【作者】 李松；

【导师】 苑立波；

【作者基本信息】 哈尔滨工程大学 ， 光学工程， 2007， 硕士

【摘要】 激光多普勒测速仪是一种测量流场和运动物体速度的精密仪器，根据激光多普勒原理，利用被测流体中的散射粒子对入射光进行散射，并通过光电探测器探测散射光的频移量，根据这个频移量便可以计算出流体的速度。具有动态响应快、空间分辨率高、测量范围大、非接触测量和实时性好等优点。为了提高激光测速系统中信号处理速度，获取更高的测量精度和实时检测能力，本文从硬件结构、信号处理和实验结果入手，提出了利用DSP芯片作为频率分析处理器的多普勒测速系统，并围绕它的测速技术中的频谱细化技术开展了有关的研究。频谱细化技术近年来发展迅速，从分析精度、计算效率、分辨率及灵活性等方面看，基于复调制的Zoom-FFT方法是一种行之有效的方法。本文采用组合算法，即小样本Zoom-FFT算法结合频率校正算法，用Matlab实现了该算法，并通过仿真验证，证明了该算法的优越性。信号处理系统采用TI(Texas Instruments)公司的TMS320VC5509作为主控芯片，设计了前置放大电路、滤波电路、AD采集电路、DSP控制模块。在处理方法上采用了实数基2的FFT算法。更多还原

【Abstract】 The Laser Doppler Velocimeter(LDV) is a kind of precise instrument, whichis used to measure velocity of liquid and the moving objects. It is based onDoppler principle of light. It uses seeding particles to scatter the laser incident onit, then detects the change of the frequency of the scattered light by photoelectricdetector. Finally gets the velocity of fluid or moving object according the velocitywhich contained in the scattered light based on the frequency achieved isproportional to the velocity. The LDV has many merits, such as a rapid dynamicresponse, good space differentiating ability, wide measure range, high precision,its non-contact and real-time operation.For improving signal processing speed in LDV system to obtain highermeasure precision and real-time detection, a LDV signal processor using DSP asspectrum-analyzing processor was described based on hardware frame, signalprocessing and trial results, and the spectrum zoom processing in LDV has beeninvestigated. The technology of analyzing local magnitude—frequency of signalhas been developed rapidly in recently few years. As in the aspects of precision,efficiency, resolving power and agility, Zoom-FFT(ZFFT) is an effective methodto analyze local magnitude—frequency of signal, and it has been widely used. Inthis paper, the working principle of ZFFT has been introduced. A combinedmethod that is small sample ZFFT in addition to energy barycenter has beenrealized under MATLAB environment and been validated through simulation.The result shows that ZFFT is simple and feasible.TMS320VC5509 is used as the main controller in the LDV signal processorsystem. We have designed the circuit of preamplifier and filter, the A/D samplecircuit and DSP control module. The algorithm of FFT based on 2 is the mainmethod for signal processing.更多还原