强噪声背景下解析解混沌雷达相参接收信号处理研究

Chaotic radar has the features of good electromagnetic compatibility, "thumbtack" ambiguity function, and low probability of being intercepted, which makes chaotic radar one of the state-of-the-art radars in the development of modern radar systems. However, it is difficult to obtain the copy signal of the transmitted signal in the receiving part of radar due to the randomness of chaotic signal, which makes it is difficult to realize coherent receiving. Meanwhile it is also difficult to realize the noise resistance of echo of chaotic radar since the noise-like feature of chaotic signal. This project aims at the problems mentioned above. Firstly, from the aspect of chaotic radar waveform generation, a new analytic solution chaotic system is proposed, driving the continuous chaotic signal with the binary signal. Then the matched filter with defined basis function is designed for the chaotic system of this project, through which the noise of echo can be filtered preliminarily. Next, the output signal of the filter is sampled during the binary signal symbol period. The binary signal which contains the target information can be obtained under strong noise condition after detecting the sum of the sampling points through the threshold. The original echo signal is then reconstructed by using the obtained binary signal to drive the chaotic system, which resists the strong noise of the echo signal. Finally, the transmitted signal copy can be obtained in the receiving part by using the saved binary signal to drive the chaotic system, and the cross-correlation processing is to be realized through the copy and the reconstructed echo signal. In this case, coherent processing and target distance measurement of chaotic radar is achieved.

混沌雷达具有良好的电磁兼容性、“图钉形”模糊函数、低截获概率等特点，因而成为现代雷达发展最具前景的新型雷达之一。但是，混沌信号的随机性使得混沌雷达接收端难以获得发射信号副本，很难实现相参接收；混沌信号的类噪声性使得混沌雷达回波信号的噪声抑制异常困难。本项目针对上述问题，首先，从混沌雷达波形产生方面入手，提出一种由二值信号驱动连续混沌信号的新型解析解混沌系统。然后，设计该系统确定基函数的匹配滤波器，并用其对回波信号中的噪声进行初步过滤；接下来通过对匹配滤波输出信号在二值信号单位码元周期内采样求和并判决检测后，可从强噪声背景中获得含有目标信息的二值信号，用该二值信号作为驱动信号能够重构原始回波信号，以此达到雷达回波信号噪声抑制的效果。最后，在雷达接收端通过已保存的原始二值信号驱动混沌系统获得发射信号副本，并用其和重构后的回波信号进行互相关处理，拟以此实现混沌雷达的相参信号处理和对目标的探测。

混沌雷达具有良好的电磁兼容性、“图钉形”模糊函数、低截获概率等特点，因而成为现代雷达发展最具前景的新型雷达之一。但是，混沌信号的随机性使得混沌雷达接收端难以获得发射信号副本，很难实现相参接收；混沌信号的类噪声性使得混沌雷达回波信号的噪声抑制异常困难。本研究针对上述问题，从混沌雷达波形产生方面入手，推导出了精确可解混沌系统和逆时混沌系统输出混沌信号之间的函数关系。然后，设计确定基函数的匹配滤波器，并用其对回波信号中的噪声进行初步过滤；接下来通过对匹配滤波输出信号在二值信号单位码元周期内采样求和并判决检测后，可从强噪声背景中获得含有目标信息的二值信号，用该二值信号作为驱动信号能够重构原始回波信号，以此达到雷达回波信号噪声抑制的效果。然后，在雷达接收端通过已保存的原始二值信号驱动混沌系统获得发射信号副本，并用其和重构后的回波信号进行互相关处理，以此实现混沌雷达的相参信号处理和对目标的距离探测。最后，通过对混沌系统的刻度参数与多普勒频移之间的关系进行，利用互耦合的同步方法实现混沌系统的同步，通过混沌同步得到刻度参数的变化，从而得到多普勒频移实现混沌雷达的测速。本申请的研究成果可为雷达信号降噪处理提供新的理论依据。