【作者】 韩广；

【导师】 王斌；

【作者基本信息】 解放军信息工程大学 ， 军事通信学， 2010， 硕士

【摘要】 干涉仪测向算法作为一种快速测向算法,具有算法简单、灵敏度高等优点,因而被广泛应用在各种测向系统中。干涉仪测向算法可分为相位干涉仪测向算法和相关干涉仪测向算法两种。相位干涉仪因其实现简单、测向速度快,而被目前多数短波宽带测向设备所采用,但是该算法对天线幅相误差敏感,抗扰性较差。相关干涉仪测向算法具有抗幅相误差能力强,受天线阵形限制较少等优点,将其应用到短波宽带测向系统中能够克服相位干涉仪所存在的问题,但是相关干涉仪测向算法的运算量很大,仅采用DSP进行实现很难做到实时处理。针对这一问题,在某项目中拟采用FPGA和DSP相结合的运算模式,本文根据项目要求,在验证平台上实现了频域相关干涉仪算法,完成了算法的验证和系统资源的评估,为项目的进行奠定了基础。文章内容如下:1、研究了相位干涉仪及其解模糊算法。首先,对长短基线法、虚拟基线法和立体基线法三种常用解模糊算法进行了研究。然后,针对长短基线法、虚拟基线法阵形受限以及立体基线法抗噪声能力不强的问题,给出一种基于复相关运算的解模糊算法。仿真结果表明该算法适用于多种天线阵,且抗噪性能优于立体基线法。2、研究了相关干涉仪测向算法。首先,研究了时域和频域两种常用的相关干涉仪测向算法的基本原理。然后,针对相关干涉仪测向算法在利用FPGA实现时需要消耗大量芯片资源的问题,给出了一种改进算法——最小间距法,并评估了传统相关干涉仪算法与最小间距法所占用的FPGA资源量,比较了两种算法各自的处理时间,结果表明最小间距法在资源使用和处理时间上都有所改善。3、完成了相关干涉仪测向算法在验证平台上的设计实现。首先,介绍了短波宽带测向系统,并对其中相关干涉仪的处理结构进行了设计。其次,给出了相关干涉仪测向算法的实现步骤,对FPGA和DSP相结合的实现模式进行了分析,完成在两种芯片中的任务划分。然后,详细介绍了FPGA内部各个功能模块的作用,并具体介绍了各功能模块的设计流程。最后,给出了系统指标,并对系统的测向性能进行了测试,测试结果表明文中验证系统可实现对跳速低于100Hops/s、带宽低于500kHz的短波跳频信号的实时测向。更多还原

【Abstract】 The algorithm of interferometer as a fast algorithm of direction finding has been widely used in many kinds of direction finding systems, because of its advantages such as high speed, simplicity and high sensitivity. It includes phase interferometer and correlation interferometer. Phase interferometer is adopted in most shortwave broad band direction finding equipments since it could be actualized both easily and fast. However, it is sensitive to gain-phase error, and has poor anti-interference performance. The algorithm of correlation interferometer direction finding, which has the virtue of good anti-interference performance together with broad adaptability in different antenna array types, could overcome the problems in phase interferometer algorithm when using it in shortwave broad band direction finding systems. But due to the correlation interferometer’ large computation real time processing is hardly realized if only use DSP. To solve the problem, a realization mode through making use of FPGA and DSP is brought in some project. According to requirement of the project, the algorithm of correlation interferometer is realized on the validation platform by this mode. The validation of algorithm and evaluation of resource are finished. This provides a foundation of this project. The main content is as follows:1. Studies phase interferometer and its relevant algorithm for solving ambiguity. Firstly, long-short baseline method, virtual baseline method and spatial baseline method which is commonly used phase algorithms of interferometer are studied in this paper. Then, because of the problems that arrays of long-short baseline method and virtual baseline method are limited, and that spatial baseline method has poor anti-noise performance, a new algorithm of solving ambiguity based on complex correlative computing is described. The emulation thows that this new ambiguity is suitable for many kinds of arrays and has better anti-noise performance than spatial baseline method.2. Researches algorithm of correlation interferometer direction finding. First of all, the principle of correlation interferometer is discussed in both time domain and spectrum domain. Secondly, in order to tackle the problem that correlation interferometer needs to consume a mass of chip resources when it is implemented on FPGA, this paper presents an improved algorithm, which is minimum distance method. And then the evaluation and comparison of resource consumption is presented when the two algorithms are carried out on FPGA. And the minimum distance method is proved that it can use lower resource and work faster by the results.3. Completes the design of correlation interferometer direction finding on the validation platform and actualizes it. First the shortwave broad band direction finding system is introduced, and the structure of the algorithm of correlation interferometer is designed. Second this paper presents the steps of implementing correlation interferometer, and analyzes the implement mode based on FPGA and DSP, achieves assignment allocation on FPGA and DSP, and detailedly introduces the function modules and design in internal FPGA. Last parameters of the direction finding system are listed, and performance of the direction finding system is tested. According to the results, the system could actualize real time direction finding for shortwave signals whose hopping rate is lower than 100, and bandwidth is lower than 500 kHz.更多还原