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对原子时进行频率稳定度评估通常采用的是Allan方差和Hadamard方差，而对脉冲星时的频率稳定度评估一般使用σz(τ),若要脉冲星时与原子时联合守时，需对脉冲星时和原子时稳定度进行统一评估。Parabolic方差是类似于Allan方差的统计量，它弥补了Allan方差在短期无法识别高频噪声的缺陷，同时兼顾了其在长期的可计算性。分别利用仿真数据和中国科学院国家授时中心地方原子时(TA(NTSC))的实测数据对原子时进行了parabolic方差的稳定度评估，结果表明parabolic方差对常见噪声类型具有较好的响应，并且在检测低频红噪声方面比Hadamard方差更具优势。针对脉冲星时的稳定度评估，首先是根据国际脉冲星计时阵第二次发布数据中的5颗毫秒脉冲星观测数据经过等间隔处理后，利用经典加权算法建立了综合脉冲星时。最后利用parabolic方差和σz(τ)对其进行了稳定度评估，在5.12年尺度上稳定度达到了4.48×10~-16,比稳定度最高的单星PSR J1909-3744提升了61.71%,符合预期结果。
Abstract：The Allan variance and Hadamard variance are commonly used to evaluate the frequency stability of atomic time, while the σz(τ) is commonly used to evaluate the frequency stability of pulsar time.If pulsar time and atomic time are used jointly for timekeeping, a unified evaluation of the stability of both pulsar time and atomic time is required.The parabolic variance is a statistic similar to the Allan variance, which makes up for the shortcomings of the Allan variance in identifying high-frequency noise in the short term, while also taking into account its calculability in the long term.The parabolic variance is used to evaluate fequency stability for simulation data and actual measurements of the local atomic time from the National Time Service Center of the Chinese Academy of Sciences(TA(NTSC)),the results show that the parabolic variance has a good response to common noise types and has an advantage over the Hadamard variance in detecting low-frequency red noise.For the stability assessment of pulsar time, firstly, based on the observation data of five millisecond pulsars in the second release of the International Pulsar Timing Array, the ensemble pulsar time scale is established using a classical weighted algorithm after processing at equal intervals.Then the stability assessment is performed using parabolic variance and σz(τ),and the stability reaches 4.48×10~-16 on the scale of 5.12-year, which is 61.71% higher than the single star PSR J1909-3744 with the highest stability and meets the expected results.
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基本信息:
DOI：10.13875/j.issn.1674-0637.2025-03-0199-11
中图分类号:P127.1
引用信息:
[1]李粽可,张哲浩,王琳琳,等.Parabolic方差在脉冲星时稳定度评估中的应用分析[J].时间频率学报,2025,48(03):199-209.DOI:10.13875/j.issn.1674-0637.2025-03-0199-11.
基金信息:
科技部SKA专项(2020SKA0120103); 中国科学院战略先导科技专项(A类)(XDA0350502); 国家自然科学基金(U1831130); 陕西省自然科学基础研究计划(2024JC-YBQN-0036)