GNSS抗干扰接收机前端的设计与实现

发布时间：2018-12-26 13:54

【摘要】：全球卫星导航系统(Global Navigation Satellite System,简称GNSS)在民用以及军事领域得到了越来越广泛的应用,但卫星导航信号弱,极易遭到各种无意或有意的电磁干扰的问题也亟待解决。天线阵和射频通道位于抗干扰接收机的最前端,该部分性能在很大程度上影响到了抗干扰算法的实现效果。本文结合实际的工程需要,通过软件仿真了各种阵列天线的性能作为硬件系统设计的理论指导,并设计和实现了抗干扰接收机的射频前端电路。论文首先总结了国内外卫星导航抗干扰技术的研究现状,介绍了本设计的应用背景和研究方向。研究了频域抗干扰技术、空域抗干扰技术以及空时抗干扰技术各自的原理和优缺点,推导了抗干扰算法应该选择哪种自适应准则,并重点研究了空域的功率倒置算法,对其原理进行了推导,并设计了抗干扰接收机系统的框架。在阵列天线设计方面,首先建立了常见的阵列天线接收模型,通过理论推导和软件仿真研究了阵元间距、阵元个数对天线阵性能的影响;通过对阵元间距的研究,得出了阵元以半波长均匀分布时阵列性能最优;仿真研究了常见的均匀线阵、均匀圆阵等阵列天线的性能,选择圆心存在阵元的平面圆阵作为接收机阵列天线的布局方式;通过比较常用的天线性能,选择微带天线作为阵列天线的阵元。在射频模块电路设计方面,通过分析对比常见的三种接收机射频前端结构的性能指标、复杂程度、功耗和成本等各方面因素,并结合抗干扰接收机的系统需求,最终采用了低中频结构的设计方案;详细的研究了抗干扰接收机射频前端设计中需要充分考虑的通道增益、噪声系数、动态范围、阻抗匹配等各项指标;依据上面的研究对射频前端的低噪声放大器、频综、混频器等关键部件进行了详细的设计。射频前端的低噪声放大器部分采用了两级级联的方式来提供足够的增益以及减小噪声系数,同时保证了不产生饱和失真和三阶互调失真。通过使用大动态范围的自动增益控制模块来保证输入到后端ADC的低中频信号的功率不但符合信号处理的灵敏度要求,同时不会引起饱和失真。考虑到射频模块可能出现的信号完整性问题,在射频前端的各模块中加入了阻抗匹配电路和必要的滤波电路。最后对系统的各个部分进行了详细的测试,对测试结果进行了分析。系统的联合测试结果表明设计的硬件能够满足抗干扰接收机前端部分的需求。
[Abstract]:(Global Navigation Satellite System, (Global Satellite Navigation system) is more and more widely used in civil and military fields. However, the satellite navigation signal is weak and vulnerable to various unintentional or intentional electromagnetic interference. Antenna array and RF channel are at the front end of the anti-jamming receiver. The performance of this part affects the effect of anti-jamming algorithm to a great extent. In this paper, the performance of various array antennas is simulated by software to guide the design of hardware system, and the RF front-end circuit of anti-jamming receiver is designed and implemented. Firstly, this paper summarizes the research status of anti-jamming technology of satellite navigation at home and abroad, introduces the application background and research direction of this design. In this paper, the principle, advantages and disadvantages of frequency domain, space domain and space-time anti-jamming are studied, which adaptive criterion should be chosen for anti-jamming algorithm is deduced, and the algorithm of power inversion in spatial domain is studied emphatically. The principle is deduced and the frame of anti-jamming receiver system is designed. In the aspect of array antenna design, the common receiving model of array antenna is established, and the effect of array element spacing and number of array elements on the performance of antenna array is studied by theoretical derivation and software simulation. Through the study of the distance between the elements, the optimal performance of the array is obtained when the array elements are uniformly distributed at half wavelength. The performance of common array antennas such as uniform linear array and uniform circular array is studied by simulation. The planar circular array with the center of the circle is chosen as the layout of the array antenna of the receiver. By comparing common antenna performance, microstrip antenna is selected as array element. In the aspect of RF module circuit design, the performance index, complexity, power consumption and cost of RF front-end structure of three kinds of receivers are analyzed and compared, and the system requirement of anti-jamming receiver is combined. Finally, the design scheme of low intermediate frequency structure is adopted. The channel gain, noise coefficient, dynamic range, impedance matching and so on, which need to be considered in the RF front-end design of anti-jamming receiver, are studied in detail. According to the above research, the key components of RF front end, such as low noise amplifier, frequency synthesizer, mixer and so on, are designed in detail. The low noise amplifier of the RF front-end adopts two-stage cascade to provide sufficient gain and reduce the noise coefficient, while ensuring no saturation distortion and third-order Intermodulation distortion. An automatic gain control module with a large dynamic range is used to ensure that the power of the low intermediate frequency signal input to the back-end ADC not only meets the sensitivity requirements of signal processing, but also does not cause saturation distortion. Considering the problem of signal integrity in RF module, impedance matching circuit and necessary filter circuit are added to each module of RF front-end. Finally, every part of the system is tested in detail, and the test results are analyzed. The joint test results show that the designed hardware can meet the requirements of the front end of the anti-jamming receiver.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN965.5

【相似文献】