• 전기의세계
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• v.43 no.12
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• pp.46-54
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• 1994

본 문에서는 최근 여러방면에서 주목받고 있는 대역확산통신방식에 대해 살펴본다. 대역확산통신의 원리를 살펴보고, 대역확산통신의 여러가지 방식의 기본개념과 특징에 대해 알아본다. 또한 대역확산통신방식을 이용한 각종 응용에 대해 고찰해 본다.

• Information and Communications Magazine
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• v.2
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• pp.91-100
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• 1985

본 소고에는 PN부호와 대역확산통신의 기본적인 관계를 설명하고 PN부호가 대역확산통신에 어떻게 사용하는가를 상술한다. 먼저 PN부호의 발생방법과 PN부호가 가지고 있는 특성을 설명하고 PN부호를 가지고 주파수도약을 위해 주파수합성기를 어떻게 구성하는가를 설명한다. 끝으로 간단한 대역확산통신방식과 PN부호 관계를 연결지어 논하기로 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.1
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• pp.84-92
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• 1989

The purpose of this paper is to demonstrate the effect of a FH spread spectrum communication interference in TV channels and frequency compatibility in 30-88 MHz frequency band. To calculate this interferece, the strength of electric field of TV signals is derived as a function of distance between TV transmitter and receiver. An interference model is established based upon thefield strength by using the relation between the transmitted power of FH spread spectrum communications and the distance between the TV image signals, which makes TV screen a cceptble, Simultaneous transmission of FH sprea spectrum signals and TV signals is shown to be feasible, as far as the interference level is lower than the TV image signal level by 23.5dBm. As a result of frequency analysis and experiment, the FH spread spectrum communication can be used together with TV channels.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1422-1430
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• 2016

Researches for oceans are limited to military purpose such as underwater sound detection and tracking system. Underwater acoustic communications with low-probability-of-interception (LPI) covert characteristics were received much attention recently. Covert communications are conducted at a low received signal-to-noise ratio to prevent interception or detection by an eavesdropper. This paper proposed optimal covert communication model based on direct sequence spread spectrum for underwater environments. Spread spectrum signals may be used for data transmission on underwater acoustic channels to achieve reliable transmission by suppressing the detrimental effect of interference and self-interference due to jamming and multipath propagation. The characteristics of the underwater acoustic channel present special problems in the design of covert communication systems. To improve performance and probability of interception, we applied BCJR(Bahl, Cocke, Jelinek, Raviv) decoding method and the direct sequence spread spectrum technology in low SNR. Also, we compared the performance between conventional model and proposed model based on turbo equalization by simulation and lake experiment.

• Journal of Navigation and Port Research
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• v.35 no.8
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• pp.643-647
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• 2011

In this paper, we study the application of DSSS(Direct Sequence Spread Spectrum) in underwater acoustic communication for robust the ISI(Inter-Symbol Interference. We confirm the application of DSSS in underwater acoustic communication in underwater by the simulation with underwater channel impulse response and experiment. As a simulation result, the BER of QPSK technique is $1.14{\times}10^{-1}$ and the BER of DSSS technique is $6.73{\times}10^{-3}$. And we performed the experiment of DSSS technique in underwater. As a experiment result, the BER of QPSK technique is $3.19{\times}10^{-1}$ and the BER of DSSS technique is $5.17{\times}10^{-4}$.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.250-252
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• 2003

본 논문에서는 콘벌루션 부호를 사용한 대역확산 방식의 디지틀 통신모뎀을 FPGA를 이용하여 설계 및 검증을 하였다. 대역확산 방식에서의 콘벌루tus부호기(K=3, R=1/2), PN code(128chip) generator와 비터비 디코더를 Xilinx사의 FPGA 디자인 툴인 Xilinx Foundations3.1을 사용하여 VHDL simulation과 timing simulation을 수행하였고, FPGA 회로설계 검증 장비인 EDA-Lab 3000 장비를 사용하여 Xilinx사의 SPARTAN2 2S100PQ208칩에 configuration 한 후 Agilent사의 1681A logic analyzer를 사용하여 설계된 회로의 동작을 검증하였다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1988.10a
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• pp.93-97
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• 1988

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.06a
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• pp.625-628
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• 1996

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1700-1706
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• 2016

To improve the number of simultaneous transmissions of machine-to-machine traffic in a spread spectrum ALOHA channel, we propose a new spreading technique called doubly truncated cyclic code shift keying (DTCCSK). By truncating the codeset of cyclic code shift keying, DTCCSK freely adjusts the spreading factor and the symbol length. As a result, DTCCSK exhibits both a high spectral efficiency of M-ary signaling and low implementation complexity of a direct sequence.