• Title, Summary, Keyword: Intensity modulation

Search Result 219, Processing Time 0.072 seconds

The Optimal Condition for Velocity Modulation

  • Park, Joon-Suk;Kim, Do-Nyun
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • /
    • pp.1157-1159
    • /
    • 2003
  • The effect of the scan velocity modulation is studied. The effect of the velocity modulation on the picture image is judged from the intensity profile of the image. The intensity profile is obtained as time integral of moving Gaussian beam. To confirm the applicability of this integral formula, the measurement and simulation data is compared. And by calculating the intensity profile for different amounts of velocity modulation, the optimum modulation displacement that gives the best image quality is obtained. This optimum modulation displacement can be used in designing scan velocity modulation system.

  • PDF

Analyses of Characteristics for Direct Intensity Modulation Scheme

  • Kim, Jung-Tae
    • Journal of information and communication convergence engineering
    • /
    • v.4 no.3
    • /
    • pp.101-104
    • /
    • 2006
  • We have investigated the spectral characteristics of the semiconductor lasers locked to the sidebands of the master laser in this paper, which were expressed by a series of the Bessel function. The numerical model for the semiconductor lasers based on the typical Lang's equation has been extended in order to take into account the simultaneous injection of the multiple sidebands of the directly modulated ML. We analyses characteristics of direct intensity modulation.

Subcarrier Intensity Modulation-Spatial Modulation for Optical Wireless Communications (광 무선통신을 위한 SIM-SM 변조)

  • Cheng, Yan;Hwang, Seung-Hoon
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.38A no.12
    • /
    • pp.1086-1093
    • /
    • 2013
  • In this paper, we propose a novel modulation that combines the spatial modulation (SM) with the subcarrier intensity-modulation (SIM) for optical wireless communications. The performance of SIM-SM scheme is compared to a conventional SIM by computer simulation. For the spectral efficiency (SE) of 2bits/s/Hz, the performance gain about 2dB is achieved. As the SE increases to 3bit or 4bits/s/Hz, the Eb/N0 gain becomes about 5dB. It is shown the attenuation for the SIM is more serious than the SIM-SM according to increasing the number of the subcarriers.

One Idea on a Three Dimensional Measuring System Using Light Intensity Modulation

  • Fujimoto Ikumatsu;Cho In-Ho;Pak Jeong-Hyeon;Pyoun Young-Sik
    • International Journal of Control, Automation, and Systems
    • /
    • v.3 no.1
    • /
    • pp.130-136
    • /
    • 2005
  • A new optical digitizing system for determining the position of a cursor in three dimensions(3D) and an experimental device for its measurement are presented. A semi-passive system using light intensity modulation, a technology that is well known in radar ranging, is employed in order to overcome precision limitations imposed by background light. This system consists of a charge-coupled device camera placed before a rotating mirror and a light-emitting diode whose intensity is modulated. Using a Fresnel pattern for light modulation, it is verified that a substantial improvement of the signal to noise ratio is realized for the background noise and that a resolution of less than a single pixel can be achieved. This opens the doorway to the realization of high precision 3D digitized measurement. We further propose that a 3D position measurement with a monocular optical system can be realized by a numerical experiment if a linear-period modulated waveform is adopted as the light-modulating one.

Dimmable Spatial Intensity Modulation for Visible-light Communication: Capacity Analysis and Practical Design

  • Kim, Byung Wook;Jung, Sung-Yoon
    • Current Optics and Photonics
    • /
    • v.2 no.6
    • /
    • pp.532-539
    • /
    • 2018
  • Multiple LED arrays can be utilized in visible-light communication (VLC) to improve communication efficiency, while maintaining smart illumination functionality through dimming control. This paper proposes a modulation scheme called "Spatial Intensity Modulation" (SIM), where the effective number of turned-on LEDs is employed for data modulation and dimming control in VLC systems. Unlike the conventional pulse-amplitude modulation (PAM), symbol intensity levels are not determined by the amplitude levels of a VLC signal from each LED, but by counting the number of turned-on LEDs, illuminating with a single amplitude level. Because the intensity of a SIM symbol and the target dimming level are determined solely in the spatial domain, the problems of conventional PAM-based VLC and related MIMO VLC schemes, such as unstable dimming control, non uniform illumination functionality, and burdens of channel prediction, can be solved. By varying the number and formation of turned-on LEDs around the target dimming level in time, the proposed SIM scheme guarantees homogeneous illumination over a target area. An analysis of the dimming capacity, which is the achievable communication rate under the target dimming level in VLC, is provided by deriving the turn-on probability to maximize the entropy of the SIM-based VLC system. In addition, a practical design of dimmable SIM scheme applying the multilevel inverse source coding (MISC) method is proposed. The simulation results under a range of parameters provide baseline data to verify the performance of the proposed dimmable SIM scheme and applications in real systems.

Eu(Ⅲ) Luminescence Phase-Modulation Spectroscopy as a Site-Selective Probe of Y Zeolite

  • 황한신;이선배;장두전
    • Bulletin of the Korean Chemical Society
    • /
    • v.19 no.4
    • /
    • pp.471-475
    • /
    • 1998
  • Phase shift spectroscopy is applied to Eu(Ⅲ) luminescence from $Eu^{3+}$-exchanged Y zeolite. The phase shift and intensity modulation of luminescence following intensity-modulated excitation are measured as a function of modulation frequency and they are fitted into a double exponential decay. The fast decay component, compared with the slow one, has narrower spectral bandwidth and is emitted from the $Eu^{3+}$ that has more polar and definite environment with higher symmetry and that interacts more easily with hydrated water molecules. The fast decay component is attributed to $Eu^{3+}$ at site Ⅱ' while the slow one to $Eu^{3+}$ at sites Ⅰ' and Ⅰ.

  • PDF

Irradiance Distribution Analysis of Inclined-cut Multi-mode Optical Fiber for Optical Microphone Design (광 마이크로폰 설계를 위한 경사 절단된 멀티모드 광섬유의 조도분포 해석)

  • Kim, Kyong-Woo;Che, Woo-Seong;Kwon, Hyu-Sang
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.693-698
    • /
    • 2008
  • For designing intensity modulation type optical microphone, the irradiance distribution which can be applied to inclined-cut geometrical configuration is suggested. The model is important in analysis of response characteristics f3r intensity modulation type optical microphone. To overcome low sensitivity problem in intensity modulation type optical microphone, inclined-cut optical fiber is considered here. Based on optical geometry, the inclined-cut optical fiber sensor is designed and fabricated. The experiments are carried out to evaluate sensor performance.

  • PDF

Irradiance Distribution Analysis of Inclined-cut Multi-mode Optical Fiber for Optical Microphone Design (광 마이크로폰 설계를 위한 경사 절단된 멀티모드 광섬유의 조도분포 해석)

  • Kim, Kyong-Woo;Che, Woo-Seong;Kwon, Hyu-Sang
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.18 no.12
    • /
    • pp.1270-1277
    • /
    • 2008
  • For designing intensity modulation type optical microphone, the irradiance distribution which can be applied to inclined-cut geometrical configuration is suggested. The model is important in analysis of response characteristics for intensity modulation type optical microphone. To overcome low sensitivity problem in intensity modulation type optical microphone, inclined-cut optical fiber is considered here. Based on optical geometry, the inclined-cut optical fiber sensor is designed and fabricated. The experiments are carried out to evaluate sensor performance.