• 제목/요약/키워드: frequency modulation

검색결과 1,907건 처리시간 0.024초

Coupled-Ring Reflector 레이저 다이오드의 변조 특성 (Modulation Characteristics of Coupled-Ring Reflector Laser Diode)

  • 윤필환;김수현;정영철
    • 한국광학회:학술대회논문집
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    • 한국광학회 2006년도 하계학술발표회 논문집
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    • pp.315-316
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    • 2006
  • The modulation bandwidth, wavelength chirp of directly modulated coupled-ring reflector laser diode have been investigated using time-domain modeling. For a specific design, the modulation frequency could be 6 GHz and the frequency chirp could be in the range of $120^{\sim}200$ MHz/mA.

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GPS의 수신기 개발을 위한 기초연구 (A Basic Study on the Design of the GPS Receiver)

  • 정세모;정규형
    • 한국항해학회지
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    • 제6권1호
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    • pp.1-18
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    • 1982
  • In this paper, author studied on the elementary data required for the design of the receiver of Pseudo Noise (PN) phase modulation communication adopted in Global Positioning System(GPS). By computer simulation technique, the phase modulator, filters, and PN generator are designed, and also required bandwidth of R-F amplifier for carrier frequency in phase modulation system is investigated. It is verified that the optimum bandwidth is about 3 times of the PN frequency and almost independent of the carrier frequency. And the low pass filter required for demodulation of slow Boolean data is also found to be about 60 times of the data signal frequency.

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주파수변조 구동에 의한 가변릴럭턴스 스텝핑모우터의 불안정 해석 (Analysis of Dynamic Instability in a Variable-reluctance Stepping Motor Operated on Frequency-modulated Supply)

  • 권용수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1994년도 하계학술대회 논문집 A
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    • pp.114-118
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    • 1994
  • A comprehensive analytical study of frequency-modulated supply of the dynamic instability in a variable-reluctance stepping motor, is described. It is shown that stability can be achieved by frequency modulation provided that the phase displacement between the modulating signal and the rotor velocity oscillation lies between certain limits. A simplified expression is derived. based on the assumption of high inertia. This model is used to obtain a qualitative understanding of how frequency modulation influences the dynamic stability of the variable-reluctance motor.

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Combined Dithered Sigma-Delta Modulation based Random PWM Switching Scheme

  • Kim, Seo-Hyeong;Choi, Woo-Jin;Choi, Se-Wan;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • 제9권5호
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    • pp.667-678
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    • 2009
  • The PWM (Pulse Width Modulation) control signals have a drawback in that their power spectrum tends to be concentrated around the switching frequency and the resulting harmonic spikes cause an EMI (Electromagnetic Interference) and switching losses in semiconductors, etc. The SDM (Sigma-Delta Modulation) is a type of switching modulation used to reduce these harmonic spikes, and several SDM schemes are investigated in this paper. In the DSDM (Dithered SDM), the SDSDM (Space-Dithered SDM) and TDSDM (Time-Dithered SDM), the signals are classified by the location of their random dither additions. In these schemes, the switching frequency is spread by a random dither generator placed on the input or the output parts. Experimental results are presented where the advantages of the new proposed CDSDM (Combined Dithered SDM) are confirmed by applying to a buck converter.

변형 램프변조를 이용한 간섭 센서의 신호처리 (Signal processing of interferometric sensor using modified ramp modulation)

  • 강현숙;예윤해
    • 센서학회지
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    • 제16권5호
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    • pp.342-348
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    • 2007
  • A high-speed signal processor for Fabry-Perot interferometric sensors using modified ramp modulation is implemented. The main idea for the signal processing is to find a modulation waveform that could induce a linear frequency change in a laser diode to linearize the relationship between the optical phase shift and measurand. It is found that the waveform could be modeled as the addition of a linear term and an exponential term. A signal processor adopting modified ramp modulation technique is implemented and evaluated to find linearity, drift and random walk of $<{\pm}1.5%$, $0.4^{\circ}C$, $5.28{\times}10^{-4}^{\circ}C/{\sqrt{Hz}}$.

Suppression of Output Distortion in a Gyroscope using Fiber Amplifier/Source by Tracking of Optimum Modulation Amplitude

  • Park, Hee-Gap
    • Journal of the Optical Society of Korea
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    • 제3권2호
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    • pp.80-85
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    • 1999
  • We propose and demonstrate a new scheme for suppression of output distortion in an open-loop gyroscope employing an erbium-doped fiber amplifier/source (FAS). In addition to the main modulation for the rotation rate measurement, a small auxiliary modulation at a different frequency is used to extract an error signal, which is necessary for keeping the quasi-dc component of the feedback signal power at a constant level for varying rotation rate. By active tracking of the optimum modulation condition using this two-frequency modulation scheme, we obtain stable gyro output with suppressed distortion as well as stable FAS characteristics. We also calculate the distortion in the gyro response due to the feedback effect, from which we estimate the FAS gyro output distortion due to the residual ac feedback effect when the dc feedback effect is removed by the proposed scheme. The measured residual deviation agrees reasonably with the estimation.

주파수 변조 분광학 연구 (Study on Frequency Modulation Spectroscopy)

  • 서호성;류갑열
    • 한국광학회:학술대회논문집
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    • 한국광학회 1991년도 광학 및 양자전자학 워크샵
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    • pp.23-31
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    • 1991
  • 최근 레이저 분광학에 있어서 고감도 분광법으로 알려져 있는 주파수 변조 분광법(frequency modulation spectroscopy)과 레이저 광 주파수 안정화 응용에 대한 원리와 특징을 살펴본다. 또 super-cavity을 이용한 단일모드 He-Ne 레이저를 사용하여 FM 분광신호를 검출하고 그 신호특성에 대하여 기술하였다.

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Pulse Density Modulation Controlled Series Load Resonant Zero Current Soft Switching High Frequency Inverter for Induction-Heated Fixing Roller

  • Sugimura, Hisayuki;Kang, Ju-Sung;Saha, Bishwajit;Lee, Hyun-Woo;Nakaoka, Mutsuo
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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    • pp.226-228
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    • 2006
  • This paper presents the two lossless auxiliary inducors-assisted voltage source type half bridge(single ended push pull:SEPP) series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation forwide its output power regulation ranges and load variations under constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operatprinciple is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation charactertics-based on the high frequency PDM strategy. The experimenoperating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimenones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliimplemented here is proved from the practical point of view.

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VVC 다이오드를 사용한 수정주파수 변조기의 응용 (The Application of Frequency Modulated Quartz Oscillator Using a V.V.C. Diode.)

  • 정만영;김영웅;김병식
    • 대한전자공학회논문지
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    • 제9권5호
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    • pp.19-26
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    • 1972
  • V.V.C다이오드를 사용한 수정주파수 변조방식에 대한 간단한 소개와 그의 변사직선성, 변조왜곡 및 중심주파수의 안정도등 제반특성이 휴대용 간이형 FM송신기 변체기로서 적합한지를 실험적결과로써 기각하였다. 또한 52.750MHz에서 직접주파수변조하는 단일채늘 송수신기 및 10.7MHz에서 순파수변조하고 채늘발진기에서 나오는 주파수와 합성하여 운용주파수로 하는 2채늘 송수신기(무조정으로40채늘)등 이종류의 송수신기를 시작품으로 제작히여 우수한 종합특성을 얻었으며 이로써 실용성을 입증하였다.

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MQAM, DPSK, OFDM-MQAM과 OFDM-DPSK의 위상 잡음 영향 연구 (Phase Noise Influence on SER of MQAM, DPSK, OFDM-MQAM, OFDM-DPSK)

  • 권요안;김인석
    • 한국전자파학회논문지
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    • 제18권2호
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    • pp.219-226
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    • 2007
  • 본 논문에서는 DPSK(Quadrature Phase Shift Keying), MQAM(M-ary quadrature Amplitude Modulation), OFDM(Orthogonal Frequency Division Multiplex)-MQAM, OFDM-DPSK 변조 방식에 대한 SER(Symbol Error Rate)을 위상 잡음에 대한 영향을 정량적으로 도출하였다. 시뮬레이션(MATLAB)을 이용하여 위상 잡음이 없는 이상적인 경우와 비교하였으며, 또한 상기 변조 방식에 대하여 심벌 레이트와 변조 대역폭간의 비에 따른 위상 잡음 영향을 분석하였고, 각 변조에서 요구되는 최소 위상 잡음 조건을 제시하고 도출하였다.