共查询到19条相似文献,搜索用时 203 毫秒
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提出了一种利用辐射噪声强度和线谱多普勒频移联合估计匀速直线运动目标的速度和正横距离的方法。该方法基于单水听器观测,首先在球面波近似下利用目标辐射噪声强度估计出正横时刻并确定目标速度和正横距离之间满足的线性关系;然后利用线谱多普勒频移,通过对一个新定义的代价函数进行一维搜索的方法估计出目标速度和正横距离。与现有各种基于噪声强度和线谱多普勒频移进行测距测速的方法相比,该方法具有以下优点:(1)要求更少的先验知识,易于确定参数搜索范围;(2)参数估计过程中仅需一维搜索,并且算法可应用于需对目标参数进行预报的场合。数值仿真给出了不同参数条件下目标运动参数估计结果的统计误差。湖试结果验证了该方法的有效性。 相似文献
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一种激光多普勒信号的频率估计算法 总被引:1,自引:0,他引:1
分析了激光多普勒回波信号的特征,提出了一种激光多普勒信号的频率估计算法.用FFT(Fast Fourier Transform)技术求得信号的自相关函数,并由功率谱得到信号频率的粗估计,然后用粗估计值对自相关函数移频,并根据移频信号自相关函数在一点的相位,估计频偏,对粗估计进行频率校正得到频率估计值.在进行信号频率粗估计和求相位时,利用计算过程中得到的结果和FFT因子的对称性,减少运算量.仿真结果表明,本算法有较小的均方根误差和平均绝对误差,应用于激光多普勒测速实验,结果与仿真一致. 相似文献
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一、前言利用激光多普勒效应进行气体液体和固体的速度测量,已在国内外得到广泛的重视和研究,并已将此新技术用于科研和生产。但是,通过测量激光的多普勒频移值△f,来求运动体的速度,其测速精度将受激光波长、接收方向及双光束夹角等换算因子精度的影响。衍射光栅多普勒频移信号△f,可由双光栅干涉系统产生,它所得到的多普勒信号和入射光的方向及光波波长均没有关系,只决定于光栅常数和光栅的运动速度。通过分偏振移相,还能得到四个90°相移的干涉信号,可直接用计数示波器和李沙育图形测量光栅的运动速度。因此,利用衍射光栅测量运动物体的速度 相似文献
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为了解决GPS接收机快速捕星问题,提高接收机定位速度,利用历书信息进行GPS卫星预报,提出了一种GPS卫星可见性预测的改进算法.在星历信息基础之上,用此算法对卫星的可见性及概略多普勒频移进行预测,并在GPS信号模拟器和GPS接收机组建的实验平台上,利用此种方法进行捕星定位实验.实验结果显示:该方法定位时间为原定位时间的39.5%. 相似文献
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宽带声学多普勒流速剖面仪,利用伪随机编码调制发射脉冲信号以及复相关算法计算各水层反射回波的多普勒频移,进而达到测速的目的。复相关算法中,在排除模糊速度干扰的情况下,测速精度与脉冲信号的长度存在正比的关系。而脉冲宽度越长,所用来调制发射脉冲信号的编码阶数也越高,随之带来的便是速度模糊的问题。在复相关测频算法的基础上,针对长编码脉冲信号出现的周期性测频模糊情况,利用短编码脉冲信号的测频结果作为判别标准,选取恰当的周期性频偏作为计算结果,既提高了测速精度,又解决了精度提高所带来的周期性速度模糊问题,并且在实际应用中,提高了低信噪比条件下的测速精度。 相似文献
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Real-time measurement capability of a frequency-modulated filtered light-scattering- (FM FLS) Doppler velocimeter has been demonstrated. Doppler-shifted light from a frequency-modulated Ti:sapphire laser scattered from a supersonic flow is imaged through a potassium vapor cell and is detected by FM spectroscopy. The FM signal is used in closed-loop feedback control of the laser frequency to lock the Doppler-shifted scattered light to the resonance frequency of the filter. The difference between the filter resonance frequency and the laser frequency when the scattered light is frequency locked to the filter resonance is the flow-induced Doppler shift. Changes in flow velocity are tracked by changes in laser frequency, which is subsequently measured to obtain the Doppler shift. The frequency-locking capability of the technique was achieved with use of a simple analog controller. The random Doppler shift measurement errors (2varsigma) were approximately 20 MHz, which correspond to velocity measurement errors for the real-time measurement of less than 3% in a 10-Hz bandwidth. 相似文献
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针对正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)在水声移动通信条件下存在对多普勒频偏敏感的缺陷,提出了一种基于频域变采样技术的多普勒补偿算法。利用移动通信条件下OFDM子载波正交性不变的特点,通过频域变采样实现对多普勒的快速补偿,并采用编码反馈校验技术跟踪系统多普勒变化,达到了OFDM移动通信条件下实时通信的目的。仿真和水池实验结果证实:频域变采样多普勒补偿算法不仅可以实时地跟踪通信载体运动变化,快速补偿多普勒,同时大幅降低了时域变采样多普勒补偿算法的计算量,降低了通信系统硬件平台复杂度。 相似文献
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Nabavizadeh A Urban MW Kinnick RR Fatemi M 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2012,59(4):752-765
We describe the theoretical principles of a new Doppler method, which uses the acoustic response of a moving object to a highly localized dynamic radiation force of the ultrasound field to calculate the velocity of the moving object according to Doppler frequency shift. This method, named vibro-acoustic Doppler (VAD), employs two ultrasound beams separated by a slight frequency difference, Δf, transmitting in an X-focal configuration. Both ultrasound beams experience a frequency shift because of the moving objects and their interaction at the joint focal zone produces an acoustic frequency shift occurring around the low-frequency (Δf) acoustic emission signal. The acoustic emission field resulting from the vibration of the moving object is detected and used to calculate its velocity. We report the formula that describes the relation between Doppler frequency shift of the emitted acoustic field and the velocity of the moving object. To verify the theory, we used a string phantom. We also tested our method by measuring fluid velocity in a tube. The results show that the error calculated for both string and fluid velocities is less than 9.1%. Our theory shows that in the worst case, the error is 0.54% for a 25° angle variation for the VAD method compared with an error of -82.6% for a 25° angle variation for a conventional continuous wave Doppler method. An advantage of this method is that, unlike conventional Doppler, it is not sensitive to angles between the ultrasound beams and direction of motion. 相似文献