cnPRTC — Coherent Network Primary Reference Time Clock: A Geographically Distributed Resilient Timescale for Telecommunications

This article describes a new work item under study at the International Telecommunications Union (ITU) standards development organization to provide highly accurate, resilient time throughout a telecommunications network, the coherent network primary reference time clock (cnPRTC). While the traditional approach for delivering time and frequency to a network has involved deploying a number of independent sources of time and frequency, such as the PRTC or enhanced PRTC (ePRTC) along with hierarchical connections to these sources, the cnPRTC adds to this high-accuracy time and frequency connections between sources to combine them for improved accuracy and greatly improved resilience. The result is not simply a clock, but rather what is termed a timescale, much as universal coordinated time (UTC) is the result of combining the best standalone clocks in the world.