• Journal of Positioning, Navigation, and Timing
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• v.9 no.2
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• pp.139-147
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• 2020

In this paper, design measure were proposed for the construction of terminal systems for airborne platforms, which are key element in the Joint Tactical Data Link System (JTDLS) complete system. The Korean perfect tactical data link (JTDLS) is a communication system to establish an independent tactical data link network and needs to develop a MIDS-LVT (Link-16) communication terminal for datalink. Once a Ground/Navy JTDLS terminal system is established around airborne platform, it will be possible to break away from reliance on NATO-based tactical data link joint operations and establish independent Korean surveillance reconnaissance real-time data sharing and tactical data link operations concepts. in this paper, the essential development elements of airborne platform mounting and operable JTDLS terminals are presented, and the concept of system design is proposed to embody them. Further, improved system performance was analyzed by applying the concepts of complex relative navigation system and Advanced TDMA protocol for the deployment of airborne tactical datalink networks.

• Journal of Astronomy and Space Sciences
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• v.37 no.2
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• pp.117-129
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• 2020

In a Satellite communication system, a link budget analysis is the detailed investigation of signal gains and losses moving through a channel from a sender to receiver. It inspects the fading of passed on data signal waves due to the process of spreading or propagation, including transmitter and receiver antenna gains, feeder cables, and related losses. The extent of the proposed tool is to make an effective, efficient, and user-friendly approach to calculate link budget analysis. It is also related to the satellite communication correlation framework by building up a graphical interface link analysis tool utilizing STK^® software with the interface of C# programming. It provides better kinds of graphical display techniques, exporting and importing data files, printing link information, access data, azimuth-elevation-range (AER), and simulation is also possible at once. The components of the link budget analysis tool include transmitter gain, effective isotropic radiated power (EIRP), free space loss, propagation loss, frequency Doppler shift, flux density, link margin, elevation plot, etc. This tool can be useful for amateur users (e.g., CubeSat developers in the universities) or nanosat developers who may not know about the RF communication system of the satellite and the orbital mechanics (e.g., orbit propagators) principle used in the satellite link analysis.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.98-100
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• 2005

This paper describes link analysis on the processed data, HRIT (High Rate Information Transmission) and LRIT (Low Rate Information Transmission), for the preliminary design of interface between COMS (Communication, Ocean and Meteorological Satellite) and ground station. At the MODAC (MeteorologicaVOcean Data Application Center), the processed data are transmitted to user station via COMS with normalization and calibration by pre-processing of MI (Meteorological Imager) data. Due to consider satellite as radio relay, overall analysis containing uplink and downlink is needed. Specific link parameters can be obtained with using the outcomes of SRR (System Requirement Review) which was held on 13-14 June 2005, in Toulouse. From the relation between overall link margin and output power of HPA (High Power Amplifier) of MODAC, it is shown that even though the minimum power related with COMS receiving power range is transmitted at MODAC, the obtained link margin of HRIT could be above 3 dB at user station which antenna elevation angle is 10 degree.

• ETRI Journal
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• v.24 no.3
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• pp.251-254
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• 2002

We developed a method for optimal superframe design in the multi-frequency time division multiple access (MF-TDMA) return-link of a satellite multimedia interactive network called a digital video broadcasting return channel over satellite (DVB-RCS) sub-network. To find the optimal superframe pattern with the maximum data throughput, we formulated the design problem as a non-linear combinatorial optimization problem. We also devised the proposed simple method so that it would have field applicability for improving radio resource utilization in the MF-TDMA return link.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.257-266
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• 2000

A satellite RF communication link is analyzed based on a simple fundamental equations by systematic approach in this paper. The number of variables related to a design and analysis of satellite RF link is often a dozen or more, thus it is a tedious and time-consuming task. With the given input data, the important parameters are calculated step by step and three communication characteristics such as communication channel capacity, carrier-to-noise ratio(CNR) at the satellite and ground station are analyzed. It gives very useful information to the system engineers for designing and analyzing the overall satellite communication system in the conceptual design phase.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2B
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• pp.118-123
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• 2007

This paper studied the transmission control protocol over IP network to enhance the performance of the GSO satellite communication networks. The focus of this study is how to reduce the long round trip time and the transmission data rates over satellite link in the bidirectional satellite network. To do it, this study applied the caching and spoofing technology. The spoofing technology is used to reduce the required time for the link connection during communication. The caching technology is to improve the transmission bandwidth efficiency in the high transmission data rate link The tests and measurements in this study was performed in the commercial GSO communication satellite network and the terrestrial Internet network. The results of this paper show that the studied protocol in this paper highly enhance the performance of the bidirectional satellite communication network compare to the using TCP/IP satellite network protocol.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.121-127
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• 2016

Satellite communication is a communication method using a satellite as a repeater communication on the air and have a communication range is wide and is possible to transmit high-speed data, so Satellite communication has been highlighted as the next generation communication. However, because the distance between the ground and the satellite is far away, there is a disadvantage that propagation delay time is very long and packet is damaged. Therefore, this study was applied to Link Relay H-ARQ system in order to complement the damage to the packet. Furthermore, we propose the Modified Link Relay H-ARQ scheme is a new scheme to supplementation the delay time. By applying the Markov channel for implementing a channel of satellite communications, the results of analyzing the performance, when applying the Link Relay HARQ scheme, BER and PER performance was improved, when applying the Modified Link Relay H-ARQ scheme, Throughput performance was confirmed improvement.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.9-14
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• 2020

In this paper, we studied on-board antenna(primary link/secondary link/satellite link) used in UAV Data-link system. As a result, it is ideal to configure the Data-link as a triple link to secure the flight stability of the UAV, but the communication link should be configured according to the operating platform. As a result of overseas R&D trend analysis, the on-board Data-link antenna is installed and operated in a location where it is easy to secure LOS. The primary link consists of a directional antenna for basic operation and an omni-directional antenna for emergency operation. The secondary link uses a monopole/dipole antenna in the UHF/C band. Satellite link has been developed to apply phased array antenna to improve UAV operability.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.2 s.332
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• pp.9-16
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• 2005

The performance of satellite range measurement using tone method was analyzed in the presence of satellite link AWGN. The phase errors in range measurement are generated by AWGN of satellite up- and down-link and the degradations of satellite range measurement are dependent on the transmission mode and loop bandwidth of satellite measurement system. The analyzed effects for satellite measurement in presence of satellite link noise were also analyzed with the measured satellite range data via satellite range measurement system operating in satellite link AWGN. In RAU mode, the satellite range differences of 14.4 to 40.6 m were occurred according to the loop bandwidth of satellite range measurement system and the degradation of 0.3 dB compared with theoretical value was generated under condition of the signal-to-noise ratio of 43 dB. In RAU and TM mode, the performances of range measurement were approximately agreed to the that of RAU mode. In order to get the equal performance characteristics with RAU mode, the signal-to-noise ratio of satellite link for RAU and TM mode should be increased by signal power of 2.3 dB, which is a power loss due to transmission of telemetry signal.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.120-137
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• 1997

Han's model, which is able to analyze optical communication between earth station and geo-satellite as a function of atmospheric conditions and elevation angles. is presented. In Han's model, atmospheric conditions are roughly classified into six basic types; clear sky, cloud, haze, fog, rain and snow. Data rate satisfying for the BER below $10^{-7}$ is analyzed by Han's model in case of up-link and down-link, respectively. Data rate is more limited by up-link than by down-link because the pointing loss caused by atmosphere on the up-link is greater than the spatial coherence degradation caused by atmosphere on the down-link.