Research On The Semi-physical Simulation Of X-ray Pulsar Signal With Multiple Physical Properties Received On The Spacecraft

Since there is no observation data,simulating X-ray pulsar signal is the main motivation to boost the development of X-ray Pulsar Navigation in domestic.Numerical simulation and Semi-physical simulation are the main approaches to generate simulation data.Numerical simulation generates photons signal across algorithms and it has the shortcoming that its simulation result is pseudo-random data which has low credibility.Semi-physical simulation utilizes the pulsar profile to modulate photons and it has the advantage that its simulation result has high credulity because it keeps the physical process.However,the functions of existing semi-physical simulation systems are limited to simulate photons signal at the SSB,which can't satisfy the research of theory.In this paper,a new semi-physical simulation method is proposed.The real-time pulsar profile at the spacecraft is established which contains Doppler effects,relativistic effects and the spinning distinction of pulsars,and when using the profile at the spacecraft to modulate photons we can get the X-ray pulsar signal with true physical characteristics.Across this method,a semi-physical simulation system is developed which includes the following module: Pulsar Profile Creation Software is designed to implement the pulsar creation algorithm and its output is the real-time pulsar profile at the spacecraft;Pulsar Profile Outputting Circuit is designed to convert the real-time pulsar profile to voltage signal which is implemented based on FPGA;Verification system is designed to verify the validity of proposed method.Experiment is made to verify the simulation result under the same time and orbit conditions with RXTE.The main results can be concluded as follows: 1)the observation profiles produced from simulation data in different ways show the same regular pattern with those produced from RXTE data;2)the correlation coefficient of observation profile with the standard one arrives at 0.99.The above results show that the photon event time stamps generated by the semi-physical simulation system proposed contain true physical characteristics.