【作者】 徐军荣；

【导师】 于盛林；

【作者基本信息】 南京航空航天大学 ， 测试计量技术及仪器， 2009， 硕士

【摘要】 FMCW(调频连续波)雷达由于其自身的良好特性,被广泛应用于各种领域。而测距则是其最基本的功能之一,各领域对测距的精度的要求也越来越高。本文从数字信号处理的角度出发对FMCW雷达回波差频信号进行处理,从而提高其测距精度。FMCW雷达的距离测量误差主要来自两个方面:1)一部分来自于噪声,在低信噪比场合下,距离测量误差比较大甚至测量结果是错误的。2)FMCW雷达的距离测量固定误差受扫频带宽的限定,信号处理过程中的FFT频谱估计精度受FFT频率量化的限制,在测量精度要求较高的场合,直接利用FFT频谱估计目标距离显然无法达到其精度的要求。如采用增大FFT运算点数来减小频率的采样间隔,将大大增加数字信号处理的运算量,从而影响到雷达工作的实时性。本文针对以上两个问题,在深入分析FMCW雷达测距理论的基础上,完成了其差频信号的处理工作,主要内容如下:1)分析、仿真了噪声对FMCW雷达实际测距精度的影响,采用提升小波降噪的方法,采用改进的阈值函数对回波差频信号进行处理,提高信号的信噪比;2)本文在不改变扫频带宽的前提下提高频率估计精度从而提高距离测量的精度。采取的方法是先利用FFT得到FMCW雷达差频信号谱峰的粗略范围,然后再对这一范围进行谱峰最大值估值,精确计算差频信号频谱的主瓣的峰值点所在位置,从而实现频率(距离)的高精度估计;3)完成差频信号DSP处理的软件设计,并在开发板成功运行所编写的程序;4)完成了FFT变换的硬件仿真,采用Verilog HDL语言对其进行描述,在QuartusⅡ仿真环境下实现算法的仿真及综合,给出了仿真结果及其RTL级电路。更多还原

【Abstract】 Because of its well identity, FMCW is used widely. Ranging is the most essential function of Radar, the request of ranging precision becomes more and more high. In this thesis, the echo IF signal of the FMCW Radar is processed form the digital signal processing, and then the ranging precision is increased.Errors of range measuring of FMCW Radar are mainly caused by the following two problems1) Part of the errors of range measuring of FMCW(Frequency modulated continues wave) Radar come from the noise, if the SNR(Signal to Noise) is very low, the errors of the range measuring will be very big, even the result is wrong.2) The level measurement accuracy of the FMCW radar is determined by the bandwidth of the transmitted signal, and when estimating frequency with the FFT, the resolution and accuracy are limited by the observation time of the signal. In the case of high resolution and accuracy, it is difficult to meet the requirement of accuracy by using of FFT directly. Increasing the number of FFT’s points can decrease the frequency interval , but it will increase the complexity of computation at large extent.In this thesis, aimed at the above-mentioned two problems, based on analyzing the theory of FMCW Radar ranging deeply, the work of its IF signal processing is implemented.1) Analyzed and simulated the effect of the noise signal, then lifting wavelet transform are utilized, and an improved thresholding is used in the process of FMCW Radar echo signal, at last, the SNR is improved.2) The thesis plans improving frequency estimation accuracy, without changing the bandwidth of the transmitted signal. The method is getting the approximate range of frequency peak of FMCW radar’s beat frequency signal, utilizing FFT, the estimating the peak of the spectrum, using the method of this article. Thus we can get the high precision frequency estimation.3) Implement the DSP software design of the echo IF signal, then run in a experimental board successfully.4) At last ,the hardware emulator of the FFT arithmetic is implemented. The arithmetic are described in Verilog HDL, the simulation and implementation are performed on QuartusⅡto verify the feasibility of the design.更多还原