对传感器阵列信号波达方向(DOA,direction of arrival)估计算法研究多集中在均匀线阵、圆阵等规则阵型阵列,但在水下传感网络等应用环境中阵元分布具有一定随机性,阵列呈现不规则特点.论文利用虚拟阵元思想,通过对不规则阵列的虚拟内插...对传感器阵列信号波达方向(DOA,direction of arrival)估计算法研究多集中在均匀线阵、圆阵等规则阵型阵列,但在水下传感网络等应用环境中阵元分布具有一定随机性,阵列呈现不规则特点.论文利用虚拟阵元思想,通过对不规则阵列的虚拟内插,在逻辑上构建多个具有相同配置参数的子阵列;对多个结构相同的子阵,利用空间平滑技术进行相关目标方位估计;为消除内插引入的非高斯有色噪声影响,引入信号高阶累积量,用累积量矩阵代替协方差矩阵,保证算法精确高效.通过计算机仿真,首先对比了不同信噪比和快拍数条件下提出的算法与传统算法性能,其次研究了构建子阵时角度间隔的取值对估计结果的影响,最后定量分析了特定信噪比和快拍数下新算法DOA估计的平均偏差和标准差,结果显示,新算法能有效提高估计精度.展开更多
针对内插变换应用于波束形成时,适用角度范围受限的问题,提出了一种利用权值约束变换误差的改进算法.该方法将权值和变换误差约束为近似正交的关系,在虚拟阵列接收信号的协方差矩阵上加载变换误差协方差矩阵,改善了变换误差过大时波束...针对内插变换应用于波束形成时,适用角度范围受限的问题,提出了一种利用权值约束变换误差的改进算法.该方法将权值和变换误差约束为近似正交的关系,在虚拟阵列接收信号的协方差矩阵上加载变换误差协方差矩阵,改善了变换误差过大时波束形成性能下降的问题.仿真结果表明,改进后的算法应用于大角度内插变换波束形成时,在干扰处仍能形成稳定的较深的零点,增加了虚拟阵列波束形成的输出信干噪比(Signal to Interference and Noise Ratio,SINR).与现有方法相比,该方法增加了内插变换应用于虚拟阵列波束形成时的适用角度范围,且能够补偿阵列本身带来的误差,计算复杂度较低.展开更多
An approach of distane map based imageenhancement (DMIE) is proposed. It is applied toconventional interpolations to get sharp images. Edgedetection is performed after images are interpolatedby linear interpolations. ...An approach of distane map based imageenhancement (DMIE) is proposed. It is applied toconventional interpolations to get sharp images. Edgedetection is performed after images are interpolatedby linear interpolations. To meet the two conditionsset for DMIE, i. e., no abrupt changes and no over-boosting, different boosting rate should be used inadjusting pixel intensities. When the boosting rate isdetermined by using the distance from enhancedpixels to nearest edges, edge-oriented imageenhancement is obtained. By using Erosion technique,the range for pixel intensity adiustment is set.Over-enhancement is avoided by limiting the pixel iutensities in enhancement within the range. A unifled linear-time algoritiml for disance transform is adopted to deal with the calculation of Euelidean distance of the images.Its computation complexity is 0(N).After the preparation,i.e.,distance transforming and erosion,the images get more and more sharpened while no over.boosting.Occurs by repeating the enhancement procedure ,The simplicity of the enhancement operation makes DMIE suitable for enhancement rate adjusting展开更多
文摘对传感器阵列信号波达方向(DOA,direction of arrival)估计算法研究多集中在均匀线阵、圆阵等规则阵型阵列,但在水下传感网络等应用环境中阵元分布具有一定随机性,阵列呈现不规则特点.论文利用虚拟阵元思想,通过对不规则阵列的虚拟内插,在逻辑上构建多个具有相同配置参数的子阵列;对多个结构相同的子阵,利用空间平滑技术进行相关目标方位估计;为消除内插引入的非高斯有色噪声影响,引入信号高阶累积量,用累积量矩阵代替协方差矩阵,保证算法精确高效.通过计算机仿真,首先对比了不同信噪比和快拍数条件下提出的算法与传统算法性能,其次研究了构建子阵时角度间隔的取值对估计结果的影响,最后定量分析了特定信噪比和快拍数下新算法DOA估计的平均偏差和标准差,结果显示,新算法能有效提高估计精度.
文摘针对内插变换应用于波束形成时,适用角度范围受限的问题,提出了一种利用权值约束变换误差的改进算法.该方法将权值和变换误差约束为近似正交的关系,在虚拟阵列接收信号的协方差矩阵上加载变换误差协方差矩阵,改善了变换误差过大时波束形成性能下降的问题.仿真结果表明,改进后的算法应用于大角度内插变换波束形成时,在干扰处仍能形成稳定的较深的零点,增加了虚拟阵列波束形成的输出信干噪比(Signal to Interference and Noise Ratio,SINR).与现有方法相比,该方法增加了内插变换应用于虚拟阵列波束形成时的适用角度范围,且能够补偿阵列本身带来的误差,计算复杂度较低.
文摘An approach of distane map based imageenhancement (DMIE) is proposed. It is applied toconventional interpolations to get sharp images. Edgedetection is performed after images are interpolatedby linear interpolations. To meet the two conditionsset for DMIE, i. e., no abrupt changes and no over-boosting, different boosting rate should be used inadjusting pixel intensities. When the boosting rate isdetermined by using the distance from enhancedpixels to nearest edges, edge-oriented imageenhancement is obtained. By using Erosion technique,the range for pixel intensity adiustment is set.Over-enhancement is avoided by limiting the pixel iutensities in enhancement within the range. A unifled linear-time algoritiml for disance transform is adopted to deal with the calculation of Euelidean distance of the images.Its computation complexity is 0(N).After the preparation,i.e.,distance transforming and erosion,the images get more and more sharpened while no over.boosting.Occurs by repeating the enhancement procedure ,The simplicity of the enhancement operation makes DMIE suitable for enhancement rate adjusting
