• Title/Summary/Keyword: Modulation method

검색결과 304건 처리시간 0.231초

Adaptive Modulation Method using Non-Line-of-Sight Identification Algorithm in LDR-UWB Systems

  • 마림천;황재호;최낙현;김재명
    • 한국통신학회논문지
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    • 제33권12A호
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    • pp.1177-1184
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    • 2008
  • Non-line-of-sight (NLOS) propagation can severely weaken the accuracy of ranging and localization in wireless location systems. NLOS bias mitigation techniques have recently been proposed to relieve the NLOS effects, but positively rely on the capability to accurately distinguish between LOS and NLOS propagation scenarios. This paper proposes an energy-capture-based NLOS identification method for LDR-UWB systems, based on the analysis of the characteristics of the channel impulse response (CIR). With this proposed energy capture method, the probability of successfully identifying NLOS is much improved than the existing methods, such as the kurtosis method, the strongest path compare method, etc. This NLOS identification method can be employed in adaptive modulation scheme to decrease bit error ratio (BER) level for certain signal-to-noise ratio (SNR). The BER performance with the adaptive modulation can be significantly enhanced by selecting proper modulation method with the knowledge of channel information from the proposed NLOS identification method.

유한 요소법을 이용한 에폭시 몰드형 PT의 설계 시뮬레이션 (Design Simulation of Epoxy Mold Type PT using Finite Element Method)

  • 박건호
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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    • pp.119-122
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    • 2005
  • In this study, the design simulation for optimal wire batch around service line was made to improve the dielectric strength at the primary winding using Finite Element Method. The automatic convergence algorithm for finding of limit object value using loop circulation method was developed to make the optimal design simulator. The modulation method was suggested to make division time faster which was very important for full simulation efficiency. As a result, the simulation time was reduced and the optimal wire batch design was obtained.

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공간벡터 전류제어 기법을 이용한 벡터제어형 인버터의 dead time 보상 (Dead Time Compensation of Vector Controlled Inverter Using Space Vector Modulation Method)

  • 홍기필;오원석;김영태;김희준
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1994년도 하계학술대회 논문집 A
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    • pp.265-269
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    • 1994
  • The switching dead time avoiding a bridge leg short circuit in PWM voltage source inverter produces distortions of the controlling inverter output performance such as current waveform, voltage vector, and torque. In this paper, the influence of dead time is investigated. The on-line space voltage vector modulation method is used for current controller. It is possible to compensate dead time by space voltage vector modulation which generates additional pulse compensating voltage distortion caused by dead time. In addition, narrow pulse which is generally neglected can be compensated. All the algorithms, including field-oriented control are performed by one chip microprocessor 80C196MC and DSP TMS320C31. Experimental results probe that the proposed scheme provides a good inverter output performance.

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신경망을 이용한 디지털 변조방식 식별 (Identification of Digital Modulation Method using an Artificial Neural Network)

  • 신용조
    • 전자공학회논문지T
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    • 제35T권3호
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    • pp.25-30
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    • 1998
  • 본 논문에서는 미지의 디지털 변조신호가 입력되는 경우에 변조방식을 식별하는 방법을 제안한다. 제안하는 식별 방법은 입력신호의 순시진폭, 순시주파수, 순시 위상을 구하고, 이를 바탕으로 특징벡터를 추출하여 신경망을 이용하여 식별하도록 구성하였다. 식별방법의 타당성을 검증하기 위해 백색 가우스성 잡음환경 하에서 8가지 입력신호를 사용하여 SNR을 변화시켜가며 모의실험을 수행하였다. 모의실험 결과 신경망을 이용하여 SNR 10 [㏈]까지 모든 입력 신호들을 식별해 낼 수 있었다.

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저임피던스 전력선 채널 환경에 적합한 통신을 위한 구동 회로 설계 (Drive Circuit Design for Smooth Communication in Low Impedance Power Line Channel Environment)

  • 최태섭;최은범;사공석진
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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    • pp.369-373
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    • 2003
  • 홈오토메이션 시스템은 보통 데이터 양이 많지 않아 저속 전력선 통신을 사용하는데, 저속 전력선 통신은 대역 확산 방식과 위상 변조 방식이 사용된다. 이 통신 방식은 신호의 정보가 진폭에 없고, 위상 변화에 있으므로 본 논문에서는 신호가 두 개의 상태로 되는 D급 증폭 회로를 사용하여 저임피던스를 가진 전력선 채널에서 적합한 통신이 되도록 하였다. 현재 전력선 모뎀에 사용되는 전압 구동 회로와 전류 구동 회로를 제작하고, 본 논문에서 설계한 D급 증폭 회로를 이용한 구동 회로와 비교 실험을 하였다. 실험 결과 본 논문에서 설계한 구동 회로가 다른 구동 회로보다 낮은 전력선 채널 임피던스에 대하여 전달 특성이 우수함을 보였다.

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WPAN LR-UWB 시스템에서 유동적인 PPM 방식을 이용한 적응적인 변복조 방법 (Adaptive Modulation Method using Flexible PPM Method in WPAN LR-UWB System)

  • 최낙현;황재호;김주경;김재명
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2007년도 하계종합학술대회 논문집
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    • pp.91-92
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    • 2007
  • LR-UWB utilizes BPSK and PPM for the transmission, which embeds the information in the transmitted pulse position. Meanwhile, by using coherent method, there is approximately 3dB enhancement on the BER performance over that using non-coherent method. However, due to the variable channel conditions, conventional system which uses fixed modulation is not efficient. To maximize the efficient and performance, in this paper, we propose an adaptive method including 4PPM+BPSK mode and 2PPM mode, in which the modulation method is dynamically changed depending on the channel condition which is determined according to the preamble correlation output.

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내잡음성 저속 전력선모뎀의 구현 (Development of Low speed Power-Line-Communication for High Noise)

  • 이승민;김명환;이흥호
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 하계학술대회 논문집 D
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    • pp.2660-2662
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    • 2003
  • In this paper, an appropriate modulation method was implemented as their results presented in details and verified by the simulations. The data compensation method at momentary high noise occurrence by using retransmission request techniques that uses error checking was discussed. Finally, application of other modulation method by detection of error rate per bit according to variation of channel error caused by electric equipment that is connected to power line was studied.

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멀티레벨 인버터의 Optimized Sine-Wave Modulation (Optimized Sine-Wave Modulation of Multi-Level inverters for Electric Propulsion System)

  • 진선호;조관준;곽준호;오진석
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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    • pp.200-201
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    • 2005
  • This paper is analyzed a new modulation method of OSW(Optimized Sine-Wave) modulation strategy for cascaded H-bridge multi-level inverter. The inverter structure was modified with the maximum output voltage level, and the switching angle was calculated easily to adjust the requested Vrms of the output. The suggested modulation method could make output waveform very close to the ideal sine wave, and the THD value was improved also remarkably.

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NTV 식별과정 없는 멀티레벨 인버터의 신속한 공간벡터 PWM 변조기법

  • 오진석;이종호;진선호;곽준호;조관준;김종도
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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    • pp.253-254
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    • 2006
  • this paper suggest a new space vector PWM modulation method with short processing time which does not need idenfication of nearest three vectors(NTV) and duty calculation for each vector. The suggested PWM method makes mean value of phase voltage to be same as reference during every modulation period by use of a triangle in small hexagon on multi-level vector space. This paper described the suggested modulation method can be successfully applied to the space vector modulation use of multi-level inverter by computer simulations and experiments.

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특정 고조파 제거를 위한 Cascaded H-bridge 7레벨 인버터의 특성해석 및 시뮬레이션 (Analysis and simulation of Cascaded H-bridge 7 level inverter for eliminating typical harmonic waveforms)

  • 진선호;오진석;조관준;곽준호;임명규;김장목
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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    • pp.1022-1028
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    • 2005
  • This paper is presented the analysis results and simulation results of cascaded H-bridge 7 level inverter with various modulation index. Stepped waveform having number of switching was used to eliminate harmonic components. Switching angles according to modulation index are calculated numerically. Therefore, 3 times of switching with 7 level topology and QWS(Quarter Wave Symmetry) could eliminate 5th and 7th harmonics. The harmonic characteristics are compared to those of space vector modulation method which known as common modulation method in industrial field. Stepped waveform method showed higher ability to reduce, especially lower order of harmonics.

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