【作者】 胡仕兵；

【导师】 汪学刚；

【作者基本信息】 电子科技大学 ， 信号与信息处理， 2009， 博士

【摘要】 超宽带(UWB)雷达是近年来兴起的一种新的雷达体制，它是雷达探测技术的主要发展方向之一，其研究和应用是雷达发展进程中一次质的飞跃。UWB雷达以其高距离分辨率、强穿透能力、低截获概率与强抗干扰性能在军事、民用等领域具有广泛而重要的应用前景，并得到人们日益关注。在UWB雷达技术的研究中，UWB雷达信号产生是一个关键且前沿的课题。本文以线性调频(LFM)信号为例，对UWB雷达脉冲压缩信号数字产生方法展开了系统而深入的研究。论文的主要工作和创新之处概括如下四大部分：1．全面研究了用于雷达LFM脉压信号数字产生的单数位产生方法、直接数字频率合成(DDFS)方法和直接数字波形合成(DDWS)方法以及用于扩展频带的正交调制方法和固态倍频方法的工作原理和误差来源，并对各种方法的性能进行了系统的理论分析和计算机数值仿真。该项研究结论明确了UWB-LFM雷达脉压信号数字产生系统设计和研制工作的重点和方向，且是UWB雷达脉压信号源得以实现的理论基础。2．研究了UWB雷达脉压信号数字产生系统误差来源及其影响问题。概括了UWB波形产生系统的各种误差来源，针对UWB波形系统的幅频和相频特性失真、UWB-LFM信号的时域畸变、LFM波形产生器的相位误差、LFM信号的调频非线性、LFM信号的相干性等问题分别建立了相应的数学模型，理论研究和计算机仿真分析了这些误差因素对产生信号性能的影响。该项研究成果为UWB雷达脉压信号产生系统的工程设计、性能分析、性能评估和性能优化提供了必要的理论依据和重要的经验参考。3．系统地研究了UWB-LFM雷达脉压信号产生系统失真的数字补偿问题。建立了比较完善的UWB波形产生系统模型，基于线性系统理论和数字产生方法的灵活性、可靠性，分析了波形产生系统失真的数字补偿原理和可行性。对数字基带产生电路失真、正交调制器非理想性和倍频系统误差的数字校正方法依次进行了深入的理论推导和分析，并作了计算机仿真验证。该数字校正方法预失真补偿精确，但需要精确地测量出UWB波形产生系统中各个关键环节的传输函数。4．研究了一种不需测量UWB雷达波形产生系统的传输函数而直接根据输出信号的失真情况对输入LFM信号进行时域数字预失真的校正方法，对该数字校正方法作了理论推导和计算机仿真验证。虽然该方法对产生信号失真情况的校正是近似的，但可以显著地改善输出信号的质量和性能，并能满足雷达系统的需求。该数字校正方法简单、方便，易于在工程实践中推广和应用。更多还原

【Abstract】 Ultra wide-band (UWB) radar is a new kind of radar system which has been developed in recent years. It is a major evolution aspect of radar detecting techniques, and its researches and applications are one qualitative leap in the course of radar development. UWB radar, well known for its high range resolution, power penetration, low probability of intercept and robust jamming immunity, is paid more attention to and has a broad and important prospect in military and civilian applications and so forth. Among the researches on UWB radar techniques, the generation of UWB radar signals is a key and frontal subject. Taking example for linear frequency modulation (LFM) signals, this dissertation investigates the digital methods of generating UWB radar pulse-compression waveforms systematically and profoundly. The main content and creative work are summarized as follows:1. The three digital methods of generating LFM pulse-compression waveforms, including the single-bit generation method, the direct digital frequency synthesis (DDFS) method and the direct digital waveform synthesis (DDWS) method, and the analogue quadrature modulating technique and the solid-state frequency multiplication technique for widening frequency band, are studied in detail. The working principles, errors sources and performances of these methods are explored by systemic theoretical analyses and computer data simulations. These research conclusions indicate the emphases and directions in the work of designing and developing digital UWB-LFM radar pulse-compression signal generation systems, and they also lay a theoretical foundation for the implementations of UWB radar pulse-compression signal sources.2. The errors sources and their influences of digital UWB radar pulse-compression signal generation systems are investigated. First of all, the various errors sources of UWB waveform generation systems are generalized. Then, the corresponding mathematical models for the characteristics distortion of UWB waveform systems in the frequency domain, the deformation of LFM signals in the time domain, the phase errors in LFM waveform generators, the FM non-linearity of LFM signals, and the coherence of LFM signals are made respectively. Furthermore, the effects of these errors factors on the performance of produced signals are studied by theoretical analyses and computer emulations. These research achievements provide necessary theoretical bases and important experience references for the engineering designs, the performance analyses, the performance evaluations and the performance optimizations of UWB radar pulse-compression signal generation systems.3. Digital compensation methods and techniques for the distortions of UWB-LFM radar pulse-compression generation systems are researched systematically. In the first place, the all-around models for UWB waveform generation systems are made. Based on the linear system theory, and the flexibility and reliability of digital generation methods, the principle and the feasibility of digital compensation for waveform generation systems are analyzed. Afterwards, the digital correction methods for the distortion of digital baseband generation circuits, the non-idealization of quadrature modulators and the errors of frequency multipliers are orderly studied by theoretical deductions and computer simulation verifications. These digital correction methods presented above have an advantage of high accuracy of pre-distortion calibration. However, the transfer functions of each key part of UWB waveform generation systems must be precisely measured.4. A digital pre-distortion correction method according to the distortion degree of outputted signals in the time domain, which doesn’t need to measure the transfer functions of UWB waveform generators, is put forward. And this digital correction method is investigated by theoretical derivations and computer simulation verifications. Although it adjusts the errors of generated signals approximately, it can significantly improve the quality and performance of outputted waveforms, and satisfy the requirements of radar systems. This method is simple and convenient, and can be easily popularized and applied in engineering practices.更多还原