共查询到16条相似文献,搜索用时 937 毫秒
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从理论上分析和推导了单传感器测距测速的几何交汇模型,该模型结合二维栅格搜索策略对具有稳定线谱的匀速直线运动目标进行距离和速度的估计。为满足交汇模型的测频精度要求,介绍了对短样本信号进行测频的谱估计法、过零法和Hilbert方法。把多组对应一定特征频率、正横距离、目标速度和信噪比的目标通过信号代入交汇模型进行计算机仿真,相应得出一系列测量误差曲线,分析结果表明,对于一定参数的通过信号该模型可以较精确的估计出目标的正横距离及速度。 相似文献
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起伏背景下目标噪声线谱检测与频率估计 总被引:3,自引:3,他引:0
针对传统的水下目标辐射噪声线谱检测与频率估计方法所存在的不足,提出一种起伏背景下的水下目标辐射噪声线谱检测与线谱频率估计的方法。通过对观测数据的预处理,滤除目标辐射噪声起伏趋势项,再分别使用FFT方法和修正的Newton-Raphson迭代法来实现对目标辐射噪声线谱频率的粗略估计和精确估计。仿真结罘表明,该方法计算量较少,提高了检测概率和频率估计精度,且频率估计值的均方根误差较传统的周期图方法更接近Cramer-Rao界。 相似文献
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多普勒测速仪是水面或水下平台速度测量的主要设备。提出了利用随机样本一致(Random Sample Consensus,RANSAC)算法来估计多普勒频移,从而使速度测量具有更高的稳定性。多普勒测速仪信号处理的核心是测量多普勒频移,该方法利用回波复相关相位是多普勒频移的一次函数来估计多普勒频移,进而计算得到平台速度,在估计频移时采用RANSAC算法以提高测频精度。为了验证方法有效性,对信号形式为连续波(Continuous Wave,CW)脉冲对的情形进行了仿真。结果表明,提出方法的稳定性得到明显提高。 相似文献
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针对目标运动等导致的辐射噪声频谱特征的时变性对目标分类稳定性的影响,提出一种基于时频图像累积变换的抗频移声谱特征提取方法,不仅能够提取淹没在强噪声中的线谱信号,还能够实时给出谱线的参数信息,同时结合听觉特征识别原理,采用抗频移的仿倍频程的三角滤波法提取目标特征。仿真和实际数据处理表明,所提出的特征有助于探测设备克服目标未知的复杂运动带来的频谱时变影响,提高了分类特征的稳定性。 相似文献
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毫米波雷达阶跳频信号分析及运动补偿方法的实现 总被引:2,自引:0,他引:2
分析了毫米波雷达阶跳频信号参数以及复杂目标运动对该信号合成目标一维距离像的影响,研究了三角波调制下运动速度参数的估计方法。仿真表明,该方法具有较高的测速精度和较好的抗噪声性能,能ADSP21062信号处理板上运行时间为1.2ms。 相似文献
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随着安静型技术的飞速进步,舰船和潜艇的辐射噪声总源级越来越低,但其低频成分很难消除。推导了低频矢量声场双曲线方程形式的声场干涉条纹方程,建立了双曲线参数与目标运动参数的关系。分别利用射线理论和波动理论模拟了低频声场,计算了运动目标声压和水平、垂直振速的干涉谱图,采用短时傅里叶变换与霍夫变换结合的方法对干涉结构图进行处理,估计舰船目标的运动参数。仿真结果表明,利用运动目标的低频矢量宽带干涉谱可以有效估计出目标的运动参数,同时,垂直振速的干涉谱图参数估计结果较前两种谱图误差小。 相似文献
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Analysis of molecular dynamics of colloidal particles in transported dilute samples by self-mixing laser Doppler velocimetry 总被引:1,自引:0,他引:1
Colloidal particles in a liquid medium are transported with constant velocity, and dynamic light scattering experiments are performed on the samples by self-mixing laser Doppler velocimetry. The power spectrum of the modulated wave induced by the motion of the colloidal particles cannot be described by the well-known formula for flowing Brownian motion systems, i.e., a combination of Doppler shift, diffusion, and translation. Rather, the power spectrum was found to be described by the q-Gaussian distribution function. The molecular mechanism resulting in this anomalous line shape of the power spectrum is attributed to the anomalous molecular dynamics of colloidal particles in transported dilute samples, which satisfy a nonlinear Langevin equation. 相似文献
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Tortoli P Bambi G Ricci S 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(8):1425-1431
Traditional Doppler methods measure only the axial component of the velocity vector. The lack of information on the beam-flow angle creates an ambiguity that can lead to large errors in velocity magnitude estimates. Different triangulation techniques so far have been proposed, which basically perform multiple measurements of the Doppler frequency shift originating from the same region. In this work, an original approach is introduced, in which two ultrasound beams with known relative orientation are directed toward the same vessel, but only one of them is committed to perform a Doppler measurement; the second (reference) beam has the specific task of detecting the beam-flow angle. The latter goal is obtained by accurately identifying the achievement of the target 900 reference-beam-to-flow angle through the inspection of the backscattered Doppler signal spectrum. In transverse flow conditions, in fact, such spectrum is expected to be centered on the zero frequency, and even small deviations from the desired 900 orientation cause noticeable losses of spectral symmetry. Validation of the new method has been performed through experimental tests, which show that the beam-flow angle can be estimated with high accuracy (rms errors lower than 1 degree), and repeatable velocity magnitude measurements are possible. A procedure for automatically tracking the desired orientation by the reference beam is also introduced and shown suitable for implementation in steerable linear array transducers. 相似文献
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Heetae Kim 《Journal of Modern Optics》2013,60(15):1330-1335
Generalized Doppler shift for light is derived by considering both velocity and acceleration, and is used to calculate time dilation ratio. A circular mirror used to measure time is transformed to the elliptical mirror in a reference frame when it is in motion. The special relativistic Doppler shift is calculated in any propagation direction of light for a constant velocity of motion. Furthermore, the generalized Doppler shift is derived by considering both the velocity and the acceleration effect. The ratio of the frequency shifts are shown as a function of velocity, acceleration, and detection angle. 相似文献