• Title/Summary/Keyword: Modulation method

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Decision of Modulation Index of Current-Source TPWM Inverter for Minimization of Speed Ripple and Position Error (속도맥동 및 위치오차를 최소로 하는 전류원 TPWM 인버터의 변조도 결정)

  • 구본호;권우현;김수중
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.11
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    • pp.1819-1828
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    • 1989
  • In this paper, we determined the modulation index for minimization of speed ripple and position error using maximum speed ripple (SRF) and maximum position error(PEF) in current source TPWM inverter. Through computer simulation, we compared with total current harmonic distortion, SRF and PEF for square wave modulation method and TPWM method. As a result, it turns out that square wave modulation method is superior to TPWM method of 3 pulses per half cycle in speed ripple and position error contents. And TPWM is better than square wave method when pulse number is more than 5. Also, in these pulse numbers, moduladtion index of minimum speed ripple and munimum position error is 0.91.

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A Video-Rate Super-Twisted Nematic (STN) Liquid Crystal DisplayUusing a New Row Signal Modulation Method (새로운 행 신호 변조 방법에 의한 고속 STN 액정표시기)

  • 이승우;한철희
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.5
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    • pp.69-79
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    • 1998
  • In this paper, we have proposed a new row signal modulation method in order to display multi-gray image using super-twisted nematic liquid crystal display (STN-LCD), which has no complex computation, high selection ratio, and low driving voltage. By the proposed method, we have implemented a 320*240, 8-gray video-rate STN-LCD. For achieving a video-rate STN-LCD, 6 lines are selected at a time. Each row line is selected 8 times by equally distributed pulses throughout one frame. As a result, we can get 8 gray, video-rate image. The repetive horizontal pattern and the filckering was analyzed and the improvements have been presented.

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Single-Phase Inverter System Using New Modulation Method (새로운 변조방식을 사용한 단상 인버터 시스템)

  • Lee, Hyoung-Ju;Won, Hwa-Young;Lim, Seung-Beom;Hong, Soon-Chan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.5
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    • pp.29-36
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    • 2010
  • In this paper, we propose a single-phase inverter system using new modulation method. The proposed system is composed of a buck-boost converter and an inverter and controlled by PWAM scheme. PWAM method is a new modulation method which is the incorporation of PWM(Pulse Width Modulation) and PAM(Pulse Amplitude Modulation) methods. The DC voltage which is the input voltage of buck-boost converter is converted into a variable DC voltage by buck-boost converter. Also, the variable DC voltage which is the output voltage of buck-boost converter is converted into a sinusoidal AC voltage by inverter. The input voltage of inverter is processed by PWM switching in PWM section and bypassed in PAM section. By using PWAM method, switching action is not existed in PAM section and thus the times of switching is reduced. As a result, the switching loss can be reduced.

Performance Analysis of M-ary APSK Modulation Method in the Presence of Phase Noise (M-ary APSK 변조 방식의 위상잡음 영향 분석)

  • Kim, Young-Wan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.7
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    • pp.1511-1517
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    • 2014
  • Based on the simulation model for phase noise effect, the phase noise performance of communication system using the M-ary APSK modulation method is analyzed in this paper. The phase noise effects for APSK higher order modulation method are modeled by considering the signal constellations of the modulation methods. The simulation model is verified by comparing the analytic results for lower order modulation signals with simulated results for those modulation signals. Based on the simulation model, then, the phase noise effects for M-ary APSK are analyzed. The simulated results for PSK lower order modulation signals are in agreement with the results by the analytic model in the order of 1 %. The proper phase noise effects for M-ary APSK modulation signals are deduced by the simulation model. Also, the required signal-to-noise ratios of phase noise are proposed for phase noise degradations, which are used as the design parameter that considers the phase noise effect.

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 $2.89{\times}10^{-1}$.

An Infrared Communication Module for the Enhancement of Hearing Aids (보청기 성능 향상을 위한 적외선 통신 모듈)

  • Park, Seong Mo
    • Smart Media Journal
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    • v.7 no.3
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    • pp.29-34
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    • 2018
  • This paper presents a study on adapting optical communication technology using infrared ray for the enhancement of hearing aids in noisy environment. The transmitter module containing microphone and infrared ray-emitting diode converts audio signal to infrared optical signal and sends it out in the air. The receiver module located in a distance receives the infrared signal, converts it to electrical signal, and transfers it to an input of a digital hearing aid. Especially, the receiver module needs to be small, low voltage, and consume low power since it will be attached to hearing aids. Experiments with applying infrared communication technology of digital modulation method and analog non-modulation method show that the analog non-modulation method is adequate for infrared communication of approximately 5m distance indoor. Prototypes of transmitter module and receiver module were manufactured, and internal parameters of the digital hearing aid were adjusted to confirm normal transmit-receive operation of audio signals.

Modulation Technique of Dual Active Bridge Converter to Improve Efficiency of Smart Transformers in Railroad Traction System (철도차량용 지능형 변압기 손실 저감을 위한 Dual Active Bridge 컨버터의 Modulation 기법 연구)

  • Kim, Sungmin;Lee, Seung-Hwan;Kim, Myung-Yong
    • Journal of the Korean Society for Railway
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    • v.19 no.6
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    • pp.727-735
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    • 2016
  • Smart transformers are effective at reducing the weight and increasing the efficiency of traction systems for railroad applications. A smart transformer generally consists of rectifier modules and the Dual-Active-Bridge (DAB) converter modules. The efficiency of the smart transformer depends on not only the electrical characteristics, but also on the control method of the converter modules. Especially, a DAB converter has a high order degree of freedom of voltage modulation to control the power transferred through the high frequency transformer, and a voltage modulation method, are very critical for the efficiency of the DAB converter. This paper proposes a new voltage modulation method for the DAB converter to increase the efficiency in the low/medium power transfer condition. The proposed modulation method controls the reactive power in the high frequency transformer, making it zero. And, the switching loss is dramatically reduced by using the received converter module as a diode rectifier. The feasibility of the proposed modulation method is verified by computer simulation of the 900Vdc DAB converter power control.