• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.134-137
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• 2007

한국수자원공사에서는 홍수예보용으로 위성통신망을 주망으로 사용하고, CDMA망이나 유선, 무선, VHF 망을 보조망으로 이용하고 있다. 현장에 설치되어 있는 우량관측국에 대하여 강우가 집중되는 기간동안 강우량에 따른 강우감쇠를 주망인 위성통신망과 보조망으로 이용하고 있는 CDMA망과 비교하여 각각의 감쇠 정도를 분석하고 이에 따른 대안을 제시하고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.779-785
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• 1999

The satellite signals have attenuation when Satellite path have rain. The signal attenuation by rain is effected over 100Hz and higher frequency signal have very serious attenuation. The rain attenuation is due mostly to rain rate and rain rate data over 10 years need to estimate characteristics of distribution of ram rate. In this paper, We have obtained the rain characteristics from on the recent data(1988-1997) for Changwon-Masan approximated with Moupfouma New Model, and then estimated the rain attenuation using ITU-R, Global and SAM methods, and finally, Effect of rain was analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1248-1256
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• 2015

It is necessary to apply an exact data and a precise prediction model for a rain attenuation to design the link margin for a data link using Ku-band with the serious effect by rain. In this paper, we investigate the regional rainfall-rate distribution of Korea proposed in TTAK.KO-06.0122/R1 and compare it with the distribution provided by Rec. ITU-R PN.837-1 and Crane. And, the rain rate climate regions similar with the rainfall-rate distribution of Korea in Rec. ITU-R PN.837-1 and Crane model are selected. Finally, using Rec. ITU-R P.618-8 and Crane rain attenuation prediction model, we derive and analyze the rain attenuation for Ku-band frequency according to the time percentage of an average year and the distance of wireless communication link between unmanned aerial vehicle (UAV) and ground data terminal (GDT).

• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.12-18
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• 2011

Signal fading due to rain is one of the most significant factors degrading link quality in satellite communication systems. Adaptive transmission is considered to be the most efficient means to countermeasure the rain attenuation. In order to develop and design a good adaptive transmission system, we need a dynamic rain attenuation model which can synthesize time series of rain attenuation. In this paper, we present a modeling technique for dynamic rain attenuation using a Markov process. We derive statistical fading properties of the rain attenuation data measured in second time interval and define four states in the Markov process. We synthesize the rain attenuation data using the 4-state Markov process, and compare statistical properties of the simulated data to those of the measured data.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.356-363
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• 2006

The demand for digital multimedia service using Ka band satellite communication are growing rapidly. So, in this paper, we have analyzed rain attenuation with typical model, and proposed prediction model of rain attenuation in high frequency(20 GHz). This paper illustrates Korea rain attenuation characteristics at the Ka band Koreasat beacon frequency based on the theoretical and empirical approaches and seek for efficient techniques by rain attenuation estimate and analyzed performance of adaptive modulation system. Propose prediction model of rain attenuation and parameter of satellite link can be available for the Ka band satellite communication.

• Magazine of the Korean Society of Hazard Mitigation
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• v.3 no.3 s.10
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• pp.23-27
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• 2003

수문학자들의 주요 관심사 중 하나인 정확한 면적 강우량을 파악하는데 있어서 강우레이더는 아주 우수한 첨단 장비이다. 그러나 S 밴드나 C 밴드 레이더를 고지대에서 운영하는 것은 많은 시설비와 운영비가 필요하다. 따라서 연구 및 대도시 소유역에 대한 강우 관찰 목적으로는 차량 탑재가 가능한 소형 X 밴드 레이더가 유용할 수 있다. X 밴드 전파는 강우 도래시 전파특성상 감쇠(減衰:attenuation)가 크며, 감쇠도는 강우강도에 영향을 받는다. 이를 극복하기 위한 이중-편파 이론이 1970년대에 제시되었으나, 기술적인 어려움으로 20여년이 지난 1990년대에 실무적용이 가능하게 되었다. 현재 이중-편파 레이더의 도입으로 감쇠보정 알고리듬이 성공적으로 개발되고 있으며, 그와 같은 발상의 전환은 차등위상(differential phase)에 의한 강우 측정방법 개발로 전파 감쇠에 영향을 받지 않는 강우 관측이 가능하게 하였다. 본 기사에서는 소형 X밴드 이중-편파(偏波) 레이더의 강우량 산정방법에 대하여 간략히 검토하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11B
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• pp.1696-1703
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• 2010

Increased demand for military satellite communications system and due to the depletion of resources of existing satellite communications frequencies, Ka-band and EHF-band satellite communication systems is growing demand for development. As a result, the study of rain attenuation mitigation for Ka/EHF-band frequencies has been achieved. The method to compensate rain attenuation on Ka-band(20/30) using the signal power measurement function in Digital Transponder of Next Military Satellite has been proposed in this paper. This method is more effective than generally used method by Beacon and UPC(uplink power control) in giving the precise rain attenuation measurement and correction.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1777_1778
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• 2009

한국수자원공사에서는 1998년부터 단계적으로 12~14 GHz의 Ku-band 대역을 사용하고 있는 무궁화위성을 이용하여 우량 및 수위, 경보 등의 데이터를 송수신하고 있으며, 특히 강우가 집중되는 기간 동안에는 그 데이터의 필요성이 더욱 큰 실정이다. 사용하고 있는 위성통신망 주파수의 파장은 2~2.5 cm 이므로 물방울 입자에 의해 산란되는 특징을 가지고 있으며, 이로 인해 안테나 및 휘드혼의 표면에 물방울이 묻어 있으면 전파가 산란되어 신호가 감쇠되는 특성을 가지고 있다. 따라서 본 연구에서는 강우시 안테나 및 휘드혼 표면에 발생하는 물방울 맺힘 현상에 대해 물방울과 전파신호간의 상관관계를 분석하고, 위성안테나 성능을 개선방안을 시험하여, 강우로 인한 위성신호의 감쇠를 최소화하여, 최적화된 안테나 성능 구현으로 강우 영향을 최소화하여 안정적인 위성단말국을 운영하고자 한다.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.415-419
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• 2018

This paper predicts and measures the C/N ratio of a beacon signal transmitted from geostationary orbit satellite KorSat 5A ($113^{\circ}E$) at a ground station located in Kimpo. Based on the ground stations, we compared the rain attenuation of the zone K of ITU-R and the rain attenuation which analyzed the domestic weather information. In ITU-R, the Korean rainfall characteristics are classified into zone K, but forecasting the rainfall intensity and attenuation of three adjacent cities based on the cumulative rainfall data per minute from 2013 to 2017. The calculation of rainfall path and attenuation is based on ITU-R recommendations. The change of the C/N according to the rainfall amount was confirmed through the 2 week satellite beacon signal C/N measurement. The predicted critical C/N was decreased to 12 dB at $A_{0.3}$. During the experiment, it was confirmed that it decreased up to 8 dB according to the concentrated rainfall.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.1
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• pp.52-59
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• 1998

We calculated the wave attenuation due to rain using the effective permittivity of the air with raindrops. The effective permittivity depends on the complex permittivity of rain drop and the fractional volume occupied by the raindrops. We calculate the complex permittivity of rain drop and the raindrops' volume using Marshall-Palmer Rain drop size distribution. The rain attenuation calculated by effective permittivity is compared with the results of ITU rain attenuation model, and the two rain attenuation models have a very close agreement. The effetive permittivity model underestimates the rain attenuation under 50 GHz, and overestimate at the frequencies under 50 GHz copmpared with the ITU model.