• Title, Summary, Keyword: Signal to Noise Ratio

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Multidimensional Adaptive Noise Cancellation of Stress ECG Signal

  • Gautam, Alka;Lee, Young-Dong;Chung, Wan-Young
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.285-288
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    • 2008
  • In ubiquitous computing environment the biological signal ECG (Electrocardiogram signal) is usually recorded with noise components. Adaptive interference (or noise) canceller do adaptive filtering of the noise reference input to maximally match and subtract out noise or interference from the primary (signal plus noise) input thereby adaptively eliminate unwanted interference from the ECG signal. Measured Stress ECG (or exercise ECG signal) signal have three major noisy component like baseline wander noise, motion artifact noise and EMG (Electro-mayo-cardiogram) noise. These noises are not only distorted signal but also root of incorrect diagnosis while ECG data are analyzed. Motion artifact and EMG noises behave like wide band spectrum signals, and they considerably do overlapping with the ECG spectrum. Here the multidimensional adaptive method used for filtering which is more effective to improve signal to noise ratio.

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Study on Cooperative Communication for Underwater Acoustic Channels (수중음향 채널에서의 협력통신에 대한 연구)

  • Kang, Heehoon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.10
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    • pp.168-174
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    • 2015
  • In this paper, we analyze the performance of cooperative communication techniques on an underwater channel. By analyzing the BER performance of cooperative transmission protocol and combining types ERC, FRC, SNRC and ESNRC on underwater channel, through the result, we can choose an a proper cooperative technique for an underwater channel. The analysis of BER performance is achieved by a computer simulation.

The Effect of Grid Ratio and Material of Anti-scatter Grid on the Scatter-to-primary Ratio and the Signal-to-noise Ratio Improvement Factor in Container Scanner X-ray Imaging

  • Lee, Jeonghee;Lim, Chang Hwy;Park, Jong-Won;Kim, Ik-Hyun;Moon, Myung Kook;Lim, Yong-Kon
    • Journal of Radiation Protection and Research
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    • v.42 no.4
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    • pp.197-204
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    • 2017
  • Background: X-ray imaging detectors for the nondestructive cargo container inspection using MeV-energy X-rays should accurately portray the internal structure of the irradiated container. Internal and external factors can cause noise, affecting image quality, and scattered radiation is the greatest source of noise. To obtain a high-performance transmission image, the influence of scattered radiation must be minimized, and this can be accomplished through several methods. The scatter rejection method using an anti-scatter grid is the preferred method to reduce the impact of scattered radiation. In this paper, we present an evaluation the characteristics of the signal and noise according to physical and material changes in the anti-scatter grid of the imaging detector used in cargo container scanners. Materials and Methods: We evaluated the characteristics of the signal and noise according to changes in the grid ratio and the material of the anti-scatter grid in an X-ray image detector using MCNP6. The grid was composed of iron, lead, or tungsten, and the grid ratio was set to 2.5, 12.5, 25, or 37.5. X-ray spectrum sources for simulation were generated by 6- and 9-MeV electron impacts on the tungsten target using MCNP6. The object in the simulation was designed using metallic material of various thicknesses inside the steel container. Using the results of the computational simulation, we calculated the change in the scatter-to-primary ratio and the signal-to-noise ratio improvement factor according to the grid ratio and the grid material, respectively. Results and Discussion: Changing the grid ratios of the anti-scatter grid and the grid material decreased the scatter linearly, affecting the signal-to-noise ratio. Conclusion: The grid ratio and material of the anti-scatter grid affected the response characteristics of a container scanner using high-energy X-rays, but to a minimal extent; thus, it may not be practically effective to incorporate anti-scatter grids into container scanners.

Enhancement of Signal-to-noise Ratio Based on Multiplication Function for Phi-OTDR

  • Li, Meng;Xiong, Xinglong;Zhao, Yifei;Ma, Yuzhao
    • Current Optics and Photonics
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    • v.2 no.5
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    • pp.413-421
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    • 2018
  • We propose a novel methodology based on the multiplication function to improve the signal-to-noise ratio (SNR) for vibration detection in a phi optical time-domain reflectometer system (phi-OTDR). The extreme-mean complementary empirical mode decomposition (ECEMD) is designed to break down the original signal into a set of inherent mode functions (IMFs). The multiplication function in terms of selected IMFs is used to determine a vibration's position. By this method, the SNR of a phi-OTDR system is enhanced by several orders of magnitude. Simulations and experiments applying the method to real data prove the validity of the proposed approach.

Research About Filter Association and Clinical Effect Noise Reduction of Digital Medical Imaging System (디지털 의료영상에서 Noise감소를 위한 필터조합과 임상적 효과에 관한 연구)

  • Min, Jung-Whan;Kim, Jung-Min;Jeong, Hea-Won;Ok, Chi-Il
    • Journal of radiological science and technology
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    • v.30 no.4
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    • pp.329-334
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    • 2007
  • This paper is for investigation of the noise reduction effect all 20 filters by combining Low Pass Filter(LPF) 5 kinds, High Pass Filter(HPF) 4 kinds, Median Filter(MF) 11 kinds. Noise is added to reduce noise and minimize the quality degradation in medical imaging system. We also compared Peak Signal to Noise Ratio(PSNR), Mean Square Error(MSE) for all the combinations of different filters. As a result, noise decrease appeared in the LPF3*3#1 + HPF3*3#1 + Vertical3*1 of highest filter. We confirmed noise reduction effect by applying the proposed filter combination in many fields of medical imaging applications.

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A Linear Prediction Based Estimation of Signal-to-Noise Ratio in AWGN Channel

  • Kamel, Nidal S.;Jeoti, Varun
    • ETRI Journal
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    • v.29 no.5
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    • pp.607-613
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    • 2007
  • Most signal-to-noise ratio (SNR) estimation techniques in digital communication channels derive the SNR estimates solely from samples of the received signal after the matched filter. They are based on symbol SNR and assume perfect synchronization and intersymbol interference (ISI)-free symbols. In severe channel distortion where ISI is significant, the performance of these estimators badly deteriorates. We propose an SNR estimator which can operate on data samples collected at the front-end of a receiver or at the input to the decision device. This will relax the restrictions over channel distortions and help extend the application of SNR estimators beyond system monitoring. The proposed estimator uses the characteristics of the second order moments of the additive white Gaussian noise digital communication channel and a linear predictor based on the modified-covariance algorithm in estimating the SNR value. The performance of the proposed technique is investigated and compared with other in-service SNR estimators in digital communication channels. The simulated performance is also compared to the Cram$\acute{e}$r-Rao bound as derived at the input of the decision circuit.

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Improvement of Noise Performance in Phased-Array Receivers

  • Kim, Jung-Hyun;Jeong, Jin-Ho;Jeon, Sang-Geun
    • ETRI Journal
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    • v.33 no.2
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    • pp.176-183
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    • 2011
  • This paper presents a new analytical approach and experimental verification for the improvement of noise performance in phased-array receivers. For analysis purposes, a multi-channel array system is converted into an equivalent single-channel system, such that the two presents the identical signal and noise powers at the output, respectively. We define an effective gain, noise figure, and signal-to-noise ratio in the equivalent system. Through the proposed approach, the noise performance of the array receiver is analyzed in a general and straightforward manner and then compared to that of each individual array channel. In addition, the phase noise of the array system is analyzed in a rigorous manner, showing its effective reduction by a factor of the array size. The predicted improvement of the noise performance is experimentally confirmed with a CMOS integrated phased-array receiver.

Acoustic Feedback and Noise Cancellation of Hearing Aids by Deep Learning Algorithm (심층학습 알고리즘을 이용한 보청기의 음향궤환 및 잡음 제거)

  • Lee, Haeng-Woo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.14 no.6
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    • pp.1249-1256
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    • 2019
  • In this paper, we propose a new algorithm to remove acoustic feedback and noise in hearing aids. Instead of using the conventional FIR structure, this algorithm is a deep learning algorithm using neural network adaptive prediction filter to improve the feedback and noise reduction performance. The feedback canceller first removes the feedback signal from the microphone signal and then removes the noise using the Wiener filter technique. Noise elimination is to estimate the speech from the speech signal containing noise using the linear prediction model according to the periodicity of the speech signal. In order to ensure stable convergence of two adaptive systems in a loop, coefficient updates of the feedback canceller and noise canceller are separated and converged using the residual error signal generated after the cancellation. In order to verify the performance of the feedback and noise canceller proposed in this study, a simulation program was written and simulated. Experimental results show that the proposed deep learning algorithm improves the signal to feedback ratio(: SFR) of about 10 dB in the feedback canceller and the signal to noise ratio enhancement(: SNRE) of about 3 dB in the noise canceller than the conventional FIR structure.

A Study on the Enhancement of Detection Performance of Space Situational Awareness Radar System

  • Choi, Eun-Jung;Lee, Jonghyun;Cho, Sungki;Moon, Hyun-Wook;Yum, Jea-Myong;Yu, Jiwoong;Park, Jang-Hyun;Jo, Jung Hyun
    • Journal of Astronomy and Space Sciences
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    • v.35 no.4
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    • pp.279-286
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    • 2018
  • Radar sensors are used for space situational awareness (SSA) to determine collision risk and detect re-entry of space objects. The capability of SSA radar system includes radar sensitivity such as the detectable radar cross-section as a function of range and tracking capability to indicate tracking time and measurement errors. The time duration of the target staying in a range cell is short; therefore, the signal-to-noise ratio cannot be improved through the pulse integration method used in pulse-Doppler signal processing. In this study, a method of improving the signal-to-noise ratio during range migration is presented. The improved detection performance from signal processing gains realized in this study can be used as a basis for comprehensively designing an SSA radar system.