Use of software-defined radio receivers in two-way satellite time and frequency transfers for UTC computation
Use of software-defined radio receivers in two-way satellite time and frequency transfers for UTC computation
复制标题
在双向卫星时间和频率传输中使用软件定义的无线电接收器进行 UTC 计算
DOI：
10.1088/1681-7575/aacbe6
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发表时间：
2018
期刊：
影响因子：
2.4
通讯作者：
P. Whibberley
中科院分区：
文献类型：
--
作者：
Zhiheng Jiang;V. Zhang;Yi Jiun Huang;J. Achkar;Dirk Piester;Shinn;Wenjun Wu;A. Naumov;Sung;J. Nawrocki;I. Sesia;C. Schlunegger;Zhiqiang Yang;M. Fujieda;A. Czubla;H. Esteban;C. Rieck;P. Whibberley
双向卫星时频传输（TWSTFT）是产生协调世界时（UTC）的主要技术。在这种情况下，全球约有20个授时实验室使用卫星时间和测距设备（SATRE）调制解调器持续运行TWSTFT，进行远程时间和频率比较。今天观测到的SATRE TWSTFT的精度受到TWSTFT结果中明显的日变化模式（日）的限制。在某些情况下，观察到的峰间变化高达2纳秒。到目前为止，对日全食起源的调查还没有提供关于日全食成因的完整理解。然而，造成昼夜节律的一个主要因素可能与调制解调器中接收部分的特性有关。2014年和2015年的研究表明，在TWSTFT地面站（SDR TWSTFT）中绕过接收部分并使用软件定义无线电（SDR）接收机可以显著降低日频和测量噪声。2016年，国际计量局（BIPM）和时间频率协商委员会（CCTF） TWSTFT工作组（WG）启动了SDR接收机在TWSTFT网络中用于UTC计算的试点研究。试点研究的第一批结果在2017年5月的TWSTFT年会上报告给了CCTF工作组，表明SDR TWSTFT在参与台站之间的几乎所有链路上都表现出优于SATRE TWSTFT的性能。特别是，对于大陆TWSTFT链路，其中出现了最强的日线，使用SDR TWSTFT会导致日线的显著抑制，抑制幅度在2到3之间。对于非常长的洲际航线，例如欧洲到美国的航线，日差不太明显，SDR TWSTFT的增益较小，但仍然显著，为30%。这些发现得到了本文所报道的基于GPS信号（GPS IPPP）的替代技术的一些链接评估的支持。在这些结果的刺激下，TWSTFT工作组为第21届CCTF会议准备了一份建议，提议在UTC生成中引入SDR TWSTFT。CCTF批准了该建议后，制定了在UTC生成中实现SDR TWSTFT的路线图。根据路线图，参与试点研究的大多数台站都更新了SDR TWSTFT设置，以方便在UTC生成中使用SDR TWSTFT数据。此外，BIPM对SDR TWSTFT链路的长期稳定性进行了最终评估，使用BIPM计算UTC的标准软件进行了试运行，现在包括SDR TWSTFT数据，并从2017年10月开始计算SDR TWSTFT时间链路作为备份。SDR TWSTFT将于2018年开始在UTC生成中使用。
Two-way satellite time and frequency transfer (TWSTFT) is a primary technique for the generation of coordinated universal time (UTC). About 20 timing laboratories around the world continuously operate TWSTFT using satellite time and ranging equipment (SATRE) modems for remote time and frequency comparisons in this context. The precision of the SATRE TWSTFT as observed today is limited by an apparent daily variation pattern (diurnal) in the TWSTFT results. The observed peak-to-peak variation have been found as high as 2 ns in some cases. Investigations into the origins of the diurnals have so far provided no complete understanding about the cause of the diurnals. One major contributor to the diurnals, however, could be related to properties of the receive part in the modem. In 2014 and 2015, it was demonstrated that bypassing the receive part and the use of software-defined radio (SDR) receivers in TWSTFT ground stations (SDR TWSTFT) instead could considerably reduce both the diurnals and the measurement noise. In 2016, the International Bureau of Weights and Measures (BIPM) and the Consultative Committee for Time and Frequency (CCTF) working group (WG) on TWSTFT launched a pilot study on the application of SDR receivers in the TWSTFT network for UTC computation. The first results of the pilot study were reported to the CCTF WG on TWSTFT annual meeting in May 2017, demonstrating that SDR TWSTFT shows superior performance compared to that of SATRE TWSTFT for practically all links between participating stations. In particular, for continental TWSTFT links, in which the strongest diurnals appear, the use of SDR TWSTFT results in a significant suppression of the diurnals by a factor of between two and three. For the very long inter-continental links, e.g. the Europe-to-USA links where the diurnals are less pronounced, SDR TWSTFT achieved a smaller but still significant gain of 30%. These findings are supported by an evaluation of some of the links with an alternate technique based on GPS signals (GPS IPPP) as reported in this paper. Stimulated by these results, the WG on TWSTFT prepared a recommendation for the 21st CCTF meeting, which proposed the introduction of SDR TWSTFT in UTC generation. With CCTF approval of the recommendation, a roadmap was developed for the implementation of SDR TWSTFT in UTC generation. In accordance with the roadmap, most of the stations that participated in the pilot study have updated the SDR TWSTFT settings to facilitate the use of SDR TWSTFT data in UTC generation. In addition, the BIPM conducted a final evaluation to validate the long-term stability of SDR TWSTFT links, made test runs using the BIPM standard software for the calculation of UTC, now including SDR TWSTFT data, and started to calculate SDR TWSTFT time links as backup from October 2017. The use of SDR TWSTFT in UTC generation will begin in 2018.