一种脉冲星周期的时域估计新方法

脉冲星信号的周期估计在脉冲星搜索、观测以及定时研究中具有重要作用.在分析脉冲星周期频域识别方法的基础上,基于脉冲星观测信号的二阶循环平稳模型,提出了一种周期估计的时域新方法-----最大相关方差搜索法.通过对观测信号按假定周期(可变)分组,计算分组后不同时刻的相关系数,进一步得到系数的方差,然后寻找不同周期下的方差最大值,即可得到脉冲星的辐射周期估计.分别对单峰脉冲星(PSRJ0437-4715)的实测信号、双峰脉冲星(PSRB1821-24)的仿真信号以及ATNFEPN数据库中的多颗脉冲星数据进行了周期估计,均得到了令人满意的结果.对众多脉冲星的计算结果表明,与傅里叶频谱法相比,该时域方法对噪声不敏感,尤其在低信噪比情况下仍表现出较优越的性能;与双谱相干统计量方法^6]相比,运算复杂度更低;尽管其在处理非连续观测数据时能力不足,但仍然可为微弱脉冲星的实时周期估计提供有力参考.

A new time-domain estimation method for period of pulsars

The estimation of pulsar period is important for pulsar searching, observation and timing. In this paper, the frequency-domain method which is popular in periodicity searches is analyzed, and further more, a novel method in time-domain is proposed to estimate the cyclo-period of pulsars based on the second-order cyclo-stationary model of the radiation signal. Firstly, the discrete-time observing signal is blocked by assumed period which is alterable. Then, the correlation estimations and their sample variances are computed each as a function of blocking operator index, where the largest peaks display a periodic pattern, from which the cyclo-period can be obtained. Using this method, the period of PSR J0437-4715 with single pulse is estimated well based on original signal, and the period of PSR B1821-24 with double pulses is also estimated based on the simulated signal. The same work is done for the observed data from ATNF EPN pulsar database. The simulation results and the experimental results for many pulsars show that compared with the classical Fourier-transform method, this algorithm is non-sensitive to the noise, and it is effective even though in the case of low signal-to-noise ratio. And it is of low computation complexity compared with the bispectrum coherence method. This method possesses higher popularization value in real-time observation and processing for weak pulsar signal, though it does not work well in dealing with noncontinuous observing data.