GENEVA—The International Telecommunication Union (ITU) today released updated guidance to help countries maintain precision time systems.
Precision timekeeping enables reliable operations of critical infrastructure, including communications networks, navigation systems, electricity networks and financial systems.
The latest guidance is published in ITU’s “Handbook on Selection and Use of Precise Frequency and Time Systems.” It offers governments, engineers and technical specialists an updated reference on the technologies used to generate, measure, compare and distribute precise frequency and time signals.
“Global connectivity depends on technologies working together seamlessly—precision time is one of the foundations that makes this possible,” said Doreen Bogdan-Martin, ITU secretary-general. “Through international cooperation and technical expertise, ITU is helping countries strengthen the reliability and resilience of the timing systems that support communications and critical infrastructure worldwide.”
The new ITU guide is the first update since 1997. It covers the fundamental principles of frequency and time measurement, the operation of modern atomic clocks and the technologies used to disseminate precise time across national and international networks.
Developed by experts from the ITU Radiocommunication Sector (ITU-R), the updated guide reflects nearly three decades of technological progress and modern society’s growing dependence on accurate, reliable time synchronization.
The 2026 edition addresses radio and satellite dissemination, optical fiber time transfer, optical atomic clocks and time as a service. It also examines a new generation of ultra-precise clocks based on optical frequency standards that could eventually change how the world defines a second.
“We rarely think about precise time, yet modern communications, navigation and critical infrastructure depend on it every second,” Mario Maniewicz, director of the ITU Radiocommunication Bureau, said. “This Handbook provides administrations and engineers with an authoritative reference for understanding the technologies behind accurate timing and for making these systems more reliable and resilient.”
The guidebook is available online.
