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CHAPTER 1 INTRODUCTION The Global Positioning System (GPS), comprised of three integral segments, is one of the newest and most efficient forms of locating a global position. It was developed by the United States of American department of Defense (DoD) for military purposes. Since its creation it has developed many different uses. The three distinct segments are the user, space, and control segments. This report will explain what each of these segments entail with an emphasis on how they work together to provide the user with a GPS position. The Global Positioning System is a large system of satellites that orbit the earth. These satellites transmit signals that are received by the user. The user to find a precise position on the earth then processes the signals. All sorts of people for all kinds of reasons use GPS. They could be military reasons, for example using GPS to aim a missile. GPS is used in vehicle navigation whether that be a plane, automobile, or boat. Land surveyors also use it since it can now produce sub-centimetre accuracy. The report will discuss the three segments of GPS, the user, space, and control segments. These three segments are all so intertwined that each would be useless on its own. CHAPTER 2 THE THREE SEGMENTS OF GPS GPS is a system of Satellites surrounding the earth. It is used to obtain accurate three-dimensional positions on the earth¡¯s surface. GPS can be divided into three separate segments; the user, space, and control segment. The user segment is made up of those who use GPS and the receivers they use. They consist of the military users, land surveyors, recreational users, and many more. The satellites orbiting around the earth make up the space segment. Thirdly, the control segment is the five monitor stations located around the world. This chapter will then take a look at the three segments of GPS. The user, space, and control segments can be found in section 2.1, 2.2, and 2.3 respectively. 2.1 User Segment Anyone who uses GPS and the receivers they use make up the user segment of GPS. GPS has a very wide range of users. The list of users runs from the United States military to professional users, such as land surveyors, all the way to recreational users. Although originally intended for military use the number of civilian users far out numbers the military users. Each different user has different needs when it comes to uses and accuracy. A land surveyor for instance may need sub-centimetre level measurements while a recreational boater would only need positions accurate two under 20 metres to find out the best possible route to a previous marked good fishing area. Although each user has various uses for GPS the receiver is the basic element of the user segment and they all work on similar principles. This chapter contains a basic run though about how a GPS works.
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