• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.8
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• pp.1543-1548
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• 2009

In this paper, a high speed code synchronization circuit is proposed. for fast code synchronization, matched filler method is used for initial code acquisition with two channel correlators. Particular frequency patterns of the limited number having the information about PN code start time are composed and transmitted repeatedly to increase the probability of accurate initial synchronization. And digital frequency synthesizer is proposed. And it's performance is analyzed theoretically. The analysis show that fast frequency hopping is possible in frequency hopping system that use digital frequency synthesizer.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.2
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• pp.98-103
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• 2008

There are the frequency shift keying(FSK), phase shift keying(PSK) and amplitude shift keying(ASK) in the conventional digital communications method. In this paper, We proposed a new robust wavelet shift keying system using scaling and wavelet function in the digital communication. Wavelet Transform consist of a low frequency and high frequency coefficient. When the input signal is one, if it finds the impulse response, the signal is separated from the scaling and wavelet function. The binary data is encoded by modulator which assigned the scaling function to 1(one), and wavelet to zero(0). It was demonstrated by experiment that the proposed algorithm can be a robust noise.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.4
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• pp.43-51
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• 1991

본 논문에서는 전력선 반송통신을 이용한 가정내 전기기기의 감시제어 시스템인 "전동선 HMCS"를 개발했다. 통신방식은 양방향으로서 반송파 주파수 125[kHz]의 FSK디지탈 신호를 전등선에 중첩시키는 방식이며, 제어방식은 Polling 방식을 채용했다. 그리고 시스템의 송신출력은 4Vp-p이고, 수신감도는 CISPR 잡음 규제등을 고려하여 10[mV] 이상으로 설계하였다. 개발 시스템의 성능은 58[dB] 시스템 여유도와 1.78$\times$10-7의 에러확률을 갖는다.에러확률을 갖는다.

• Information and Communications Magazine
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• v.30 no.5
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• pp.88-94
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• 2013

본고에서는 TV White Space (TVWS) WPAN 표준 기술 동향을 알아본다. TVWS WPAN의 표준화가 진행중인 IEEE 802.15.4m의 표준화 현황과 현재 진행중인 표준 전송기술 (TVWS-FSK, TVWS-OFDM, TVWS-NB-OFDM), 그리고 표준화 완료 시 적용될 수 있는 응용 분야에 대해서 서술하였다.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1132-1134
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• 2001

전력선통신 변조방식 중 FSK(Frequency Shift Keying)변조방식을 이용하여 컴퓨터와 RS232케이블로 전력선모뎀과 연결하여 컴퓨터의 데이터신호를 전력라인으로 직접 송신할 수 있게 하였으며, 수신부에서 데이터신호를 검출하여 가전기기의 전원을 ON/OFF 하였다.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.666-668
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• 2001

전력선통신 변조방식 중 FSK(Frequency Shift Keying) 변조방식을 이용하여 컴퓨터와 RS232 케이블로 전력선모뎀과 연결하여 컴퓨터의 데이터신호를 전력라인으로 직접 송신할 수 있게 하였으며, 수신부에서 데이터신호를 검출하여 가전기기의 전원을 ON/OFF하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.6
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• pp.553-558
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• 2011

This paper describes the development and test result of S-band Transmitter flight model(FM) of STSAT-3 by satellite research center(SaTReC), KAIST. The communication sub-system of STSAT-3 is consist of two different frequency band channels, S-band for Telemetry & Command and X-band for mission data. S-band Transmitter(STX) functionally made of modulator, frequency synthesizer, power amp and DC/DC converter. The transmission data is modulated by FSK(Frequency Shift Keying) and the interface between spacecraft sub-module and STX is RS-422 standard method. The FM STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under $1{\times}10^{-5}$ which meets the specification respectively. The FM STX is delivered Spacecraft Assembly, Integration and Test(AIT) level through the completion of functional Test and environmental(vibration, thermal vacuum) Test successfully.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.436-442
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• 2022

In this paper, the performance of the selective combining according to the channel selection decision method of frequency diversity is evaluated in the underwater frequency selective channel. The underwater acoustic channel in the shallow sea has a complex multipath characteristic by combining various environmental factors such as boundary surface reflection and sound wave refraction according to the water temperature layer. In particular, frequency selectivity due to multipath causes energy fluctuation in a communication channel, which reduces SNR (Signal to Noise Ratio) and deteriorates communication performance. In this paper, we applied the frequency diversity technique using multiple channels to secure the communication performance according to the frequency selectivity by multipath. For each channel, 4-FSK (Frequency Shift Keying) and selective combining were applied, the performance was evaluated by applying the maximum value, average value, and majority decision of the signal in order to decide the demodulation channel selection of the selective combining.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.429-432
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• 2000

수중에서 AUV신호나 화상데이터의 정확한 고속 전송 등을 위해 수중 데이터 통신에 대한 많은 연구가 진행되어 왔다. 수중 데이터 통신에서 잔향과 배경 잡음 등의 해양 환경 특성을 극복하는 것은 신뢰성 있는 통신 환경을 이룩하는데 중요하다. 특히 해면과 해저로 이루어진 천해 환경에서 해면과 해저 반사파에 의한 영향은 수중 데이터 통신의 성능을 좌우하는 중요한 요소 중의 하나로 알려져 있다. 이러한 환경적 영향을 최소화하여 높은 성능의 통신 환경을 제공하기 위해 다중경로의 영향을 적게 받는 변조방식을 선택하는 것이다. 수중 데이터 통신에서 일반적으로 사용되는 변조방식은 FSK, PSK, DPSK 등이 있다. 본 연구에서는 해면$\cdot$해저로 이루어진 해양 통신 채널에서 세 가지 변조방식의 성능을 수치모의실험을 통하여 비교$\cdot$분석하였다. 수치모의실험에서 해면 해저로 이루어진 천해의 해양 통신 채널은 음원 영상법을 적용하여 구성하였으며 각 변조방식의 성능은 BER(Bit Error Ratio)로 나타내었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.3
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• pp.280-292
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• 1989

In this paper, the error rate equations of digitally modulated signals transmitted through the channel which is not only Gaussian/Impulsive noise but also multi-path fading have been derived. Using the derived equations for the error probabilities of ASK, QAM, CPSK, DPSK, FSK, and MSK signals, the error rate performances of digital modulation systems have been evaluated and represented in the graphs as the functions of CNR, Impulsive indes, the ratio of Gaussian noise power component to Impulsive noise power component, and fading figures. The results show that, in the deep fading environment, the error is occurred more frequency by Gaussian noise than Impulsive noise. And the comparison of various systems certifies that PSK is superior to the ohter systems in the deep fading or shallow fading environment.