Abstract:

The time delay of the pulsar integrated pulse profile relative to the standard pulse profile is one of the important observations in an X-ray pulsar-based navigation system, with the measuring accuracy directly affecting the the pulsar-based navigation system. In order to improve the measuring accuracy of the time delay of the pulsar integrated pulse profile and reduce the computation complexity, a method called fast maximum likelihood (FML) estimation is proposed in this paper, which first distills the pulse profile of the X-ray pulsar by the epoch folding. Then, the likelihood function is estimated to obtain the time delay of the pulsar integrated pulse profile. This paper also improves the fast maximum likelihood time delay estimation by narrowing the phase interval of the standard pulse profile and combines rough estimation with accurate estimation to effectively compute the time delay. Real pulsar data observed by the Rossi X-ray Timing Explorer (RXTE) are used to validate the effectiveness of the proposed method from the aspects of the observed time and computational complexity. Compared with the Taylor FFT algorithm, the measurement accuracy of the proposed method can be significantly improved while keeping the total computational complexity.

Key words: X-ray pulsar, pulse profile, epoch folding, time delay, fast maximum likelihood estimation