• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.20-23
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• 2004

Tropospheric and ionospheric scintillation may impact on C-band satellite communication systems, particularly at lowmargin systems and low elevation angles. This paper presents the characteristics of C-Band scintillation at low elevation angle received and recorded the satellite signal from INTELSAT above the Pacific Ocean Region (POR) from January 2002 to December 2002 in the period of solar maximum. We received 3.9525 GHz beacon signal at Sri-Racha satellite earth station by the 32 meters in diameter antenna with 8 degrees of elevation. The analysis was found that the values of amplitude fluctuation is mostly about 0.5-0.6 dB peak to peak and $S_4$ = 0.03-0.04. The maximum amplitude fluctuation is about 9 dB peak to peak occurring in April. The occurrence numbers of scintillation is most frequently in April and minimum in November. The occurrence numbers of tropospheric scintillation are most frequently in April and October, and minimum in November. It relates to temperature and water vapor pressure variation in $N_{wet} $. The occurrence numbers of ionospheric scintillation are most frequently in April and September, and minimum in November. It varies corresponding to both equinoctial periods (vernal and autumnal equinox in March and September) and solstice periods (June and December) respectively.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2078-2081
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• 2003

This paper presents the studies on prediction models of tropospheric scintillation. The prediction scintillation models are Karasawa and ITU-R , which can be improved for different locations and circumstances. In this paper, the investigation of average time between variance ${\sigma}_n\;^2$ and the wet part of refractivity $N_{wet}$ under various conditions of meteorological parameters have been carried out at King Mongkut’s Institute of Technology Lankrabang , Bangkok , Thailand , in the range of Ku-band (12.260 GHz) on high elevation angle from Thaicom2 satellite. From the studies results shows that average period of time of 30 days are best suitable for find out the relation between average time variance ${\sigma}_n\;^2$ and the wet part of refractivity $N_{wet}$ according to Karasawa model, the average time variance is express as ${\sigma}_n\;^2=(0.003N_{wet}-0.1313)^2$ , the appropriation model for occurrence of scintillation has been analyzed and experimental results are carried out.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.469-479
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• 2014

N-RTK(Network based RTK) methods are able to improve the accuracy of GNSS positioning results through modelling of the distance-dependent error sources(i.e. primarily the ionospheric and tropospheric delays and orbit errors). In this study, the comparison of the TTFF(Time-To-Fix-First ambiguity), accuracy and discrepancies in horizontal/vertical components of N-RTK methods(VRS and FKP) with the static GNSS at 20 Unified Control Stations covering Incheon metropolitan city area during solar storms(Solar cycle 24 period) were performed. The results showed that the best method, compared with the statics GNSS survey, is the VRS, followed by the FKP, but vertical components of both VRS and FKP were approximately two times bigger than horizontal components. The reason for this is considered as the ionospheric scintillation because of irregularities in electron density, and the tropospheric scintillation because of fluctuations on the refractive index take the place. When the TTFF at each station for each technique used, VRS gave shorter initialization time than FKP. The possible reasons for this result might be the inherent differences in principles, errors in characteristics of different correction networks, interpolating errors of FKP parameters according to the non-linear variation of the dispersive and non-dispersive errors at rover when considering both domestic mobile communication infra and the standardized high-compact data format for N-RTK. Also, those test results revealed degradation of positing accuracy, long initialization time, and sudden re-initialization, but more failures to resolve ambiguity during space weather events caused by Sunspot activity and solar flares.