Accuracy of two-way time transfer via a single coaxial cable

Abstract

In order to find limits of the accuracy of the two-way time transfer (TWTT) via a single coaxial cable, we have carried out a detailed analysis which is presented in this paper. We applied the TWTT concept when a transmission line is driven by pulse current drivers and the times of arrival of the pulses are measured at the ends of the line. In addition to the estimation of the accuracy, the analysis provides several rules for proper design of a TWTT system with optimal performance. Based on this concept, a TWTT system for highly accurate time distribution or comparison has been designed and realized. For distances up to 1 km the accuracy was better than 100 ps without any additional correction or adjustment. After the influence of the non-symmetry of input–output circuits was corrected, the errors were lower than 20 ps for distances up to 2 km. The TWTT system is designated for keeping unified time in a net of event timers distributed in one building or in a relatively small area. The timing units forming the system guarantee the time transfer parallel to the time tagging of external pulses.

Photon counting delay stability as a key factor for optical time transfer

“…Photon counting approach to the detection of optical pulses is significantly reducing the systematic errors contributors list. The detailed analysis of the systematic errors contributions [11] shows, that the resulting accuracy of the two way time transfer as high as 10 ps may be achieved. Considering the statistical nature of photon (6 GHz) components to ensure low timing jitter and good delay stability.…”

Indoor demonstration of free-space picosecond two-way time transfer on single photon level

“…two pairs of epochs EA× and EB× can be combined producing the difference DS between the two time scales (1) along with the delay of the optical channel DC interconnecting the two OTWTT modules (2). Reference points are defined symmetrically inside each optical signal combiner.…”

“…In our previous work we have demonstrated electronic circuits for two-way time transfer via a single coaxial cable with picosecond accuracy and precision [2] . The experiment proved the capability of this technique to maintain picosecond stability over the periods of seconds to days.…”

“…The experiment proved the capability of this technique to maintain picosecond stability over the periods of seconds to days. The systematic errors of the order of units of picoseconds have been achieved [2] . This technique may be effectively applied in configurations, where the sites may be interconnected by a broad bandwidth coaxial cable.…”

Photon counting detector for high-repetition-rate optical time transfer providing extremely high data yield

“…The systematic errors on the order of units of picoseconds have been achieved. 3 For distances longer than a few kilometers, the optical approach may be considered. The photon counting approach to the signal detection provides several additional key advantages: the reduction of most systematic errors found in commonly used multiphoton detection systems and the capability to operate with ultimately low signals.…”