• 한국전자파학회논문지
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• 제16권7호
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• pp.671-680
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• 2005

CQPSK(Compatible QPSK) 디지털 변조 기술을 이용하는 초협대역 단말기용 송신기에 가장 핵심적인 부품들 중의 하나인 카테지안 궤환 루프(CFL: Cartesian Feedback Loop) 선형화 칩을 $0.35{\mu}m$ CMOS 기술을 이용하여 설계 및 제작하였다. 직접 변환 방식 및 CFL칩을 이용하여 요구되는 부품 수를 줄임에 의하여 송신기의 저비용 및 소형화가 가능하고, 이를 통하여 송신 전력 효율 및 선형성을 향상시켰다. 또한 CMOS기술을 통하여 저전력 구동이 가능하도록 하였다. 송신 성능 시험 결과 PEP 37 dBm(5 W)의 출력 전력에서 CFL 칩을 구동하여 -25 dBc의 상호 변조 왜곡(@ 3 kHz주파수 오프셋) 개선을 통하여 FCC 47 CFR 90.210 E에 정의된 방사 마스크 규격을 만족함을 확인하였다. 또한 상기 언급된 송신 특성 개선에 가장 영 향을 미치는 성분들인 DC-offset 성분, 궤환 루프에서 발생하는 왜곡 성분을 보상하기 위한 루프 이득 및 위상 값들을 조정할 수 있도록 컴퓨터와의 외부 인터페이스를 구현하여 소프트웨어적으로 이러한 값들을 제어할 수 있도록 프로그램화 하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.379-380
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• 2008

• International Journal of Control, Automation, and Systems
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• 제6권6호
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• pp.884-893
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• 2008

This paper analyzes, through simulations, GNSS interference mitigation performance against wideband and narrowband interferences by using spatial-temporal adaptive processing(STAP). The mathematical analysis results demonstrate that the array configuration has a considerable effect on the spatial-temporal correlation function. Based on the results, different array configurations are presented to evaluate and observe the effect on interference mitigation. The analysis results are further assessed through simulations.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.25-28
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• 2000

In this paper, we assume various number of multipaths in one chip duration according to spreading bandwidth. And we take into account of the effects of autocorrelation and relative phases among multipath components within one chip duration, and analyze fading effects. We derive the average error probability for different number of users. Then, we compare the performance of W-CDMA systems with different bandwidths. From the simulation results for different band-widths, wideband CDMA systems show better performance than narrowband CDMA systems in vehicular and pedestrian environments.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.185-188
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• 2000

In this paper, performance of a PN code acquisition scheme is analyzed and simulated for a DS/CDMA overlay system where a CDMA user and a narrowband user coexist in the same frequency band. To suppress the NBI, an interference suppression filter is employed at the receiver front-end. From the simulation results, it is shown that the interference suppression filter is very effective for suppression of the NBI and rapid PN code acquisition in a DS/CDMA overlay environment. It is also shown that the one-sided tap number of 5 fur interference suppression filter is sufficient to suppress the NBI.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1191-1194
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• 1998

This paper presents a new computationally efficient adaptive algorithm for blind signal separation, which is able to recover the narrowband source signals in the presence of cochannel interference without a prior knowledge of array manifold. We derive a new blind signal separation algorithm using the Natural gradient 〔1〕from an information-theoretic approach. The resulting algorithm has the Bussgang property which has been widely used in blind equalization 〔12〕. Extensive computer simulation results comfirm the validity and high performance of the proposed algorithm.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.578-581
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• 2003

UWB 시스템은 매우 넓은 주파수 대역에 걸쳐 스펙트럼이 발생하기 때문에 기존에 공존하는 협대역 시스템의 신호로부터 간섭의 영향을 받게 된다. 이는 협대역 신호가 UWB 신호 대역폭에 유입되는 부분 대역 간섭으로 고려 할 수 있다. 따라서, 본 논문에서는 협대역 간섭 모델을 대역 점유율에 따른 부분대역 간섭으로 모델링 하였으며, 협대역 간섭 점유율에 따른 TH binary PPM UWB 시스템의 성능을 분석하였다. 또한 강력한 오류 정정능력을 갖는 Turbo code를 사용함으로써 성능 개선 정도를 평가하였다.

• 전자공학회논문지A
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• 제33A권7호
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• pp.34-43
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• 1996

In this paper a simpel algorithm for all-digial high speed symbol synchronization is proposed. The proposed algorithm has a structure based on BECM (band-edge component maximization). The algorithm requires only tow samples per symbol for its operation. We analyze and evaluate performance of the proposed algorithm. Simulation results reveal that the proposed algorithm has better performance than the gardner algorithm in narrowband.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1920-1923
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• 2002

This paper proposes an impulse response shortening algorithm applicable to decision feedback equalization of single carrier wideband signal. When he impulse response shortening methods for narrowband signaling are applied to single carrier wideband signals, they result in noise enhancement problem, significantly deterioriting the receiver performance. This problem can be alleviated by educing the eigenvalue spread ratio of the impulse response, which can be achieved by adding additive white noise with small variance to the impulse response of the channel. The performance of the proposed scheme is verified by computer simulation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.1001-1002
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• 2006

As most of the powerline modems use spread spectrum modulation method which has strong immunity against the narrowband fading, or psk modulation method, the amplitude of the signal contains no useful informations. In this paper, we used class D amplifier to implement the drive circuit of the analog front end, and showed that it has great superiority over other existing drive circuits in rapidly impedance changing power line channel.