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The SIM Time and Frequency Network



Michael A. Lombardi, Andrew N. Novick, Jose M. Lopez, Francisco Jimenez, Jean-Simon Boulanger, Raymond Pelletier, Ricardo de Carvalho, Raul Solis, Carlos Donado, Harold Sanchez, Carlos A. Quevedo, Gregory Pascoe, Daniel Perez


The Sistema Interamericano de Metrologia (SIM) consists of national metrology institutes (NMIs) located in the 34 member nations of the Organization of American States (OAS), which extends throughout North, Central, and South America, and the Caribbean region. SIM is one of the world's five major regional metrology organizations (RMOs) recognized by the Bureau International des Poids et Mesures (BIPM). Currently about half of the 34 member NMIs maintain time and frequency laboratories. In order for these NMIs to establish metrological traceability and to determine the uncertainty of their measurements, it is important for each of them to participate in international comparisons. The SIM network was developed to advance the state of metrology in the SIM region and to allow as many laboratories as possible to participate in international time coordination. It provides continuous, near real-time comparisons between the national time and frequency standards located throughout the SIM region, by utilizing both the Internet and the Global Positioning System (GPS). As of August 2008, twelve SIM NMIs have been added to the SIM network, and four additional NMIs will be added to the network as soon as resources become available. The paper provides an overview of SIM and a technical description of the network. It also discusses the network's measurement uncertainties and presents results obtained from ongoing interlaboratory comparisons.
INFOSIM: Informative Bulletin of the Interamerican Metrology System - OAS


common-view, GPS, metrology, time transfer, traceability


Lombardi, M. , Novick, A. , Lopez, J. , Jimenez, F. , Boulanger, J. , Pelletier, R. , de, R. , Solis, R. , Donado, C. , Sanchez, H. , Quevedo, C. , Pascoe, G. and Perez, D. (2008), The SIM Time and Frequency Network, INFOSIM: Informative Bulletin of the Interamerican Metrology System - OAS, [online], (Accessed May 22, 2024)


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Created December 1, 2008, Updated February 19, 2017