共查询到19条相似文献,搜索用时 46 毫秒
1.
针对水下成像时圆弧阵常规波束旁瓣级较高,当存在强干扰时容易带来较多虚警的缺点,提出一种基于二阶锥规划的稳健低旁瓣自适应波束形成方法。该方法通过对波束旁瓣进行优化设计,可以将波束旁瓣级进行严格控制,并进一步结合协方差矩阵重构法,使波束形成器的稳健性得到提高,最后将该波束优化问题转化为二阶锥规划问题进行求解。计算机仿真结果表明,相较于其他算法来说,文中算法在波束旁瓣级得到严格控制的同时,可以在存在各类失配的情况下获得更高的输出信干噪比,稳健性更高。水池实验进一步验证了该方法的有效性,该研究成果可以在声呐成像领域应用。 相似文献
2.
3.
4.
5.
6.
舷侧阵正常工作时,由于海洋环境比较复杂,以及每路水听器通道的传输特性不完全一致,使舷侧阵每一个水听器输出信号的相位和幅度叠加了一个随机误差。在作MVDR自适应波束形成时,该随机误差的存在将影响到基阵的阵增益,降低检测能力。仿真结果表明:幅度和相位误差的存在会降低MVDR波束形成器的阵增益,两类误差越大,阵增益就越小;输入信噪比越高,MVDR波数形成器的阵增益就越小。文中从统计学角度分析了随机相幅误差对协方差矩阵的影响,然后通过数值仿真得到阵增益的变化规律。 相似文献
7.
8.
采用一种宽带相关结合稳健自适应波束形成的检测方法,来提高弱目标在强干扰背景下的检测能力。宽带相关检测具有多目标方位分辨力高的优点,它基于常规波束形成得到,但由于其旁瓣级有限,存在强干扰时会导致其旁瓣区域的相关检测产生凹陷,因此直接影响弱目标的检测能力。通过分析常规宽带相关检测中目标旁瓣区域产生凹陷原因,利用宽带稳健自适应波束形成的干扰抑制能力,提出了一种将宽带稳健导向最小方差波(Steered Minimum Variance,STMV)与宽带相关检测结合的宽带检测新方法。该方法能有效消除相关检测中强干扰的影响,提高被动声呐的宽带检测性能。仿真和试验数据处理结果验证了该方法的有效性。 相似文献
9.
在分析二阶锥规划(Second-Order Cone Programming,SOCP)算法的基础上,设计了声呐阵列并采用SOCP方法对其波束图进行了优化;根据SOCP的波束优化设计方法,设计了基于FPGA的16元均匀圆阵的波束形成器。目的在于提高波束优化设计的稳健性以及信号处理系统的运算实时性、运算精度等。对FPGA波束形成器的仿真性能进行了分析,主要分析了以下两个方面:首先分析了当权值位数不同时对波束形成器输出的影响,其次分析了波束优化设计方法的抗阵列流形误差的性能。仿真设计结果和实验表明本文方法的有效性。二阶锥波束优化设计的波束图有着良好的稳健性,采用12位权值的FPGA波束形成器,抗阵元位置误差性能也比较好。 相似文献
10.
利用自适应方法对"米"字形体积阵进行波束形成,发现在预成的多波束中奇偶号波束效果差别较大,影响了检测性能、定位精度.从预成波束方向阵等效孔径入手,解释了奇偶号波束不一致的原因,通过改变预成波束方向、构造阵等效孔径相等措施来改进体积阵波束形成.计算机仿真、水池实测验证了这种方法可以有效地提高体积阵波束形成的整体效果. 相似文献
11.
12.
The objective of the blind beamforming is to restore the unknown source signals simply based on the observations, without a priori knowledge of the source signals and the mixing matrix. In this paper, we propose a new joint multiple matrix diagonalization (JMMD) algorithm for the robust blind beamforming. This new JMMD algorithm is based on the iterative eigen decomposition of the fourth-order cumulant matrices. Therefore, it can avoid the problems of the stability and the misadjustment, which arise from the conventional steepest-descent approaches for the constant-modulus or cumulant optimization. Our Monte Carlo simulations show that our proposed algorithm significantly outperforms the ubiquitous joint approximate diagonalization of eigen-matrices algorithm, relying on the Givens rotations for the phase-shift keying source signals in terms of signal-to-interference-and-noise ratio for a wide variety of signal-to-noise ratios 相似文献
13.
Phasor Measurement Units (PMUs) provide Global Positioning System (GPS) time-stamped synchronized measurements of voltage and current with the phase angle of the system at certain points along with the grid system. Those synchronized data measurements are extracted in the form of amplitude and phase from various locations of the power grid to monitor and control the power system condition. A PMU device is a crucial part of the power equipment in terms of the cost and operative point of view. However, such ongoing development and improvement to PMUs’ principal work are essential to the network operators to enhance the grid quality and the operating expenses. This paper introduces a proposed method that led to low-cost and less complex techniques to optimize the performance of PMU using Second-Order Kalman Filter. It is based on the Asyncrhophasor technique resulting in a phase error minimization when receiving the signal from an access point or from the main access point. The MATLAB model has been created to implement the proposed method in the presence of Gaussian and non-Gaussian. The results have shown the proposed method which is Second-Order Kalman Filter outperforms the existing model. The results were tested using Mean Square Error (MSE). The proposed Second-Order Kalman Filter method has been replaced with a synchronization unit into the PMU structure to clarify the significance of the proposed new PMU. 相似文献
14.
二阶锥规划在工程、控制、金融等领域具有广泛的应用.本文研究一种求解二阶锥规划的非精确不可行内点法.该算法的基本思想是首先定义不可行中心路径及其邻域,然后通过求解一个非线性方程组得到非精确的搜索方向,再取一个合适的步长,使得新的迭代点落在不可行中心路径的邻域内.该算法不要求初始点和迭代点位于严格可行解集内.在适当的假设条件下证明了算法只需迭代O(√n ln(1ε))次就可以找到问题的ε-近似解. 相似文献
15.
Array gain is a common parameter used in laser phased array research. This paper will present a new parameter called the frequency
modulation of laser phased array (FMLPA). The array gain model for laser phased arrays was derived using an assumption that
ultrasound from each array member interferes with each other. This would be always true if laser generated ultrasound is narrow
band. However, laser generation of ultrasound is broad band. Broad band ultrasound signals have short duration in the time
domain. If the time delay between generated wave fronts from each array member is longer than the duration of the broad band
ultrasound signal from each array member, the ultrasound signals from each array member will not interfere with each other.
The time delay between generated wave fronts from each array member is 0 s at a laser phased array’s beam steering angle and
increases away from the beam steering angle. Therefore, ultrasound from each array member always interfere at angles close
to the beam steering angle. However, ultrasound from each array member may not interfere at angles away from the beam steering
angle depending on the time delay between generated wave fronts and duration of the broad band ultrasound signal. A theoretical
model of the FMLPA was developed and experimentally verified for use when ultrasound from each array member does not interfere
with each other. It was experimentally verified that current array gain equations still apply when ultrasound from array members
interfere with each other. The FMLPA can be used to create new techniques for measuring weld penetration depth, crack location,
and dimensions of objects. 相似文献
16.
针对提高阵列天线波束性能问题,本文提出了基于共轭虚拟阵列的信号导向矢量扩展方法.利用共轭虚拟阵元扩展阵列,增大了阵列孔径却不改变实际阵元数,降低了副瓣电平并且不会增加天线制造成本.在虚拟阵列的基础上对信号导向矢量进行扩展,使阵列波束形成效果更加稳健.本文通过在有无干扰以及存在幅度和相位误差情况下对11个阵元阵列天线进行... 相似文献
17.
18.
19.
This paper suggests the solution of geometric programs with degrees of difficulty by means of an auxiliary problem which is the reduced equivalent of the primal problem. The auxiliary problem is derived from the primal program by direct algebraic transformation and has a highly simplified convex separable structure. Using a condensation technique introduced by Duffin, it is shown that generalized polynomial programs can be solved via a sequence of approximating problems with a similar convex separable structure. 相似文献