基于Nyquist折叠接收结构的多分量雷达信号分离与参数估计研究

Nyquist folding receiver (NYFR) is a novel ultra wideband receiver and it can break the sampling rate limitation of current analog to digital converter (ADC). Because of the wideband receiving, the NYFR will receive multiple radar signals. When the non-cooperative radar signals are folded by the periodical non-uniform local oscillator (LO) of the NYFR, the multiple NYFR outputs with the added LO modulation parts will meet the time-frequency aliasing situation. Based on the theories of prior information signal model, signal decomposition, base expansion, optimization, transformation domain analysis and parametric estimation, this project will investigate the separation and parameter estimation methods of the multiple NYFR output radar signals. Firstly, in terms of receiving architecture, this project will study the optimal LO for the multiple NYFR outputs separation. Then, in terms of signal processing, based on the optimal LO, this project will investigate the multiple NYFR outputs separation approaches. At last, according to the mathematic characteristics of the NYFR, the parameter estimation algorithms of the NYFR complex outputs will be studied. This project will improve the novel ultra wideband NYFR receiving theory and the signal processing performance of the NYFR outputs. Meanwhile, this project can break through the key technical bottleneck of the multiple signals processing in the novel ultra wideband receiving theory. It is an innovative work with significant theory values and practical meanings.

Nyquist折叠接收结构（NYFR）是一种可突破当前模数转换器（ADC）采样率制约的新型超宽频段接收结构。由于频域宽开侦收，NYFR将面临多分量雷达信号。经过NYFR周期非均匀采样本振折叠后，含有本振调制成分的多分量NYFR输出信号将出现时频混叠情况。项目拟基于先验信息信号建模、信号分解、基展开、优化、变换域分析和参数化估计等理论，研究多分量NYFR输出复杂调制雷达信号分离与参数估计方法。首先，从接收结构层面，开展适用于多分量雷达信号分离的NYFR本振优化研究；其次，从信号处理层面，基于优化本振，研究多分量NYFR输出雷达信号分离方法；最后，利用NYFR数学特性，开展NYFR输出复杂调制雷达信号参数估计研究。本项目将完善新型超宽带NYFR接收理论，提升NYFR输出雷达信号处理能力，突破新型超宽带接收理论中多分量信号处理的关键技术瓶颈，是一项具有重要理论价值和实际意义的创新性工作。

本项目基于Nyquist折叠接收（NYFR）架构所截获的多分量同时到达雷达信号，首先研究了单通道NYFR结构下的多同时到达雷达信号的分离与处理方法，从理论上分析了相关参数对信号处理能力影响；同时，基于调制采样理论，分析了密集信号条件下时频完全混叠的折叠后多信号分离失效数学原理和物理机理，进一步提出了一种克服原型结构缺陷的优化本振调制，从数学上证明了该优化本振调制的有效性；此外，定量分析了折叠结构的射频采样调制和参数设定对系统输出质量的影响；进一步，基于提出的优化本振单通道NYFR，提出了周期分数阶自相关理论，研究了密集信号条件下的多种雷达信号分离、重构和处理算法，所提出的部分算法可使用快速计算；最后，搭建了NYFR硬件平台，验证了单通道NYFR具有突破Nyquist采样定理限制的瞬时超宽带接收能力，证明了提出的相关估计算法的有效性，验证了优化LO调制的有效性和适应性，为NYFR架构进一步应用奠定了理论和技术基础。