【作者】 崔文玲；

【导师】 潘明海；

【作者基本信息】 燕山大学 ， 信号与信息处理， 2007， 硕士

【摘要】 在雷达技术领域,各种体制雷达的研制越来越离不开实验室内半实物仿真技术的支持。在实验室环境下雷达信号模拟器能够利用仿真技术,通过建立雷达信号模型灵活地产生雷达目标回波信号、雷达干扰信号和雷达环境信号,满足雷达系统设计、开发和测试的需要。对于半实物的仿真系统而言,需要对宽带雷达信号进行实时重构,本文对宽带雷达信号的实验室重构方法进行了深入的研究。雷达信号通常属于随机信号,其频率域统计特性比较容易得到,因此本文采用工程上易于实现的重构算法:根据功率谱特征求得其幅度谱,相位随机化后得到矢量频谱,再傅立叶反变换得到有限长时域序列,通过时域随机化处理得到无限长序列,然后进行内插扩展、数字正交调制实现上变频过程,通过D/A和低通滤波生成目标信号。对于宽带雷达信号而言,该算法的重构精度和实时性都要求的比较严格。本文针对影响信号重构精度和实时性的重点部分:时域随机化处理和内插扩展过程,分别进行了详细的分析。考虑到时域随机化处理中所选窗函数的不同频谱特性,提出了加汉宁窗并进行幅值修正的方法来完成有限长序列的无限扩展。同时由于多项式插值滤波器具有实时计算量小的优点,而多级结构又可以大大降低滤波器的设计要求和系统运算量,提出了一种将多相滤波器和拉格朗日插值滤波器相组合的多级实现结构来完成基带信号的采样率转换,并针对多相内插滤波器和多项式插值滤波器在实际设计中的不同缺点,分别进行了一定的改进。最后,本文给出了基于DSP和FPGA的宽带信号数字正交调制方法,将运算量很大的内插及低通滤波部分用FPGA器件来实现,并讨论了用硬件电路实现的数字内插滤波器内部结构。更多还原

【Abstract】 In the field of radar technology, hardware-in-the-loop simulation in the laboratory is very important for the development of various radar systems. Based on simulated radar signal model, radar signal simulator can nimbly reconstruct radar target signal, interference signal and environment signal, which meet the need of new radar system design and test. For hardware-in-the-loop simulation, it refers to the real-time reconstructing architecture of wideband radar signal. In this paper, related reconstructing methods are discussed and researched thoroughly, and certain improvement is estimable for applications of radar system.Generally, the frequency-domain statistical property of radar signal which is a kind of random signal can be derived easily in the laboratory. A signal reconstructing algorithm applied in the project extensively is mainly studied in this paper, which includes conversion from power spectrum to magnitude spectrum, randomization of phase to obtain vector spectrum, inverse Fourier transform, randomization of series of finite time-domain sequences, interpolation of the infinite sequence, digital quadrature modulation for frequency up conversion, D/A conversion, and lowpass filtering.The reconstructing algorithm of wideband radar signal must be characteristic of real time and high resolution. Because of the restriction, the emphasis of this paper includes two parts: randomization of series of finite time-domain sequences and interpolation of the infinite sequence, which affect the simulated signal’s characteristics greatly. Considered different frequency spectrum properties of several windows in the time-domain randomization, a new randomizing method is proposed, which includes addition of hanning window, overlap, and amplitude amending process. The interpolation ofbaseband signal which raises the sample rate is implemented by a new kind of multistage architecture combined multiphase filter with Lagrange polynomial filter. The polynomial interpolating filter has a little computation in real-time digital signal processing, and the multistage structure can reduce the filters’design requirement and decrease the quantity of computation efficiently. Aiming at different defects of multiphase filter and polynomial filter in practical design, certain improvement has been made accordingly. Finally, a method of wideband signal digital quadrature modulation based on DSP and FPGA is proposed. The parts of interpolation and lowpass filtering with large quantity of computation are carried on by FPGA device, and the hardware design structure of digital interpolating filter is discussed deeply.更多还原