• Title, Summary, Keyword: Signal to Noise Ratio

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De-Noising of Electroretinogram Signal Using Wavelet Transforms (웨이브렛 변환을 이용한 망막전도 신호의 잡음제거)

  • Seo, Jung-Ick;Park, Eun-Kyoo
    • Journal of Korean Ophthalmic Optics Society
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    • v.17 no.2
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    • pp.203-207
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    • 2012
  • Purpose: Electroretinogram(ERG) signal noise as well as conducting other bio-signal measurement were generated. It was intened to enhance the accuracy of retinal-related diagnosis with removing signal noise. Methods: Sampling signal was made with generating 60 Hz noise and white noise. The noise were removed using wavelet transforms and bandpass filter. De-noising frequency was compared with Fourier transform spectrum. Removed noises were compared numerically using SNR(signal to noise ratio). Results: The result compared Fourier transform spectrum was showed that 60 Hz noise removed completely and most of white noise was removed by wavelet transforms. 60 Hz and the white noise remained using bandpass filters. The result compared SNR showed that wavelet transforms was 22.8638 and bandpass filter was 4.0961. Conclusions: Wavelet transform showed less signal distortion in removing noise. ERG signal is expected to improve the accuracy of retinal-related diagnosis.

Pulse Integration Technique for VTS Application (VTS 적용을 위한 펄스 적분 기법)

  • Park, Dong-Hwa;Jeong, Se-Young;Choi, Kwan-Beum;Kim, Byung-Doo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39C no.7
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    • pp.521-527
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    • 2014
  • Most of Sea Surveillance Radar(SSR)s which are used in Vessel Traffic Service are Magnetron-based Non-Coherent Method and use the pulse integration technique having a signal to noise ratio enhancement function to satisfy a surveillance performance about target. Especially, Pulse Integration technique has an effect on target serveillance performance through signal to noise ratio, in addition, has an effect to improve a signal interference and noise spike. In this paper, we have a simulation experiment by using MATLAB simulation tool for appling a pulse integration technique in VTS system using a Non-Coherent radar, and verify an optimum pulse integration technique through out performance analysis between frequently use pulse integration techniques.

Performance Improvement of Perceptual Filter Using Noise Energy Control (잡음 에너지 제어를 통한 지각 필터 성능 개선)

  • Seo Joung-Kook;Cha Hyung-Tai
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.1
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    • pp.43-51
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    • 2005
  • In this paper, we propose an algorithm that improves a tone quality of a noisy audio signal in order to enhance a Performance of perceptual filter using noise energy control. Most of the algorithms which were proposed by the other researchers usually applied a filter using the noise energy acquired from a silent range. In this case. the improvement rate of tone quality decreases if the noise energy is changed by the magnitude or environment variation in a signal frame. But the Proposed method Provides the means to find a food estimated noise through energy control of the estimated noise which is obtained from a silent range. Also we can get the enhancement of tone qualify in low frequency band unlike other methods. To show the performance of the Proposed algorithm, various input signals which had a different signal-to-noise ratio (SNR) such as 5dB, l0dB, 15dB and 20dB were used to test the proposed algorithm. With the proposed algorithm, we could confirm the enhancement of tone quality in terms of segmental SNR (SSNR). noise-to-mask ration (NMR) and mean opinion score (MOS) test.

A Comparison of an Improvement Performance of S/N ratio with the Method of Weighting in DMTI System using a Uniform Pulse Train (일정한 펄스 예을 사용한 DMTI 시스템에서 Weighting 방법에 따른 S/N 북 개선 특성에 관한 비교)

  • Go, Seong-Seon;Lee, Jae-Gyun;Yun, Hyeon-Bo
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.22 no.1
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    • pp.41-45
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    • 1985
  • A degradation of the signal-to-noise ratio (SNR) in a digital moving target indicator system (DMTI System) can be Improved by weighting of the DMTI output pulses before the integration process. and it Is shown that the signal-to-noise ratio Is unproved as the nunlber of delay line cancellers. It is Known that signal-to-noise ratio obtained with optimum weighting is greater than that obtained with binomial weighting. An improvement performance of the signal-to-noise ratio for each case is presented through the results or a computter simulation.

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A Study on Weighted Filters using Expansion Mask in Salt and Pepper Noise Environments (Salt and Pepper 잡음 환경에서 확장 마스크를 이용한 가중치 필터에 관한 연구)

  • Hong, Sang-Woo;Kwon, Se-Ik;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.671-673
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    • 2016
  • In image data, noise occurs due to various external factors in the process of obtaining and transmitting. There are various types of noise according to the cause and form and research to remove this noise is being continued. Therefore the study suggested a way to filter to restore images damaged by salt and pepper noise which preserves non-noise signal and processes noise signal by expanding mask size according to the local mask noise density. In addition, as an objective evaluation standard of improvements, the study used PSNR(peak signal to noise ratio) to compare with previous methods.

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Analysis of Signal-to-Noise Ratio in High Field Multi-dimensional Magnetic Resonance Imaging (고자장 다차원 자기공명영상에서 신호대잡음비 분석)

  • Ahn, C.B.;Kim, H.J.;Chang, K.S.
    • Proceedings of the KIEE Conference
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    • pp.2783-2785
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    • 2003
  • In multi-dimensional magnetic resonance imaging, data is obtained in the spatial frequency domain. Since the signal variation in the spatial frequency domain is much larger than that in the spatial domain, analog-to-digital converts with wide conversion bits are required. In this paper, the quantization noise in magnetic resonance imaging is analyzed. The signal-to-quantization noise ratio(SQNR) in the reconstructed image is derived from the level of quantization in the data acquisition. Since the quantization noise is proportional to the signal amplitude, it becomes more dominant in high field imaging. Using the derived formula the SQNR for several MRI systems are evaluated, and it is shown that the quantization noise can be a limiting factor in high field imaging, especially in three dimensional imaging in magnetic resonance imaging.

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Design of a PIV objective maximizing the image signal-to-noise ratio

  • Chetelat Olivier;Kim Kyung Chun
    • 한국가시화정보학회:학술대회논문집
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    • pp.123-137
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    • 2001
  • PIV (particle image velocimetry) systems use a camera to take snapshots of particles carried by a fluid at some precise instants. Signal processing methods are then used to compute the flow velocity field. In this paper, the design of the camera objective (optics) is addressed. The optimization is done in order to maximize the signal-to-noise ratio of in-focus particles. Four different kinds of noise are considered: photon shot noise, thermal and read noise, background glow shot noise, and noise made by the other particles. A semi-empirical model for the lens aberrations of a two-doublet objective is first addressed, since further, it is shown that lens aberrations (low f-value $f_{\#}$) should be used instead of the Fraunhofer diffraction (high f-value) for the fitting of the particle image size with the pixel size. Other important conclusions of the paper include the expression of optimum values for the magnification M, for the exposure period $\tau$ and for the pixel size $\xi$.

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Improvement of Signal-to-Noise Ratio for Speech under Noisy Environment (잡음환경 하에서의 음성의 SNR 개선)

  • Choi, Jae-Seung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.7
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    • pp.1571-1576
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    • 2013
  • This paper proposes an improvement algorithm of signal-to-noise ratios (SNRs) for speech signals under noisy environments. The proposed algorithm first estimates the SNRs in a low SNR, mid SNR and high SNR areas, in order to improve the SNRs in the speech signal from background noise, such as white noise and car noise. Thereafter, this algorithm subtracts the noise signal from the noisy speech signal at each bands using a spectrum sharpening method. In the experiment, good signal-to-noise ratios (SNR) are obtained for white noise and car noise compared with a conventional spectral subtraction method. From the experiment results, the maximal improvement in the output SNR results was approximately 4.2 dB and 3.7 dB better for white noise and car noise compared with the results of the spectral subtraction method, in the background noisy environment, respectively.

A Study on Simulation Of Readout Signal of Magnet-Optic Disk (광자기 디스크 재생신호 시뮬레이션에 관한 연구)

  • 손장우;조순철;이세광;김순광
    • Journal of the Korean Magnetics Society
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    • v.6 no.3
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    • pp.174-178
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    • 1996
  • A method was studied which simulate signal and noise for magneto-optical disk drive system Recorded mark patterns and incident laser beam were modeled and discretized. Using them readout waveformj and amplitude were simulated. Adding Gaussian random noise to the readout signal and executing one dimensional discrete FFT (Fast Fourier Transform) algorithm signal and noise spectrum was estimated. From the spectrum, CNR (Carrier to Noise Ratio) was obtained.

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DANTE Fast MR imaging Using Frequency Modulation (주파수 변조를 이용한 MR DANTE 고속 영상법)

  • Ro, Y.M.;Chung, S.T.;Hong, I.K.;Cho, Z.H.
    • Proceedings of the KOSOMBE Conference
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    • v.1995 no.05
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    • pp.42-44
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    • 1995
  • The original DANTE sequence and its variations have limitation in excitation profile (a sinc function-like excitation) due to the finite duration of the DANTE pulsetrain. This sinc function-like selection profile excites only a small fraction of the spins in the pixel thereby results in poor signal to noise ratio (only about ${\sim}1%$ of normal MR imaging sequence). Therefore, this poor signal to noise ratio (SNR) has been the main drawback of the original DANTE sequence. To improve the signal to noise ratio, phases of individual RF pulses in the DANTE pulse train were modulated so that more spins in the object were excited ($1{\sim}3$). We have introduced a new FM (Frequency Modulation) DANTE sequence and analyzed the signal intensity and excitation profiles.

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