A High-Precision Transfer of Time and RF Frequency via the Fiber-Optic Link Based on Secure Encryption

Abstract

This paper presents a high-precision transfer system of time and RF frequency via the fiber optic link based on secure encryption. On the basis of the two-way time transfer of optical fiber, a security strategy composed of an SM2 encryption algorithm is introduced, which can resist the security risk of time information being tampered with. The experimental results show that the developed picosecond-precision fiber-optic time transfer equipment can ensure high stability while realizing the encryption function. Time synchronization stability in terms of time deviation (TDEV) of 1 PPS can reach around 10.7 ps at 1 s and 7.1 ps at 10 s averaging time. The stability of the 10 MHz frequency can reach around 4.7 × 10−12 at 1 s and 1.1 × 10−12 at 10 s averaging time. There is no significant difference in time transfer accuracy, compared with unencrypted conditions. Furthermore, this paper realizes a ring time transfer network via a 150 km fiber-optic link with three nodes using three devices. The TDEV of 1PPS can reach around 20.8 ps at 1s averaging time. This paper provides a reference to establish a high-precision, safe, and stable time synchronization fiber network in the future.

Simultaneous transmission of time-frequency and data with co-amplification over urban fiber links

“…With active compensation based on an optical delay line, the frequency instability 5:9 × 10 −17 at 10,000 s over a 106-km urban fiber link is obtained. Much excellent research has been done on long distance optical frequency [22] , radio frequency [23,24] , time [25,26] , and simultaneous transmission [27][28][29][30][31] . All of the present research is focused on the joint transmission of metrological signals over longer or more complex optical fiber links.…”

A high-precision bidirectional time-transfer system over a single fiber based on wavelength-division multiplexing and time-division multiplexing

“…The development of optical fiber time-transfer equipment will provide time signals and technical support for major scientific and technological facilities and also meet the needs of rapid economic and social development. The application range of high-precision time and frequency has penetrated from basic research to the engineering technology application field, which is related to many important departments of the national economy and the people's livelihood [5][6][7].…”

Secure Two-Way Fiber-Optic Time Transfer Against Sub-ns Asymmetric Delay Attack With Clock Model-Based Detection and Mitigation Scheme

“…Although the performance of the time transfer is improved by these technologies, there are security threads for TWFTT, which can deteriorate the performance significantly. Security strategy based on encryption is proposed in [19]. However, there is a threat called asymmetric delay attack which can not be protected by encryption.…”