Research On Key Technologies For Interference Detection And Elimination In Pulsar Timing Observation

In order to meet the requirements for the accuracy of time scales,people have been exploring time measurement methods,using solar clocks,mechanical clocks,quartz clocks,atomic clocks,etc.for timekeeping.In china,national standard time is maintained by a set of atomic clocks,which needs to be compared with international time,and its autonomy is hidden to a certain extent at present.With the development of radio astronomy,people have discovered pulsars with extremely high rotation period stability.Pulsars are known as the most stable natural clocks because of their extremely small periodic rate of change.The long-term practice of pulsar timing observation shows that pulsar time has higher long-term frequency stability than atomic time.The use of pulsar timing observations for time scale research is expected to build a time scale that has the advantages of both the short-term stability of atomic time and the long-term stability of pulsar time,thereby improving the independence of our country’s time reference.Because the electromagnetic waves radiated by pulsars travel over long distances,it was weak when reach to earth.A large number of large radio telescopes have been established at domestic and abroad for pulsar research.While the large-aperture radio telescope improves the sensitivity of observation,it also becomes sensitive to interference signals.With the development of wireless communication technology and electromagnetic equipment,the research on interference elimination of pulsar timing observation has become increasingly urgent.Based on the above requirements,this article has carried out the following work:(1)In order to effectively identify the interference signals of radio telescope stations and take timely shielding measures,a set of targeted electromagnetic environment monitoring system was built according to the electromagnetic interference test method of the square kilometer array radio telescope site selection,using the Y factor Method to calibrate the system;monitor the electromagnetic environment in many places and process the monitoring results to provide a basis for eliminating interference sources.(2)Perform post-correlation processing for the interference in the pulsar timing observation data.Analyze the assumptions of the independent component analysis model,and apply the independent component analysis algorithm to the fits format file obtained from the timing observation of the Luonan 40 m Radio Telescope to eliminate interference,good results have been obtained.(3)Long-term timing observation of Crab pulsar using Luonan 40 m radio telescope.Analysis of the rotation instability in the observation data shows that the star has undergone a glitch near July 23,2019.Through processing and fitting the observation data,analyze the glitch process.