Actual solar interference time observed from TU media ground station in Seongsu-dong (Provided by TU media dated Oct. 09, 2007) (TU media 2007). 

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... formula (29), sys is the system noise temperature of an antenna system when there is no solar interference, whilst T ant is the antenna noise temperature calculates via formula (27). While T sys can calculate and measure an actual antenna system, general antenna systems has between roughly 250 ∼ 300K values (Lee et al. 1991). A calculation program is created for solar interference based on the aforementioned formulas. The Visual C++ .Net 2008 was used for programming, and the Origin program was utilized to simulate graphics. In addition, we calculated the solar interference time of TU media ground station in Seongsu-dong displayed in Table 1, to verify the accuracy of the program, and compared with actual observed value. The actual C/N value and time observed from TU media ground station on Seoungsu-dong on October 9, 2007 is illustrated in Figure 3. As of an observation result, the time of solar interference commenced at about 11 h 01 m a.m. on KST, of which reached its maximum at 11 h 02 m 30 s a.m., and over at about 11 h 04 m a.m.. ∆( C/N ) value of maximum interference time is 9.8 dB. Figure 4 is a graph calculated using a model. Where, the calculation is implemented assuming, system noise as 250 K, and efficiency of an antenna system as 65% (Mohamadi & Lyon 1988). The time in Figure 4 displays minute and second units only. As a calculation result, the time of sun interference had commenced at a.m., ended at a.m., showing the maximum interference time as 11 h 02 m 26 s a.m.. Maximum ∆( C/N ) of the maximum interference time is 9.2 dB, which is lower than observation value by 0.6 dB. Through this, we were able to confirm the consistency with a model and actual observation value. Figure 5 is a graph demonstrates the time of solar interference expected in spring quarter of 2010. According to Figure 5, solar interference starts between 5th and 6th of March, in the case of spring quarter in 2010, and the occurrence time is between 11 h 24 m a.m. – 11 h 28 m a.m.. Solar interference occurs the most in March 6, while maximum interference time is at 11 h 26 m 19 s a.m., and the maximum ∆( C/N ) value is 9.29 dB. Solar interference occurs throughout many days, and as days go by, the maximum occurrence time shows a tendency to become faster gradually. An error analysis is implemented based on March 6, 2010. The date is forecasted as the day, which most solar interference would occur in the spring quarter of 2010. The maximum solar interference occurred time on this day was at 11 h 26 m 19 s a.m., and based on the MBSAT satellite information and earth station antenna illustrated in Table 1, we calculated solar interference occurrence time according to each error, and compared the time, which maximum solar interference occurred, and compared with ∆( C/N ) value. The direction of each earth station antenna shown in Figures 6 and 7 shows the change of ∆( C/N ) value and solar interference time, which would occur in case of error of 0 . 1 ◦ and 0 . 25 ◦ , respectively. The El of Figures 6 and 7 signifies the altitude of the antenna, while Az represents the azimuth angle of the antenna. Figure 6 represents when the error of direction of an antenna shows 0 . 1 ◦ . The maximum time of solar interference occurs 9 seconds faster than 11 h 26 m 19 s a.m. when the altitude of an antenna is lower than the standard altitude 0 . 1 ◦ . When the azimuth angle is as little as 0 . 1 ◦ , the maximum solar interference occurs 35 seconds faster. When altitude is increased by 0 . 1 ◦ , the maximum interference occurs 13 seconds faster, and when, azimuth angle is increased by 0 . 1 ◦ , the interference occurs 16 seconds later. Through this, we are able to confirm that when the altitude of an antenna changes by , there is an error range with solar interference time at seconds. Figure 7 shows the difference when 0 . 25 ◦ error is given to an antenna. The time of maximum solar interference when altitude is as little as 0 . 25 ◦ , it occurs 22 seconds faster than standard time, and when azimuth angle is as big as 0 . 25 ◦ , it occurs 41 seconds late. Thus, suppose we calculate the rest, when the error of bearing of an antenna is 0 . 25 ◦ , we are able to confirm an error range of − 27 ∼ +41 seconds. When we examined Figure 6 and 7, we can see that the intensity of maximum solar interference changes when antenna error occurs, and that changes in the width of ∆( C/N ) is even bigger in 0 . 25 ◦ change, compare to 0 . 1 ◦ angle change of an antenna, and the error of a solar interference occurrence time increase as much as the antenna pointing angle variance. Through this, we confirmed that the more the accurate measurement is carried on the antennas direction, the higher the accuracy of solar interference time predictions. Figure 8, illustrates the change in solar interference time when the position of geostationary satellite changes according to perturbation. Suppose we examine Figure 8, when the position of a satellite moves to east by 0 . 05 ◦ , that is when it is located at the latus rectum 144 . 05 ◦ , the maximum interference time is 11 h 26 m 05 s a.m., which is faster by 14 seconds compare to when it is positioned at the latus rectum 144 . 0 ◦ , the standard position. When a satellite moves to west by 0 . 05 ◦ and positioned at 143 . 95 ◦ east, the time of maximum solar interference is 11 h 26 m 32 s a.m., which is 13 seconds delayed than that of standard position. The change of maximum interference period according to the position of a satellite is 0 . 05 ◦ , and has error range of − 14 ∼ +13 seconds at the time of change. However, in a case where there is more than 0 . 1 ◦ position change, an error occurs with range of one minute or more. In addition, we can also check the change of intensity of solar interference. However, unlike the error occurrence of antennas, we recognized that there is no significant change of in respective cases when a satellite’s position changes. The purpose of this study is to forecast precise prediction of solar interference time. The study calculated the precise position of the Sun, using DE406 and an earth ellipsoid model, and via a solar interference program, we predicted noise temperature and C/N decline of earth station antenna in accordance with solar interference of stationary satellite and earth station. As a result of applying a communication satellite ground station in Seongsu-dong and MBSAT operated by TU media, we confirmed that they are consistent with actual observation, and verified their accuracy through error analysis. In-depth of consideration is needed for the intensity of solar interference, not only the affect of the Sun, but also on the specific system of each earth station antenna. Specifically, the size of antennas and a wavelength range of radio wave used in antennas affect the most in the time of solar interference, thus it is necessary to have precise information for a better and precise prediction. An error according to the position change of a geostationary communication satellite will result a time difference within 30 seconds, if position maintenance is implemented within ± 0 . 05 ◦ . Therefore, we expect there will be no significant affect as practical purposes in precise position calculation of satellites. On the other hand, since the direction of antennas can be a significant error factor, precise calculation of the direction of antennas is imperative to the prediction of solar interference time. In the study, we calculated the time of solar interference between geostationary communication satellite and earth station. In a case of general low orbit satellite, a solar interference time calculation can be conducted using the same method the study employed, if satellite altitude and azimuth angle is obtained from earth station through the orbital elements of satellites. Moreover, even the precise position of the Moon can be calculated using DE406. It is known that there is noise of about 250K in the Moon, and the interference time according to the Moon can be calculated by taking advantage of this study. Acknowledgments: This research was supported by WCU (World Class University) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Tech- nology (R31-10016) and BK21 (KRF-2005-070-C00059). CCIR 1982, Recommendations and Reports of CCIR, Vol.IV-part I (Geneva:International Telecom- munication Union), pp.198-200 Johannsen, K. 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