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The Development of a Unified Time and Frequency Program in the SIM Region



Michael A. Lombardi, J. Mauricio Lopez-Romero


The Sistema Interamericano de Metrologia (SIM) is one of five major regional metrology organizations (RMOs) recognized by the Bureau International des Poids et Mesures (BIPM). SIM is composed of the national metrology institutes (NMIs) located in the 34 member nations of the Organization of American States (OAS). Its goal is to create a unified measurement network that extends to the entire SIM region, ensuring the uniformity of measurements and strengthening traceability throughout North, Central, and South America back to the International System (SI) of units. To help reach this goal, SIM sponsors working groups in ten different metrological fields, including time and frequency. Developing a unified time and frequency measurement network in the SIM region has been a challenging task, but much progress has been made in recent years and many obstacles have been overcome. This paper summarizes work done by the SIM Time and Frequency metrology working group from 2004 to 2010. It discusses the challenges faced by the working group, the progress made by individual laboratories, and the important role played by metrology education. It also provides an overview of two major achievements of the working group, the SIM Time Network (SIMTN) and the SIM Time (SIMT) scale.
Measure: The Journal of Measurement Science


calibrations, frequency, time, time scale, traceability


Lombardi, M. and , J. (2010), The Development of a Unified Time and Frequency Program in the SIM Region, Measure: The Journal of Measurement Science, [online], (Accessed July 18, 2024)


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Created September 1, 2010, Updated February 19, 2017