• Title/Summary/Keyword: 잡음광소거

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Optical Noise Reduction using a Solar Cell in a Wireless Optical Interconnection (무선광 연결에서 솔라 셀을 이용한 잡음광 소거)

  • 이성호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.4
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    • pp.336-342
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    • 2003
  • In this paper, a new differential detector is introduced, in which a solar cell is used to reduce the low frequency interference from environmental optical noise. The solar cell also supplies electrical power to the detector circuit using the optical noise power. The DC voltage from the solar cell is used as a power supply to the detector, and the AC voltage is used to reduce the optical noise in a photodiode with the differential detection method. The signal to noise ratio was improved by about 20 dB.

Optical Noise Reduction in A Wireless Optical System using Two Orthogonal Polarizers (무선광시스템에서 직교편광기를 이용한 잡음광의 소거)

  • 이성호;이준호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.8
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    • pp.891-897
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    • 2003
  • In this paper, a circular orthogonal polarizer is newly fabricated and used in a differential detector to reduce the optical noise in a wireless optical interconnection. The orthogonal polarizer is composed of two semicircular polarizers whose transmission axes are orthogonal each other, The orthogonal polarizer is driven by a motor and matched to the signal polarization in order to reduce the optical noise interference. The noise power was reduced by about 20 dB using a differential detector with the orthogonal polarizer.

Optical Noise Reduction Using Polarizers in Wireless Optical Interconnections (무선광연결에서 편광판을 이용한 광잡음 감소)

  • 이성호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.3
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    • pp.365-371
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    • 2000
  • In this paper, we introduce a noise reduction method using polarizers in a wireless optical interconnections. If we use polarizers in a differential detector, the noise reduction capability is improved. In a case that two optical signal beams of similar wavelength are overlapped in space and crosstalk is a serious problems, we can detect each channel separately without crosstalk using two orthogonal polarizers. This method is very simple and easy to use.

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Optical Noise Reduction Using Approximate Average Noise Detection in Wireless Optical Interconnection (무선광연결에서 근사적 평균잡음검출을 이용한 광잡음 감소)

  • 이성호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.2
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    • pp.228-233
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    • 2000
  • In this paper, we introduce a differential detection method using approximate average noise detection, which improves the noise reduction efficiency in a wireless optical interconnection. Approximate average noise detection reduces the output voltage fluctuation that may result from the instantaneous change of the coupling coefficients with the movement of some objects or human beings. This method is very useful for noise reduction in an environment with optical noise whose spatial distribution varies instantaneously.

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Reducing the Effects of Optical Noise in an Optical Wireless System Using a Fiber Coupler (무선광시스템에서 광섬유 커플러를 이용한 잡음광의 영향 감소)

  • Lee Seong-Ho
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.5 s.96
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    • pp.494-500
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    • 2005
  • In this paper, optical noise is reduced by a differential detector with an optical fiber coupler in an optical wireless system. An $1\times2$ optical fiber coupler divides the received optical signal by 2 equally, and connects them to the two photodiodes in a differential detector. The output voltage variation due to the abrupt change of optical noise distribution in space disappears because the two photodiodes effectively detect the optical signal at the same point. The signal to noise ratio in a differential detector with a fiber coupler was 8 dB higher than in a single photodiode with an optical filter.

SNR Improvement in A Wireless Optical Differential Detector Using Plastic Fibers (플라스틱 광섬유를 이용한 무선광 차동검출기의 신호대잡음비 개선)

  • Lee Seong-Ho
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.4 s.95
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    • pp.410-417
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    • 2005
  • In this paper, optical noise is reduced by a differential detector with a plastic optical fiber bundle in a wireless optical interconnection. A plastic optical fiber bundle divides the received optical signal equally and connects it to two photodiodes. In this configuration two photodiodes effectively detect the optical signal at one point, and the output voltage variation due to the abrupt change of optical noise distribution in space disappears. The signal to noise ratio in a differential detector with a fiber bundle was improved to be $10\;\cal{dB}$ higher than in a single photodiode with an optical filter.

Optical Noise Reduction using a Digital Potentiometer in a Wireless Optical Differential Detector (무선광 차동검출기에서 디지털가변저항을 이용한 잡음광의 감소)

  • 이성호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.6
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    • pp.599-604
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    • 2002
  • In this paper, a digital potentiometer is used as a load resistor of a wireless optical differential detector with a polarizer, to improve the noise reduction capability. In this structure, the noise voltages of the two photodiodes are made equal by controlling a digital potentiometer and the optical noise is cancelled out. With a digital potentiometer, the signal to noise ratio is enhanced by about 23 dB.

A Wireless Optical Differential Detector using a Beam Splitter (빔 분할기를 이용한 무선광 차동검출기)

  • 이성호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.1
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    • pp.96-102
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    • 2004
  • In this paper, optical noise is reduced by a differential detector, which is composed of a beam splitter and two photodiodes whose spectral responses are different each other. In this configuration, the automatic gain control circuit is not required for noise cancellation because the noise intensities at the two photodiodes are kept equal by a beam splitter. The signal to noise ratio in a differential detector with a beam splitter was improved to be 14 ㏈ higher than in a single photodiode with optical filtering.

Reducing the Effects of Noise Light in A Visible Light Communication System Using Orthogonal Polarizers (가시 광통신에서 직교 편광기를 이용한 잡음광의 영향 감소)

  • Hwang, Da-Hyun;Lee, Seong-Ho
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.5
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    • pp.560-567
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    • 2011
  • In this paper, we reduced the optical noise interference using polarizers in a visible light communication system. In a transmitter, two light-emitting diodes(LEDs) are modulated synchronously by the original and the reversed signals of the transmitted data, and the two LED lights are radiated through orthogonal polarizers. In a receiver, two optical signals are detected through orthogonal polarizers and differentially amplified to remove the optical noise. In an environment that noise light from a fluorescent lamp is much stronger than the signal, the receiver with orthogonal polarizers removed the 120 Hz noise, and synchronous light transmission of the original and the reversed signals using two LEDs reduced the illumination flickering to about one-eighth that using one LED.

Signal to Noise Improvement in Optical Wireless Interconnection Using A Differential Detector (차동검출기를 이용한 무선광연결에서 신호대잡음비의 개선)

  • 이성호;강희창
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.1
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    • pp.54-62
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    • 1999
  • In this paper, we investigated the signal-to-noise ratio improvement in a differential detector, which is a function of the optical noise coupling ratio and the differential gain ratio. A differential detector consists of two photodiodes and a differential amplifier. The differential detector reduced the noise component and improved the signal-to-noise ratio by about 20 dB when the differential gain ratio equals to the optical noise coupling ratio. The differential detector is very effective in removing the environmental optical noise or interference from an adjacent optical channel. This method is also effective when the noise wavelength is similar to the signal.

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