General relativity theory(GRT)concludes that a precise clock ticks at different running rates if it is under the influence of different geopotentials.Therefore,by comparing the running rates of clocks at arbitrary two...General relativity theory(GRT)concludes that a precise clock ticks at different running rates if it is under the influence of different geopotentials.Therefore,by comparing the running rates of clocks at arbitrary two stations,the geopotential difference between them can be determined.In this study,with the help of two hydrogen atomic clocks(noted as H-masers),using the two-way satellite time and frequency transfer(TWSTFT)technique,we carried out experiments of the geopotential difference determination at the China Aerospace Science&Industry Corporation(CASIC),Beijing.Here the ensemble empirical mode decomposition(EEMD)method is adopted to remove periodic signals included in the original observations.Finally,the clock-comparison-determined geopotential difference in the experiments is determined.Results show that the difference between the geopotential difference determined by GRT and that determined by measuring tape is about 1316.1±931.0 m2s-2,which is equivalent to 134.3±95.0 m in height,and in consistence with the stability of the H-masers applied in the experiments(at the level of10-15/day).With the rapid improvement of atomic clocks’accuracy,the geopotential determination by accurate clocks is prospective,and it is promising to realize the unification of the world vertical height system(WVHS).展开更多
A time and frequency system is a critical component of Very Long Baseline Interferometry(VLBI)stations,providing stable and reliable standards that directly impact data processing quality.At the Tianma 65 m radio tele...A time and frequency system is a critical component of Very Long Baseline Interferometry(VLBI)stations,providing stable and reliable standards that directly impact data processing quality.At the Tianma 65 m radio telescope(TMRT),this system has been meticulously designed to ensure long-term reliability and high performance.It incorporates high-performance hydrogen atomic clocks,high-precision time standards,automatic signal switching,and robust system software.This comprehensive approach has enabled the system to achieve long-term reliable operation,successfully supporting both major national engineering tasks and daily scientific observations.The effectiveness of the system is evidenced by its consistent delivery of the precision and stability required for radio astronomy.This article provides an in-depth exploration of the design and operation of the time and frequency system at the Tianma 65 m telescope,examining various aspects of its architecture,implementation,and performance.By sharing these insights,we aim to contribute knowledge that could benefit similar systems at other VLBI stations,greatly advancing radio astronomy infrastructure.展开更多
守时型原子钟主要包括氢原子钟和铯原子钟,为进一步探究不同类型守时原子钟计算时间尺度相关性能,本文开展全氢钟及氢铯联合时间尺度研究。首先依据国际权度局(Bureau International des Poids et Mesures,BIPM)发布的d公报将氢原子钟...守时型原子钟主要包括氢原子钟和铯原子钟,为进一步探究不同类型守时原子钟计算时间尺度相关性能,本文开展全氢钟及氢铯联合时间尺度研究。首先依据国际权度局(Bureau International des Poids et Mesures,BIPM)发布的d公报将氢原子钟进行分类,针对分类结果分别运用原子时尺度理论方法计算全氢钟时间尺度,并给出分析结果。随后计算全铯钟时间尺度,并分析探究两种不同的氢铯联合钟组时间尺度。结果表明,基于频率漂移量较小的氢钟组形成的时间尺度波动范围小,且稳定度优于频率漂移量较大的氢钟组形成的时间尺度。氢铯联合形成的时间尺度稳定度优于全铯钟时间尺度,不同的氢铯联合钟组计算得到的时间尺度结果相近。展开更多
基金supported by National Natural Science Foundation of China(NSFC)(grant Nos.41721003,41631072,41874023,41804012,41429401,41574007)Natural Science Foundation of Hubei Province(grant No.2019CFB611)
文摘General relativity theory(GRT)concludes that a precise clock ticks at different running rates if it is under the influence of different geopotentials.Therefore,by comparing the running rates of clocks at arbitrary two stations,the geopotential difference between them can be determined.In this study,with the help of two hydrogen atomic clocks(noted as H-masers),using the two-way satellite time and frequency transfer(TWSTFT)technique,we carried out experiments of the geopotential difference determination at the China Aerospace Science&Industry Corporation(CASIC),Beijing.Here the ensemble empirical mode decomposition(EEMD)method is adopted to remove periodic signals included in the original observations.Finally,the clock-comparison-determined geopotential difference in the experiments is determined.Results show that the difference between the geopotential difference determined by GRT and that determined by measuring tape is about 1316.1±931.0 m2s-2,which is equivalent to 134.3±95.0 m in height,and in consistence with the stability of the H-masers applied in the experiments(at the level of10-15/day).With the rapid improvement of atomic clocks’accuracy,the geopotential determination by accurate clocks is prospective,and it is promising to realize the unification of the world vertical height system(WVHS).
基金supported by the National Natural Sci-ence Foundation of China(12273098).
文摘A time and frequency system is a critical component of Very Long Baseline Interferometry(VLBI)stations,providing stable and reliable standards that directly impact data processing quality.At the Tianma 65 m radio telescope(TMRT),this system has been meticulously designed to ensure long-term reliability and high performance.It incorporates high-performance hydrogen atomic clocks,high-precision time standards,automatic signal switching,and robust system software.This comprehensive approach has enabled the system to achieve long-term reliable operation,successfully supporting both major national engineering tasks and daily scientific observations.The effectiveness of the system is evidenced by its consistent delivery of the precision and stability required for radio astronomy.This article provides an in-depth exploration of the design and operation of the time and frequency system at the Tianma 65 m telescope,examining various aspects of its architecture,implementation,and performance.By sharing these insights,we aim to contribute knowledge that could benefit similar systems at other VLBI stations,greatly advancing radio astronomy infrastructure.
文摘守时型原子钟主要包括氢原子钟和铯原子钟,为进一步探究不同类型守时原子钟计算时间尺度相关性能,本文开展全氢钟及氢铯联合时间尺度研究。首先依据国际权度局(Bureau International des Poids et Mesures,BIPM)发布的d公报将氢原子钟进行分类,针对分类结果分别运用原子时尺度理论方法计算全氢钟时间尺度,并给出分析结果。随后计算全铯钟时间尺度,并分析探究两种不同的氢铯联合钟组时间尺度。结果表明,基于频率漂移量较小的氢钟组形成的时间尺度波动范围小,且稳定度优于频率漂移量较大的氢钟组形成的时间尺度。氢铯联合形成的时间尺度稳定度优于全铯钟时间尺度,不同的氢铯联合钟组计算得到的时间尺度结果相近。
