In order to further improve the safety, reliability and accuracy of Chinese timing system, the High Accurate Ground-based Time Service System, the major national science and technology infrastructure projects in the 13th Five Year Plan, proposed by the National Time Service Center was approved by the national government. The system planned to start construction in the early of 2020 and complete in 2025.

The purpose of this system is to build a high accurate ground-based time service system which is relatively independent, complementary enhancement and fuse-share with the satellite based time service system. Specially, by adding three enhanced long wave time service stations in the west of China, the enhanced Loran time service system in China will be perfected, and the nationwide coverage of long wave time service will be realized, the time service accuracy in key areas will better than hundreds nanoseconds；by using China's communication optical fiber network, a high-precision optical fiber time-frequency transmission backbone network covering major cities and important users will be constructed. The time transmission accuracy will better than 100 picoseconds, and the frequency transmission accuracy will reach the level of E-19. After the completion of the facility, it will work together with the satellite based timing system as a integrated satellite ground timing system in China, which not only supports the long-term development of China's economy, society and national security, but also provides an important experimental platform for the scientific researches, such as precise measurement physics and precise time-frequency technology.

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