS error as it flies to the target, such weapons are designated "precise" and will offer accuracies greater than laser or TV guided weapons, potentially CEPs of several feet. For an aircraft to support such munitions, it will require a DGPS receiver, a GPS receiver and interfaces on its multiple ejector racks or pylons to download target and launch point coordinates to the weapons. The development of purely GPS/inertial guided munitions will produce substantial changes in how air warfare is conducted.

22Unlike a laser-guided weapon, a GPS/inertial weapon does not require t hat the launch aircraft remain in the vicinity of the target to illuminate it for guidance - GPS/inertial weapons are true fire-and-forget weapons, which once released, are wholly autonomous, and all weather capable with no degradation in accuracy. Existing precision weapons require an unobscured line of sight between the weapon and the target for the optical guidance to work.

APPLICATIONS OF GPS:Many civilian applications use one or more of GPS's three basic components: absolute location, relative movement, and time transfer.

Astronomy: Both positional and clock synchronization data is used in Astrometry and Celestial mechanics calculations. It is also used in amateur astronomy using small telescopes to professionals observatories, for example, while finding extrasolar planets.

Automated vehicle: Applying location and routes for cars and trucks to function without a

human driver.

Cartography: Both civilian and military cartographers use GPS extensively.

Cellular telephony: Clock synchronization enables time transfer, which is critical for synchronizing its spreading codes with other base

stations to facilitate inter-cell handoff and support hybrid GPS/cellular position detection for mobile emergency calls and other applications. The first handsets with integrated GPS launched in the late 1990s. The U.S. Federal Communications Commission (FCC)

mandated the feature in either the handset or in the towers (for use in triangulation) in 23Clock synchronization: The accuracy of GPS time signals (10 ns)[71] is second only to the atomic clocks upon which they are based.

Disaster relief/emergency services: Depend upon GPS for location and timing capabilities.

Fleet Tracking: The use of GPS technology to identify, locate and maintain contact reports with one or more fleet vehicles in real-time.

Geofencing: Vehicle tracking systems, person tracking systems, and pet tracking systems use GPS to locate a vehicle, person, or pet. These devices are attached to the vehicle, person, or the pet collar. The application provides continuous tracking and mobile or Internet updates should the target leave a designated area.

Geotagging: Applying location coordinates to digital objects such as photographs (in exif data) and other documents for purposes such as

creating map overlays with devices like Nikon GP-1 GPS Aircraft Tracking

GPS for Mining: The use of RTK GPS has significantly improved several mining operations such as drilling, shoveling, vehicle tracking,

and surveying. RTK GPS provides centimeter-level positioning accuracy.

Military

Target tracking: Various military weapons systems use GPS to track potential ground and air targets before flagging them as hostile. These weapon systems pass 24

target coordinates to precision-guided munitions to allow them to engage targets accurately. Military aircraft, particularly in air-to-ground roles, use GPS to find targets (for example, gun camera video from AH-1 Cobras in Iraq show GPS co-ordinates that can be viewed with specializedsoftware).

Missile and projectile guidance: GPS allows accurate targeting of various military weapons including ICBMs, cruise missiles, precisionguide. DEVELOPMENTWith these parallel developments in the 1960s, it was realized that a superior system could be developed by synthesizing the best technologies from 621B, Transit, Timation, and SECOR in a multi-service program.

During Labor Day weekend in 1973, a meeting of about 12 military officers at the Pentagon discussed the creation of a Defense Navigation Satellite System (DNSS). It was at this meeting that "the real synthesis that became GPS was created." Later that year, the DNSS program was named Navstar, or Navigation System Using Timing and Ranging.[19] With the individual satellites being associated with the name Navstar

(as with the predecessors Transit and Timation), a more fully encompassing name was used to identify the constellation of Navstar satellites, Navstar-GPS, which was later shortened simply to GPS.[20] After Korean Air Lines Flight 007, a Boeing 747 carrying 269 people, was shot down in 1983 after straying into the USSR's prohibited airspace,[21] in the vicinity of Sakhalin and Moneron Islands, President Ronald Reagan issued a directive making GPS freely available for civilian use, once it was sufficiently developed, 25as a common good.[22] The first satellite was launched in 1989, and the 24th satellite was

launched in 1994. The GPS program cost at this point, not including the cost of the user equipment, but including the costs of the satellite launches, has been estimated to be about USD$5 billion (then-year dollars).[23] Roger L. Easton is widely credited as the primary inventor of GPS.

Initially, the highest quality signal was reserved for military use, and the signal available for civilian use was intentionally degraded (Selective Availability). This changed with President Bill Clinton ordering Selective Availability to be turned off at midnight May 1, 2000, improving the precision of civilian GPS from 100 meters (330 ft) to 20 meters (66 ft). The executive order signed in 1996 to turn off Selective Availability in 2000 was proposed by the U.S. Secretary of Defense, William Perry, because of the widespread growth of differential GPS services to improve civilian accuracy and eliminate the U.S. military advantage. Moreover, the U.S. military was actively developing technologies to deny GPS service to potential adversaries on a regional basis.[24]

Over the last decade, the U.S. has implemented several improvements to the GPS service, including new signals for civil use and increased

accuracy and integrity for all users, all while maintaining compatibility with existing GPS equipment. GPS modernization[25] has now become an ongoing initiative to upgrade the Global Positioning System with new capabilities to meet growing military, civil, and commercial needs. The program is being implemented through a series of satellite acquisitions, including GPS Block III and the Next Generation Operational Control 26System (OCX). The U.S. Government continues to improve the GPS space and ground segments to increase performance and accuracy.

GPS is owned and operated by the United States Government as a national resource. Department of Defense (DoD) is the steward of GPS. Interagency GPS Executive Board (IGEB) oversaw GPS policy matters from 1996 to 2004. After that the National Space-Based Positioning, Navigation and Timing Executive Committee was established by presidential directive in 2004 to advise and coordinate federal departments and agencies on matters concerning the GPS and related systems.[26] The executive committee is chaired jointly by the deputy secretaries of defense and transportation. Its membership includes equivalent-level officials from the departments of state, commerce, and

homeland security, the joint chiefs of staff, and NASA. Components of the executive office of the president participate as observers to the executive committee, and the FCC chairman participates as a liaison. The DoD is required by law to "maintain a Standard Positioning Service (as defined in the federal radio navigation plan and the standard

positioning service signal specification) that will be available on a continuous, worldwide basis," and "develop measures to prevent hostile use of GPS and its augmentations without unduly disrupting or degrading civilian uses." 27

CONCLUSION

The proliferation of GPS and INS guidance is a double-edged sword. On the one hand,This technology promise in revolution warfare not seen since the laser guided bomb, with

Single bombers being capable of doing task of multiple aircraft packages. In summary

GPS-INS guided weapons are not affected by harsh weather conditions or restricted by

a wire, nor do they leave the gunner vulnerable for attack. GPS guided weapons, with

their technological advances over previous, are the superior weapon of choice in modern day warfare.

28REFERENCES

1) GPS Theory and Practice. B. Hofmann - Wellenhof, H. Lichtenegger, and J. Collins. Springer-Verlag Wien. NewYork. 1997. Pg [1-17, 76].

2) ttp://www.navcen.uscg.gov/pubs/gps/icd200/icd200cw1234.pdf

3) E.D. Kaplan, Understanding GPS: Principles and Applications.

4)http://www.aero.org/news/current/gpsorbit. html.

5) http://www.trimble.com/gps/29

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