• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.12
• /
• pp.8643-8648
• /
• 2015

In this paper presents the design and demonstrate 8 W 3-stage HPA(High Power Amplifier) MMIC(Monolithic Microwave Integrated Circuits) for Ka-band down link satellite communications payload system at 19.5 GHz ~ 22 GHz frequency band. The HPA MMIC consist of 3-stage GaN HEMT(Hight Electron Mobility Transistors). The gate periphery of $1^{st}$ stage, $2^{nd}$ stage and output stage is determined $8{\times}50{\times}2$ um, $8{\times}50{\times}4$ um and $8{\times}50{\times}8$ um, respectively. The fabricated HPA MMIC shows size $3,400{\times}3,200um^2$, small signal gain over 29.6 dB, input matching -8.2 dB, output matching -9.7 dB, output power 39.1 dBm and PAE 25.3 % by using 0.15 um GaN technology at 20 V supply voltage in 19.5~22 GHz frequency band. Therefore, this HPA MMIC is believed to be adaptable Ka-band satellite communication payloads down link system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.1
• /
• pp.1-7
• /
• 2001

WRC-2000 adopted the Regions 1 and 3 BSS and associated feeder-link Plans as well as the Regions 1 and 3 BSS and associated feeder-link Lists. These Regions 1 and 3 BSS and associated feeder-link Plans provide, in general, each country of Region 1 with 10 digital channels of 27MHZ bandwidth and each country of Region 3 with 12 digital channels of 27MHZ bandwidth. In this study, we summarize the results of associated meetings and analyze the effects of BSS replanning in Korea. We study the effective interference analysis through the review of Radio Regulations and associate Resolution. Furthermore, interference analysis of inter-broadcasting satellite systems will be done with MSPACEG S/W.

• Journal of Astronomy and Space Sciences
• /
• v.33 no.4
• /
• pp.335-344
• /
• 2016

Scientific CubeSat with Instruments for Global Magnetic Fields and Radiations (SIGMA) is a 3-U size CubeSat that will be operated in low earth orbit (LEO). The SIGMA communication system uses a very high frequency (VHF) band for uplink and an ultra high frequency (UHF) band for downlink. Both frequencies belong to an amateur band. The ground station that communicates with SIGMA is located at Kyung Hee Astronomical Observatory (KHAO). For reliable communication, we carried out a laboratory (LAB) test and far-field tests between the CubeSat and a ground station. In the field test, we considered test parameters such as attenuation, antenna deployment, CubeSat body attitude, and Doppler frequency shift in transmitting commands and receiving data. In this paper, we present a communication performance test of SIGMA, a link budget analysis, and a field test process. We also compare the link budget with the field test results of transmitting commands and receiving data.

• Bulletin of the Korean Space Science Society
• /
• 2008.10a
• /
• pp.36.2-36.2
• /
• 2008

This paper presents the impact of Japanese radio source on the S-Band communication between KOMPSAT-2 satellite and TT&C ground system. Major specifications such as transmitting EIRP (Effective Isotropic Radiated Power) and location of Japanese terrestrial station were informed from Radio Research Laboratory in Korea Communication Commission. To estimate path loss in S-Band, the distance between Japanese station and TT&C ground system was obtained by using COTS (Commercial Off-The-Shelf) software. After that the signal strength of Japanese radio source placed at the TT&C ground system was calculated from link parameters such as transmitting EIRP, path loss, and receiving antenna gain. Consequently, this paper shows that the degradation caused by Japanese radio source is acceptable to TT&C ground system for satellite operation.

• Journal of information and communication convergence engineering
• /
• v.7 no.1
• /
• pp.78-85
• /
• 2009

In order to increase system capacity and reduce the transmitting power of the user's equipment, we propose an advanced power control scheme consisting of a modified open-loop power control (OLPC) and closed-loop power control (CLPC) for land mobile satellite communication systems. The improved CLPC scheme, combining delay compensation algorithms and pilot diversity, is mainly applied to the ancillary terrestrial component (ATC). ATC link in urban areas, because it is more suitable to the short round-trip delay (RTD).

• Journal of Communications and Networks
• /
• v.12 no.6
• /
• pp.533-543
• /
• 2010

This paper proposes an orthogonal frequency division multiplexing (OFDM) waveform for the forward link of a fixed broadband satellite system. We focus on the synchronization tasks in the receiver. Our objective is to minimize the required overhead, in order to improve the spectral efficiency with regard to a single carrier waveform system. A non pilot aided algorithm is used for fine synchronization. It is preceded by a coarse synchronization stage, which relies on a limited overhead (short cyclic prefix associated to some pilots). The performance of the proposed receiver is assessed through simulation results.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1699-1700
• /
• 2008

The dissertation is based on the 'remote monitoring control system' for a water desalination plant which changes seawater into safe clean drinkable water. The system is operated and supported by a satellite link which can be easily handled and monitored by any professional. Therefore the system can be operated from any given location. The design allows it to function on islands that have frequent and severe water shortages via the satellite from the main sector. It shows the specific details for the main provision on building the remote monitoring control system for the water desalination.

• The KIPS Transactions:PartC
• /
• v.8C no.3
• /
• pp.367-372
• /
• 2001

지도제작, 해양생태감시, 기상관측, 및 우주환경감시 등의 분야에 이용되는 저궤도 위성을 관제(위성추적, 원격측정 및 명령)하기 위해 본 논문에서는 최적의 PM 변조지수를 결정하는 방법을 기술하고 수신 데이터의 성능을 평가한다. 이 저궤도 위성인 아리랑 위성은 한국에서는 첫 번째 저궤도 위성이며 1999년 12월 발사되어 현재 임무를 충실히 수행하고 있다. 아리랑 위성 관제시스템의 파라미터에 의해 위성링크를 설계하면, PB 원격측정 신호의 최적 변조지수는 Eb/No마진과 PFD마진의 교차점이 되며 1.92라디안으로 결정된다. 또한 위성의 통과시간에 따라 예측되는 BER은 RT모드에서 최고의 성능을 나타애고, RT+RNG모드에서 최악의 성능을 나타내기 때문에 데이터 전송순서를 위성의 통과시간에 따른 BER 성능 순서인 RT, PB, RT+RNG모드의 순서로 결정함으로써 수신성능을 높일 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1998.05a
• /
• pp.119-125
• /
• 1998

In recent years there has been a huge increase in demand for new various communication services due to the rapid advances in wireless communication. These new emerging services give rise to the interference with the existed radio system. As the new representative systems NGSO/MSS systems have been developed, using NGSO, especially Low Earth Orbit (LEO), satellites such as Iridium, Globalstar systems to provide the rapid transfer of information and the positioning services for the moving persons whenever they want to communicate, even if wherever they are. In this paper we have analysed on the interference between the feeder link of NGSO/MSS and M/W fixed system, that is the interference from the mobile satellite earth station into M/W station, as well as the interference from M/W station into the mobile satellite earth station, and the coordinated area.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2008.11a
• /
• pp.1344-1347
• /
• 2008

VSAT시스템은 중심지구국, 무궁화위성 그리고 다수의 단말지구국을 포함하는 성형망으로 구성되고, 광범위한 데이터서비스를 제공할 수 있으며 사용자의 사용목적과 용도에 따라서 여러 가지 형태의 위성전송망 구성이 가능하다. 홍수경보망을 구성 시 최적의 전송품질을 구현하기 위한 위성링크설계는 한국의 환경특성, 무궁화위성의 특성 그리고 VSAT 시스템의 특성을 고려하여 설계한다. VSAT 시스템은 디지털 데이터 전송용으로 인바운드(Inbound)는 TDMA, 아웃바운드(Outbound)는 TDM 전송방식을 이용하였으며 중심국과 단말국의 크기는 3.7m, 1.2m로 설계되었다. VSAT망에서 링크설계는 VSAT망에 할당된 위성 중계기(Satellite Transponder)의 출력전력 및 대역폭 범위 내에서 중심지구국(Hub Station)과 단말지구국(Remote Station)이 주어진 전송규격에 따라 정보를 효율적으로 전송할 수 있도록 설계하여. VSAT망으로 홍수관리의 효율적 운영을 제안한다.