• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.3
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• pp.239-254
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• 1988

In this paper an exciter which performs modulation and amplification is composed of high power(30dBm) VCO(Voltage Controlled Oscillator) using push-pull circuit. Modulation is FSK using PLL(Phase Locked Loop). A single loop PLL synthesizer having sequency range of 42.5-100.5MHz, 25KHz channel spacing and switching time of 1msec converts down the exciter VCO frequency to 1.25MHz. This signal mixed with the FSK modulated signal coming in the phase detector of exciter. The acquisition time of exciter for frequency hoppng is less than 200usec, so the total acquisition time for transmission is less that 1.5msec. There is no need of additional power amplification because power amlifiction by high power VCO is high enough to communicate within near distance. The proposed frequency synthesizer is not complex so it is suitable for low cost slow frequency hopping spread spectrum communication.

• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.179-183
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• 2007

This paper is to implement a low power frequency Shift Keying(FSK) receiver using Xilinx System Generator. The receiver incorporates a 16 point Fast Fourier Transform(FFT) for symbol detection. The design units of the receiver are digital designs for better efficiency and reliability. The receiver functions on one bit data processing and supports data rates 10kbps. In addition CORDIC algorithm is used for avoiding complex multiplications while computing FFT, multiplication of twiddle factor is substituted by rotators. The design and simulation of the receiver is carried out in Simulink, then the simulink model is translated to a hardware model to implement FPGA using Xilinx System Generator and to verify performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2173-2183
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• 1998

We consider a frequency-hopped multiple-access communication system that employs reed-solomon code over GF(Q) and M-ary FSK signaling ($M{\leq}Q$) in rayleigh fading channel. We investigate the tradeoff among the modulation symbol size (M), the number of frequency slots, and the code rate in maximizing the average number of successfully transmitted information bits per unit time and unit bandwidth (called normalized throughput). We find that it is desirabel to use a large M in noise-limited environment. In interference-limited environment, it is more improtant to prevent errors (hits) by increasing the number of frequency slots than to correct them with formward error correction techniques or to reduce the error rate by increasing M.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10C
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• pp.999-1006
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• 2005

The difference threshold test (DTT) declares erasures whenever the difference between the largest and second largest energy detector outputs does not exceed a given threshold. we show that the DTT outperforms the ratio threshold test (RTT) for finite modulation size and diversity order in the detection of M-FSK signals. The asymptotic performance for infinite modulation size and diversity order is then investigated. It is shown that the minimum signal-to-noise ratio required to achieve error-free communication for the DTT is the same as that for the RTT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.3
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• pp.263-279
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• 1989

In part-1 of this paper, the error rate equations of digitally modulated signals transmitted though the Gaussian/Impulsive noise channel 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 figures as the functions of carrier-to-noise power ratio(CNR), impulsive index, and the ration of Gaussian noise power component to impulsive noise power component. The results are shown in graphs to known how much impulsive noise effects on digital signals than Gaussian noise.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.2
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• pp.259-266
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• 1998

406MHz and INMARSAT-E EPIRB facility transmits the distress alerts by the relay of the polar-satellites and INTELSAT, but may cause the probability of delayed transmission because of the orbital period and not compliance with the implementation of GMDSS rules for small ships in A1 area.. Digital Selective Calling forms a critical part of the terrestrial elements of the GMDSS system and ensures the reliability and the efficiency in the system. In this paper, we suggests that new DSC EPIRB in the VHF band to overcome this defect for small ships in A1 area, and analyze the ITU-R recommendations and technical characteristics, design and implement the algorithm of calling sequences, frequency synthesizer for the RF signal and FSK moulation signals.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.1
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• pp.24-36
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• 2002

It is important to use frequency resource effectively to support much more users, to maximize the DS-CDMA system performance. In this paper, we use MPSK, QAM, MFSK and PR coder as a baseband modulation method for DS-CDMA system. Increasing user's number, we compare the performance of each system using different baseband modulation method, by expecting BER performance. BPSK has generally good performance, in case of low power operation of terminal 8FSK has excellent performance relatively, PR has excellent performance when high power operation of terminal and also good for situation of excessive user's number. QAM is not suitable for DS-CDMA system.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.86.1-86
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• 2002

Polarity correlation is a simplified version of the usual, having a possibility of real-time processing without any reduction of precision. In this paper, its applicability in deterministic signals is first explored generally, by theoretical or numerical analysis of four kinds of the typical signals. Then, based on the results, its two applications are proposed, that are detection and demodulation of FSK signals in digital communication, and time delay estimasion in ultrasonic A-mode measurement. The effectiveness of the proposed applications is confirmed by its superior implementation ability and the results of numerical experiments under practical circumstances.