A GPS receiver or devise consists of an antenna, tuned to the frequency transmitted by satellites. The user segment is composed of thousands of civil, commercial and military positioning service. In control segment there is a master control station, an alternate master control station, ground antennae and monitor station. Next to space segment is control segment. At least six satellites are always in line of sight from almost everywhere on earth’s surface. The space segment comprises 24 to 32 satellites or space vehicles in the same orbit, 8 each in three circular orbits. Launching the satellite into medium earth orbit is a strenuous job. It consists of three major segments of a space segment, a control segment and a user segment. The structure of the GPS is a complex one. Then the coordinates are displayed on the screen. The location is usually converted to latitude, longitude and height relative to geoids (essentially, mean sea level). TOF is the four values that the receiver forms using time of arrival and time of transmission of the signal. Practically, the receiver position and the offset of receiver clock relative to receiver system time are computed simultaneously, using the navigation equations to process time of flight (TOFs). Further, a pseudorandom code is a sequence of zeros and ones. The signal broadcasted by GPS is also called carrier frequency with modulation. The work of the GPS receiver is to receive signals from the network of satellites to compute three basic unknown equations of time and position.Ī GPS signal includes a pseudorandom codes and time of transmission and satellite position at that time. Four unknown quantities (three coordinates and clock deviation from satellite time) are required to be computed from the synchronized network of satellites and the receiver. Any deviation of actual time of satellites from ground clock should be corrected daily. GPS receiver also has a clock but it is not synchronized and is not stable (less stable). The satellite clocks are synchronised with each other and ground clocks. Each satellite and the receiver are equipped with stable atomic clock. The system, however, should comprise at least four satellites. GPS is a navigation technology which, by use of satellites, tells the precise information about a location. Basically a GPS system consists of group of satellites and well developed tools such as receiver.
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