• Proceedings of the KIPE Conference
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• 1997.07a
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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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• v.14 no.3
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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.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.1
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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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• v.3 no.6
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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 $250um{\times}440um$.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1983.10a
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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.

• Proceedings of the KIEE Conference
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• 2006.07d
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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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• v.15 no.3
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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.

• The Journal of the Acoustical Society of Korea
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• v.41 no.2
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• pp.150-158
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• 2022

This paper presents the results of a sea trial for very long range spread spectrum underwater acoustic communication conducted in the East Sea in September 2021. Signals were collected through 8 vertical sensors, and the range between the transmitter and receiver was about 160 km. 30 bps Multi-Code Spread Spectrum (MCSS) method and 100 bps Chirp Spread Spectrum method were used for the transmitting signal generation. The results show that when the channel coding technique was not used in a single channel, the uncoded bit error rate was high, but when the Equal Gain Combining (EGC) diversity technique was used after frame synchronization in each receiving channel, the uncoded bit error rate was reduced to 0.1 or less.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1983.10a
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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

• Proceedings of the KIEE Conference
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• 1987.07b
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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.