• Proceedings of the KOSOMBE Conference
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• v.1993 no.11
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• pp.167-170
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• 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.

• 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).

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1983.10a
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• pp.85-87
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• 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

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.6
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• pp.140-146
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• 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.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.3
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• pp.15-19
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• 2006

In shallow water active sonar environment, reverberation which is a non-white noise is one of the main source of performance degradation of target detection. In this case, the received signal is whitened before applying matched filter known as an optimum filter in the presence of white noise. However implementation of this method is very difficult because of the non-stationary characteristic of reverberation. Traditionally reverberation is assumed local stationary. In this paper, we estimate a range of stationary of reverberation signal, and then propose a pre-whitening method which improve the performance of pre-whitening block normalized matched filter in presence of non-white reverberation noise. Proposed whitener shows better whitening performance than traditional whitener because it use later as well as before reverberation of target signal. To evaluate performance of the proposed whitener, an actual measurement data sampled at the East-Sea is used for computer simulation. The target detector with new whitener is shown better performance than detector with traditional whitener.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.80-86
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• 2008

Uncontrolled regeneration characteristics of two different type SiC DPFs(diesel particulate filters) were investigated by DPF test rig devised to facilitate DPF evaluation, especially for regeneration and MSL(maximum soot loading) test similar to engine dynamometer test. In order to estimate the limits of maximum filter temperature and temperature gradient causing filter fracture, such as crack or whitening, the temperature distributions inside the filter were measured by thermocouples. The maximum filter temperature was observed near the rear plane of central filter region due to heat accumulation by exothermic reaction of PM but the maximum temperature gradient occurred at the boundary of high filter temperature. These two parameters induced the different SiC DPFs to fracture with different modes, whitening and crack.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.2
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• pp.62-69
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• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.10
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• pp.8-13
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• 2009

The MF(matched filter) is the optimum signal detector that maximizes the output instantaneous signal power to average noise power ratio in white noise environment. But it cannot give the optimum detection performance if the background noise is not white. So, the whitening process preceding the matched filter is needed in the conventional detector which results in a PWMF(pre-whitening matched filter). Its performance is mainly affected by the estimation accuracy of non-white noise model which is used in the whitening procedure. To estimate more accurate model to improve performance, the computational complexity is increased. Therefore, a spectrum based detector which shows better performance than the PWMF under the similar complexity condition or less complexity under the similar performance condition is proposed in this paper. And its performance and complexity are analyzed and compared with the conventional PWMF.

• 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.

• Proceedings of the Acoustical Society of Korea Conference
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• 1991.06a
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• pp.157-162
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• 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.