High-accuracy pulsar time delay estimation using an FrFT-based GCC

To improve the accuracy of estimating the time delay of X-ray pulsar-based navigation (XNAV), this paper proposes a new generalized cross-correlation (GCC) algorithm based on fractional Fourier transform (FrFT). Given that the effect of noise on signal can be suppressed or eliminated in a highly effective manner in some FrFT domain, we identify the optimum FrFT domain before computing the self- and cross-power spectrums of the standard and observed pulsar integrated pulse profiles. We also apply the FrFT of the standard and observed pulsar integrated pulse profiles in the optimum FrFT domain. By using the FrFT-based GCC, we obtain highly accurate estimations of time delay. The experimental results reveal that the proposed algorithm outperforms the conventional GCC in terms of accuracy.