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摘要随着科学技术的发展，雷达定距测速技术也在不断进步，调频法定距日益得到广泛的应用。调频法定距的发射信号是频率按调制信号规律变化的等幅连续波，其目标回波延迟时间正比于回波信号和发射信号的频率差，具有较高的测距精度。
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当目标静止时，其差频谱线仅受距离信息调制，分析起来较简单。然而，当目标运动时，由于多普勒效应的存在，与静止目标的差频相比，谱线将发生变化，各次谐波处的谱线消失，取而代之的是与原来谐波相差正负fd的谱线，差频既受信号距离信息调制，又受速度信息调制的，使得差频更加复杂，距离和差频的对应性更加模糊。因此，必须将回波信号中的多普勒频率提取出来，以获取目标的距离和速度信息。6140
针对静止与运动目标调频定距测速原理的研究，得知多普勒信号在运动目标定距测速过程中的重要性。本课题针对运动目标，深入研究了多普勒滤波器的设计方法，利用matlab和Quartus II软件仿真，并加载到FPGA硬件电路中。FPGA,即现场可编程门阵列，作为专用集成电路（ASIC）领域中的一种半定制电路，它既解决了定制电路的不足，又克服了原有可编程器件门电路数有限的缺点。同时，由于发射信号选为三角波线性调频信号，所以对利用DDS设计三角波的方法做了简单介绍。
数字滤波器是由数字乘法器、加法器和延时单元组成的一种算法或装置，可分为FIR和IIR两种。本课题选用FIR滤波器，探讨了FIR滤波器常见的串行、并行两种结构和实现方法，给出了优化方案，同时介绍了调用IP核设计滤波器的具体过程，并对结果进行了比较，进一步了解了各种方案的优缺点，论证了系统方案的正确性。6140
关键词 差频分析,多普勒滤波，FPGA ，DDS，IP核
毕业设计说明书（论文）外文摘要
Title Doppler Filter Design Based on FPGA
Abstract
With the development of science and technology, the technology in range/speed measurement radar has made great progress,and the FM ranging method is widely used.The transmit of FM ranging radar with great ranging accuracy is persisten wave whose frequency changes according to the modulation signal.The target echo delay time is proportional to the frequency difference of the echo signal and the transmit signal.
When the target is standstill, the spectrum line of the frequency differency subject only to the distance information modulation, which is easy to analyse. However, when the target motion, the spectral lines will change with the effect of doppler frequency. Every harmonic place spectrum line disappears ,and the doppler frequency that has a different frequency of fd takes place.The difference frequency turns out to be modulated not only by distance information,but also the information of speed,which makes the difference frequency more complex.Thus in order to analyze the distance and velocity of the target,we must extract the doppler frequency.
According to the research of the static and moving targets,we know the importance of doppler frequency in measuring the distance and speed of the target. Aiming at the moving target, this research focuses mainly on doppler filter design methods, with simulation of matlab and Quartus II software , and the loading platform of FPGA. As a special integrated circuits (ASIC) in the field of a half a custom circuit, FPGA,the field programmable gates array,can resolve the shortcomings of the designed circuit and overcome the limited number of gate of the original programmable device.Also, because the signal transmitted is triangle wave linear frequency modulation signal, the method of DDS design of triangle wave is also introduced.