• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.211-215
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• 1997

Localized communication networks for office automation, security monitoring, environmental management of buildings, computer communications, and other applications enjoy every increasing demand. This paper proposes a direct sequence spread spectrum communication system for use in power line data transmission. Advantages of power distribution circuits include reasonably universal coverage and easy access vis a standard wall plug. Disadvantages include limited communication bandwidth, relatively high noise levels, and varying levels of impedance, noise, and attenuation. Spread spectrum signalling provides immunity to narrow-band signal impairments and multiplexing capability. Our prototype power line communication module supports completely physical and data link layers based on the international standard ISO 10368 for reliable high-speed power line communication system. Moreover it provides useful functions to compose a plant monitoring and control system. All the circuits of the communication module are included in one compact circuit. Thus a functional communication system for the power line plant monitoring and control is implemented.

• Journal of Communications and Networks
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• 제14권3호
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• pp.280-285
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• 2012

We propose self-encoded spread spectrum with two different iterative detection methods in multi-channel communication. The centralized iterative detection outperforms the iterative detection distributed over multiple channels. The results show that self-encoded spread spectrum with the centralized iterative detection is an excellent candidate for cognitive radio network.

• 한국군사과학기술학회지
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• 제14권1호
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• pp.69-73
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• 2011

In the defence wireless communications, conventional Anti-Jamming techniques(Frequency Hopping/Spread Spectrum or Direct Sequence/Spread Spectrum) are used to overcome a intentional interfering signals which are single/multitone or partial band jammer etc. DS/SS techniques is very strong on tone jamming signal but not to be on a partial band jammer. So FH/SS AJ performances are expected method of an substitution of DS/SS, however FH/SS could not have good performance on some BMTJ(Band Multi-tone Jammer). So this paper proposes FH-CSS (Frequency Hopped - Chirp Spread Spectrum) to get more robustness against jammers(BMTJ, PBNJ) and analyze the AJ performances.

• IEIE Transactions on Smart Processing and Computing
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• 제3권6호
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• pp.404-409
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• 2014

This paper presents a Spread Spectrum Clock Generator (SSCG) based on Relaxation oscillator using Up/Down Counter. The current is controlled by a counter and the spread spectrum of the Relaxation Oscillator. A Relaxation Oscillator with temperature compensation using the BGR and ADC is presented. The current to determine the frequency of the Relaxation Oscillator can be controlled. The output frequency of the temperature can be compensated by adjusting the current according to the temperature using the code that is the output from the ADC and BGR. EMI Reduction of SSCG is 11 dB, and Spread down frequency is 150 kHz. The current consumption is $600{\mu}A$ from 5V and the operating frequency is from 2.3 MHz to 5.75 MHz. The rate of change of the output frequency with temperature was approximately ${\pm}1%$. The SSCG is fabricated in a 0.35um CMOS process with active area $250um{\times}440um$.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1983년도 추계학술발표회논문집
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• pp.93-96
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• 1983

This paper is a study on the performance of ASK combined with Frequency-Hopping spread Spectrum techniques in the presence of interfering channel with uniformly distribyted frequency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.2017-2018
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• 2006

전력선 통신기술은 추가 배선이 필요 없는 유용성에도 불구하고 전력선 채널에 대한 정확한 채널 모델링과 전력선 모뎀의 전송 신뢰성에 대하여 많은 문제점을 나타내고 있다. 본 논문에서는 전송선로의 주파수에 대한 잡음과 임피던스 특성을 분석하고, 이의 해결을 위하여 전력선 채널에 Spread Spectrum 기법을 적용한 신호를 전송하였을 때의 시뮬레이션 결과와 구현된 FPGA 보드를 비교분석 하였다. 채널 모델링은 잡음과 감쇄 특성을 고려하였으며, Spread Spectrum 변조 방식을 적용한 전력선 모뎀의 FPGA를 구현하여 성능을 분석하였다.

• Journal of Communications and Networks
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• 제15권3호
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• pp.258-265
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• 2013

In this study, we investigate the multi-carrier spread spectrum (MCSS) communication system which adopts the self-encoded spread spectrum in a downlink synchronous channel. It is very difficult to completely eliminate the frequency offset in practical channel scenarios. We demonstrate that the self-encoded MCSS (SE-MCSS) with iterative despreading manifests a remarkable immunity to residual frequency offset. The SE-MCSS can be an excellent candidate for the future generation of wireless services.

• 한국음향학회지
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• 제41권2호
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• pp.150-158
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• 2022

본 논문에서는 2021년 9월 동해에서 수행된 초장거리 대역확산 수중음향통신의 해상실험 결과를 제시한다. 8개의 수직 배열 센서를 이용하여 수중음향통신 신호를 수집하였으며, 전송 거리는 160 km로 하였다. 송신 신호로 30 bps의 다중 코드 대역 확산 방식과 100 bps의 처프 대역확산 방식이 사용되었다. 실험 결과 단일 채널에서 채널 부호화 기법이 적용되지 않은 경우에 높은 비트 오류율을 나타내었으나 각 수신 채널에서 프레임 동기화를 수행한 후 신호들에 등이득 조합 다이버시티 기법을 적용하면 비부호화 비트 오류율이 순방향 오류 정정 한계인 0.1 이하로 감소하였다.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1983년도 추계학술발표회논문집
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• pp.85-87
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• 1983

In this paper, a improved whitening filter for narrowband interference rejetion in PN spread spectrum communication systems is proposed. This whitening filter has the feedback from the output to the input of adaptive transversal filter and is superior to conventional LMS whitening filter in respect to SNR and power spectrum since the calculation of tap weight is based on maximum likelihood estimation

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.833-836
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• 1987

The error probability for coherent frequency-hopped spread-spectrum multiple-access communications is computed. We employ PSK as a modulation scheme. The channel capacity is performance measure and the minimum bit signal-to-noise ratio for reliable communications is obtained.