• Title/Summary/Keyword: Nonlinear correlation filter

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Information Authentication of Three-Dimensional Photon Counting Double Random Phase Encryption Using Nonlinear Maximum Average Correlation Height Filter

  • Jang, Jae-Young;Inoue, Kotaro;Lee, Min-Chul;Cho, Myungjin
    • Journal of the Optical Society of Korea
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    • v.20 no.2
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    • pp.228-233
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    • 2016
  • In this paper, we propose a nonlinear maximum average correlation height (MACH) filter for information authentication of photon counting double random phase encryption (DRPE). To enhance the security of DRPE, photon counting imaging can be applied because of its sparseness. However, under severely photon-starved conditions, information authentication of DRPE may not be implemented successfully. To visualize the photon counting DRPE, a three-dimensional imaging technique such as integral imaging can be used. In addition, a nonlinear MACH filter can be utilized for helping the information authentication. Therefore, in this paper, we use integral imaging and nonlinear MACH filter to implement the information authentication of photon counting DRPE. To verify our method, we implement optical experiments and computer simulation.

Applications and analysis on the subband nonlinear adaptive Volterra filter (부대역 비선형 Volterra 적응필터의 응용과 성능분석)

  • Yang, Yoon Gi;Byun, Hee Jung
    • Journal of IKEEE
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    • v.17 no.2
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    • pp.111-118
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    • 2013
  • In this paper, the subband nonlinear adaptive Volterra filters are introduced and its analysis are presented. From the eigenvalue analysis of the input correlation matrix, we show that the proposed subband adaptive Volterra filter has superior convergence performance as compared to the conventional one, which shows that the it can be useful for the recently proposed subband nonlinear adaptive echo canceller. Also, the optimum filter in each subband are introduced and verified from the computer simulations.

A study on robust generalized cross correlation-phase transform based time delay estimation in impulsive noise environment using nonlinear preprocessing and frequency domain low-pass filter (비선형 전처리와 주파수 영역 저역 필터에 의한 임펄스성 잡음 환경에 강인한 위상 변환 일반 상호 상관 시간 지연 추정기 연구)

  • Jun-Seok Lim;Keunwa Lee
    • The Journal of the Acoustical Society of Korea
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    • v.43 no.4
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    • pp.406-413
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    • 2024
  • The proposed method uses Generalized Cross Correlation - Phase Transform (GCC-PHAT) method with nonlinear preprocessing and a frequency domain low-pass filter. In this paper, by reinterpreting the calculation process of GCC-PHAT as DFT, we derive that there is an effective frequency band used for time delay estimation in GCC-PHAT, and by using only the effective band using a low-pass filter, the noise component is reduced and it improvesthe time delay performance in impulsive noise environments. By comparing the proposed method with the traditional GCC-PHAT in an impulsive noise environment, we show that the GCC-PHAT becomes more robust to the impulsive noise.

Nonlinear Echo Cancellation using a Correlation LMS Adaptation Scheme (상관(Correlation) LMS 적응 기법을 이용한 비선형 반향신호 제거에 관한 연구)

  • Park, Hong-Won;An, Gyu-Yeong;Song, Jin-Yeong;Nam, Sang-Won
    • Proceedings of the KIEE Conference
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    • 2003.11c
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    • pp.882-885
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    • 2003
  • In this paper, nonlinear echo cancellation using a correlation LMS (CLMS) algorithm is proposed to cancel the undesired nonlinear echo signals generated in the hybrid system of the telephone network. In the telephone network, the echo signals may result the degradation of the network performance. Furthermore, digital to analog converter (DAC) and analog to digital converter (ADC) may be the source of the nonlinear distortion in the hybrid system. The adaptive filtering technique based on the nonlinear Volterra filter has been the general technique to cancel such a nonlinear echo signals in the telephone network. But in the presence of the double-talk situation, the error signal for tap adaptations will be greatly larger, and the near-end signal can cause any fluctuation of tap coefficients, and they may diverge greatly. To solve a such problem, the correlation LMS (CLMS) algorithm can be applied as the nonlinear adaptive echo cancellation algorithm. The CLMS algorithm utilizes the fact that the far-end signal is not correlated with a near-end signal. Accordingly, the residual error for the tap adaptation is relatively small, when compared to that of the conventional normalized LMS algorithm. To demonstrate the performance of the proposed algorithm, the DAC of hybrid system of the telephone network is considered. The simulation results show that the proposed algorithm can cancel the nonlinear echo signals effectively and show robustness under the double-talk situations.

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Spacecraft Attitude Estimation by Unscented Filtering (고른 필터를 이용한 인공위성의 자세 추정)

  • Leeghim, Hen-Zeh;Choi, Yoon-Hyuk;Bang, Hyo-Choong;Park, Jong-Oh
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.9
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    • pp.865-872
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    • 2008
  • Spacecraft attitude estimation using the nonlinear unscented filter is addressed to fully utilize capabilities of the unscented transformation. To release significant computational load, an efficient technique is proposed by reasonably removing correlation between random variables. This modification introduces considerable reduction of sigma points and computational burden in matrix square-root calculation for most nonlinear systems. Unscented filter technique makes use of a set of sample points to predict mean and covariance. The general QUEST(QUaternion ESTimator) algorithm preserves explicitly the quaternion normalization, whereas extended Kalman filter(EKF) implicitly obeys the constraint. For spacecraft attitude estimation based on quaternion, an approach to computing quaternion means from sampled quaternions with guarantee of the quaternion norm constraint is introduced applying a constrained optimization technique. Finally, the performance of the new approach is demonstrated using a star tracker and rate-gyro measurements.

Binary Nonlinear Joint Transform Correlator with Sinusoidal Iterative Filter in Spectrum Domain

  • Jeong, Man-Ho
    • Journal of the Optical Society of Korea
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    • v.14 no.4
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    • pp.357-362
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    • 2010
  • The joint transform correlator (JTC) has been the best known technique for pattern recognition and identification. This paper proposes a new technique of fringe adjustment by adopting a sinusoidal amplitude-modulated iterative filter convolved with an interference fringe pattern in the joint power spectrum (JPS) domain. The comparison of our new technique and other techniques is presented to show that the newly proposed technique can successfully improve both the correlation peaks and the peak signal-to-noise ratio (PSNR). Simulated results of enhanced interference fringes are also presented.

Design of an Adaptive Nonlinear Compensator using a Wavelet Transform Domain Volterra Filter and a Modified Escalator Algorithm

  • Hwang, Dong-Oh;Kang, Dong-Jun;Nam, Sang-Won
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.98.5-98
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    • 2001
  • An efficient adaptive nonlinear compensator, based on a wavelet transform domain adaptive Volterra filter along with a modified escalator algorithm, is proposed to speed up the convergence rate of an adaptive LMS algorithm. In particular, it is well known that the e.g., slow convergence speed of an adaptive LMS algorithm depends on the statistical characteristics (e.g., large eigenvalue spread) of the corresponding auto-correlation matrix of the input vector. To solve such a convergence problem, the proposed approach utilizes a modified escalator algorithm and a wavelet transform domain adaptive LMS Volterra filtering technique, which leads to diagonalization of the auto-correlation matrix of the ...

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Performance of PN Code Acquisition with Nonlinear Power Amplifier based on DMF for CDMA Mobile Communications

  • Park, Seung-Keun;Chung, Hee-Chang;Park, Se-Jun;Kim, Seong-Cheol
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.1E
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    • pp.22-26
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    • 2000
  • In this paper, the DS/CDMA PN code acquisition system with nonlinear transmitter power amplifier based on digital matched filter (DMF) which has the rapid acquisition time is presented and the performance is evaluated in terms of mean acquisition time, detection probability, and signal to interference under multiuser environment. The performance is presented with respect to the output backoff of the nonlinear amplifier and the correlation window.

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Analysis of Noise Influence on a Chaotic Series and Application of Filtering Techniques (카오스 시계열에 대한 잡음영향 분석과 필터링 기법의 적용)

  • Choi, Min Ho;Lee, Eun Tae;Kim, Hung Soo;Kim, Soo Jun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.1B
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    • pp.37-45
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    • 2011
  • We studied noise influence on nonlinear chaotic system by using Logistic data series which is known as a typical nonlinear chaotic system. We regenerated Logistic data series by the method of adding noise according to noise level. And, we performed some analyses such as phase space reconstruction, correlation dimension, BDS statistics, and DVS Algorithms which are known as the methods of nonlinear deterministic or chaotic analysis. If we see the results of analysis, the characteristics of data series are gradually changed from nonlinear chaotic data series to random stochastic data series according to increasing noise level. We applied Low Pass Filter (LPF) and Kalman Filter techniques for the investigation of removing effect of the added noise to data series. Typical nonparametric method cannot distinguish nonlinear random series but the BDS statistic can distinguish the nonlinear randomness of the time series. Therefore this study used the BDS statistic which is well known as nonlinear statistical method for the investigation of randomness of time series for the effect of removing noise of data series. We found that Kalman filter is better method to remove the noise of chaotic data series even for high noise level.

Nonlinear Kalman filter bias correction for wind ramp event forecasts at wind turbine height

  • Xu, Jing-Jing;Xiao, Zi-Niu;Lin, Zhao-Hui
    • Wind and Structures
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    • v.30 no.4
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    • pp.393-403
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    • 2020
  • One of the growing concerns of the wind energy production is wind ramp events. To improve the wind ramp event forecasts, the nonlinear Kalman filter bias correction method was applied to 24-h wind speed forecasts issued from the WRF model at 70-m height in Zhangbei wind farm, Hebei Province, China for a two-year period. The Kalman filter shows the remarkable ability of improving forecast skill for real-time wind speed forecasts by decreasing RMSE by 32% from 3.26 m s-1 to 2.21 m s-1, reducing BIAS almost to zero, and improving correlation from 0.58 to 0.82. The bias correction improves the forecast skill especially in wind speed intervals sensitive to wind power prediction. The fact shows that the Kalman filter is especially suitable for wind power prediction. Moreover, the bias correction method performs well under abrupt weather transition. As to the overall performance for improving the forecast skill of ramp events, the Kalman filter shows noticeable improvements based on POD and TSS. The bias correction increases the POD score of up-ramps from 0.27 to 0.39 and from 0.26 to 0.38 for down-ramps. After bias correction, the TSS score is significantly promoted from 0.12 to 0.26 for up-ramps and from 0.13 to 0.25 for down-ramps.