• Title/Summary/Keyword: Whitening filter

Search Result 18, Processing Time 0.053 seconds

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

  • 김종욱;유창동
    • The Journal of the Acoustical Society of Korea
    • /
    • v.22 no.3
    • /
    • pp.169-174
    • /
    • 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).

A study on narrowband interference rejection in PN spread spectrum communication system (PN 대역 확장 통신시스템에서 협대역 간섭신호의 제거방식에 관한 연구)

  • 김동길;김원후
    • Proceedings of the Korean Institute of Communication Sciences Conference
    • /
    • /
    • pp.85-87
    • /
    • 1983
  • In this paper, a improved whitening filter for narrowband interference rejetion in PN spread spectrum communication systems is proposed. This whitening filter has the feedback from the output to the input of adaptive transversal filter and is superior to conventional LMS whitening filter in respect to SNR and power spectrum since the calculation of tap weight is based on maximum likelihood estimation

  • PDF

A Study on the Performance of a Radar Clutter Suppression Algorithm Based on the Adaptive Clutter Prewhitening Filter and Droppler Filter Bank (Adaptive Clutter Prewhitening Filter와 Doppler Filter Bank를 이용한 레이다 Clutter 제거 알고리듬의 성능에 관한 연구)

  • Kim, Yong-Ho;Lee, Hwang-Soo;Un, Chong-Kwan;Lee, Won-Kil
    • Journal of the Korean Institute of Telematics and Electronics
    • /
    • v.26 no.6
    • /
    • pp.140-146
    • /
    • 1989
  • In many situations, radar targets are embedded in a clutter environment and clutter rejection is required. The clutter is unwanted radar echoes and may arise owing to reflections from ground and weather disturbances and statistical properties of the clutter vary with range and azimuth as well as time. That is, adaptive signal processing is required. In this paper, a clutter suppression algorithm based on the clutter whitening filter (WF) and doppler filter bank(DFB) is described which provides improved performance compared with conventional nonadaptive clutter suppression algorithm that is the cascaded moving target indicator (MTI) and (DFB). The clutter whitening filter algorithm is based on the Burg's maximum entropy method.

  • PDF

Adaptive Filtering for QRS Detection (QRS검출을 위한 Adaptive Filter)

  • Lee, Soon-Hyouk;Jun, Young-Il;Choi, Kyoung-Hoon;Yoon, Hyung-Ro
    • Proceedings of the KOSOMBE Conference
    • /
    • v.1993 no.11
    • /
    • pp.167-170
    • /
    • 1993
  • matched filter는 신호와 잡음의 통계적 값을 알고 있을 때 신호대 잡음비를 최대로 하는 filter이다. 그런데, matched filter가 최적화 되려면 잡음이 white noise이어야한다. 그러나 ECG신호에 존재하는 잡음은 여러가지 성분이 공존하는 서로 연관되어있는 잡음이다. 따라서 whitening filter를 사용하여 잡음을 whitening시킨후에 matched filter를 통과 시켜야한다. 본 논문에서는 QRS complex를 검출하기 위한 matched filter에 있어서 LMS방법을 이용한 linear whitening filter와 neural network을 이용한 non-linear whitening filter의 특성을 비교하였다.

  • PDF

A Study on Narrow band Interference Rejection in PN-SS System (PN-SS통신시스템에서 협대역간섭신호의 제거방식에 관한 연구)

  • 김동길;김원후
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.9 no.2
    • /
    • pp.62-69
    • /
    • 1984
  • The performance of direct-sequence spread spectrum(DS-SS) receiver may be enhanced by using the digital whitening filter. In this paper, the hard limited feedback whitening filter that whiten the interference and noise alone is proposed to obtain the additional resistance to narrowband interference. The recursive solution for the calculation of tap weights is presented and the expression for SNR and BER is derived and compared with the conventional digital whitening filter. As the result of computer simulation it is proved that the error performance is improved considerably.

  • PDF

Spectral Subtraction Usnig Whitening Filter for Reducing Residual Noise (잔류잡음 감소를 위한 백색화 스펙트럼 차감법)

  • 오태호
    • Proceedings of the Acoustical Society of Korea Conference
    • /
    • /
    • pp.411-414
    • /
    • 1998
  • 음성의 음질 향상(Speech Enhancement)을 위한 여러 가지 방법 중에서 주파수 차감법(Spectral Subtraction)은 계산량이 적기 때문에 현재 실시간으로 Speech Enhancement를 할 수 있는 가장 적절한 방법이다. 그러나, 이 방법은 원래의 입력음성에 없던 새로운 잡음을 만들어내는 큰 단점이 있는데, 이를 제거하기 위해 많은 연구가 되어오고 있다. 이러한 연구의 방향은 대부분 주변프레임 또는 주변의 주파수 성분과의 평균을 통해 피크값을 무디게 해 줌으로써 새로 생긴 튀는 잡음을 감소시키는 것이다. 이런 방법은 음성자체의 정보 또한 평균이 되어버리게 하는 새로운 단점을 낳는데, 이런 현상은 무성음구간에서 특히 심각해진다. 본 논문에서는 입력음성의 LPC 분석으로 백색필터(Whitening Filter)를 구성하여 이를 통과시킨 잔류신호(Residual)를 주파수 차감하여 얻은 새로운 잔류신호를 역 필터링하여(Synthesis Filter) 개선된 음성을 얻는 방법을 제안하였다. 제안된 알고리듬은, 주파수 차감시 포만트(Formant)의 정보가 더 유지 될 수 있기 때문에 잔류잡음을 줄일 수 있다. 청취 테스트 결과 제안한 방법이 기존의 방법보다 잔류잡음을 더 줄이는 사실을 확인할 수 있었다.

  • PDF

A New Adaptive Echo Canceller with an Improved Convergence Speed and NET Detection Performance (향상된 수렴속도와 근달화자신호 검출능력을 갖는 적응반향제기기)

  • 김남선;박상택;차용훈;윤일화;윤대희
    • Journal of the Korean Institute of Telematics and Electronics B
    • /
    • v.30B no.12
    • /
    • pp.12-20
    • /
    • 1993
  • In a conventional adaptive echo canceller, an ADF(Adaptive Digital Filter) with TDL(Tapped-Delay Line) structure modelling the echo path uses the LMS(Least Mean Square) algorithm to compute the coefficients, and NET detector using energy comparison method prevents the ADF to update the coefficients during the periods of the NET signal presence. The convergence speed of the LMS algorithm depends on the eigenvalue spread ratio of the reference signal and NET detector using the energy comparison method yields poor detection performance if the magnitude of the NET signal is small. This paper presents a new adaptive echo canceller which uses the pre-whitening filter to improve the convergence speed of the LMS algorithm. The pre-whitening filter is realized by using a low-order lattice predictor. Also, a new NET signal detection algorithm is presented, where the start point of the NET signal is detected by computing the cross-correlation coefficient between the primary input and the ADF output while the end point is detected by using the energy comparison method. The simulation results show that the convergence speed of the proposed adaptive echo canceller is faster than that of the conventional echo canceller and the cross-correlation coefficient yields more accurate detection of the start point of the NET signal.

  • PDF

On Improving Convergence Speed and NET Detection Performance for Adaptive Echo Canceller (향상된 수렴 속도와 근단 화자 신호 검출능력을 갖는 적응 반향 제거기)

  • 김남선
    • Proceedings of the Acoustical Society of Korea Conference
    • /
    • /
    • pp.23-28
    • /
    • 1992
  • The purpose of this paper is to develop a new adaptive echo canceller improving convergence speed and near-end-talker detection performance of the conventional echo canceller. In a conventional adaptive echo canceller, an adaptive digital filter with TDL(Tapped-Delay Line) structure modelling the echo path uses the LMS(Least Mean Square) algorithm to cote the coefficients, and NET detector using energy comparison method prevents the adaptive digital filter to update the coefficients during the periods of the NET signal presence. The convergence speed of the LMS algorithm depends on the eigenvalue spread ratio of the reference signal and NET detector using the energy comparison method yields poor detection performance if the magnitude of the NET signal is small. This paper presents a new adaptive echo canceller which uses the pre-whitening filter to improve the convergence speed of the LMS algorithm. The pre-whitening filter is realized by using a low-order lattice predictor. Also, a new NET signal detection algorithm is presented, where the start point of the NET signal is detected by computing the cross-correlation coefficient between the primary input and the ADF(Adaptive Digital Filter) output while the end point is detected by using the energy comparison method. The simulation results show that the convergence speed of the proposed adaptive echo canceller is faster than that of the conventional echo canceller and the cross-correlation coefficient yield more accurate detection of the start point of the NET signal.

  • PDF

Implementation of Optimum Radar Signal Processor Using Adaptive Whitening Filter (적응 Whitening 필터를 이용한 최적 레이다 신호처리기의 구현)

  • 김기만
    • Proceedings of the Acoustical Society of Korea Conference
    • /
    • /
    • pp.157-162
    • /
    • 1991
  • 본 연구에서는 적응 whitening 필터를 이용하여 최적 레이다 신호처리기를 구현하였다. 사용된 필터는 Gram-Schmidt와 lattice 구조를 가지며, 이들을 이용하여 레이다 clutter를 제거하고, 프로세서 특성을 원하는 표적신호에 일치시킨다. 또한 필터 계수들을 변화하는 레이다 환경에 따라 조정하기 위하여 여러 가지 적응 알고리듬을 적용하였다. 실험결과 구현된 시스템은 빠른 수렴 특성을 갖고 있으며, 역행렬 연산이 필요없기 때문에 향상 안정된 특성을 보임을 알 수 있다.

  • PDF

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
    • /
    • v.45 no.12
    • /
    • pp.152-158
    • /
    • 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.