• Journal of Astronomy and Space Sciences
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• v.29 no.1
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• pp.33-40
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• 2012

Triplet Ionospheric Observatory (TRIO) CubeSatforIon, Neutral, Electron MAgneticfields (CINEMA) is a CubeSat with the weight 3 kg that will be operated in the orbit conditions of about 800 km altitude and $90^{\circ}$ inclination angle, using the S-band and ultra-high frequency (UHF)-band communication frequencies. Regarding the communication antenna loaded on the satellite, the two patch antennas has the downlink function in the S-band, whereas the two whip antennas has the function to receive the command sent by the ground station to the satellite in the UHF-band. The uplink ground station that communicates through the UHF-band with the CINEMA satellite was established at Kyung Hee University. The system is mainly composed of a terminal node controller, a transceiver, and a helical antenna. The gain of the helical antenna established at the Kyung Hee University ground station was 9.8 dBi. The output of the transceiver was set to be 5 W (6.9 dB) for the communication test. Through the far-field test of the established system, it was verified that the Roman characters, figures and symbols were converted into packets and transmitted to the satellite receiver in the communication speed of 9,600 bps.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.2
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• pp.158-164
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• 2015

The main mission of OTM(On-The-Move) satellite communication system is to provide satellite communication service while moving on a vehicle. So it should have a capability to maintain a reliable communication channel when it travels at high speeds or in a severe fluctuation region. This paper presents a small-sized multi-mode monopulse structure applicable to OTM satellite communication system which has only single mode-coupler with a pair of slot using a feature of circular polarized received signal. And tracking error signal is defined using fundamental and high-order modes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1632-1639
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• 2004

The exist email program between Ship and Land has developed to reduce communication fee because of high satellite communication cost and low speed. Owing to this proper, the exist program has less flexibility and high speed. but to add or change functions is not easy. and it also have many difficulties for programmer to develop marine application because of delicate Satellite Radio communication. In this paper we design new protocol which consist of packet to give flexiblity and implement windows service program for programer to make marine applications easily like monitoring data, DB for Ship Management System, Planned Maintenance System.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.10
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• pp.868-878
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• 1990

Upon introducing satellite communication system to Korea, one of the important problems to cope with is the effect from the probable intentional interference I.e. jamming. In this paper we have investigated how much the performance of ordinary PSK signal and Directed Sequence Spread Spectrum PSK signal degrade by the effect of jamming in the satellite communication system. In analysis we have consider the M ary PSK signal and the liniter type nonlinear satellite transponder in an environment of uplink tone or noise jamming plus Gaussian noise and downlink Gaussian noise. Using the derived error rate equation we have evaluated the error performance of BPSK and QPSK systems and compared this with that of DS BPSK system. Form the results, we know that the nonlinear satellite system is degraded more severely by the effect of noise jamming than tone jamming and the effect of tone jamming on the error rate performance can be reduced more remarkably by increasing the process gain in DS BPSK system rather than increasing carrier to jamming noise power ratio in conventional BPSK system.

• Journal of Satellite, Information and Communications
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• v.2 no.1
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• pp.14-20
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• 2007

The Korean Military Satellite Communication System (KMILSATCOM) is composed of military payload of KOREASAT 5 and military satellite terminals. The military satellite terminals communicate with each other in satellite service area. The satellite terminal management system is developed for centralized management of satellite terminals and communications link. The satellite terminal management system dose not use terrestrial networks (i.e. Fiber optic, Microwave) for management because the KMILSATCOM is system for emergency (i.e. war time) and the satellite terminals has to move to operational area, so the management link must use satellite link. The management link is composed of 1 to N communication scheme for one manager and multiple terminals. This paper describes the satellite terminal management protocol architecture and the performance of the protocol of the KMILSATCOM system.

• Journal of Advanced Navigation Technology
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• v.13 no.2
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• pp.172-177
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• 2009

Mugunghwa Satellite N0.1 is fired after operation was 13 years. The establishment of communication satellites, as well as Internet service backbone network the country, including satellite broadcasting services to provide multimedia services to general users and contribute to have a big role. High-speed Internet Access Network was expanded and satellite Internet subscribers Access Network rapidly decreasing, but it also a difficult situation, satellite communications network is still important as a component is located. Launched the first communication satellite to be launched and operated several commercial communications satellite, but satellite communications services and the pace of the system is in place. In this paper VSAT, satellite communications service to provide a service based on the status and problems of the status of operating system and will present alternative policies to solve.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1632-1638
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• 2020

In this paper, we investigate a multi-beam satellite communication system where multiple terminals transmit information signals to the gateway via a satellite. The satellite is equipped with phased array antennas to form multiple spot beams of which bandwidths are not identically allocated. We formulate an optimization problem to maximize fairness of beam bandwidth allocation. In order to solve the problem, we propose two heuristic algorithms; iterative beam bandwidth allocation (IBBA) and request ratio-based beam bandwidth allocation (RRBBA) algorithms. The IBBA algorithm iteratively equalizes the ratio of allocated bandwidth of each beam to their resource request while the RRBBA algorithm allocates beam bandwidth calculated from the ratio. Simulation results show that the IBBA algorithm has close fairness performance to the optimum while the RRBBA algorithm has less performance than the IBBA algorithm at the price of reduced computational complexity.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.14-18
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• 2010

The future of communication systems is expected to combine with the terrestrial and satellite networks. A commonality between wireless interfaces is important consideration for cost of user equipment in the integrated satellite and the terrestrial system. Because IMT-Advanced system take into account LTE based on the terrestrial system for the next generation of communication, a study of the LTE-based satellite system is especially required. A frame of the existing terrestrial wireless networks is designed to use for a random access up to the maximum cell radius of 100 km. However, the random access scheme for the terrestrial system cannot be used in the satellite system, because the satellite systems generally have large coverage than the terrestrial system. Therefore, we propose that the efficient random access procedure to reduce latency and complexity for the satellite system maintaining commonality with the terrestrial system in this paper.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.65.6-65
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• 2001

The satellite communication has been widely applied in the various fields included the remote monitoring and control system through the technical progress. In the star network that is a type of the satellite communication network, users can easily use an earth station because of the large scale and high power of the hub station. This type has many profits which are flexible of network configuration, and can conveniently and inexpensively supply various services which is used in the data acquisition and distribution by important communication means for construction of information society. Using these profits, the satellite communication system is applied to the unmaned remote operation field for the remote control and monitor of the water treatment plants But, ...

• Journal of Astronomy and Space Sciences
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• v.39 no.3
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• pp.109-116
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• 2022

The small-scale magnetospheric and ionospheric plasma experiment (SNIPE) is a mission initiated by the Korea Astronomy and Space Science Institute (KASI) in 2017 and comprises four 6U-sized nano-satellites (Korea Astronomy and Space Science Institute Satellite-1, KASISat-1) flying in formations. The main goal of the SNIPE mission is to investigate the space environment in low Earth orbit at 500-km. Because Iridium & GPS Board (IGB) is installed on the KASISat-1, a communication simulation is required to analyze the contact number and the duration. In this study, communication simulations between the Iridium satellite network and KASISat-1 are performed using STK Pro (System Tool Kit Pro Ver 11.2) from the AGI (Analytical Graphics, Inc.). The contact number and durations were analyzed by each orbit and date. The analysis shows that the average access number per day is 38.714 times, with an average of 2.533 times per orbit for a week. Furthermore, on average, the Iridium satellite communication is linked for 70.597 min daily. Moreover, 4.625 min is the average duration of an individual orbit.