• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.19-22
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• 2004

위성 DMB(Digital Multimedia Broadcasting)는 위성을 통하여 이동 흑은 고정 무선 가입자 수신기에게 비디오 방송 및 정지화상 CD 음질의 오디오 방송과 각종 데이터 서비스와 같은 Multimedia 서비스를 제공하는 서비스이다. 향후 새로운 사업으로 다양한 부가가치를 이끌어 낼 것으로 기대를 받고 있다. 우리나라의 경우 위성 DMB기술기준으로 System E방식이 선정되었다. 본 논문에서는 위성DMB 서비스 의 음영지역을 해소하기 위해 사용되는 재생중계방식의 중계기인 Gap Filler 개발에 대해 기술한다. System E용 Cap Filler용 보조 방송의 전송 방식 선정과 보조방송에서 주 방송으로의 변환 기법, Gap Filler 망설계시에 고려해야 할 사항 등에 대해 기술한다.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.299-301
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• 2009

Current standard for T-DMB Automatic Emergency Alert Service(AEAS) contains controversial problems in service signaling. In this paper, we first describe two important characteristics of AEAS which hinder normal MCI service signaling: Common Service and Aperiodic Service. Next, we propose four method to overcome the problems, followed by the characteristics of each method. In this analysis, current T-DMB standard, the broadcasting system, and receivers are the major player to decide the optimum service signaling method. This analysis will be also applied to the design of transmission standard for other media such as cable, satellite, the Internet, etc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.423-429
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• 2007

The clock recovery module of gap filler for satellite DMB is proposed. Proposed module sustains the output frequency of 10 MHz whether the received signal from the satellite is unstable or cut off within 0.5 sec. The advantages of this module is without frequency tuning at regular interval and low material cost. This module is fabricated by using CPLD as clock recovery IC and new type of loop filter for satisfying the fast lock time and long hold over time simultaneously. The measured performance of the fabricated module has a holdover time of 11 sec at frequency stability less than 0.01 ppm, and phase noise of -113 dBc/Hz at 100 Hz offset.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.351-356
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• 2009

A dual-mode annular ring antenna for both global positioning system(GPS) and satellite digital multimedia broad-casting(DMB) is designed. The proposed antenna consists of a coupling feed line and four slots on the annular ring patch. The gap between the feed line and the annular ring patch is used for an input impedance matching, and the slot length is used for adjusting the resonant frequency of the $TM_{21}$ mode at the DMB frequency. The antenna was fabricated and measured. The experimental results show that the antenna resonants at the GPS and DMB frequencies with suitable bandwidths, and had a broadside radiation pattern at the GPS band and a conical beam radiation pattern at the DMB band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.491-498
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• 2012

Recently, many papers have been proposed in order to improve the OFDM system performance in T-DMB DOCR (Digital On Channel Repeater), by using removing the feedback signal so that the transmitter power can be increased or by using the equalizer to remove ICI. Despite these efforts, however, signal quality at the receiving terminal has not been improved because of constellation smearing in T-DMB DOCR. In this paper, in order to suppress constellation smearing, we propose an effective equalizer algorithm that can improve system performance. We perform adaptive channel estimation and non-coherent decision directed noise cancellation method that can estimate the channel subsequently during data symbols period in the frequency domain. So we can obtain better quality of the signal at the receiving terminal. In order to secure QoS(Quality of Service) required in T-DMB handsets, we evaluate SNR and BER in T-DMB DOCR(Digital On Channel Repeater) and verified by simulation. In this simulation results, this system is satisfied the performance of BER=$10^{-5}$ at less than SNR=14 dB at the receiver after compensation of phase noise -18 dBc.

• Journal of Digital Contents Society
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• v.8 no.2
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• pp.173-189
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• 2007

This study attempted to analyze factors influencing S-DMB adoption. The theoretical background of this study is 'Technology acceptance model.' Based on this theory and literature review this study set 5 hypotheses. For this research, a survey was conducted by online research lab. from October 25 to 31. Data were collected from 350 subjects. Complete and useable questionnaires were received from 303 respondents. The result and conclusion are as follow: 'Instant accessibility,' 'service quality,' 'Cost,' 'advertising,' 'perceived easy of use' are significant factors influencing 'perceived usefulness'. 'Compatibility,' is a significant variable influencing 'perceived easy of use'. However, 'self efficacy' and 'innovativeness' are not significant factors influencing 'perceived easy of use.' The result of the analysis showed that most of the hypotheses were verified the same as preceding studies, but some results were different with the result of preceding studies. Therefore, it implies the characteristics of S-DMB different with other IT systems and mass media that were research subject mostly before, and it influences the result of this study as well.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.211-216
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• 2005

In this paper, GPS/PCS/Satellite DMB compact chip antenna is designed using stacked meander line for mobile communication handset. The fabricated antenna size is $12.52mm\times19.95\times1.05mm$. The coupling is adjusted by via and arrangement among meander lines to improve FR(Frequency Ratio) and return-loss. The fabricated antenna achieve triple-band. The resonance frequencies are 1.696 GHz, 1.888 GHz and 2.680 GHz. The impedance bandwidths are 150 MHz, 120 MHz and 60 MHz. The maximum gains of antenna are 0.08 dBi, 1.70 dBi and -1.27 dBi at resonance frequencies.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.31-34
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• 2004

본 논문에서는 현재 위성 DMB 국내 표준으로 채택되어 있는 System E 방식의 Dual Mode 신호 전송에 따른 신호변환시 Time Delay측정 방법에 대해서 제안을 하였다. 제안된 방식의 경우 아날로그 방식이 아닌 디지털 방식으로 정확한 Time Delay 측정이 가능하다. 그리고 위성 DMB Gap Filler System의 입 출력 단자를 통하여 측정이 가능함으로 측정값에 대한 신뢰성 확보가 가능하며 자동측정 방식임으로 측정시 발생될 수 있는 Human Error를 최소화 할 수 있다는 장점을 가지고 있다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.307-309
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• 2011

국토해양부에서는 우리나라 해안과 내륙에 17개소의 기준국을 구축하여 전국토에서 실시간 DGNSS(Differential Global Navigation Satellite System) 측위가 가능하도록 서비스를 제공하고 있다. 그러나 현재 제공하는 DGNSS 서비스는 사용자가 비콘(beacon) 수신기를 이용해야만 하는 한계와 이로 인한 응용 범위의 제약을 받고 있으며, 위치정보의 폭발적 사용 증가로 인해 다양한 분야에서 더 높은 정밀도 및 정확도를 요구하고 있는 실정이다. 따라서 국토해양부에서는 국내에서 보편적 정보제공 매체로 사용 중인 지상파 DMB(Digital Multimedia Broadcasting)를 이용한 가상 기준국 기반 DGNSS 서비스 제공 시스템을 구축함으로써 DGNSS 서비스를 상용화하고 광역화 할 계획이다. 이 연구에서는 국토해양부에서 개발 중인 지상파 DMB 기반 DGNSS 서비스 기술개발 현황을 소개하고, 이를 상용화 및 광역화하기 위한 방안을 제시하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.93-97
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• 2007

In this paper a new clock generation scheme for TDM-CDM converter in the Gap Filler for satellite DMB systems has been proposed. The scheme uses the frame sync signal from the Ku band TDM receiver to lock the VCXO which provides the system clock for the TDM-CDM converter. The locking algorithm can be easily implemented in the FPGA, so that no separate circuitry is needed as in conventional PLL. With a stable OCXO, The scheme can be used to generate the reference clock to the local oscillator for RF parts.