X射线脉冲星光子序列频域加权测相方法

A Frequency Domain Weighted Measurement Method for X-Ray Pulsar Photon Sequences

针对X射线脉冲星信号累积轮廓位相测量误差大的问题,提出了一种直接位相测量的频域加权方法。首先,直接对X射线探测器捕获和采样形成的光子序列进行频域变换得到幅度谱,分别提取幅度谱各个成分的相位,再用幅度对相位变量加权平均,得到位相测量结果;进一步采取分段加权的策略,解决序列过长引起的内存溢出问题;最后对所提出方法的计算复杂度进行了理论分析。仿真结果表明:在观测时长和采样间隔相同的条件下,与平均法相比,加权法的测相精度提高了10%以上;与最大似然(ML)和非线性最小均方误差(NLS)法相比,加权法的比相精度提升了1倍以上,计算速度处于ML法和NLS法之间;分段情况下性能会随着分段数增加有所改善。

A weighted direct phase estimation algorithm in frequency domain for photon sequence is proposed to solve the problem that the error of accumulated phase estimation in the average profile is too large for X-ray pulsar signals. The photon sequence that is captured by the X-ray detector and then sampled is directly transformed to the frequency domain, then the phase of each frequency is respectively extracted and is weighted according the amplitude of the frequency component. Furthermore, the segmented fast Fourier transform strategy is adopted to solve the memory overflow problem caused by long sequences. Finally, the computational complexity of the proposed estimator is investigated in theory. Simulations and comparisons with existing methods under the condition of the same observation time and sampling interval show that the accuracy of the weighted approach increases by 10% over the average method and is two times higher than those of the nonlinear least square （NLS） and maximum likelihood （ML） methods, and that the computational complexity of the algorithm is between NLS and ML methods. Moreover, the performance of the algorithm with segments is improved by increasing the number of segments.