Ionospheric Parameters Estimation for Accurate GPS Navigation Solution
Shaik Gowsuddin1, Dr. V. B. S. Srilatha Indira Dutt2
1Shaik Gowsuddin, ECE, Gitam University, Vishakapatnam, India.
2Dr.V.B.S.Srilatha Indira Dutt, ECE, Gitam University, Vishakapatnam, India.
Manuscript received on November 12, 2012. | Revised Manuscript received on December 26, 2012. | Manuscript published on December 30, 2012. | PP: 302-305 | Volume-2, Issue-2, December 2012. | Retrieval Number: B0943112212 /2012©BEIESP
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Abstract: Satellite navigation system plays an increasing role in modern society. Various satellite navigation systems are in operation and being currently developed including global positioning system (GPS), global navigation satellite system (GLONASS), and Galileo. Thus, there is an increasing need for the research and development in various areas such as signal generation, signal reception, precise positioning, high-precision geodesy and survey. The satellite system transmits the navigation message signal to the earth station (or) directly to GPS users .The errors due to transmitter end, receiver end and due to atmosphere, the signal is degraded and sometimes it may be lost in space ,which in turn causes errors in accuracy of navigation solution. The errors that effect the navigation solution accuracy are: Atmospheric errors, Satellite clock errors, Ephemeris errors, Receiver noise error and error due to Multipath. Among various kinds of error factors, the GNSS signal delay by the ionosphere is the greatest after the elimination of selective availability. The total electron content present in the ionosphere causes refraction to the GPS signal, due to this delay occurs in the GPS signal during its journey to the ground receivers which results in range delay and This delay can be estimated using single frequency receivers and as well as using dual frequency receivers. This delay due to the Ionospheric refraction is estimated around 14m-20m in range, Hence to obtain the precise navigation solution, it is necessary to estimate the ionospheric parameters such as TEC and delay. With available different modeling methods we can reduce the error in range. Hence in this paper, TEC as well as ionospheric delay are estimated for precise computation of the navigation solution.
Keywords: Total Electron Content, Pseudo Random Codes, Global Positioning System.