首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 109 毫秒
1.
本文讨论了一种带有参考通道的自适应环境噪声滤波器原理,该滤波器采用最小均方误差(LMS)算法。将此滤波器应用于复杂噪音背景的语音信号提取,能很好地抑制背景噪声,从而获得清晰的语音信号。  相似文献   

2.
自适应BPSK解调方法研究   总被引:4,自引:0,他引:4  
提出了一种新型的基于自适应滤波算法的解调二进制相移键控(BPSK)信号的方法。以常用的最小均方误差自适应算法(LMS)为例,讨论了新型的BPSK自适应解调的过程及其性能。该解调算法不需要自适应滤波器完成收敛,从而降低了采样频率。给出的理论性能与仿真结果表明,BPSK自适应解调的误码率仿真结果与理论值吻合非常好;而且该方法具有抗干扰性能强、输出响应快、便于数字信号处理(DSP)技术实现等特点,在相同的采样频率下其误码率优于相关解调的误码率。  相似文献   

3.
线性修正下的神经网络盲均衡算法   总被引:1,自引:1,他引:0       下载免费PDF全文
肖瑛  李振兴  董玉华 《声学技术》2008,27(4):601-604
研究了一种利用横向滤波器对神经网络进行线性修正的盲均衡算法。在神经网络的输入层之前加入一个横向滤波器,以横向滤波器的节点输出作为神经网络盲均衡器的输入,利用常数模代价函数分别得到横向滤波器和神经网络盲均衡器的瞬时输出误差,将瞬时误差加权处理作为调节误差分别对横向滤波器和神经网络盲均衡器的权系数进行调节,算法实现了对非凸性误差曲面进行线性和非线性寻优的组合。计算机仿真证明提出的算法有效提高了神经网络盲均衡算法的收敛速度,降低了稳态剩余误差,具有更好的实用性和均衡性能。  相似文献   

4.
提出了一种近似重构、过采样DFT调制滤波器组的设计方法。根据滤波器组的系统失真和输出混迭方面的要求,构造一个简单的目标函数,并采用等纹波法优化设计原型滤波器。与现有方法相比,该设计方法将复杂的非线性优化问题转化为对单一参数的选取,简化了设计过程,并且可在满足DFT调制滤波器组设计准则的条件下使得通带范围内误差逼近最小。利用加权叠接相加(Weighted Overlap and Add,WOLA)的快速实现结构,使整个系统更加高效、易行,可用于助听器语音信号分频带处理与综合。  相似文献   

5.
本文讨论中子迁移方程Au=F的数值方法,这里A是迁移算子,A=B+J,而B=Ω.V+σI,Ω是中子运动方向单位矢量,△是梯度算子,I是恒等算子,σ是横载面积,J是积分算子,F是外中子源。本文提出上述方程的迭代算法:B-u^(n+1)=-Jj^(n)+F,结合不连续Galerkin方法给出迭代有限元算法,讨论了算法的收敛性和误差估计,给出计算实例,理论分析和计算结果表明此方法结构简单,计算方便和精度  相似文献   

6.
本文提出了三坐标测量机三维位置精度的概念,分析研究了采用《三坐标测量机(试行)》国家检定规程(JJG799-92)所述的坐标轴移动直线度,相互垂直度及(单轴)示值误差的检定方法的检定结构与所述三维位置精度的关系,应用最小二乘回归原理,提出了位置误差的消减与软件误差补偿方法。  相似文献   

7.
在空时分组编码(STBC)的MC-CDMA系统中,根据STBC正交编码的特点,提出了一种简单可行 的基于常模(CM)准则的盲多用户检测算法。该算法基于最小二乘常模算法(LSCMA)的盲多用户检测算法, 算法大为简化,抽头系数减少了一半,性能略有下降。  相似文献   

8.
圆柱度误差评定的最小面积准则及其应用   总被引:1,自引:0,他引:1  
本文提出圆柱面形状误差评定的一个新准则--“最小面积准则”,以此建立空间一般位置圆柱度误差评定的数学模型,用有效集法方便地求得理想圆柱面的描述参 和圆柱度误差。文章从理论上证明了在小误差条件下,最小面积准则等价于ISO关于形状误差评定的最小区域准则,因而本文方法为圆柱度平定实现最小条件提供了一个有效方法。  相似文献   

9.
卡尔曼滤波器被广泛应用于目标位置预测领域,但由于算法复杂、计算量大,采用软件实现难以满足现代跟踪系统的实时性要求,本文介绍了卡尔曼(Kalman)算法的理论推导,提出了一种基于FPGA的可重配置实时卡尔曼滤波器硬件结构,在Simulink中的DSP Builder实现卡尔曼滤波器,最后在FPGA中实现。  相似文献   

10.
空频域量化误差最小的光学小波滤波器设计   总被引:1,自引:1,他引:0  
田逢春  韩亮  王宇  徐鑫 《光电工程》2008,35(7):109-115
通过理论分析和仿真计算,研究利用不同小波基构造的光学小波滤波器的量化误差,分析交换分解和重构滤波器对光学小波滤波器量化误差的影响.实验结果表明不同小波基的量化误差通常是不同的,具有最小空、频域量化误差的小波基是交换分解和重构滤波器后的5/3 小波.根据光学小波滤波器的空、频域量化误差最小原则,基于提升算法,构造出空、频域量化误差最小的最优小波.  相似文献   

11.
This study focuses on meeting the challenges of big data visualization by using of data reduction methods based the feature selection methods. To reduce the volume of big data and minimize model training time (Tt) while maintaining data quality. We contributed to meeting the challenges of big data visualization using the embedded method based “Select from model (SFM)” method by using “Random forest Importance algorithm (RFI)” and comparing it with the filter method by using “Select percentile (SP)” method based chi square “Chi2” tool for selecting the most important features, which are then fed into a classification process using the logistic regression (LR) algorithm and the k-nearest neighbor (KNN) algorithm. Thus, the classification accuracy (AC) performance of LR is also compared to the KNN approach in python on eight data sets to see which method produces the best rating when feature selection methods are applied. Consequently, the study concluded that the feature selection methods have a significant impact on the analysis and visualization of the data after removing the repetitive data and the data that do not affect the goal. After making several comparisons, the study suggests (SFMLR) using SFM based on RFI algorithm for feature selection, with LR algorithm for data classify. The proposal proved its efficacy by comparing its results with recent literature.  相似文献   

12.
BGA (Ball Grid Array) surface defect detection requires faster and more accurate methods for semiconductor industry applications. Traditionally, the BGA inspection used gray-scale images. However, the solder pad, wiring and gray scales shown in images depict little variance. Therefore, when the threshold value is poorly set or the contract rate is insignificant, BGA detection may fail to segment an object. This research proposes a modified methodology that uses Gamma correction for image enhancement. Three-color bands were applied to a modified Gamma correction algorithm (i.e. RGB) to better separate the high and low image contrasts. Better results were obtained by dividing the image into background and foreground portions using the Gamma correction. As a result, the proposed method improved the contrast value by 52.09%. After the images were enhanced and segmented, the compactness and internal holes were calculated as features for classification. The results showed that classification correctness was 96.43%. The proposed method used a 640?×?480 pixel image, performing complete defect detection 0.3 seconds faster than the traditional enhancement method, which requires 1?second. The research results provide an effective solution for the detection and classification of the BGA surface tin ball defect problem.  相似文献   

13.
Sjöberg H  Noharet B 《Applied optics》1998,37(29):6922-6930
A new heuristic filter based on the optimum filter for disjoint noise developed by Javidi and Wang [J. Opt. Soc. Am. A 11, 2604 (1995)] is presented. In this new filter a number of optimum filters built from single training images are combined linearly by use of the synthetic discriminant function (SDF) approach into a distortion-invariant filter for disjoint noise. Like the traditional SDF approach, this summation technique makes it possible to control the height of the correlation peak easily, for example, if a uniform filter response is needed. The filter is compared with the distortion-invariant version of the optimum filter on images with low contrast and high levels of nonoverlapping clutter. The new filter shows good results, demonstrating that it is, with very simple heuristic methods, possible to improve the performance of distortion-invariant filters for nonoverlapping noise.  相似文献   

14.
Abstract

In this paper we present one method for the characterization of the spatial light modulators (SLMs) of a real-time Vander Lugt type of correlator. This correlator uses two SLMs: one to introduce the scene and a second to introduce the frequency‐matched filter. The SLM characterization methods are in situ, that is in the correlator set‐up. Illumination conditions are different for each SLM, and consequently different characterization techniques must be used in each case. For the characterization of the scene SLM a diffraction method is used, while for the characterization of the filter SLM an interferometric technique is more convenient. Finally, we take into account the operating curves of scene and filter SLMs in the design of the filter in order to optimize the correlation peak.  相似文献   

15.
The ordinary least square (OLS) method is commonly used in regression analysis. But in the presence of outlier in the data, its results are unreliable. Hence, the robust regression methods have been suggested for a long time as alternatives to the OLS to solve the outliers problem. In the present study, new ratio type estimators of finite population mean are suggested using simple random sampling without replacement (SRSWOR) utilizing the supplementary information in Bowley’s coefficient of skewness with quartiles. For these proposed estimators, we have used the OLS, Huber-M, Mallows GM-estimate, Schweppe GM-estimate, and SIS GM-estimate methods for estimating the population parameters. Theoretically, the mean square error (MSE) equations of various estimators are obtained and compared with the OLS competitor. Simulations for skewed distributions as the Gamma distribution support the results, and an application of real data set containing outliers is considered for illustration.  相似文献   

16.
Graph filtering, which is founded on the theory of graph signal processing, is proved as a useful tool for image denoising. Most graph filtering methods focus on learning an ideal lowpass filter to remove noise, where clean images are restored from noisy ones by retaining the image components in low graph frequency bands. However, this lowpass filter has limited ability to separate the low-frequency noise from clean images such that it makes the denoising procedure less effective. To address this issue, we propose an adaptive weighted graph filtering (AWGF) method to replace the design of traditional ideal lowpass filter. In detail, we reassess the existing low-rank denoising method with adaptive regularizer learning (ARLLR) from the view of graph filtering. A shrinkage approach subsequently is presented on the graph frequency domain, where the components of noisy image are adaptively decreased in each band by calculating their component significances. As a result, it makes the proposed graph filtering more explainable and suitable for denoising. Meanwhile, we demonstrate a graph filter under the constraint of subspace representation is employed in the ARLLR method. Therefore, ARLLR can be treated as a special form of graph filtering. It not only enriches the theory of graph filtering, but also builds a bridge from the low-rank methods to the graph filtering methods. In the experiments, we perform the AWGF method with a graph filter generated by the classical graph Laplacian matrix. The results show our method can achieve a comparable denoising performance with several state-of-the-art denoising methods.  相似文献   

17.
一种具有特殊滤波器的递推极大似然法   总被引:2,自引:0,他引:2  
蓝康孟  洪文学 《计量学报》1995,16(4):290-296
本文提出一种采用特殊滤波器的递推极大似然法,该法不需单独估计滤波器的参数与阶次,而只需递推估计模型参数,其算法简单,计算量小,辨识精度高,收敛性好,并可用于在线辨识和实时数据处理。文中还通过计算机仿真与传统的参数辨识方法进行了分析比较。  相似文献   

18.
Hah D  Bordelon J  Zhang D 《Applied optics》2011,50(22):4320-4327
A new type of optical filter based on mechanical tuning and a microring resonator is proposed. The proposed filter is expected to consume much less standing power compared to the conventional thermo-optic and carrier-injection tunable filters. In this work, two methods are used to prove the concept of the proposed device: (1) the analytical method and (2) the finite-difference time-domain method. The dependence of the filter characteristics on some of the device parameters is studied as well.  相似文献   

19.
Riasati VR  Abushagur MA 《Applied optics》1997,36(14):3022-3034
The projection-slice synthetic discriminant function (PSDF) filter is introduced and proposed for distortion-invariant pattern-recognition applications. The projection-slice theorem, often used in tomographic applications for medical imaging, is utilized to implement a distortion-invariant filter. Taking M projections from one training image and combining them with (N - 1)M projections taken from another N - 1 training image accomplishes this. With the projection-slice theorem, each set of these M projections can be represented as M one-dimensional slices of the two-dimensional Fourier transform of the particular training image. Therefore, the PSDF filter has the advantage of matching each of the training images with at least M slices of their respective Fourier transforms. This filter is theoretically analyzed, numerically simulated, and experimentally implemented and tested to verify the simulation results. These tests show that the PSDF filter significantly outperforms the matched-filter and the basic synthetic discriminant function technique for the particular images used.  相似文献   

20.
Shi J  Reichenbach SE  Howe JD 《Applied optics》2006,45(6):1203-1214
Two computationally efficient methods for superresolution reconstruction and restoration of microscanning imaging systems are presented. Microscanning creates multiple low-resolution images with slightly different sample-scene phase shifts. The digital processing methods developed here combine the low-resolution images to produce an image with higher pixel resolution (i.e., superresolution) and higher fidelity. The methods implement reconstruction to increase resolution and restoration to improve fidelity in one-pass convolution with a small kernel. One method uses a small-kernel Wiener filter and the other method uses a parametric cubic convolution filter. Both methods are based on an end-to-end, continuous-discrete-continuous microscanning imaging system model. Because the filters are constrained to small spatial kernels they can be efficiently applied by convolution and are amenable to adaptive processing and to parallel processing. Experimental results with simulated imaging and with real microscanned images indicate that the small-kernel methods efficiently and effectively increase resolution and fidelity.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号