共查询到20条相似文献,搜索用时 187 毫秒
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基于Stein的无偏估计原理的自适应小波降噪阈值选择(rigrsure)算法,利用小波变换分解低信噪比下的Block信号,使用rigrsure算法获得重构后的低频信号和各层细节信号小波降噪阈值,提出了一种改进降噪算法,对Block信号降噪,通过仿真取得良好的降躁降噪效果。 相似文献
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数字阵列雷达方位超分辨角度估计的仿真 总被引:1,自引:1,他引:0
基于幅度比较单脉冲方法的测角局限性,采用先进的阵列超分辨测向技术MUSIC算法,对处于同一距离门和频率门的2个目标,在纯噪声背景和杂波背景下进行了波达方向(DOA)估计,对不同的信噪比和目标进入角度,仿真了目标的分辨情况并计算了DOA角度估计的精度,证明了机载雷达方位超分辨角度估计可以较好地实现落入清晰区或者副瓣杂波区目标的角度分辨与精度估计,但是对目标的信噪比和进入角度有一定的要求. 相似文献
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传统的和差测角方法在雷达、对抗、通信等多个领域得到了广泛的应用,但受限于信噪比的影响,角度测量盲区较大。超分辨算法(如MUSIC等)能够达到非常高的角度测量精度,但计算复杂度随着阵元或波束个数的增大而增加,为了降低实时处理的难度,同时考虑到实际环境中都是针对单目标的角度测量,提出了一种基于两波束的超分辨MUSIC算法,该算法涉及到的二维矩阵特征分解在角度估计过程中具有闭式形式,不仅运算复杂度很低,而且适用于目前大多数的阵列处理系统。 相似文献
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基于贝叶斯估计的小波阈值图像降噪方法 总被引:8,自引:0,他引:8
提出一种新的基于贝叶斯估计的小波收缩阈值的图像降噪方法,该方法是通过最小Bayes风险的方法对图像小波变换后的小波系数进行估计,这种对小波系数的估计不仅与子带的方向和层次有关,而且与小波系数的大小有关。试验结果该方法比一般小波收缩阈值方法的降噪效果要好;还表明在峰值信噪比较低时该方法的降噪效果比Wiener滤波差,当峰值信噪比较高时该方法的降噪效果比Wiener滤波好。 相似文献
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Fernando KL Mathews VJ Varner MW Clark EB 《IEEE transactions on bio-medical engineering》2003,50(8):950-957
This paper presents a new measure of heart rate variability (HRV) that can be estimated using Doppler ultrasound techniques and is robust to variations in the angle of incidence of the ultrasound beam and the measurement noise. This measure employs the multiple signal characterization (MUSIC) algorithm which is a high-resolution method for estimating the frequencies of sinusoidal signals embedded in white noise from short-duration measurements. We show that the product of the square-root of the estimated signal-to-noise ratio (SNR) and the mean-square error of the frequency estimates is independent of the noise level in the signal. Since varying angles of incidence effectively changes the input SNR, this measure of HRV is robust to the input noise as well as the angle of incidence. This paper includes the results of analyzing synthetic and real Doppler ultrasound data that demonstrates the usefulness of the new measure in HRV analysis. 相似文献
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El-Sayed A. El-Dahshan 《Telecommunication Systems》2011,46(3):209-215
This paper introduces an effective hybrid scheme for the denoising of electrocardiogram (ECG) signals corrupted by non-stationary
noises using genetic algorithm (GA) and wavelet transform (WT). We first applied a wavelet denoising in noise reduction of
multi-channel high resolution ECG signals. In particular, the influence of the selection of wavelet function and the choice
of decomposition level on efficiency of denoising process was considered. Selection of a suitable wavelet denoising parameters
is critical for the success of ECG signal filtration in wavelet domain. Therefore, in our noise elimination method the genetic
algorithm has been used to select the optimal wavelet denoising parameters which lead to maximize the filtration performance.
The efficiency performance of our scheme is evaluated using percentage root mean square difference (PRD) and signal to noise
ratio (SNR). The experimental results show that the introduced hybrid scheme using GA has obtain better performance than the
other reported wavelet thresholding algorithms as well as the quality of the denoising ECG signal is more suitable for the
clinical diagnosis. 相似文献
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利用小波阈值去噪方法和传统空间域Lee 滤波的特点, 提出了一种图像去噪的的组合滤波方案。首先在小波域对图像阈值去噪, 得到预去噪图像; 再在空间域上利用自适应Wiener 滤波器进一步提高恢复图像的精度。为了保证小波域和空间域两种算法之间的匹配, 对预去噪图像中残留噪声的分布进行了研究, 对其噪声方差估计做了改进, 提出了一种估计噪声方差的近似最优公式。仿真实验表明, 与单独的在小波域或空域去噪相比, 该方法的均方误差和信噪比指标均得到了改善。 相似文献
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多载频MIMO雷达的空时超分辨算法 总被引:1,自引:0,他引:1
该文建立了多载频MIMO (Multi-Carrier-Frequency MCF-MIMO) 雷达的信号模型,指出信号预处理后在接收端形成一个阵元数为NtNr的等效阵列(Nt, Nr分别为发射和接收阵元数),推导出窄带情况下导向矢量是发射和接收导向矢量的kronecker积,并针对该特点提出了采用空时2维MUSIC方法来实现距离和角度的超分辨,从而提高在多目标环境中目标距离以及角度的估计精度。推导了距离和角度估计的Cramer-Rao界,并仿真研究了估计性能与信噪比、快拍数和波达方向的关系,最后给出了面阵情况下3维空时超分辨的仿真结果,验证了该算法在面阵多维情况下的有效性。 相似文献
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Wavelet thresholding techniques for power spectrum estimation 总被引:3,自引:0,他引:3
Estimation of the power spectrum S(f) of a stationary random process can be viewed as a nonparametric statistical estimation problem. We introduce a nonparametric approach based on a wavelet representation for the logarithm of the unknown S(f). This approach offers the ability to capture statistically significant components of ln S(f) at different resolution levels and guarantees nonnegativity of the spectrum estimator. The spectrum estimation problem is set up as a problem of inference on the wavelet coefficients of a signal corrupted by additive non-Gaussian noise. We propose a wavelet thresholding technique to solve this problem under specified noise/resolution tradeoffs and show that the wavelet coefficients of the additive noise may be treated as independent random variables. The thresholds are computed using a saddle-point approximation to the distribution of the noise coefficients 相似文献