Precision time-transfer in transport networks using digital cross-connect systems

1990 ◽  
Vol 38 (9) ◽  
pp. 1325-1332 ◽  
Author(s):  
W.D. Grover ◽  
T.E. Moore
Keyword(s):  
Time Transfer ◽  
Transport Networks ◽  
Precision Time ◽  
Cross Connect

Distributed high-precision time transfer through passive optical networks

2014 ◽  
Vol 53 (9) ◽  
pp. 096113
Author(s):  
Guiling Wu ◽  
Liang Hu ◽  
Hao Zhang ◽  
Jianping Chen
Keyword(s):  
Optical Networks ◽  
High Precision ◽  
Passive Optical Networks ◽  
Time Transfer ◽  
Precision Time

scholarly journals Influence of Precise Products on the Day-Boundary Discontinuities in GNSS Carrier Phase Time Transfer

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1156
Author(s):  
Xiangbo Zhang ◽  
Ji Guo ◽  
Yonghui Hu ◽  
Baoqi Sun ◽  
Jianfeng Wu ◽  
...  
Keyword(s):  
Satellite System ◽  
Observation Data ◽  
Time Transfer ◽  
Noise Characteristics ◽  
Julian Date ◽  
Precision Time ◽  
Gps Products ◽  
Code Pseudorange ◽  
Pseudorange Noise ◽  
Global Navigation Satellite

Global navigation satellite system (GNSS) precise point positioning (PPP) has been widely used for high-precision time and frequency transfer. However, the day-boundary discontinuities at the boundary epochs of adjacent days or batches are the most significant obstacle preventing PPP from continuous time transfer. The day-boundary discontinuities in station estimates and time comparisons are mainly caused by the code-pseudorange noise during the analysis of observation data in daily batches, where the absolute clock offset is determined by the average code measurements. However, some discontinuities with amplitudes even more than 0.15 ns may still appear in station clock estimates and time comparisons, although several methods had been proposed to remove such discontinuities. The residual small amplitude of the day-boundary discontinuities in some PPP station clock estimates and time comparisons through new GNSSs like Galileo seems larger, especially using precise clock products with large discontinuities. To further understand the origin of the day-boundary discontinuities, the influence of GNSS precise products on the day-boundary discontinuities in PPP station clock estimates and time comparisons is investigated in this paper. Ten whole days of Multi-GNSS Experiment (MGEX) from modified Julian date (MJD) 59028 to 59037 are used as the observation data. For a comparative analysis, the station clock estimates are compared with global positioning system (GPS) and Galileo observations through PPP and network solutions, separately. The experimental results show that the daily discontinuities in current combined GPS final and rapid clock products are less than 0.1 ns, and their influence on the origin of day-boundary discontinuities in PPP station clock estimates and time comparison are statistically negligible. However, the daily discontinuities in individual Analysis Centers (ACs) GPS products are more extensive, and their influence on the origin of the day-boundary discontinuities in GPS PPP station clock estimates cannot be ignored. The day-boundary discontinuities demonstrate random walk noise characteristics and deteriorate the station clocks’ long-term frequency stability, especially at an average time of more than one day. Although Galileo clock daily discontinuities are different from those of GPS, their influence on the day-boundary discontinuities in station clock estimates is nearly similar to the GPS PPP. The influence of daily discontinuities of Galileo clocks on PPP time comparison is similar to GPS and is not particularly critical to time comparison. However, combined and weighted MGEX products should be developed or Galileo IPPP should be used for remote comparison of high-stability clocks.

High-precision time transfer over a local ring fiber link

2020 ◽  
Vol 466 ◽  
pp. 125636
Author(s):  
Rongrong Xu ◽  
Faxing Zuo ◽  
Liang Hu ◽  
Jianping Chen ◽  
Guiling Wu
Keyword(s):  
Local Ring ◽  
High Precision ◽  
Time Transfer ◽  
Precision Time ◽  
Fiber Link
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