亚皮秒级星地时频比对微波链路大气修正技术研究

Research on Atmospheric Correction Technology for Subpicosecond Satellite Earth Time Frequency Comparison Microwave Link

  • 摘要: 发展空间高精度原子钟组是国内外空间前沿科学探索和时频体系建立的重要研究方向。其中,如何建立高精度星地时差测量比对链路,客观、准确评价空间钟组效能,促进高精度时频基准应用,是建立空间时频体系迫切需要形成的核心能力。在整个星地时频比对链路中,大气传输误差是最大的误差来源,因此大气传输误差的修正是星地时频比对的关键。针对中国空间站星地微波时频链路长期高稳定度需求,我们分析了空间传输环境中电离层和对流层的影响,提出了“三频链路”组合对消方法,分别构建了电离层和对流层的误差修正模型。利用上、下行链路消除对流层的非色散效应影响;借助两个下行链路计算同一路径的电离层总电子含量,进而修正电离层引起的时延误差;采用模型修正、微波辐射计实测结合的方式,修正了高频信号对流层色散误差。结果表明,该误差修正模型可实现亚皮秒量级测量精度的星地微波时间传递。其精度满足中国空间站时间频率传递稳定度指标,可进一步支撑冷原子光钟E-18量级的长期稳定度需求。

     

    Abstract: Objectives: The development of high-precision atomic clocks in space is an important research direction for cutting-edge scientific exploration and time-frequency system establishment both domestically and internationally. Among them, how to establish a high-precision satellite ground time difference measurement in comparison link, objectively and accurately evaluate the effectiveness of the space clock group, and promote the application of high-precision time-frequency benchmarks is an urgent core capability that needs to be formed to establish a space time-frequency system. In the entire satellite ground time-frequency comparison link, atmospheric transmission error is the largest source, so the correction of atmospheric transmission error is the key to satellite ground time-frequency comparison. Methods: We focus on the long-term high stability requirements of the satellite ground microwave time-frequency link of the Chinese space station, analyze the impact of the ionosphere and troposphere in the space transmission environment, propose a "three frequency link" combination cancellation method, and construct error correction models for the ionosphere and troposphere respectively. We use uplink and downlink to eliminate the non-dispersion effect in the troposphere, and use two downlink links to calculate the total ionospheric electron content of the same path, thereby correcting the delay error caused by the ionosphere. At the same time, we used a combination of model correction and microwave radiometer measurements to correct the tropospheric dispersion error in the high-frequency signals. Results: The results indicate that the error correction model can achieve satellite to ground microwave time transfer with measurement accuracy below 1 picosecond. Conclusions: The accuracy meets the time frequency transmission stability index of the Chinese space station, which can further support the long-term stability requirements of the E-18 level cold atomic clock.

     

/

返回文章
返回