• Title/Summary/Keyword: Reverberation suppression

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Application of LFM Reverberation Suppression Using Difference of Singular Values in the Underwater Obstacle Detection (수중 장애물 탐지에서의 특이 값 차이를 이용한 LFM 잔향 감소 기법 적용 연구)

  • Lee, Hyung-Soo;Kwon, Bum-Soo;Cho, Chom-Gun;Lee, Kyun-Kyung
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.8
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    • pp.755-760
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    • 2009
  • In this paper, we apply a reverberation suppression method using difference of singular values to improve the short-distance underwater obstacle detection probability in reverberation environment induced by a linear frequency modulation signal. The reverberation suppression method using difference of singular values suppresses LFM reverberation based on subtracting the singular values for a reference beam, assumed to contain only the reverberation, from those for the current beam of interest, assumed to contain the reverberation and target echo. For the validation, the reverberation suppression method using difference of singular values is applied to real oceanic data, which are acquired using the cross type array.

A study on the active sonar reverberation suppression method based on non-negative matrix factorization with beta-divergence function (베타-발산 함수를 활용한 비음수 행렬 분해 기반의 능동 소나 잔향 제거 기법에 대한 연구)

  • Seokjin Lee;Geunhwan Kim
    • The Journal of the Acoustical Society of Korea
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    • v.43 no.4
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    • pp.369-382
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    • 2024
  • To suppress the reverberation in the active sonar system, the non-negative matrix factorization-based reverberation suppression methods have been researched recently. An estimation loss function, which makes the multiplication of basis matrices same as the input signals, has to be considered to design the non-negative matrix factorization methods, but the conventional method simply chooses the Kullback-Leibler divergence asthe lossfunction without any considerations. In this paper, we examined that the Kullback-Leibler divergence is the best lossfunction or there isthe other loss function enhancing the performance. First, we derived a modified reverberation suppression algorithm using the generalized beta-divergence function, which includes the Kullback-Leibler divergence. Then, we performed Monte-Carlo simulations using synthesized reverberation for the modified reverberation suppression method. The results showed that the Kullback-Leibler divergence function (β = 1) has good performances in the high signal-to-reverberation environments, but the intermediate function (β = 1.25) between Kullback-Leibler divergence and Euclidean distance has better performance in the low signal-to-reverberation environments.

Reverberation Characterization and Suppression by Means of Low Rank Approximation (낮은 계수 근사법을 이용한 표준 잔향음 신호 획득 및 제거 기법)

  • 윤관섭;최지웅;나정열
    • The Journal of the Acoustical Society of Korea
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    • v.21 no.5
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    • pp.494-502
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    • 2002
  • In this paper, the Low Rank Approximation (LRA) method to suppress the interference of signals from temporal fluctuations is applied. The reverberation signals and temporally fluctuating signals are separated from the measured data using the Ink. The Singular value decomposition (SVD) method is applied to extract the low rank and the temporally stable reverberation was extracted using the LRA. The reverberation suppression is performed on the LRA residual value obtained by removing the approximate reverberation signals. In overall, the method can be applied to the suppression of reververation in active sonar system as well as to the modeling of reverberation.

Experimental performance analysis on the non-negative matrix factorization-based continuous wave reverberation suppression according to hyperparameters (비음수행렬분해 기반 연속파 잔향 제거 기법의 초매개변숫값에 따른 실험적 성능 분석)

  • Yongon Lee; Seokjin Lee;Kiman Kim;Geunhwan Kim
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.1
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    • pp.32-41
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    • 2023
  • Recently, studies on reverberation suppression using Non-negative Matrix Factorization (NMF) have been actively conducted. The NMF method uses a cost function based on the Kullback-Leibler divergence for optimization. And some constraints are added such as temporal continuity, pulse length, and energy ratio between reverberation and target. The tendency of constraints are controlled by hyperparameters. Therefore, in order to effectively suppress reverberation, hyperparameters need to be optimized. However, related studies are insufficient so far. In this paper, the reverberation suppression performance according to the three hyperparameters of the NMF was analyzed by using sea experimental data. As a result of analysis, when the value of hyperparameters for time continuity and pulse length were high, the energy ratio between the reverberation and the target showed better performance at less than 0.4, but it was confirmed that there was variability depending on the ocean environment. It is expected that the analysis results in this paper will be utilized as a useful guideline for planning precise experiments for optimizing hyperparameters of NMF in the future.

Improvement of non-negative matrix factorization-based reverberation suppression for bistatic active sonar (양상태 능동 소나를 위한 비음수 행렬 분해 기반의 잔향 제거 기법의 성능 개선)

  • Lee, Seokjin;Lee, Yongon
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.4
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    • pp.468-479
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    • 2022
  • To detect targets with active sonar system in the underwater environments, the targets are localized by receiving the echoes of the transmitted sounds reflected from the targets. In this case, reverberation from the scatterers is also generated, which prevents detection of the target echo. To detect the target effectively, reverberation suppression techniques such as pre-whitening based on autoregressive model and principal component inversion have been studied, and recently a Non-negative Matrix Factorization (NMF)-based technique has been also devised. The NMF-based reverberation suppression technique shows improved performance compared to the conventional methods, but the geometry of the transducer and receiver and attenuation by distance have not been considered. In this paper, the performance is improved through preprocessing such as the directionality of the receiver, Doppler related thereto, and attenuation for distance, in the case of using a continuous wave with a bistatic sonar. In order to evaluate the performance of the proposed system, simulation with a reverberation model was performed. The results show that the detection probability performance improved by 10 % to 40 % at a low false alarm probability of 1 % relative to the conventional non-negative matrix factorization.

Reverberation suppression algorithm for continuous-wave active sonar system based on overlapping nonnegative matrix factorization (중첩 비음수 행렬 분해 기법에 기반한 지속파 능동 소나의 잔향 신호 제거 기법)

  • Lee, Seokjin;Lim, Jun-Seok;Cheong, Myoung Jun
    • The Journal of the Acoustical Society of Korea
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    • v.36 no.4
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    • pp.273-278
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    • 2017
  • In this paper, a post-processing algorithm to suppress reverberation for continuous-wave active sonar system is developed. The developed algorithm is designed for a low-doppler environment where the target echo is not distinguishable from the reverberation. The algorithm is developed based on overlapping nonnegative matrix factorization method. The algorithm analyzes the frequency characteristics of transmitting ping signal, then suppresses the reverberation using time-frequency characteristics of the received signal. Simulations performed in order to evaluate the proposed algorithm, and the results show that the proposed algorithm makes 6 dB signal-to-reverberation ratio enhancement in various reverberation energy conditions.

Design of the Robust Generalized Sinusoidal Frequency Modulated Pulse in Reverberation Environments (잔향환경에 강인한 Generalized Sinusoidal Frequency Modulated 펄스 생성 기법)

  • Kim, Guenhwan;Yoon, Kyungsik;Lee, Donghwa;Cho, Chomgun;Hong, Jungpyo;Lee, Kyunkyung
    • Journal of Korea Society of Industrial Information Systems
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    • v.24 no.5
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    • pp.95-104
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    • 2019
  • In this paper, we propose a method to design a generalized sinusoidal frequency modulated(GSFM) pulse that is robust to reverberation environment. GSFM pulses are a generalized form of SFM(Sinusoidal frequency modulated) pulses, which have the advantage of having a thumbtack ambiguity function with excellent range and Doppler resolution. However, the periodicity disappears during the generalization process, therefore, the detection performance is reduced in reverberation environment compared to SFM pulse with comb spectrum. In this paper, the trade-off relationship between the reverberation suppression performance of the SFM pulse and the range resolution performance of the GSFM pulse is analyzed by appropriately changing the parameter ${\rho}$ of the GSFM pulse. In order to verify the performance of the proposed GSFM pulse, the simulation was performed and it was confirmed that the proposed GSFM pulse has excellent distance resolution while detecting the slow Doppler target.

Wideband Suppression of Radiated Emissions from a Power Bus in High-Speed Printed Circuit Boards

  • Shim, Yujeong;Kim, Myunghoi
    • Journal of information and communication convergence engineering
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    • v.14 no.3
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    • pp.184-190
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    • 2016
  • We present experimental demonstrations of electromagnetic bandgap (EBG) structures for the wideband suppression of radiated emissions from a power bus in high-speed printed circuit boards (PCBs). In most of the PCB designs, a parallel plate waveguide (PPW) structure is employed for a power bus. This structure significantly produces the wideband-radiated emissions resulting from parallel plate modes. To suppress the parallel plate modes in the wideband frequency range, the power buses based on the electromagnetic bandgap structure with a defected ground structure (DGS) are presented. DGSs are applied to a metal plane that is connected to a rectangular EBG patch by using a via structure. The use of the DGS increases the characteristic impedance value of a unit cell, thereby substantially improving the suppression bandwidth of the radiated emissions. It is experimentally demonstrated that the DGS-EBG structure significantly mitigates the radiated emissions over the frequency range of 0.5 GHz to 2 GHz as compared to the PPW.