• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.7
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• pp.959-969
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• 1993

In this paper, the performance of DS/SS DPSK communications is analysed over fading dispersive channels considering the spreads of the channel in time and in frequency. The two spreads mentioned above are represented with multipath spread and Doppler spread, respectively. The bit error probabilities of DS/SS DPSK systems are derived in terms of channel and system parameters, and an approximation method is presented for computational efficiency. And the numerical results are given for various chip numbers in Rayleigh and Rician fading channels using the approximation method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.6
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• pp.494-505
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• 1990

This paper reports on the development of a DPSK demodulator of DS spread spectrum communications that use one SAW convolver. The spreading code chip pattern is changed from bit to bit in data portion of packet. And code chip is PSK modulated. Compared with simulation, experiment shows that the DPSK signal spreaded can be demodulated by using only one SAW convolver. And the theoretical performance of this DPSK demudulator is equal to CSK demodulator wich uses two SAW convolvers.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.545-548
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• 2003

본 논문은 UWB 통신 시스템에서 DPSK를 적용한 다중비트 변조 알고리즘을 제안한다. UWB 통신 시스템은 매우 낮은 파워의 신호를 사용하므로, 한 펄스를 이용한 다중비트를 보낼 수 있는 변조 알고리즘이 중요한 부분으로 작용한다. 이 논문에서는 UWB 시스템에서Gaussian 펄스에 정현파 가 곱해진 두 개 펄스의 조합을 이용하여 FCC Mask 에 저촉되지 않으면서 한 펄스에 다중 비트를 전송을 실현한 M-ary 전송 방식을 사용한다. 또한 채널상에서 펄스의 원치 않는 위상변화에 민감하지 않도록 하기 위해 DPSK 방식을 적용한 UWB 제안한다. 제안된 알고리즘의 성능 평가를 위해 시뮬레이션 하였고 그 결과와 구조를 본 논문에 제시한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.1
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• pp.37-45
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• 1982

We have analyzed the effect of multipath cochannel interference and Gaussian noise on binary DPSK systems used in land mobile radio communications. Considering multipath channel as non-selective Rayleigh channel, we have found a gnenral equation for bit error rates (BER) deriving the probability density function (p.d.f) of output of phase detector. The numerical results are shown in graphs and discussed as functions of carrier to noise power ratio (CNR), carrier to interferer power ratio (CIR) and correlation of signal component over the pulse length.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.52-60
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• 2001

In this paper proposes a multi-carrier MFSK-DPSK/DS-CDMA combined modulation techniques in Nakagami fading environment. Also, multi-carrier DS-CDMA combined system is a promising technique for mobile communications systems, since it has a strong immunity to multipath fading and increasing bandwidth efficiency. The modulations under consideration are noncoherent M-ary frequency shift keying (MFSK)and an MFSK based joint frequency phase modulation utilizing differential phase shift keying (DPSK). With the result, performance improvement of power efficiency and bandwidth efficiency combined system in multi-carrier MFSK-DPSK/DS-CDMA are better then conventional communication system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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• pp.899-906
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• 1997

It is known that the Differential Phase Shift Keying (DPSK) modulation scheme in the coherent optical communication system is suitable for design of long-distance transmission system because its receiver performance is 3-5dB better than ASK and FSK. In this paper, we descrive a fundamental understanding of the effects of laser phase noise on the performance of coherent lighwave communication systems. Formulas are derived for the bit error rate in homodyne and heterodyne DPSK. Based on detailed mathematical analysis and estimates, we explain the following finding. DPSK can operates at rates only 300 times greater than the laser linewidth.

• The Journal of the Acoustical Society of Korea
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• v.35 no.5
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• pp.368-374
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• 2016

This paper presents constructing transmitter and receiver by using a direct sequence spread spectrum techniques to DPSK (Differential Phase-Shift Keying) scheme in underwater acoustic communication. Since DPSK signal can be demodulated if the receiver knows only the phase difference between the adjacent bits, DPSK receiver structure has the advantage of being simplified. In the conventional receiver, two adjacent symbols of transmitted signal before despread are passed to the transition correlator that detects data by comparing maximum correlation outputs. At this time, the error for maximum value of the correlator output may increase because of low SNR (Signal to Noise Ratio) or high Doppler shift frequency according to the underwater channel. In this paper, we propose a method for accurate detection result using the width as well as the magnitude among outputs produced by the correlator. The performances of the proposed method was evaluated by simulation and lake trial data.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.461-464
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• 2000

본 논문에서는 위성통신 환경에서 DS/CDMA DPSK 시스템의 성능을 분석한다. 성능분석의 척도로 비트오류확률을 사용한다. 위성전송로는 쉐도잉이 있는 라이시안 페이딩 전송로로 모델링한다. 수치계산의 결과, 위상잡음이 존재할 때 비트오율 성능이 저하되므로 시스템 용랑이 감소될 것이 예상된다. 또한 위성전송로에서는 쉐도잉이 시스템 전체 성능에 커다란 영향을 미침을 알 수 있다. 본 논문에서의 분석은 DS/CDMA 기반의 위성통신 시스템 설계에 적용할 수 있다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.04a
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• pp.107-112
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• 1986

This paper presents one method to resolve the end-to-end digital connectivity through 2-wire subscriber loop. This system which consists of the subscriber`s device and the line termination device makes use of the advantages of time compressed multiplexing and modified DPSK. Experimental results show that the transmission range of the lab test covers 2km and that of the field test covers 1.5km.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.3
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• pp.112-119
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• 1982

An experimental 2400bps modem emlpoying 4-phase DPSK in compliance with the CCITT recommendation V.26 is developed. Integrated circuits are used throughtout the circuit implementation, including active filters and a semiconductor delay line. A new timing recovery scheme is proposed and adopted successfully. The error rate perfromance is found to be in fair agreement with the theoretical prediction.