The global positioning system (GPS) refers to satellite based navigation model used to determine position and locations on the earth surface. Various researches have indicated that the garget can promptly be used to determine locations, navigate and create digitalized maps. It majorly utilized in the defense, commercial and government departments. The ability of the (GPS) to fully transmit information from the satellite and navigate it to the user’s position through triangulation has proved it to be the most effective garget in determining the exact position of the client (Denish. S).
The base of the GPS is a composite of satellites continuously orbiting the surface of the globe. In order to maximize the intended survey accuracy standards without the discrepancies, the satellites are equipped with atomic clocks whose mandates are to relay the constant radio signals, which show their locations, distance and time. The satellites produce radio signals, which are, constantly picked, monitored, and corrected by the GPS units at the end of the base line by the receiver. The base line is composed of the two independent and one dependent baseline to form a more accurate rough 2D position (Denish. S).
Figure showing: 2D Global Positioning System
The GPS utilized three prompt segments; this includes the spaces, which consist of 29 satellites arranged on their own orbits circulating at a speed of 12,000miles in every 12hours on the Earth surface. These satellites are capable of at least four signal satellites at every time. This space satellite sends low radio signals with unique coding operations on different frequencies to be detected and allow accurate calculations to be done by the GPS receiver. The control segment which compost of five unmanned stations and one master control station to help in controlling and monitoring the operations. This helps them to relay accurate orbital and time information. The third is the user segment, majorly utilized by the civilian and military to receive relevant information relayed by the GPS at the required time and position (Silva).
Researches indicated that new demand for precise location of the satellites; distance and advancement in technology have led to the integration of the GPS system to provide a generally accredited operational to next generation III control system and satellite (Denish. S).
The precise determination of the location is done by the almanac when it receives all the downloaded information, where it analyzed and stored for future reference. The receiver calculates the distance from each satellite by getting the product of velocity and time. That is always D= 186000m/s*(n), where (n) is the number of time it takes to a signal to arrive at the receiver. The triangulation to precisely determine the exact position when at least three satellites sends signals to the receiver to calculate in either 2D or 3D and accurately be reported in the UTM, latitude or longitude coordinate system (Denish. S).
The Satellite Geometry
The available journals analysis showed clearly that factors that are fully necessary for the planning and implementation of the accurate modern and internationally accepted GPS survey is defined by the elevation mask, number of satellites available, Positional Dilution of Precision (PDoP), Vertical Dilution of Precision (VDoP) and Obstructions limiting satellite visibility (Yoon-Ki Cho).
Sources showed that the modernization of the system is an ongoing process across the globe. Its utilization is increasingly demanded in the growing military, commercial, and civil sectors. This is due to their necessity to maintain credible and private information without the interference of the unscrupulous and malicious interference in these sectors. This has made it to be actively to be developed in the United States military camp, this has upgraded to amore-synthesized system that is capable of prompt navigation to fully achieve operational status of delivering precise commands that are achievable (Denish. S).
In early 2003, the U.S.A military tested their improved GPS to verify the optimal parachute rigging on heavy cargo pallets using the Onyx and to evaluate and verify a new troop-parachute architecture developed by the Atair Aerospace. In 2004 U.S.A military made it available to the Iraq through the assisted Sherpa Para foil cargo delivery system, this made the demonstration programme to be available to the concise of the generation (Yoon-Ki Cho).
According to the research conducted by Montana State University, The system can be fully implemented in agricultural sector to apply variable units of inputs such as seeds and fertilizers. This has helped to maximize yields in the most efficient and economic manner (Yoon-Ki Cho).
Limitations of the Design and Specifications
In general, observation, the GPS is not a perfect system for prompt positioning performance. It is always coupled with several errors during the operations. These errors can be either technical or human in nature. The human errors account for most of the failures in the system as they include; entry of incorrect data into the receiver, confusing the 2D and 3D in determination of the coordinates and holding the GPS receiver near the body that may block the sensors and satellite signals hindering accurate positioning.
The technical error includes the multipath interface caused by the off reflection of the interface signals of the satellite by the interfering objects such as buildings and vehicles. They are highly undetectable and hard to correct (Yoon-Ki Cho). Others are the discrepancies of the atomic clocks in the satellite, this may cause elevation of angles in positioning operations, and the errors may be adjusted in the master control room, through by the use of highly GPS antennae with broad and uniform radiation pattern. In jamming environments, application of metallic conical structure to provide the direction for antennae elevation should be considered (Denish. S).
Orbital errors are also very common due to the fluctuations in the position, altitude, ionized air, and speed of the satellite due to the gravitational pull and pressure of the solar. These errors can also be corrected the Master Control Stations. Sometimes selective availability may also occur for security reasons thereby limiting the usage (Administration).
Recommendation and Corrections on the Utilization of the GPS
Research indicated by majority of scientist have availed possible solutions for the above errors such as Real-time Differential GPS and wide area-augmentative system designed to enhance and improve real time differential GPS, which uses its own geo-stationary satellites. For every department to become efficient in their production, every qualified technologist must also learn to use different types and models of GPS.
Administration, National Academy of Public. "Global Positioning System: Charting the Future." (1995): 62-68.
Denish. S, Foudzi. M, Fitry, M. "Evaluation of Effects of Radio Frequency; Imterference on Global Positioning System (GPS) Accuracy via GPS Simulation." Defence Science Journal (September 2012): 338-342.
Silva, J. Olsen, R.G. "Global Positioning Systems(GPS) Receivers Under Power-Time Conductor ." IEEE Transaction on Power Delivery (2002): 938-944.
Yoon-Ki Cho, Hee-Do, Kang . Se-Young Hyun.Jong -Gwang , Yook. GPS Antanna with Metallic Conical Structurefor Anti- Jamming Application. Seoul: University of Yonsei, 2013.