Ground Verification System For Range Finding And Enhanced Navigation Based On X-ray Source

With the continuous development of international satellite navigation technology and the increasingly urgent demand for autonomous navigation of spacecraft,the related fields of Xray 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 sourcebased ranging and enhanced navigation ground verification,has good performance,and provides a more realistic and convenient ground verification environment for subsequent Xray pulsar navigation verification.