Abstract: The analysis of X-ray pulsars principle shows that the beacon pulsars position and measurement error directly affect the navigation performance. To select the best beacon pulsars group, a selection method was developed based on the error covariance analysis. This method defines the criteria of PDOP (Positioning Dilution of Precision)and PSC (Pulsars Select Criteria), considering the effect of pulsars distribution and the measurement errors. Taking the circle phase of the Mars as an example, the method is validated through numerical simulation.

Key words: X-ray pulsars, Positioning dilution of precision, Measurement error, Pulsars navigation