• Title/Summary/Keyword: B-modulation

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PCM/FM With Modulation Index of 2/3 (변조지수가 2/3인 PCM/FM)

  • Gu, Young Mo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.11
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    • pp.941-944
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    • 2021
  • PCM/FM with a modulation index of 0.7 is widely used in the telemetry field. If the modulation index is slightly changed to 2/3, it can be interpreted as 3-PSK with a state number of 3 in phase transition trellis and can be received with a simple Viterbi decoder. As a result of computer simulation, the Eb/No performance in the AWGN channel is about 8.3 dB when the BER is 10-5, which is close to the theoretical limit.

A Study on The Modulation Method for Low Power Communication in Underwater Sensor Network (수중 센서 네트워크에서 저전력 통신을 위한 변조기법의 적용성 연구)

  • Jang, Chul-Hee;Han, Jeong-Woo;Kim, Ki-Man;Lee, Seong-Ro
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.6B
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    • pp.689-696
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    • 2011
  • In this paper, we propose the result of PSSK(Phase Silence Shift Keying) modulation scheme that is mixed PSK(Phase Shift Keying) modulation and PPM(Pulse Position Modulation) method. The performance of underwater communication systems are influenced underwater channel characteristics. In particular, delay spread can make ISI(Inter Symbol Interference) because of reverberation and multi path. It degrade the performance of the communication system. Also underwater sensor networks consider about power efficient due to the particularities of their operating environment. PSSK modulation method transmit two orthogonal symbol and using silence period in a period so it can reduce the power. Increasing the distance of between modulation symbols, to enhance the performance of BER(Bit Error Rate) as well as to improve power efficient. The result of sea trial, QPSK modulation BER is $3.19{\times}10^{-1}$ and PSSK modulation BER is $2.89{\times}10^{-1}$.

Performance Analysis of M-ary Impulse Communications over AWGN Channels (AWGN 채널에서 M진 임펄스 통신의 성능 분석)

  • 김동호;백승선;문용규;강희조
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.05a
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    • pp.559-562
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    • 2002
  • 본 논문에서는 최근 제한적으로 사용이 승인된 UWB(초광대역: Ultra-Wideband) 통신을 AWGN 하에서 다중 접속을 고려하지 않은 단일 사용사일 경우로 가정시, M진 값이 변화함에 따른 에러율과 성능 개선 기법으로 BCH를 채용시의 에러율을 비교 분석하였다. 기존에 연구되어 오던 변조로 PAM(Pulse Amplitude Modulation)과 PPM(Pulse Position Modulation)방식을 비교하였으며 에러율 $10^{-6}$을 기준으로 M=2, 4일 경우 PAM이 PPM보다 약 E$_{b}$/N$_{o}$ =3~4[dB], M=8 이상의 경우 PPM이 약 E$_{b}$/N$_{o}$ =9[dB], M=16일 경우 약 E$_{b}$/N$_{o}$ =15[dB]정도 성능이 우수하였다. AWGN 채널 하에서 에러 정정 부호인 BCH(15,7)를 도입하였을 경우 에러율 $10^{-6}$을 기준으로 PAM방식은 약 E$_{b}$/N$_{o}$ 가 약 1[dB], PPM 방식은 M=2, 4일 경우 약 E$_{b}$/N$_{o}$ =1~1.5[dB]정도 개선되었다.

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A New Modified MPPM for High-Speed Wireless Optical Communication Systems

  • Rouissat, Mehdi;Borsali, Riad A.;Chikh-Bled, Mohammad E.
    • ETRI Journal
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    • v.35 no.2
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    • pp.188-192
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    • 2013
  • Previous work proposed combining multipulse pulse position modulation (MPPM) with pulse amplitude modulation to form multipulse amplitude and position modulation (MPAPM), which is a hybrid modulation that results in an improvement in bandwidth efficiency but a degradation in power efficiency. In this paper, to achieve greater power efficiency and a better data rate, we propose multipulse dual amplitude-width modulation, based on MPAPM and pulse width modulation. The proposed scheme shows a remarkable improvement in data rate and a 1.5-dB improvement in power efficiency over MPAPM, while sustaining the bandwidth efficiency. After introducing symbol structure, we present the theoretical expressions of spectral efficiency, the power requirements, and the normalized data rate, as well as the results of comparing the proposed modulation to MPPM and MPAPM.

격자코드 변조 시스템에서 DFE의 심볼판정 알고리즘 제안 (Symbol Detection Methods for DFEs in Trellis Coded Modulation Systems)

  • Chung, Won-Zoo
    • Journal of IKEEE
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    • v.10 no.1 s.18
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    • pp.69-74
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    • 2006
  • In this paper, we present symbol detection methods for decision feedback equalizers (DFE) in trellis coded modulation systems. The proposed symbol detectors improve symbol error rate (SER) by exploiting the coding structure of trellis coded modulation (TCM). For example, for 8-PAM signals the achieved SER with the proposed detection scheme is improved to $2{\times}10^{-5}$ from $2.5{\times}10^{-2}$ of the conventional symbol-by-symbol detector under AWGN channel at 20dB SNR. This SER improvements mitigate error propagation of DFE.and produces significant over-all SER improvement for under multipath channels (for example, from 0.26 to 0.01 and 0.005 under a severe multipath channel 20dB SNR as shown in the simulation result of this paper).

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ELINT Intra-pulse Modulation Recognition using Fuzzy Algorithm (퍼지 알고리즘을 이용한 전자정보의 펄스 내 변조 인식)

  • Kim, Young-Min
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.9
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    • pp.1986-1995
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    • 2013
  • The ELINT system which derives intelligence from electromagnetic radiations plays an important role in modern electric warfares. Among radar characteristics inferred from the signals, intra-pulse modulation scheme is a useful feature to identify modern radars. This paper proposes the method to classify intra-pulse modulation schemes such as UM, PSK, BFSK, QFSK, LFM and NLFM based on the fuzzy algorithm. The proposed method defines fuzzy membership functions to characterize input signals, and then it calculates accordance rates for each modulation scheme with fuzzy inference rules. The experimental results show that the probability of correct recognition is more than 95% for SNR > 10dB.

A study on the Frequency Modulation-based Audio Transmission System for Short-range Underwater Optical Wireless Communications (근거리 수중 광무선 통신을 위한 주파수 변조 기반 오디오 전송 시스템 연구)

  • Kim, Yeon-Joo;Sohn, Kyung-Rak
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.1
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    • pp.166-171
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    • 2012
  • In this paper, short-range underwater wireless communication technique using visible LEDs is proposed. As an alternative to conventional acoustic system, visible LED communications show high quality and high speed data transmission characteristics. We design a frequency modulation-based optical wireless audio transmission system. The CD4046B phase-locked loop device is applied to implement the frequency modulation and demodulation. With a transmission modulation of 100 kHz, audio signal has successfully received at a transmission distance of 30 cm.

A scalar MSDD with multiple antenna reception of Differential Space-Time π/2-Shifted BPSK Modulation

  • Kim Jae-Hyung;Hwang Seung-Wook;Kim Jung-Keun;Kim Yong-Jae
    • Journal of Navigation and Port Research
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    • v.30 no.2
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    • pp.167-172
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    • 2006
  • In this paper, the issue of blind detection of Alamouti-type differential space-time (ST) ${\pi}/2$-shifted BPSK modulation in static Rayleigh fading channels is considered. We introduce a novel transformation to the received signal from each receiver antenna such that this binary ST modulation, which has a second-order transmit-diversity, is equivalent to QPSK modulation with second-order receive-diversity. The pre-detection combining of the result of transformation allows us to apply a low complexity detection technique specifically designed for receive-diversity, namely, scalar multiple-symbol differential detection (MSDD). With receiver complexity proportional to the observation window length, our receiver can achieve the performance 1.5dB better than that of conventional differential detection ST and 0.5dB worse than that qf a coherent maximum ratio combining receiver (with differential decoding) approximately.

Fabrication of High Speed Modulation Doped SMQW-PBH-DFB-LD (변조 도핑된 SMQW-PBH-DFB-LD의 고속변조 특성)

  • 장동훈;이중기;조호성;박경형;김정수;박철순;김흥만;편광의
    • Korean Journal of Optics and Photonics
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    • v.6 no.3
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    • pp.228-232
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    • 1995
  • We have made modulation doped SMQW-PBH-DFB-LD for high speed optical communications. The waveguide and barrier layers were doped by Zn with the concentration of $1.2 \times 10^{18}cm^{-1}$. Mean threshold current and slope efficiency were 24.88 mA (minimum 16 mA) and 0.197 mW/mA (maximum 0.275 mW/mA) respectively. Linewidth enhancement factor ($\alpha$) of MD-SMQW-PBH-DFB-LD was reduced than that of SMQW-PBH-DFB-LD. Linewidth enhancement factor of 1.8 owes to the large gain coefficient of modulation doped active layer. The resonance frequency was linearly increased with the square root of optical power. The resonance frequency in small signal modulation was measured as 8 GHz and -3 dB modulation bandwidth was 10 GHzat $46mA(I_{th}+30mA)$..

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Layer-by-layer Composition Modulation by Ion-induced Atomic Rearrangement in Metallic Alloys

  • Kim, Byeong-Hyeon;Kim, Sang-Pil;Lee, Gwang-Ryeol;Jeong, Yong-Jae
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.359-359
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    • 2010
  • Self-organized nanostructures of dots, holes or ripples produced by energetic ion bombardment have been reported in a wide variety of substrates. Ion bombardment on an alloy or compound also draws much attention because it can induce a surface composition modulation with a topographical surface structure evolution. V. B. Shenoy et al. further suggested that, in the case of alloy surfaces, the differences in the sputtering yields and surface diffusivities of the alloy components will lead to a lateral surface composition modulation [1]. In the present work, the classical molecular dynamics simulation of Ar bombardment on metallic alloys at room temperature revealed that this bombardment induces a surface composition modulation in layer-by-layer mode. In both the $Co_{0.5}Cu_{0.5}$ alloy and the CoAl B2 phase, the element of higher-sputtering yield is accumulated on the top surface layer, whereas it is depleted in lower layers. A kinetic model considering both the rearrangement and the sputtering of the substrate atoms agrees with the puzzling simulation results, which revealed that the rearrangement of the substrate atoms plays a significant role in the observed composition modulation.

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