• Title/Summary/Keyword: 백색화 필터

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Subspace Speech Enhancement Using Subband Whitening Filter (서브밴드 백색화 필터를 이용한 부공간 잡음 제거)

  • 김종욱;유창동
    • The Journal of the Acoustical Society of Korea
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    • v.22 no.3
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    • pp.169-174
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    • 2003
  • A novel subspace speech enhancement using subband whitening filter is proposed. Previous subspace speech enhancement method either assumes additive white noise or uses whitening filter as a pre-processing for colored noise. The proposed method tries to minimize the signal distortion while reducing residual noise by processing the signal using subband whitening filter. By incorporating the notion of subband whitening filter, spectral resolution in Karhunen-Loeve(KL) domain is improved with the negligible additional computational load. The proposed method outperforms both the subspace method suggested by Ephraim and the spectral subtraction suggested by Boll in terms of segmental signal-to-noise ratio (SNRseg) and perceptual evaluation of speech quality (PESQ).

Performance Analysis of the Pre-Whitening Matched Filter in Shallow Water Environment (천해환경에서 선-백색화 정합필터의 성능 분석)

  • Yu, Seog-Kun;Kim, Jeong-Goo;Joo, Eon-Kyeong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.45 no.12
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    • pp.152-158
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    • 2008
  • In shallow water environment, the detection performance of an active sonar using matched filter with LFM(linear frequency modulation) pulse can be seriously degraded by reverberation which is considered as non-white noise. To reduce the effect of reverberation, a whitening filter preceding the matched fitter, is usually adopted. In the conventional pre-whitening filter, it is assumed that local stationarity is preserved between detection block and its right ahead block. And then by using the characteristics of the reverberation of preceding block, the reverberation of detection block is estimated and whitened. According to the environment of shallow water, the stationarity of reverberation may be preserved for more blocks. In this case, the reverberation of the detection block can be estimated more accurately if more blocks are used. In this paper, the real reverberation signal which is obtained from shallow sea is analyzed and its proper region of estimation block is examined. And the performance of pre-whitening matched filter is compared and analyzed according to the region of estimation block.

Efficient Detection Scheme for Turbo Coded QO-STBC Schemes (터보 부호와 결합된 준직교 시공간 블록 부호의 효율적인 검출 기법)

  • Park, Un-Hee;Oh, Dae-Sub;Kim, Young-Min;Kim, Soo-Young
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.5A
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    • pp.423-430
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    • 2010
  • The performances of turbo-coded space-time block coding (STBC) schemes are subject to how soft decision detection (SDD) information are generated from the STBC decoder. For this reason, we have to pay particular attention to estimation of SDD. In this paper, we evaluate the performance of a turbo coded STBC scheme depending on the accuracy of the SDD. Recently, a new quasi orthogonal STBC (QO-STBC) scheme using a noise whitened filter was proposed in order to reduce noise enhancing effect of zero forcing detection process. This QO-STBC scheme was proven to be efficient in computational complexity compared to the other conventional QO-STBC schemes. In this paper, we first present detailed mathematical analysis on the noise whitened QO-STBC scheme, and by using the result we propose the optimum SDD method.

Noise Whitening Decision Feedback Equalizer for SC-FDMA Receivers (SC-FDMA 수신기를 위한 잡음 백색화 판정궤환 등화기)

  • Lee, Su-Kyoung;Park, Yong-Hyun;Seo, Bo-Seok
    • Journal of Broadcast Engineering
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    • v.16 no.6
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    • pp.986-995
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    • 2011
  • In this paper, we propose a noise whitening decision feedback equalizer for single carrier frequency division multiple access (SC-FDMA) receivers. SC-FDMA has the same advantage as that of orthogonal frequency division multiple access (OFDMA) in which the multipath effect can be removed easily, and also solves the problem of high peak to average power ratio (PAPR) which is the main drawback of OFDMA. Although SC-FDMA is a single carrier transmission scheme, a simple frequency domain linear equalizer (FD-LE) can be implemented as in OFDMA, which can dramatically reduce the equalizer complexity. Moreover, some residual intersymbol interference in the output of the FD-LE can be further removed by an additional nonlinear decision feedback equalizer (DFE) in time domain, because the time domain signal is a digitally modulated symbol. In the conventional DFE, however, the noise is not white at the input of the decision device and correspondingly the decision is not optimum. In this paper, we propose an improved DFE scheme for SC-FDMA systems where a linear noise whitening filter is inserted before the decision device of the conventional DFE scheme. Through computer simulations, we compare the bit error rate performance of the proposed DFE scheme with the conventional equalizers.