• Title/Summary/Keyword: Wavelet domain

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A Study on Estimation of Coefficient Using Wavelet Transform and Its Application to the Evaluation of Harshness in Passenger Car (웨이브렛 해석을 이용한 승용차의 충격 하쉬니스 개선)

  • Lee, Sang-Kwon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1710-1715
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    • 2000
  • Estimation of damping ratio for vibration signals measured on the passenger car's seat is useful for the objective evaluation of impact harshness in car. The vibration signal is a transient signal represented by many coupled modes of suspension system. Wavelet transform automatically decouples these modes in the time-frequency domain. Damping ratios for decoupled modes are obtained by logarithmic treatment for the Wavelet transformed signal. The objective evaluation using Wavelet transform has been well corresponded with subjective evaluation done by skilled engineers.

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On-line Signature Verification Method Using Adaptive Algorithm in Wavelet Transform Domain

  • Nakanishi, Isao;Nishiguchi, Naoto;Itoh, Yoshio;Fukui, Yutaka
    • Proceedings of the IEEK Conference
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    • 2002.07a
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    • pp.385-388
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    • 2002
  • In this paper, a new signature verification method is proposed. In the proposed method, on-line signature features are decomposed into multi-level signals by using the discrete wavelet transform, and then they are verified using the adaptive algorithm in time-frequency domain. Through computer simulations, the effectiveness of the proposed method is examined.

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A Blind Watermarking Technique Using Difference of Approximation Coefficients in Wavelet Domain (웨이블릿 영역에서 근사 계수의 증감 정보를 이용한 블라인드 워터마크)

  • 윤혜진;성영경;최태선
    • Proceedings of the IEEK Conference
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    • 2002.06d
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    • pp.219-222
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    • 2002
  • In this paper, we propose a new blind image watermarking method in wavelet domain. It is necessary to find out watermark insertion location in blind watermark. We use horizontal and vertical difference of LL components to select watermark insertion location, because increment or decrement of successive components is rarely changed in LL band. A pseudo-random sequence is used as a watermark. Experimental results show that the proposed method is robust to various kinds of attacks such as JPEG lossy compression, averaging, median filtering, resizing, histogram equalization, and additive Gaussian noise.

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Denoising Based on the Adaptive Lifting

  • Lee, Chang-Soo;Yoo, Kyung-Yul
    • The Journal of the Acoustical Society of Korea
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    • v.18 no.1E
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    • pp.13-19
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    • 1999
  • This paper introduces an adaptive wavelet transform based on the lifting scheme, which is applied to signal denoising. The wavelet representation using orthogonal wavelet bases has received widespread attention. Recently the lifting scheme has been developed for the construction of biorthogonal wavelets in the spatial domain. Wavelet transforms are performed through three stages: the first stage or Lazy wavelet splits the data into two subsets, even and odd, the second stage calculates the wavelet coefficients (highpass) as the failure to interpolate or predict the odd set using the even, and the third stage updates the even set using neighboring odd points (wavelet coefficients) to compute the scaling function coefficients (lowpass). In this paper, we adaptively find some of the prediction coefficients for better representation of signals and this customizes wavelet transforms to provide an efficient framework for denoising. Special care has been given to the boundaries, where we design a set of different prediction coefficients to reduce the prediction error.

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A Study on Application of Wavelet Transform to Electrical Load Discriminations (부하 판별을 위한 Wavelet 변환의 응용에 관한 연구)

  • 정종원;김민성;김태홍;이준탁
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2001.05a
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    • pp.109-112
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    • 2001
  • Recently, the subject of \"wavelet analysis\" has drawn much attention from both mathematical and engineering application fields such as Signal Processing, Compression/Decomposition, Statistics and ets. Analogous to Fourier analysis, wavelets is a versatile tool with very rich mathematical content and great potential for applications. Specially, wavelet transform uses localizable various mother wavelet functions in time-frequency domain. In this paper, discrimination analyses of acquired electrical current signals for each and mixed loads were tried by using Morlet wavelet transform. Their representative loads were classified as TV, DRY(Dryer), REF(Refrigerate), and FL(Fluorescent Lamp).

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1D Wavelet Filtering for Groundroll Suppression in Land Seismic-Reflection Data

  • Sa, Jin-Hyeon;Lee, Jae-Eun;Kim, Sung-Soo;Kim, Ji-Soo
    • The Journal of Engineering Geology
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    • v.27 no.4
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    • pp.513-518
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    • 2017
  • Groundroll is a coherent noise showing dispersive behavior in land seismic-reflection records and its rejection has been a stubborn problem in data processing because they severely degrade the continuities and resolution of reflection signals. Conventional processing schemes of attenuating noises are the kind of frequency filtering (i.e., bandpass and f-k) that uses the Fourier transform (FT) along the entire trace in the time domain. To suppress them in this study, 1D wavelet filtering (WT) that can control time-varying frequency properties is tested and performed in the land-based synthetic and field seismic data. The results are compared to the ones from conventional filtering techniques in terms of continuities and resolution of reflection events. This filtering technique enhanced the reflection events by effectively eliminating the dispersive groundroll and random noises with control of time-scale function on wavelet domain.

Windowed Wavelet Stereo Matching Using Shift ability (이동성(shift ability)을 이용한 윈도우 웨이블릿 스테레오 정합)

  • 신재민;이호근;하영호
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.1C
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    • pp.56-63
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    • 2003
  • In this paper, a wavelet-based stereo matching algorithm to obtain an accurate disparity map in wavelet transformed domain by using a shift ability property, a modified wavelet transform, the similarities for their sub-bands, and a hierarchical structure is proposed. New approaches for stereo matching by lots of feature information are to utilize translation-variant results of the sub-bands in the wavelet transformed domain because they cannot literally expect translation invariance in a system based on convolution and sub-sampling. After the similarity matching for each sub-band, we can easily find optimal matched-points because the sub-bands appearance of the shifted signals is definitely different from that of the original signal with no shift.

A Study on the Spread Spectrum Watermarking Method (스프레드 스펙트럼 워터마킹 기법의 연구)

  • 강환일;김갑일;한승수
    • Journal of the Korean Institute of Intelligent Systems
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    • v.11 no.8
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    • pp.731-735
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    • 2001
  • In this paper, we propose the new audio watermarking method and can be used on line processing. Instead of the wavelet transform, we use the integer wavelet transform for the reduction of the computational load. The watermark associated with the chi-square distribution is inserted into the signal on the integer wavelet domain. When extracting the watermark, the spread spectrum methods are used with the coefficients associated with the covariance sequence. We show that the chi-square distribution is a good tool for the spread spectrum method on the wavelet domain. This watermarking technique may be sued for the control of the electrical product which can be controlled with the hidden signals and can be moved according to the audible signals simultaneously.

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Application of Wavelet Transform for Fault Discriminant of Generator (발전기의 고장 판별을 위한 웨이브릿 변환의 적용)

  • Park, Chul-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.64 no.1
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    • pp.35-40
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    • 2015
  • Generators are the most complex and expensive single element in a power system. The generator protection relays should to minimize damage during fault states and must be designed for maximum reliability. A conventional CDR(Current Differential Relaying) technique based on DFT(Discrete Fourier Transform) filter have the disadvantages that the time information can lead to loss in the process of converting the signal from the time domain to the frequency domain. A WT(Wavelet transform) and WT analysis is known that it is possible with the local analysis of the fault and transient signal. In this paper, to overcome the defects in the DFT process, an application of WT for fault detection of generator is presented. This paper describes an selection of mother Wavelet to detect faults of generator. Using collected data from the fault simulation with ATPdraw, we analyzed the several mother Wavelet through the course of MLD(multi-level decomposition) using MATLAB software. Finally, it can be seen that the proposed technique using detail coefficient of Daubechies level 2 which can be fault discriminant of generator.

Design of LMS based adaptive equalizer using Discrete Multi-Wavelet Transform (Discrete Multi-Wavelet 변환을 이용한 LMS기반 적응 등화기 설계)

  • Choi, Yun-Seok;Park, Hyung-Kun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.3
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    • pp.600-607
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    • 2007
  • In the next generation mobile multimedia communications, the broad band shot-burst transmissions are used to reduce end-to-end transmission delay, and to limit the time variation of wireless channels over a burst. However, training overhead is very significant for such short burst formats. So, the availability of the short training sequence and the fast converging adaptive algorithm is essential in the system adopting the symbol-by-symbol adaptive equalizer. In this paper, we propose an adaptive equalizer using the DWMT (discrete multi-wavelet transform) and LMS (least mean square) adaptation. The proposed equalizer has a faster convergence rate than that of the existing transform-domain equalizers, while the increase of computational complexity is very small.