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The SIM Time Network



Michael A. Lombardi, Andrew N. Novick, J. Mauricio Lopez-Romero, Francisco Jimenez, Eduardo de Carlos Lopez, Jean-Simon Boulanger, Raymond Pelletier, Ricardo de Carvalho, Raul Solis, Harold Sanchez, Carlos A. Quevedo, Gregory Pascoe, Daniel Perez, Eduardo Bances, Leonardo Trigo, Victor Masil, Henry Postigo, Anthony Questelles


The Sistema Interamericano de Metrologia (SIM) is a regional metrology organization (RMO) whose members are the national metrology institutes (NMIs) located in the 34 nations of the Organization of American States (OAS). The SIM/OAS region extends throughout North, Central, and South America and the Caribbean Islands. About half of the SIM NMIs maintain national standards of time and frequency and must participate in international comparisons in order to establish metrological traceability to the International System (SI) of units. The SIM time network (SIMTN) was developed as a practical, cost effective, and technically sound way to automate these comparisons. The SIMTN continuously compares the time standards of SIM NMIs and produces measurement results in near real-time by utilizing the Internet and the Global Positioning System (GPS). Fourteen SIM NMIs have joined the network as of March 2010. This paper provides a brief overview of SIM and a technical description of the SIMTN. It presents international comparison results and examines the measurement uncertainties. It also discusses the metrological benefits that the network provides to its participants.


GPS, Internet, metrology, time scale, time transfer, traceability


Lombardi, M. , Novick, A. , , J. , Jimenez, F. , de, E. , Boulanger, J. , Pelletier, R. , de, R. , Solis, R. , Sanchez, H. , Quevedo, C. , Pascoe, G. , Perez, D. , Bances, E. , Trigo, L. , Masil, V. , Postigo, H. and Questelles, A. (2011), The SIM Time Network, Metrologia (Accessed May 27, 2024)


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Created March 1, 2011, Updated February 19, 2017