数字电视辐射源雷达参考信号获取及干扰抑制算法研究

发布时间：2018-04-29 15:06

本文选题：外辐射源雷达 + 数字电视信号　；参考：《北京理工大学》2014年博士论文

【摘要】：无线电频谱是一种非常宝贵和有限的资源，随着现代无线电应用的高速发展，人们对频谱资源的需求急剧增加，如何实现频谱资源的高效共享成为世界各国的研究热点。数字电视信号处于UHF频段，适合宽带无线通信应用。其带宽宽、发射功率稳定、低空覆盖良好等优点使其成为一种较为理想的雷达辐射源。因此，数字电视信号非常适合于军民共享的应用。对基于数字电视信号的外辐射源雷达进行深入研究，可以为该频段频谱资源的充分利用和军民共享提供理论依据和技术支撑。本课题在国家自然科学基金和国防基础科研项目的支持下，深入分析了数字电视辐射源雷达干扰特点，重点研究了空、时域联合的参考信号获取及回波通道干扰抑制算法。研究成果对数字电视辐射源雷达的实际应用具有一定的理论指导意义。本文主要研究内容如下： 1、建立了数字电视辐射源雷达干扰和目标回波模型。深入分析了参考通道干扰、天线频率特性、分数时延、回波天线转动造成干扰非平稳以及距离徙动和多普勒徙动对系统性能的影响。分析了自适应对消和互模糊函数的运算量与信号带宽的关系，指出数字电视信号带宽宽造成运算量急剧增加，实时处理实现困难，需要研究运算效率高的自适应对消算法和互模糊函数计算方法。通过以上分析，为参考信号获取及回波通道干扰抑制算法的研究打下了基础。 2、分析了参考通道干扰对系统对消增益和相参积累性能的影响，提出了空、时域联合的参考信号获取方法。对于较强的副瓣干扰采用基于宽零陷的数字波束形成方法抑制并获取参考信号。提出了一种基于发射信号恢复的参考信号提纯方法，对主瓣干扰和副瓣干扰残余进行抑制。 3、分析了单纯采用空域或时域方法抑制回波通道干扰的局限性，提出了空、时域联合的回波通道干扰抑制方法。根据回波天线的不同工作状态采用不同的空域干扰抑制方法，当回波天线固定指向工作时，采用基于宽零陷的数字波束形成方法；当回波天线转动工作时，采用基于对角加载的SMI和自适应零陷展宽方法。针对干扰的不同特点，提出了三种时域自适应对消算法。（1）针对分数时延影响及运算量大的问题，提出了将考虑分数时延的LMS与快速块LMS（fast block LMS algorithm，，FLMS）相结合的自适应对消算法；（2）针对天线频率特性不同造成的对消增益降低、回波天线转动造成杂波非平稳以及RLS算法运算量大的问题，提出了基于子带分解的RLS和NLMS相结合的自适应对消算法；（3）针对参考通道存在多径干扰残余的问题，提出了考虑参考通道存在多径干扰及分数时延影响的自适应对消算法。提出了回波天线转动工作时进一步提高积累增益的改进的波束聚焦方法。 4、分析了影响系统威力的主要因素。为解决数字电视信号互模糊函数运算量大的问题，采用基于脉压的快速实现方法，该方法通过将信号分段并等效为脉冲信号，采用段内脉压和段间FFT实现相参积累。为解决长时间相参积累过程中目标距离徙动和多普勒频率徙动对积累增益的影响，采用基于keystone变换和分数阶傅里叶变换的徙动补偿方法。提出了一种改进的基于CZT方法实现距离徙动补偿的互模糊函数快速实现方法，与现有方法相比，在性能相当的前提下，运算量减小约50%。分别通过实测数据验证了上述所提算法的有效性，并给出了回波天线不同工作状态下的综合验证结果。所提算法能够有效抑制参考通道及回波通道干扰，提高对消增益和系统探测性能，并大大减小了实时处理的运算量。
[Abstract]:Radio spectrum is a very valuable and limited resource. With the rapid development of modern radio applications, the demand for spectrum resources is increasing rapidly. How to realize efficient sharing of spectrum resources has become a hot topic in the world. Digital TV signals are in the UHF band, suitable for broadband wireless communication applications. The advantages of power stability and low altitude coverage make it an ideal radar source. Therefore, the digital TV signal is very suitable for the application of military and civilian sharing. The in-depth study of the external radiant radar based on digital television signals can provide theoretical basis for the full utilization of the frequency spectrum resources and the sharing of military and civilian. Technical support. Under the support of National Natural Science Foundation and national defense research projects, this paper deeply analyzes the characteristics of digital TV radiant radar interference, and focuses on the study of the reference signal acquisition and echo channel interference suppression algorithm in the space and time domain. The practical application of the logarithmic type TV radiant radar is certain. The main contents of this paper are as follows:
1, the jamming and target echo model of digital television radiation source radar are established. The influence of the reference channel interference, the antenna frequency characteristic, the fractional delay, the interference nonstationary of the echo antenna rotation, the distance migration and the Doppler migration on the system performance are analyzed. The operation amount and the signal band of the adaptive cancellation and the cross ambiguity function are analyzed. With the wide relationship, it is pointed out that the bandwidth of the digital TV signal increases rapidly and the real-time processing is difficult. It is necessary to study the algorithm of adaptive cancellation and the calculation of the cross fuzzy function, which has high operational efficiency. Through the above analysis, it lays the foundation for the research of the reference signal acquisition and the echo channel interference suppression algorithm.
2, the influence of the reference channel interference on the gain and the coherent accumulation performance of the system is analyzed. A method of obtaining the reference signal in the space and time domain is proposed. For the strong sidelobe interference, a digital beamforming method based on the wide zero sink is used to suppress and obtain the reference signal. A reference signal based on the signal recovery is proposed to be purified. Methods the main lobe interference and sidelobe interference residual were suppressed.
3, the limitation of using space or time domain method to suppress echo channel interference is analyzed. The method of suppression of echo channel interference in space and time domain is proposed. Different air interference suppression methods are adopted according to the different working state of the echo antenna. When the echo antenna is fixed to the work, the digital beamforming based on wide zero sink is adopted. Methods: when the echo antenna rotates, we use diagonal loading based SMI and adaptive zero sink broadening method. In view of the different characteristics of the interference, three time domain adaptive cancellation algorithms are proposed. (1) for the problem of the influence of the fractional delay and the large amount of operation, the LMS and the fast block LMS (fast block LMS algorith) are proposed. M, FLMS) combined adaptive cancellation algorithm; (2) the adaptive cancellation algorithm based on subband decomposition of RLS and NLMS is proposed in view of the reduction of the cancellation gain caused by different antenna frequency characteristics, the non stationary clutter caused by the rotation of the echo antenna and the large computation of the RLS algorithm. (3) there is a multipath interference for the reference channel. In addition, the adaptive cancellation algorithm, which considers the presence of multipath interference and the effect of fractional delay in the reference channel, is proposed. An improved beam focusing method is proposed to further improve the accumulation gain when the echo antenna is rotated.
4, the main factors affecting the power of the system are analyzed. In order to solve the problem of the large amount of computation of the mutual fuzzy function of the digital TV signal, a fast realization method based on the pulse pressure is adopted. By segmenting the signal and equivalent to the pulse signal, this method uses the intra segment pulse pressure and the intersegment FFT to realize the coherent accumulation. The effect of distance migration and Doppler frequency migration on accumulation gain is based on the migration compensation method based on keystone transform and fractional Fu Liye transform. An improved method for realizing fast realization of distance migration compensation based on CZT method is proposed. Compared with the existing methods, the computational complexity is reduced on the premise of the equivalent performance. Small about 50%.
The effectiveness of the proposed algorithm is verified by the measured data, and the comprehensive verification results of the echo antenna in different working states are given. The proposed algorithm can effectively suppress the interference of the reference channel and echo channel, improve the performance of the cancellation gain and the system detection, and greatly reduce the computation of the real-time processing.

【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN949.197

【参考文献】