共查询到18条相似文献,搜索用时 156 毫秒
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针对在低信噪比下机载气象雷达回波多普勒参数(谱矩)估计不准确的问题,本文在气象目标的雷达回波频谱服从高斯分布的基础上,给出了一种利用协方差矩阵分解的快速参数化谱矩估计算法。通过理论分析,推导出雷达回波的协方差矩阵具有范德蒙结构特性,进而将用于谱矩估计的代价函数转化为类傅里叶变换结构,然后进一步通过快速傅里叶变换和高斯加权滑窗计算代价函数,实现快速的谱矩估计。仿真实验结果表明,该方法在信噪比低于5 dB时仍可以有效估计雷达回波的谱矩参数,同时运算复杂度大大降低,而且在谱宽值较大情况下仍能保持较好的估计性能。 相似文献
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天气雷达信号处理过程中,回波信号经谱矩估计得到反映气象目标信息的平均回波功率、平均径向速度和速度谱宽等信息参数,但是处理得到的回波数据中不仅包含有用回波数据,而且保留有地物杂波、系统噪声和失真回波数据等干扰回波,它们严重影响雷达数据质量。但是干扰回波和降水回波是有很明显的信号特征差异的,比如信号强度和信号相干性,根据这些特征参数可以有效识别干扰回波数据,选取信号特征差异比较明显的参数进行研究,通过设置门限阈值,对谱矩估计得到的基数据进行质量控制。实际处理结果表明,通过联合使用多种门限参数能够有效识别和滤除各种干扰回波数据,天气雷达基数据质量得到明显改善。 相似文献
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《现代电子技术》2016,(16):31-35
为更好地去除动态地物和海浪杂波,采用工程化数学模型建立下击暴流风场,并叠加海陆杂波数据。根据飞行参数和雷达性能参数,获取机载雷达回波仿真信号。预先获取飞行区域地形高度参数、环境风场及海浪、陆地等地物杂波谱宽近似估计值,确定需要进行杂波抑制的距离库。对采样信号进行频谱分析,确定杂波中心谱线,消除宽度等于杂波谱宽估计值内的功率谱线,从而达到消除地物杂波的目的。以剩余功率谱为采样值,进行高斯曲线拟合,完成功率谱重构。对重构的功率谱,计算其总功率、径向平均速度和谱宽值,获取抑制地物杂波后的气象回波信号。仿真结果表明,该方法能够根据飞行区域实时探空资料和地形数据,自适应确定海陆混合运动杂波位置,并消除地物杂波。 相似文献
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常规机载气象雷达采用脉冲对法估计谱宽实现湍流检测,当信噪比较低时脉冲对法的谱宽估计误差大。晴空湍流(clear air turbulence,CAT)含水量较少,雷达回波信噪比很低,因此常规机载气象雷达无法检测CAT。为提高低信噪比下机载气象雷达回波谱宽估计性能,提出了一种基于降秩多级维纳滤波器(Reduced-Rank Multistage Wiener Filter, RR-MWF)的回波谱矩估计方法。该方法在机载气象雷达引入空时体制的基础上,利用空时域联合处理对湍流回波进行处理,通过空时积累改善信噪比。在最小均方误差准则下,构造了适用于分布式气象目标的自适应RR-MWF权矢量和代价函数,估计回波谱矩。仿真实验表明,提出的RR-MWF估计器在信噪比低于10dB时明显优于常规的脉冲对法,可用于CAT检测。 相似文献
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Moisseev D. Unal C. Russchenberg H. Ligthart L. 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(2):239-246
This paper introduces a new ground clutter suppression technique which preserves weather echoes. This clutter suppression method uses both statistical and polarimetric properties of the target and clutter. This technique is intended for use in atmospheric studies for weather echoes the spectral properties of which do not differ much from those of ground clutter. This technique can be applied both to the total signal or to its separate Doppler frequency components 相似文献
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Classification of Ground Clutter and Anomalous Propagation Using Dual-Polarization Weather Radar 总被引:2,自引:0,他引:2
Rico-Ramirez M.A. Cluckie I.D. 《Geoscience and Remote Sensing, IEEE Transactions on》2008,46(7):1892-1904
This paper presents the results of a study designed to classify weather radar clutter echoes obtained from ground-based dual-polarization weather radar systems. The clutter signals are due to ground clutter, sea clutter, and anomalous propagation echoes, which represent sources of error in quantitative radar rainfall estimation. Fuzzy and Bayes classifiers are evaluated as an alternative approach to traditional polarimetric-based methods. Both systems were trained and validated by using C-band dual- polarization radar measurements, and a novel technique is proposed to calculate the texture function to mitigate against the edge effects at the boundaries of precipitation regions. A methodology is presented to extract the membership functions and conditional probability density functions to train the classifiers. The critical success index indicates that the Bayes classifier has, on average, a slightly better performance than the fuzzy classifiers. However, when optimal weighting was applied, the fuzzy classifier gave one of the best performances. The classifiers are sufficiently robust to be used when only single-polarization radar measurements are available. 相似文献
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针对双极化气象雷达中非气象回波的滤除问题,该文提出一种基于谱极化参数(SPP)的杂波滤波方法。不同于传统时域或频域的杂波抑制方法,该方法根据气象和杂波在距离-多普勒(RD)域内的特征不同进行前者的保留和后者的抑制。首先利用频谱极化特征构造SPP,结合形态学方法,在RD域内生成一个2元掩模。基于面向对象的思想,将2元掩模标记为气象对象掩模和杂波对象掩模。然后引入谱宽作为额外的参数,筛选出所有气象对象掩模,将其进行叠加可以获取完整的气象信息,最终生成SPP杂波滤波器。实测X波段和C波段气象雷达数据验证了所提方法的有效性。与移动双重谱线性退极化比(MDsLDR)滤波器和基于时域的门限因子杂波抑制方法相比,SPP滤波器在保留弱气象信息方面效果更好。此外,该方法计算复杂度低,可以实时应用于同时发射同时接收(STSR)和交替发射同时接收(ATSR)双极化气象雷达。 相似文献
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This paper presents a technique that enables the estimation of spectral moments of overlaid first and second trip weather echo signals in a pulsed Doppler radar. The transmitted pulses are phase coded with a sequence that allows manipulation of the signal spectrum in such a way that either the first or the second trip signal autocorrelation can be made zero, thus removing the bias error in mean velocity estimates due to overlaid echo. With a sufficiently large number of samples, desired mean velocities can be recovered using autocovariance processing provided that the interfering overlying echo power is not more than 10 dB higher than the desired echo power. Also presented is a spectral processing technique that, in conjunction with autocovariance processing, can recover all three spectral moments of both the first and second trip echoes, when their spectrum widths are narrow compared to the Nyquist interval and their power ratio is in the range ±15 dB. An algorithm is developed that can be easily implemented in existing Doppler radars, with the addition only of a lowpower switchable phase shifter and associated drive circuit. 相似文献
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针对机载气象雷达在复杂的地形环境下探测低空风切变时,地杂波呈现非均匀特征和难以获取足够的独立同分布(IID)样本,导致空时自适应处理(STAP)杂波抑制性能变差,使得风切变风速估计不准的问题。该文基于杂波信号稀疏特性,提出一种广义近似消息传递(GAMP)STAP方法,GAMP-STAP仅利用少量的样本在复杂地形环境下实现了风速较准确的估计。该方法首先利用杂波脊的先验信息构造稀疏字典,然后在贝叶斯框架下利用GAMP算法估计杂波幅度,恢复杂波功率谱,进而计算杂波协方差矩阵,最后构造STAP滤波器实现杂波抑制以及风切变风速估计。后续实验仿真结果证明了该方法的有效性。 相似文献
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机载气象雷达系统进行气象探测时易受到强地杂波的干扰,从而导致目标信息丢失。为准确检测地杂波中的气象目标,获取完整的目标信息,本文提出了一种基于卷积神经网络(Convolution Neural Networks, CNN)的机载气象雷达目标检测方法。该方法联合时域、多普勒域和俯仰维空域信息,将杂波相位对准指标、多普勒速度和干涉相位作为CNN的输入,并给出详细的网络结构。本文通过模拟雷达回波仿真产生训练集和测试集,并对所提网络进行训练和测试。仿真结果表明,与目前的气象目标检测方法相比,该方法具有较高的检测概率,而且在谱矩信息变化的情况下仍可维持较好的检测性能,具有很好的鲁棒性。此外,仿真结果表明CNN比传统的贝叶斯分类器和支持向量机等分类网络具有更好的分类性能。 相似文献
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The article studies parametric estimation of spectral moments of a zero-mean complex Gaussian stationary process immersed in independent Gaussian noise. With the merit of the maximum-likelihood (ML) approach as motivation, this work exploits a Whittle's (1953) type objective function that is able to capture the relevant features of the log-likelihood function while being much more manageable. The resulting estimates are strongly consistent and asymptotically efficient. As an example, application to Doppler weather radar data is considered 相似文献