• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.121-127
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• 1999

In this paper, it propose channel format, characteristics, call establishment and removal algorithm about the telex services of maritime satellite communication system. It would adapt the propose to a basic technic of internal maritime affairs satellite communication system.

• Journal of Satellite, Information and Communications
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• v.1 no.2
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• pp.71-75
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• 2006

This paper describes operation plans for satellite communications system (SATCOM) which is consisted of Ka band communication payload, geostationary satellite control system and communication test earth station system for the communication, ocean and meteorological satellite system (COMS). Also this paper describes the communication service and mission plans by each system of the SATCOM, and configurations and functions of the system interface between each system. Especially this paper proposes operational items, functions and their configuration diagrams, touches their operational plans. This paper describes function definitions, configuration diagram and operation plans of the PCS )Payload Control System) for monitor and control of the communication payload and communication service network of the SATCOM.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.59-64
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• 2020

Occasionally, MODEM test in satellite communication systems are needed. But Rx terminals in satellite communications are designed to obtain high SNR generally, therefore artificial bad conditions and environments are demanded for the test. One of the typical method is satellite output power reduction. Using noise generator can be another method. However, these costs a lot of money, time, and procedures in reality. In order to overcome these problems, this paper proposes an artificial noise generation method for MODEM test in satellite communication systems. First of all, SNR of a general heterodyne Rx terminal is calculated. Based on the calculation, a new model which is including variable attenuator is proposed to increase noise level. Simulation results illustrate the variable attenuator can control SNR, and these show that MODEM test in satellite communication systems be possible.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.36-40
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• 2007

EGSE is used to check out satellite payload during the development prior to launch. The EGSE represented in this paper is a test system for Ka band communication transponder of COMS. The EGSE consist of two subsystems as CTS subsystem and PCTS subsystem. Communication Test subsystem (CTS) performs satellite transponder RF performance testing, data analysis and trending. Most of transponder RF performances are automatically tested by the CTS subsystem. Power, Command & Telemetry subsystem (PCTS) monitor telemetry messages from the transponder and send tele-commands to satellite transponder for the configuration change. PCTS also provide simulated S/C power to the transponder during the ground validation testing. The EGSE test functions are verified by the transponder simulator testing and will be used for the flight model transponders testing.

• ETRI Journal
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• v.39 no.6
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• pp.771-781
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• 2017

For efficient spectral utilization of satellite channels, a shared band transmission technique is introduced in this paper. A satellite transmits multiple received signals from a gateway and terminal in the common frequency band by superimposing the signals. To improve the power efficiency as well as the spectral efficiency, a travelling wave tube amplifier in the satellite should operate near the saturation level. This causes a nonlinear distortion of the superimposed transmit signal. Without mitigating this nonlinear effect, the self-interference cannot be properly cancelled and the desired signal cannot be demodulated. Therefore, an adaptive compensation scheme for nonlinearity is herein proposed with the proper operation scenario. It is shown through simulations that the proposed shared band transmission approach with nonlinear compensation and self-interference cancellation can achieve an acceptable system performance in nonlinear satellite channels.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.93-100
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• 2021

Satellite communication for high altitude platform stations (HAPS) and geostationary orbit (GEO) systems suffers from sand and dust (SANDU) storms in desert and arid regions. The focus of this paper is to propose common relations between HAPS and GEO for the atmospheric impairments affecting the satellite communication networks operating above Ku-band crossing the propagation path. A double phase three-dimensional relationship for HAPS and GEO systems is then presented. The comparison model present the analysis of atmospheric attenuation with specific focus on sand and dust based on particular size, visibility, adding gas effects for different frequency, and propagation angle to provide systems' operations with a predicted vision of satellite parameters' values. Thus, the proposed system provides wide range of selecting applicable parameters, under different weather conditions, in order to achieve better SNR for satellite communication.

• Electronics and Telecommunications Trends
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• v.37 no.3
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• pp.41-51
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• 2022

This article presents an overview of the key technologies in the communications payload of broadband LEO satellite communications systems. In recent years, new developments have been realized for LEO satellite communications. SpaceX's Starlink, a technology leader in this field, offers premium services with satellites carrying in-house developed communications payloads. OneWeb, Amazon, Telesat, and Boeing are also developing LEO satellite communications payloads. The communications payload consists of user link antennas, inter-satellite link communications equipment, feeder link antennas, and a digital processor. Highly sophisticated technologies of compact active phased array antennas for generating multiple hopping beams and light laser communication equipment for ultra-high-speed inter-satellite communication will be applied to next- generation payloads.

• Electronics and Telecommunications Trends
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• v.38 no.5
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• pp.114-124
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• 2023

Recently, there have been the World Economic Forum's space economy guidelines, the International Telecommunication Union's regulations for each satellite orbit, the development of chips using satellite communication by global manufacturers and service providers, and the registration of key telecommunication businesses. Accordingly, trends in low-orbit 5G satellite communication services in Korea were investigated and analyzed, and the current situation in Korea was diagnosed. Korea's satellite communications accounts for 0.31% of all satellites when analyzed centering on countries with 20 or more satellites. Korea's communication satellite holdings are insufficient compared to 187 times that of the United States, 45 times that of Russia, and 18 times that of China. There is no link technology between 5G and LEO, and the cost of launch vehicles is high. In addition, it is judged that the ecosystem of equipment companies in the low-orbit 5G-NTN business model is insufficient.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.351-355
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• 2004

A multibeam switching satellite system technology have started localized development to overcome the limitation of the frequency resource and geostationary orbit existing relay type satellite transponder and the required performance of the spot beam, and looked around the configuration and functions of the multibeam switching satellite communication system. This paper proposed that operation scheme and network control features for service definition, network architecture, transmission method of the natural disaster service network and public communication service network using this system.

• Bulletin of the Korean Space Science Society
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• 2006.10a
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• pp.169-169
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• 2006