Time-Frequency Encyclopedia

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2024

Timekeeping Characteristics of Atomic Clocks in Timing Systems

The U.S. National Institute of Standards and Technology is developing an actively coherent‑scheme trapped‑ion atomic clock and announced on August 31, 2004, that it had successfully demonstrated an experimental apparatus for such a clock.

The U.S. National Institute of Standards and Technology is developing an actively-cooled, coherent‑state‑trapping atomic clock and announced on August 31, 2004, that it had successfully built a prototype experimental device. Meanwhile, the University of Bern in Germany, U.S. observatories, national laboratories, and institutions such as NIST and Harvard University have all conducted experiments and research on passively‑cooled, coherent‑state‑trapping atomic clocks. These passive CPT clocks are compact, low‑power devices with rapid startup times. Compared with today’s small rubidium clocks, they offer comparable frequency stability while reducing size and power consumption to roughly one‑third and shortening the startup time to about one‑fifth. As highly miniaturizable atomic clocks, they can be engineered into wristwatch‑sized, button‑battery‑powered units. Owing to their trend toward extreme miniaturization, passive CPT clocks hold great promise for applications such as portable atomic‑clock‑based timing in handheld communication devices, mobile base stations in communication networks, and satellite‑navigation timing terminals. They can enhance the security and expand the scope of communications, enabling autonomous networking and mutual navigation and positioning even in areas without satellite‑navigation signals or when such signals are jammed. At present, two commercially available miniature passive CPT clocks are already on the market abroad. Furthermore, the Institute of Physics and the Institute of Mathematics of the Chinese Academy of Sciences have also developed passive CPT clocks, whose frequency stability, power consumption, physical dimensions, and temperature coefficients have now reached the level of comparable foreign products.

Reliability Measures for the Frequency Source of a Time‑Synchronization System

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Reliability Measures for the Frequency Source of a Time‑Synchronization System

Beidou timing terminal 1PPS signal output