• Title/Summary/Keyword: Modulation method

Search Result 304, Processing Time 0.187 seconds

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

  • Ma, Lin Chuan;Hwang, Jae-Ho;Choi, Nack-Hyun;Kim, Jae-Moung
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.33 no.12A
    • /
    • pp.1177-1184
    • /
    • 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.

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

  • Park, Geon-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2005.05b
    • /
    • pp.119-122
    • /
    • 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.

  • PDF

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

  • Hong, Ki-Phil;Oh, Won-Seok;Kim, Young-Tae;Kim, Hee-Jun
    • Proceedings of the KIEE Conference
    • /
    • 1994.07a
    • /
    • pp.265-269
    • /
    • 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.

  • PDF

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

  • 신용조
    • Journal of the Korean Institute of Telematics and Electronics T
    • /
    • v.35T no.3
    • /
    • pp.25-30
    • /
    • 1998
  • In this Paper, a new method is proposed to identify a modulation method in the case of unknown digitally modulated input signals. The proposed identification method is implemented with an artificial neural network which is based on characteristic features extracted from the instantaneous amplitude, the instantaneous phase and the instantaneous frequency of the input signals. The proposed method was simulated with 8 type signals in a noisy communication environment. The results show that the artificial neural network can accurately recognize all kinds of patterns.

  • PDF

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

  • 최태섭;최은범;사공석진
    • Proceedings of the IEEK Conference
    • /
    • 2003.11c
    • /
    • pp.369-373
    • /
    • 2003
  • As most of the powerline modems use spread spectrum modulation method which has strong immunity against the narrowband fading, or psk modulation method, the amplitude of the signal contains no useful informations. In this paper, we used class D amplifier to implement the drive circuit of the analog front end, and showed that it has great superiority over other existing drive circuits in rapidly impedance changing powerline channel.

  • PDF

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

  • Choi, Nak-Hyun;Hwang, Jae-Ho;Kim, Joo-Kyung;Kim, Jae-Moung
    • Proceedings of the IEEK Conference
    • /
    • 2007.07a
    • /
    • pp.91-92
    • /
    • 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.

  • PDF

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

  • Lee, Seung-Min;Kim, Myung-Hwan;Lee, Heung-Ho Lee
    • Proceedings of the KIEE Conference
    • /
    • 2003.07d
    • /
    • pp.2660-2662
    • /
    • 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.

  • PDF

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

  • Jin, Sun-Ho;Jo, Kwan-Jun;Kwak, Jun-Ho;Oh, Jin-Suk
    • Proceedings of the Korean Society of Marine Engineers Conference
    • /
    • 2005.11a
    • /
    • pp.200-201
    • /
    • 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.

  • PDF

NTV 식별과정 없는 멀티레벨 인버터의 신속한 공간벡터 PWM 변조기법

  • Oh, Jin-Seok;Lee, Jong-Ho;Jin, Sun-Ho;Kwak, Jun-Ho;Jo, Kwan-Jun;Kim, Jong-Do
    • Proceedings of the Korean Society of Marine Engineers Conference
    • /
    • 2006.06a
    • /
    • pp.253-254
    • /
    • 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.

  • PDF

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

  • Jin, Sun-Ho;Oh, Jin-Suk;Jo, Kwan-Jun;Kwak, Jun-Ho;Lim, Myoung-Kyu;Kim, Jang-Mok
    • Proceedings of the Korean Society of Marine Engineers Conference
    • /
    • 2005.06a
    • /
    • pp.1022-1028
    • /
    • 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.

  • PDF