Millisecond Pulsars Mean Pulse Dispelrsition-Limiting And De-Noising Methods Research

The high stability and accuracy of rotation of millisecond pulsars may rival that of the atomic clocks.Although pulsars had intensive radiant power,current density of millisecond pulsars' PSR time of arrival which accepted by radio astronomy observations was only 0.01mJy-100mJy.The pulsar signal was swamped by powerful noise background.It was too hard to detect signal.In the filed of timing used millisecond pulsars,the index requirement is high.Therefore,in the millisecond pulsars timing system,detecting weak signal,de-noising and dispelrsition-limiting became important and key research subject.In this paper,The author formulated dispelrsition-limited principle,method and experimental result of pulsars mean pulse.On the basis of compare and analysis,the author used the wavelet algorithm which had ascendancy in signal processing domain.She applied different wavelet thresholding de-noising methods in the observation data of Millisecond pulsar PSR 0437-4715,also appraised the experimental result by signal to mask ratio(SNR)and root-mean-square error(RMSE).At one time,the author adopted wavelet denoising method by spatial correlation,also developed a novel adaptive de-noising method based on wavelet shrinkage method and spatial correlation filtering.The experimental results show that the adaptive de-noising method was a good manner in extracting millisecond pulsars TOA data.Furthermore,the author used Higher Order Statistics,Kalman filters and Particle filters to detecting millisecond pulsars' pulsing signal then analyzed and compared experimental result. For Higher Order Statistics,She talked about in two ways as follows.Fist,Higher Order Cumulants,talked cumulant domain adaptive filtering algorithm,improved CDLMS algorithm based on error criteria J₁(n)and HOS4-MSEA algorithm based on error criteria J₂(n).The author also presents CDEFWLMS algorithm by using descent method on error criteria J₃(n) from which the CDRLS algorithm was derived.Then we presents CDSWLMS algorithm based on J(n).The experimental results show that the CDSWLMS algorithm was a good manner in extracting millisecond pulsars TOA data;Second,Higher Order Spectra Analysis.The author presents a new method for accurate phase reconstruction of the signals from bispectrum. Appling the new method to millisecond pulsars' pulsing signal,the author discovered that the outline drawing more real,but the noise was higher.This method can be improved some time. For Kalman filters and Particle filters,the author considered the non-line factor of the observation model.The author adopted linear filtering methods and non-line filtering methods, also analyzed and compared the experimental result.