National Time and Frequency Standard Laboratory, Telecommunication Laboratories, Taoyuan, Taiwan, R.O.C.
IEEE Trans Ultrason Ferroelectr Freq Control. 2012 Mar;59(3):539-44. doi: 10.1109/TUFFC.2012.2225.
Two major time and frequency transfer techniques, two-way satellite time and frequency transfer (TWSTFT) and global navigation satellite systems (GNSS: GPS, GALILEO, GLONASS, etc.), are used for the generation of Coordinated Universal Time (UTC)/International Atomic Time (TAI). These time and frequency transfer links comprise a worldwide network and the utilization of the highly redundant time and frequency data is an important topic. Two methods, either TW-only network (i.e., TWSTFT) or single-link combination of TW and Global Positioning System (GPS), have been developed for combining the redundant data from different techniques. In our previous study, we have proposed a feasible method, utilizing full time-transfer network data, to improve the results of TWSTFT network. The National Institute of Information and Communications Technology (NICT) has recently developed a software-based two-way time-transfer modem using a dual pseudo-random noise (DPN) signal. The first international DPN TWSTFT experiment, using these modems, was performed between NICT (Japan) and Telecommunication Laboratories (TL; Taiwan)and its ability to improve the time transfer precision was demonstrated. In comparison with the conventional NICT–TLTWSTFT link, the DPN time transfer results have higher precision and lower diurnal effects. The estimation also shows that DPN is comparable to GPS precise point positioning (PPP).Because the DPN results show better performance than the conventional TWSTFT results, we would adopt the DPN data for the NICT–TL link and solve the TW+DPN network solutions by using our proposed method. The concept of this application is similar to the so-called multi-technique-network time/frequency transfer. The encouraging results confirm that the TWSTFT network performance can benefit from DPN data by improving short-term stabilities and reducing diurnal effects.The results of TW+PPP network solutions are also illustrated.
两种主要的时频传递技术，即双向卫星时频传递（TWSTFT）和全球导航卫星系统（GNSS：GPS、GALILEO、GLONASS 等），被用于产生协调世界时（UTC）/国际原子时（TAI）。这些时频传递链路构成了一个全球网络，利用高度冗余的时频数据是一个重要的课题。已经开发了两种方法，即仅 TW 网络（即 TWSTFT）或 TW 和全球定位系统（GPS）的单链路组合，用于组合来自不同技术的冗余数据。在我们之前的研究中，我们提出了一种可行的方法，利用完整的时频传递网络数据来改进 TWSTFT 网络的结果。日本信息通信技术研究所（NICT）最近开发了一种基于软件的双向时频传递调制解调器，使用双伪随机噪声（DPN）信号。使用这些调制解调器进行的第一次国际 DPN TWSTFT 实验是在 NICT（日本）和电信实验室（TL；台湾）之间进行的，证明了它提高时频传递精度的能力。与传统的 NICT-TLTWSTFT 链路相比，DPN 时频传递结果具有更高的精度和更低的日变化效应。估计还表明，DPN 与 GPS 精密单点定位（PPP）相当。由于 DPN 结果比传统的 TWSTFT 结果具有更好的性能，我们将采用 DPN 数据用于 NICT-TL 链路，并使用我们提出的方法解决 TW+DPN 网络解决方案。这种应用的概念类似于所谓的多技术网络时频传递。令人鼓舞的结果证实，TWSTFT 网络性能可以通过提高短期稳定性和减少日变化效应来从 DPN 数据中受益。还说明了 TW+PPP 网络解决方案的结果。
