• International Journal of Aeronautical and Space Sciences
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• v.2 no.1
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• pp.44-54
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• 2001

This paper describes the antenna alignment method of the tracking antenna system for LEO satellite. The purpose of the antenna alignment is to reduce the angular error due to the structural alignment and the monopulse null point alignment error. The angular error of 3 axis tracking system is the key performance parameter that should be minimized to accurately track satellite movement. The angular error is analyzed via a simulation and boresight measurement. The simulation is done with formulas to be derived from vector concept for 3-axis movement. The formulas of the structural alignment are verified by comparing the formula result with the field measurement. Also, the angular error due to monopulse null shift is obtained via boresight measurement. Based on the analyzed and measured results, the antenna alignment was performed and was verified via tracking test of operating LEO satellite.

• ETRI Journal
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• v.30 no.1
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• pp.1-12
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• 2008

In this paper, we propose an efficient single-resource task scheduling algorithm for the Communication, Ocean, and Meteorological Satellite. Among general satellite planning functions such as constraint check, priority check, and task scheduling, this paper focuses on the task scheduling algorithm, which resolves conflict among tasks which have an exclusion relation and the same priority. The goal of the proposed task scheduling algorithm is to maximize the number of tasks that can be scheduled. The rationale of the algorithm is that a discarded task can be scheduled instead of a previously selected one depending on the expected benefit acquired by doing so. The evaluation results show that the proposed algorithm enhances the number of tasks that can be scheduled considerably.

• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.4
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• pp.181-186
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• 2009

This paper presents an efficient synchronizer architecture using a common autocorrelator for Digital Video Broadcasting via Satellite, Second generation (DVB-S2). To achieve the required performance under the worst channel condition and to implement the efficient H/W resource utilization of functional synchronization blocks, we propose a new efficient common autocorrelator structure. The proposed architecture can decrease about 92% of multipliers and 81% of adders compared with the direct implementation. Moreover, the proposed architecture has been thoroughly verified in XilinxTM Virtex IV and R&STM SFU (Signaling and Formatting Unit) broad-cast test equipment.

• ETRI Journal
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• v.25 no.5
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• pp.379-386
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• 2003

This paper presents the design of a narrow-band channel filter and its group-delay equalizer for a Ka-band satellite transponder. We used an 8th order channel filter for high selectivity with an elliptic-integral function response and an inline configuration. We designed a 2-pole, reflection-type, group-delay equalizer to compensate for the steep variation of the group-delay at the output of the channel filter, keeping the thermal stability at ${\pm}7$ ns of group-delay variation at the band edges over 15-55$^{\circ}C$. We devised a new tuning technique using short-ended dummy cavities and used it for tuning both the filter and equalizer; this removes the necessity of additional tuning after the cavities are assembled. Through measurement, we demonstrate that the group-delay-equalized filter meets the equipment requirements and is appropriate for satellite input multiplexers.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.368-371
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• 2004

ETRI has developed the EQM (Engineering Qualification model) payload system for the communications and broadcasting satellite (CBS) with Korean local companies. This paper describes a series of environmental tests such as vibration, thermal/thermal vacuum, and EMC tests. All the development processes including the design, implementation, integration and workmanship were verified and evaluated by these tests. The results of the functional tests and the compliance to the requirements are also presented. The technologies and heritage obtained from this development will be applied to the development of the payload system for the Korean communication satellite in the near future.

• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.372-382
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• 2005

DS/CDM-QPSK (ITU-R Recommendation BO.1130-4 Annex 6, 'Digital System E'), which has been adoptedas a standard of Korean Satellite DMB (Digital Multimedia Broadcasting) system, is a satellite-based multimedia broadcasting service which transmits the multi-channel and high quality contents to the terrestrial users through a satellite or gap-fillers. The broadcast from a satellite is directly received in the plain terrain which are within line-of-sight, but in cities where the broadcast cannot be received directly due to the shadow of buildings, an attempt is being made to install 'Gap-Fillers' to improve the reception in those areas. The gap-fillers, however, may induce interference to service of adjacent band, when their output power is substantially higher compared to the received signal power of signal from a satellite of the adjacent service. In this paper, a link budget analysis is performed, and the optimal EIRP of a gap-filler to maximize the gap-filler coverage, while preventing adjacent band interference is derived.

• Journal of Satellite, Information and Communications
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• v.3 no.1
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• pp.22-28
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• 2008

In this paper, Korean digital radio services is introduced and utilized by the analysis of digital radio broadcasting and the standard model of DMB based disaster broadcasting

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.11
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• pp.12-18
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• 1998

In non-geostationary orbit(NGSO) satellite communication links, satellite's elevation angle at terminal is changed continuously because of the satellite movement relative to earth surface. Therefore the characteristics of the fade-effected signal received by a terminal from a NGSO satellite is also varied continuously even if the terminal is operated at fixed location. In this paper, we determine a general statistic model for the fading characteristics over NGSO satellite communication links and set up the parameters of the fading model in terms of the elevation angle according to various propagation environment and find the parameter values using the data of fading margin for commercial NGSO mobile satellite communication systems. And the fading charateristics for each environment are analyzed using this model. These results can be applied to develop the compensation algorithm and to analyze the performance of the transmission schemes for NGSO mobile satellite communication systems.

• ETRI Journal
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• v.27 no.1
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• pp.43-52
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• 2005

In this paper, we introduce an adaptive radio resource allocation for IP-based mobile satellite services. We also present a synchronous multibeam CDMA satellite system using an orthogonal resource sharing mechanism among downlink beams for the adaptive packet transmission. The simulation results, using a Ka-band mobile satellite channel and various packet scheduling schemes, show that the proposed system and resource allocation scheme improves the beam throughput by more than two times over conventional systems. The simulation results also show that, in multibeam satellite systems, a system-level adaptation to a user's channel and interference conditions according to user locations and current packet traffic is more efficient in terms of throughput improvement than a user-level adaptation.

• Convergence Security Journal
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• v.23 no.3
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• pp.57-64
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• 2023

Due to the COVID-19 pandemic, the broadcasting industry has been greatly affected, to the extent that the footprint of travel programs has disappeared. Although travel programs have been back on the air since 2022, there remains a task of recovering the stagnant desire for travel. Based on a study that travel programs have a positive impact on viewers' travel intentions, this study examined a data service that provides preferred additional information on travel programs, considering the broadcasting environment of satellite broadcasters that transmit multiple travel programs through various channels. Specifically, preferred additional information was investigated for travel programs of various genres and formats, and a feature model based on FODA was designed to be used when the satellite broadcaster decides the data service configuration. In addition, the necessary information for operating the data service was defined based on the feature model, and a method of transmitting it using the DVB-S SI, a domestic satellite broadcasting standard, was devised. The feasibility of this study was also confirmed using a DVB-MHP based data service prototype.