GPS stands for Global Positioning System, which is basically a satellite navigation system that provides location and time information to the users in every climate conditions. This system has been used in planes, cars, ships, and trucks too. This Global Positioning System provides critic abilities to military and civilian users across the globe (Carter, 1997). Along with these, it also provides a real-time, 3-dimensional positioning navigation system worldwide.
How does it work?
Global Positioning System (GPS) includes three segments named as:
- The user Segments which includes both military and civilian users and their respective GPS equipment.
- The Control System, which is effectively operated by U.S military
- The Space Segment (GPS satellites)
The user segment
The user segment is considered as GPS receiver which receives the signal from GPS satellite to determine how far it is from each satellite. This segment is mainly used for the military, missile guidance system and navigating civilians from different applications. It has been used in almost every field (Daniels & Huxford, 2001). Most of the civilians use this system to natural resources with the purpose of agriculture and mapping.
Sometimes, control segment is also referred to as monitor station. The control segment consists of a master control station and five different monitor stations, which are outfitted with atomic clocks and spread around the globe. These monitor stations receive signals from GPS satellite and send qualified information back to master control stations where these signals are revised in an effective manner and then they are sent back to GPS satellites via ground antennas.
The space segment consists of a number of satellites which are present in space in order to send signals back to the ground, so, the user can use the GPS services in an effective manner. Space segment comprises of 29 satellites which are circling around the earth every 12 hours at 12,000 miles in altitude. The main functions of this segment are to utilize the route navigation signals and store and transmit the route or navigation message sent by the control segment. This transmission of signals is highly controlled by a stable atomic clock on the satellites.
How the positions are determined by GPS?
Basically, the working of GPS is based on the mathematical principle named as “trilateration”. The position is determined from the distance measurements to the satellites. As shown in the figure, the four satellites will be used to determine the position of the receiver on earth. The fourth satellite will be used to confirm the target on the ground. While, other three satellites will be used to trace the location of the place (Liu, 2011). Global positioning system consists of the control station, satellites monitor stations and receiver. The GPS receiver gathers information from the satellite and uses the method of triangulation in order to determine the user’s exact position.
GPS is used in several cases in several different ways, for example
- To decide on the areas of position; for example, you need to send a helicopter pilot some clues about the area of your position so that the pilot can pick it up.
- To explore from one area and then to the next; for example, you have to get out of the mail to the point of fire.
- To create digital maps; for example, you are assigned to define the boundaries of the fire and the problem areas.
- To decide on the elimination of two different points.
Three advantages of GPS:
- A GPS based on routes is an important device for military, ordinary, and commercial clients.
- Vehicle tracking system with a GPS-based navigation system can provide turn by turn directions to the users.
- The speed of Global positioning system signal is pretty much high.
Two disadvantages of GPS:
- GPS satellite signals are too important when they contrast with phone signals, so they do not fill up too much submerge under trees, and so on.
- The most notable precision requires a path visible from the collector to the satellite, so the GPS does not work very well in an urban situation.
There are many sources of possible errors that will reduce the accuracy of the positions set by the GPS receiver. The movement time of GPS satellite signals can be changed by barometric times; when the GPS flag passes through the ionosphere and the troposphere, it decays, which makes the speed of the flag is not the same as the speed of GPS in space. Another source of error is the noise or twisting of the flag, which causes electrical obstacles or birth defects in the same GPS beneficiary. The data on the satellite districts will also cause errors in the position decisions, since the satellites are not located so much in places where the GPS receiver "thought" in the light of the data obtained, deciding the positions. Small variations in the nuclear serpentine after loading satellites can mean huge position errors; A 1 nanosecond clock error means 1 or 0.3 meters of client error on the ground. The multitrack impact occurs when the signals transmitted from the satellites bounce off the smart surface before reaching the receiver that receives the cable. As part of this procedure, the recipient receives a flag in a straight line in a deferred manner (in different ways). The effect is like a ghost or a double image on the television.
Carter, C. (1997). A Brief Primer on the Operation of the Global Positioning System. Retrieved from https://www.inventeksys.com/wp-content/uploads/2011/11/GPS_Facts_Principles_of_GPS.pdf
Daniels, R., & Huxford, R. (2001). Using Global Positioning Systems (GPS): How it Works, Limitations, and Some Guidelines for Operation. Retrieved from https://fortress.wa.gov/ecy/publications/documents/0006015.pdf
Liu, Z. (2011). Introduction to GPS. Retrieved from http://www.zhang-liu.com/tutorials/GPSTutorial.pdf?i=1