基于软件无线电的GNSS干扰和多径监测系统设计

针对干扰和多径导致全球导航卫星系统（GNSS）不能精确、安全和可靠地提供位置、速度和时间服务等问题，分析了研制GNSS干扰和多径监测系统的意义，介绍了当前干扰和多径常用的检测方法，设计了一套针对当前四大导航系统（美国GPS、俄罗斯GLONASS、欧盟Galileo和中国BDS）各信号带内以及附近频率的干扰和多径监测系统。系统基于软件无线电（SDR）思想，采用模块化设计，具有良好的功能扩展性和配置灵活性。根据不同干扰的特点，结合实际应用改进了其检测算法：采用能量阈值法检测不同形式的压制式干扰，采用基于捕获多相关峰法判别欺骗式干扰，采取基于最大似然准则的多径估计延迟锁定环（MEDLL）技术估计多径信号的参数。实验结果表明系统能够有效检测各种干扰和多径信号的存在，使用户获取其特征参数，为干扰源的定位、查处、排除、规避以及多径信号的抑制提供决策依据。

Design of a GNSS interference and multipath monitoring system based on software-defined radio

The global navigation satellite system(GNSS)can not provide Position,Velocity,and Time(PVT) service accurately,safely and reliably due to interference and multipath.For this problem,the significance of developing a GNSS interference and multipath monitoring system is analyzed,followed by the introduction to the currently used interference and multipath detection methods. As the main content,the design and implementation of a GNSS interference and multipath monitoring system is introduced,which is able to monitor interference and multipath signals in the bands of navigation signals of current four major GNSS systems(i.e.,GPS,GLONASS,Galileo,and BDS),as well as nearby frequency bands. The system based on software-defined radio(SDR) has preferable flexibility and extensibility by using modular design. According to the characteristics of different interferences,the detection algorithms are improved in terms of the demand for actual application. Firstly,the principle of energy threshold detection is adopted for the suppression jamming,and corresponding methods are designed for interference with different forms. Secondly,the multi-correlation peaks detection algorithm based on acquisition is used to check the existence of deception jamming signal. Thirdly,the Multipath Estimate Delay Lock Loop(MEDLL) technique,which is based on the Maximum-Likelihood criterion,is adopted to estimate the parameters of the multipath effects. The experimental results show that the system can detect the existence of various kinds of interference and multipath signals. The characteristic parameters of those signals can be extracted and then provided to the users to facilitate the localization,elimination and avoidance of the interference sources,as well as the suppression of the multipath signals.