• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.81-84
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• 2005

지상파 디지털 방송신호의 방송구역 확장이나 난시청지역 해소를 위해 사용되는 동일채널중계기(On-Channel Repeater : OCR)는 수신신호와 송신신호의 주파수를 완벽히 일치시켜야한다. 송수신신호의 주파수가 일치하지 않을 경우 주 송신신호와 중계신호가 동시에 수신되는 중첩지역에서 수신기의 수신성능이 현저히 저하되기 때문이다. 본 논문에서는 ATSC 지상파 디지털 방송신호를 중계하는 등화형 동일채널중계기(Equalization Digital On-Channel Repeater : EDOCR)에서 송수신신호의 주파수를 일치시키는 알고리즘에 대해 기술한다. 등화형 동일채널중계기는 주 송신신호를 수신하여 복조한 후 재 변조 하므로 송수신신호의 주파수를 일치시키기 위한 별도의 장치나 알고리즘이 반드시 사용되어야 한다. 제안하는 알고리즘은 주 송신신호의 동기복원 과정에서 획득한 주파수 오차 정보를 재 변조 과정에 사용함으로써 GPS와 같은 별도의 장치 없이 송수신신호의 주파수를 일치시킨다. 반송파 복원과정에서 획득한 반송파 오차와 심볼타이밍 복원과정에서 획득한 심볼타이밍 오차를 재 변조 신호에 추가하면 수신신호와 송신신호가 같은 주파수 오차를 갖게 되어 두 신호의 중심주파수가 일치된다.

• Journal of Digital Contents Society
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• v.8 no.1
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• pp.77-83
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• 2007

The handoff area is the region where a call can be handled by the base station in any of the adjacent cells, and duration time is viewed as the time a mobile station resides in the handoff area. In this paper, probability distribution about hand off time one of important parameter at traffic modelling in mobile communication system was estimated. First, point statistic is applied using sample data obtained from simulation result to choose the group of distribution of handoff duration time. Second, parameters are estimated to decide specific distribution function. For this, the value of parameters is calculated using MLE(Maximum Likelihood Estimate.) and goodness of fit test is performed. finally these results show that handoff duration time follows gamma distribution.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.679-686
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• 2002

Based on the alternating series expansion of error probability function due to phase noise in PSK systems, the performance evaluations for Tikhonov and Gaussian probability density functions were performed in this paper. The range of the signal-to-noise ratio of recovered carrier signal which provides the same dependency between the error performances by Tikhonov function and Gaussian function was analyzed via loss evaluation due to phase noise. The phase noise with 1/f$^2$ characteristic was generated based on the relationship of the phase noise spectral density and the modulation index for frequency modulation signal. Using the generated phase noise as the input signal for digital satellite communication receiver, the performance losses due to the phase noise were measured and evaluated with the analyzed performance characteristics.

• Journal of Digital Contents Society
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• v.8 no.4
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• pp.459-465
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• 2007

In this paper, we implemented a ray-tracing simulator with a ray-launching technique and generated the propagation path of each ray in a multiple-wall indoor environment. In this simulator, we adopted two dimension ray-tracing techniques considering the reflection and penetration were dominant propagation factor in the indoor channel. From the result, we verified that this ray-tracing simulator shows the similar path pattern and delay distribution with the experiment results of the previous research. Especially, impulse responses of the ray were corresponding to reference result in non-line of sight of multiple-wall indoor environment. Furthermore, we confirmed that channel profiles having respectively different departure angle 1 degree to 7 degree were similar between them.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2003.11a
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• pp.201-204
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• 2003

본 논문에서는 디지털 데이터 방송에서 동기화 데이터 서비스를 제공하기 위한 전송 시스템과 이를 이용한 동기화 데이터 서비스 방법을 제안한다. 데이터 방송을 통해 전송되는 부가 데이터는 그 특징에 따라 비동기, 동기, 동기화 데이터로 구분된다. 이들 중 동기화 데이터는 사용자의 선택에 의해 데이터 방송 수신기에서 재생되는 비동기 데이터와는 달리 비디오 또는 오디오의 특정 장면에 통기되어 재생될 수 있는 데이터고서, 데이터를 전송하는 단계에서 데이터가 재생되어야 하는 시전의 시간 정보인 재생시각이 함께 전송되는 특징이 있다. 동기화 데이터의 이와 같은 특징으로 인해 현재 대부분의 데이터 방송에 사용되고 있는 비동기 데이터 서비스를 위한 전송 시스템은 동기화 데이터의 전송에는 부적합하며, 동기화 데이터 서비스를 위해서는 새로운 전송 시스템에 대한 연구가 필요하다. 본 논문에서는 데이터 방송을 동해 동기화 데이터 서비스를 제공하기 위해 기존의 비동기 데이터 전송 시스템에 MPEG-2 오디오/비디오 TS(Transport Stream)를 출력하는 장치와 동기화 데이터를 다중화 하는 장치를 추가한 새로운 동기화 데이터 전송 시스템과 이를 이용한 동기화 데이터 서비스 방법을 제안한다

• Journal of Broadcast Engineering
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• v.8 no.2
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• pp.153-162
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• 2003

This paper describes a structure of adaptive equalizer to improve reception performance of ATSC digital television (DTV) for 8-VSB receivers. There are many strong and dynamic echoes affecting reliable reception of DTV signal. Conventional DFE based least mean square (LMS) algorithm is readily implemented and has good Performance. There are still problems to be solved, however, in handling strong echoes and indoor reception. In this paper, structure of adaptive equalizer to mitigate these Problems in strong multipath interference conditions and indoor reception environment is first presented. Methods to reduce error propagation effects on DFE and initialization scheme of filter coefficients for fast convergence are then introduced. Computer simulation results prove that an adaptive equalizer with proposed design methods can combat with Brazil Ensemble and the Threshold of Visibility(TOV) is improved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.44-52
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• 2017

In this paper, we propose a DFD (Digital Frequency Discriminator) design that has better frequency discrimination and a smaller size. Electronic warfare equipment can analyze different types of radar signal such as those based on Frequency, Pulse Width, Time Of Arrival, Pulse Amplitude, Angle Of Arrival and Modulation On Pulse. In order for electronic warfare equipment to analyze radar signals with a narrow pulse width (less than 100ns), they need to have a special receiver structure called IFM (Instantaneous Frequency Measurement). The DFD (Digital Frequency Discriminator) is usually used for the IFM. Because the existing DFDs are composed of separate circuit devices, they are bulky, heavy, and expensive. To remedy these shortcomings, we use a three delay line ($1{\lambda}$, $4{\lambda}$, $16{\lambda}$) in the DFD, instead of the four delay line ($1{\lambda}$, $4{\lambda}$, $16{\lambda}$, $64{\lambda}$) generally used in the existing DFDs, and apply the microwave integrated circuit method. To enhance the frequency discrimination, we detect the pulse amplitude and perform temperature correction. The proposed DFD has a frequency discrimination error of less than 1.5MHz, affording it better performance than imported DFDs.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.69-72
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• 2000

This paper shows the more improved design of MRI receiver compared to conventional one based on Elscint Spectrometer. At first, the low-cost ADC is 16 bits, 3MHz sampling A/D converter Comparing to conventional one with signal bits of 14 bits, this device with those of 16 bits helps getting Improved the image resolution improved. If frequency is designed centering around 7.6 MHz to be satisfied in 10 MHz of maximum input bandwidth of ADC. For 1st demodulation, fixed IF is used for the purpose of the implementing multi nuclei system. Control parts & partial digital parts are integrated on one chip(FPGA). In DDC(Digital Down Converter), we got required bandwidth of LPF by controlling its decimation rate. With above considerations, we designed optimal receiver for high resolution imaging to be implemented through PC interface & experimental test of receiver of MRI after receiver's fabrication.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.639-642
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• 2008

In this paper, we present the storage manager for digital broadcast environment. Data stream in real-time broadcast environment flows into set-top box continuously but, Given the file-system doesn't consider such characteristics. The storage manager provides reliability and flexibility for digital broadcast in set-top box.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.329-332
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• 2009

이동방송 환경에서는 이용자의 시청환경이 제한적이어서 자신이 원하는 방송 콘텐츠를 용이하게 소비할 수 없는 경우가 발생한다. 이를 개선하기 위하여 언제 어디서나 시청이 용이한 개인 맞춤형 방송 서비스가 필요하다. 본 논문은 이동방송 환경에서 개인맞춤형방송 서비스를 제공하기 위하여 국내에서 표준화된 지상파 디지털미디어방송 전자콘텐츠안내(ECG) 표준 및 이를 기반으로 한 개인맞춤형방송 전송시스템 및 수신기의 개발에 대하여 기술한다.