随着国际卫星导航技术的不断发展和对航天器自主导航日益迫切的需求，近几年X射线脉冲星导航的相关领域引来各个国家的持续关注和研究。脉冲星导航算法验证需要真实连续的脉冲星信号，为避免深空探测难度大、成本高的问题，需要在地面模拟系统中对导航算法进行验证。本文针对测距增强导航算法验证的需求，在现有可见光源导航验证系统的基础上，提出了基于X射线源的测距增强导航地面验证系统，该系统采用X射线源替换可见光源模拟真实X射线脉冲星辐射信号的改进方案，同时采用DSP作为导航算法的硬件平台，实现由两颗脉冲星和一颗中继星组成的测距增强导航算法的半物理验证。本文在现有半物理地面验证系统的研究基础上，进行了基于X射线源的测距增强导航地面验证系统的开发和测试，主要从信号模拟、导航验证DSP平台开发、系统测试几个方面展开研究。

       X射线脉冲星动态信号模拟方面，首先为实现航天器处动态脉冲星轮廓实时调制X射线源的功能，基于具有多物理特性的航天器处脉冲星轮廓生成原理，设计并实现了将动态脉冲星轮廓数据通过PCIE接口输入到FPGA存储后进行数模转换（DA转换）和高速电压转换，生成符合X射线源栅控电压范围的调制电压，实现对X射线源的调制。其次根据导航算法对不同脉冲星导航精度的需求，研究了利用单通道同时或分时模拟多颗脉冲星信号的方法，分析了两种方法的适用性。研究结果表明同时模拟方法中，如果导航选取的两颗脉冲星流量和频率差别较大，在两路叠加脉冲星信号中提取低流量脉冲星信号就会涉及极低信噪比的问题，需采用长时、大探测面积和频域分析的方法来进行提取；分时模拟方法中，通过对所在轨道中两颗脉冲星的可见性分析，合理分配不同脉冲星的观测时间来恢复清晰的轮廓数据。最后对X射线源自身的非线性进行补偿，分析了X射线源生成光子和调制流量的原理，通过多次测量和拟合栅控与流量非线性曲线的方法对轮廓电压进行补偿，保证了X射线源出射光子对应的频率和时间特性，提高了X射线脉冲星信号模拟精度。

       导航验证DSP平台方面，本文采用TMS320C6678平台开发，实现了测距增强X射线脉冲星导航算法的移植，利用EMIF16、RS422等数据传输方式和内存提前分配等方法，完成了主控计算机、脉冲星光子到达时间序列模块与DSP平台间的数据传输，并对DSP平台下的时间转换、轮廓折叠、相位估计、无迹卡尔曼滤波等算法进行验证，通过与计算机MATLAB导航仿真结果对比，验证DSP平台下导航算法运行的准确性。

       系统测试方面，本文首先对生成的动态脉冲星轮廓和光子脉冲信号进行测试，确保输出信号的可靠性，其次对控制X射线源光子流量的阳极高压和灯丝电流以及地面验证系统中的时间延迟等参数进行了标定，最后对脉冲星导航算法进行对比验证，实现导航验证系统的设计需求。系统的性能分析和功能测试结果表明，该系统实现了基于X射线源的测距增强导航地面验证的需求，具有良好的性能，为后续X射线脉冲星导航验证提供了更加真实便捷的地面验证环境。

With the continuous development of international satellite navigation technology and the increasingly urgent demand for autonomous navigation of spacecraft, the related fields of X-ray pulsar navigation have attracted continuous attention and research from various countries in recent years. Pulsar navigation algorithm verification requires true and continuous pulsar signals. In order to avoid the difficulty and high cost of deep space detection, the navigation algorithm needs to be verified in the ground simulation system. In response to the need for range finding enhanced navigation algorithm verification, based on the existing visible light source navigation verification system, this paper proposes a range finding enhanced navigation ground verification system based on X-ray sources, which uses X-ray sources to replace visible light sources to simulate real X The improved scheme of the radiation signal of the ray pulsar, while using DSP as the hardware platform of the navigation algorithm to realize the semi-physical verification of the range finding enhanced navigation algorithm composed of two pulsars and a relay star. In this paper, based on the existing semi physical ground verification system, the development and test of ranging enhanced navigation ground verification system based on X-ray source are carried out, mainly from signal simulation, navigation verification DSP platform development, system testing.

In terms of X-ray pulsar dynamic signal simulation, first of all, in order to realize the function of real-time modulation of the X-ray source of the dynamic pulsar profile at the spacecraft, based on the principle of generating the pulsar profile at the spacecraft with multi-physical characteristics, the design and realization of the dynamic pulsar The profile data is input to the FPGA for storage through the PCIE interface, and then performs digital-to-analog conversion (DA conversion) and high-speed voltage conversion to generate a modulation voltage that conforms to the X-ray source gate control voltage range to realize the modulation of the X-ray source. Secondly, according to the navigation accuracy requirements of navigation algorithms for different pulsars, the method of using a single channel to simulate multiple pulsar signals at the same time or in time sharing is studied, and the applicability of the two methods is analyzed. The research results show that in the simultaneous simulation method, if the flow and frequency of the two pulsars selected for navigation are quite different, the extraction of low flow pulsar signals from the two superimposed pulsar signals will involve extremely low signal-to-noise ratio problems, and need to be adopted Long-term, large detection area and frequency domain analysis methods are used to extract; in the time-sharing simulation method, the visibility of two pulsars in the orbit is analyzed, and the observation time of different pulsars is reasonably allocated to restore clear contour data . Finally, the non-linearity of the X-ray source itself is compensated, and the principle of photon generation and flow modulation of the X-ray source is analyzed. The contour voltage is compensated by multiple measurements and the method of fitting the non-linear curve of grid control and flow to ensure the X-ray source. The corresponding frequency and time characteristics of the photons emitted by the ray source improve the accuracy of the X-ray pulsar signal simulation.

The hardware platform of the ground verification system is developed with DSP (TMS320C6678). This paper implements the transplantation of the ranging enhanced X-ray pulsar navigation algorithm, and uses EMIF16, RS422 and other data transmission methods and memory advance allocation methods to realize the main control computer and pulsar light Data transmission between the sub-arrival time sequence module and the DSP platform, and verify the time conversion, contour folding, phase estimation, unscented Kalman filter and other algorithms under the DSP platform, and the accuracy of navigation algorithm under DSP platform is verified by comparing with the navigation simulation results of computer MATLAB software.

In terms of system testing, this article first tests the generated dynamic pulsar profile and photon pulse signal to ensure the reliability of the output signal, and secondly verifies the anode high voltage and filament current that controls the photon flow of the X-ray source and the time delay in the ground verification system. The parameters were calibrated, and finally the pulsar navigation algorithm was compared and verified to meet the design requirements of the navigation verification system. The performance analysis and functional test results of the system show that the system has fulfilled the requirements of X-ray source-based ranging and enhanced navigation ground verification, has good performance, and provides a more realistic and convenient ground verification environment for subsequent X-ray pulsar navigation verification.