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Challenges in SIM to Create a Coordination Program for Time and Frequency



J. Mauricio Lopez-Romero, Michael A. Lombardi


The Sistema Interamericano de Metrologia (SIM), one of the world s five major regional metrology organizations (RMOs) recognized by the Bureau International des Poids et Mesures (BIPM), is comprised of national metrology institutes (NMIs) located in all 34 member nations of the Organization of American States (OAS). Although SIM is divided into five sub-regions, 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, not only because the region is so large, but also because the available resources and the quality of the standards varies significantly from nation to nation. However, in recent years many obstacles have been overcome and much progress has made. This paper provides an overview of work done by the SIM Time and Frequency metrology working group from 2005 to 2010. It discusses the challenges that have been faced, the progress made by individual laboratories, and the important role that metrology education has played in this progress. It also provides an overview of two major achievements of the working group, the SIM Time Network (SIMTN) and the SIM Time Scale (SIMT).
Proceedings Title
21st Century Innovations in Metrology
Conference Dates
July 25-29, 2010
Conference Location
Providence, RI, US
Conference Title
Proc. 2010 NCSLI International Workshop and Symposium


calibrations, frequency, time, time scale, traceability


Lopez-Romero, J. and Lombardi, M. (2010), Challenges in SIM to Create a Coordination Program for Time and Frequency, 21st Century Innovations in Metrology, Providence, RI, US, [online], (Accessed July 16, 2024)


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Created July 25, 2010, Updated October 12, 2021