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相关测速声呐的基本原理是“波形不变性”。该原理指出:发射具有一定时间间隔的信号,接收回波相关性最大的两个基元之间的间距与载体移动速度成正比。相关测速算法首先通过回波数据构建数据相关矩阵,然后利用速度估计算法将理论相关模型和回波数据构建的相关矩阵进行拟合得到最优参数信息,进而解算出载体速度信息。文章以简化最优参数求解流程为目标,提出了基于矩阵推导的参数拟合运算方法。该方法通过将底混响时空相关函数模型中的目标参量进行分离,进而将函数转变为矩阵形式,随后通过矩阵QR分解等手段,根据局部最小二乘法推导目标参数的求解公式,并直接求解出目标参数的解析解。仿真和湖上试验数据验证了该方法可以作为一种速度解算方法的可行性,并且具有运算复杂度低的优点。 相似文献
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声相关计程仪首先利用加权最小二乘法确定目标函数,然后通过序列二次规划法估计速度。考虑海底混响数据时空相关函数宽度的减小、相关系数点与相关函数中心点间距的增大,都会导致相关系数的均值减小、分布范围增大,此时相关系数在目标函数中对应项的权重也应当减小。在这样的前提下,引入调节参数μ,调节权重函数的宽度,使设备在各个速度下测速相对偏差的一致性达到最优,提高速度估计精确度。调节参数在设备标定与验证试验中确定,不同的设备可能具有不同的调节参数。试验数据证明了该方法对不同声相关计程仪测速精确度的提高都有效果。 相似文献
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通过对比分析了传统的地感线圈、视频、雷达等测速系统的应用现状,明确了现存各种检测方式的不足.基于此,本文提出了一种新型的基于地磁车辆检测器的测速系统,介绍了该系统的组成、工作流程和应用领域;重点分析了基于地磁车辆检测器的车辆速度检测原理和算法流程;对该系统进行了实地速度测试和超速抓拍试验,验证了该系统的有效性.整个系统运行稳定可靠,速度检测精度基本符合应用需求.通过深入分析影响测速精度的各主要因素,提出了进一步提高测速精度的改进措施. 相似文献
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随着通信技术的不断发展,通信系统及其配套设备数量都日益增多,通信机房已成为电信网络的重要组成部分。机房内的动力、环境设备必须时时刻刻为通信系统提供正常的运行环境,一旦机房环境设备出现故障,就会影响通信网络运行,后果不堪设想。为了保证通信系统安全可靠工作,对机房里面动力、环境设备进行自动监视和有机管理是极其必要的一通信机房动力环境集中监控对机房电源、环境、空调、消防、门禁、图像进行全面监控和管理,实现实时监测、实时记录、实时报警的监控目的,同时系统对所采集的各类数据进行存储备份并作自动分析,为通信设备的有效运行提供充分的决策支持。文章结合工程实例论述了基于物联网技术的通信动力设备及环境监控系统的构造设计。 相似文献
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声呐系统性能检测需要一种多通道可控相位信号和多通道大容量高速数据采集系统。通过多种高速数据采集和信号发射方案的对比,选用基于图形化编程语言LabVIEW和相应的硬件设备,设计、研制了一种32通道发射和128通道高速数据采集系统,用于多数声呐系统的性能检测。发射系统利用直接数字合成技术,生成可以单独调节相位的32通道正弦信号;采集系统采用分块读取减少缓冲区数据占用的方式,实现有限数据采集,并采用减少显示图形更新次数、使用DAQmx配置记录函数等方法,实现连续数据采集。测试结果表明,系统实现在采样率为2 MHz时,128通道中每通道1 300 000点的有限数据采集,以及采样率最高为0.7 MHz的128通道的连续数据采集。利用该系统对高分辨率测深侧扫声呐的发射信号进行检测,发射信号正常,系统工作良好。 相似文献
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声呐图像数据集获取困难,导致很多水下工作无法正常开展,如水下目标检测与跟踪、声呐图像的超分辨等,因此构建充足的声呐图像数据库成为很多水下研究工作的重要前提条件。受光学图像与合成孔径雷达(Synthetic Aperture Radar,SAR)图像转换研究工作的启发,提出了基于CycleGAN实现声呐图像库的构建,即利用光学图像合成声呐图像,实现光学到声呐的图像风格迁移。通过对CycleGAN网络损失函数的改进,提高了声呐图像的合成效果。通过与Pix2Pix等图像风格迁移网络进行比较的实验结果证明,修正后的CycleGAN网络具有更好的图像风格迁移效果。最后用合成的声呐图像训练Mask RCNN目标检测网络,并用真实的声呐图像进行测试,训练得到的模型能够成功地检测出真实声呐图像中对应的目标,进一步验证了利用光学图像构建声呐图像库的有效性。 相似文献
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Ferrara KW Algazi VR 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1991,38(1):17-26
For pt.I see ibid., vol.38, p.1-16, Jan. 1991. The signal models and performance of the estimation strategies described in pt.I are tested with experimental ultrasonic data. The ultrasonic data analyzed verify the theoretical model and predicted performance. The averaged correlation, verified experimentally, confirms that the correlation envelope can be used to estimate the velocity of scatterers and that the shape of the correlation function conveys information regarding the velocity profile within the sample volume. For both the wideband point and range spread estimators, the predicted improvement in velocity resolution and the reduction in height of subsidiary velocity peaks are demonstrated. Through the use of these estimation strategies, information regarding the mean velocity and velocity variation are available for each spatial location within the vessel. This information is presented using a three-dimensional spatial velocity profile display, which appears to offer a number of advantages in the rapid identification of pathology. 相似文献
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The area navigation system, discussed in this paper, is composed of ground
responders and a navigation terminal and can position a high-velocity aircraft and measure
its velocity. This navigation system is silent at ordinary times. It sends out a request signal
when positioning is required for an aircraft, and then the ground responders send a signal
for resolving the aircraft. Combining the direct sequence spread spectrum and frequency
hopping, the concealed communication mode is used in the whole communication process,
with short communication pulses as much as possible, so the system has strong
concealment and anti-interference characteristics. As the transmission delay is apparent in
the response communication mode, there is a big error where the common navigation
algorithm is used for the positioning and velocity measurement of a high-velocity aircraft.
In this paper, a new algorithm is proposed, which can eliminate the influence of response
communication delay on the positioning of a high-velocity moving target to realize the
precise positioning and velocity measurement of a high-velocity aircraft. 相似文献
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Embree PM O'Brien WR 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1990,37(3):176-189
A novel ultrasonic volumetric flow measurement method using time-domain correlation of consecutive pairs of echoes has been developed. An ultrasonic data acquisition system determined the time shift between a pair of range gated echoes by searching for the time shift with the maximum correlation between the RF sampled waveforms. Experiments with a 5-MHz transducer indicate that the standard deviation of the estimate of steady fluid velocity through 6-mm-diameter tubes is less than 10% of the mean. Experimentally, Sephadex (G-50; 20-80 mum dia.) particles in water and fresh porcine blood have been used as ultrasound scattering fluids. Two-dimensional (2-D) flow velocity can be estimated by slowly sweeping the ultrasonic beam across the blood vessel phantom. Volumetric flow through the vessel is estimated by integrating the 2-D flow velocity field and then is compared to hydrodynamic flow measurements to assess the overall experimental accuracy of the time-domain method. Flow rates from 50-500 ml/min have been estimated with an accuracy better than 10% under the idealized characteristics used in this study, which include straight circular thin-walled tubes, laminar axially-symmetric steady flow, and no intervening tissues. 相似文献
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A correlation receiver is presented for communication using the symbolic dynamics of a chaotic system. A chaotic system offers the potential for power efficient transmitters but many proposals to date have either been susceptible to noise and distortion in the channel, or are spectrally inefficient. The proposed system has a spectrum efficiency equivalent to conventional BPSK and offers a 2 dB performance improvement in AWGN. This is achieved by exploiting diversity in the transmitted signal, whereby each data symbol influences the transmitted pulse shape for the preceding symbols. Correlation detection over multiple symbols allows full exploitation of this diversity. In addition, each symbol can be detected multiple times and so a decoding gain is possible without the need for parity symbols. The diversity mechanism is investigated and the performance gains demonstrated. 相似文献
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S. R. Lapalikar A. C. Rao 《International journal for numerical methods in engineering》1983,19(10):1537-1547
Correlation is a measure of similarity between two functions. When two functions are exactly similar and equal, the correlation between them is maximum. The correlation concept can be used for system design, e.g. the four-bar mechanism, the slider crank mechanism, etc. The motion generated by four-bar linkage can be expressed as a function of link dimensions, input and output angles. The product of generated function and desired function gives correlation. The best possible design would be when the deviation of actual correlation from its maximum value (i.e. 100 per cent correlation) is least. This concept, in fact, leads to a modified least squares approach and based on this an objective function is formulated and minimized to give link dimensions. The results obtained are better than the least squares technique, and this is illustrated through different numerical examples. 相似文献