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Search Publications by Michael A. Lombardi

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Displaying 1 - 25 of 132

SIM Time Scale: 10 years of operation

Author(s)
J. M. Lopez, Michael A. Lombardi, E. de Carlos, N. Munoz, C. Ortiz
The Inter-American Metrology System (SIM) is one of the world's five major Regional Metrology Organizations (RMO's). Starting in 2005, the SIM Time and

Metrological and legal traceability of time signals

Author(s)
Demetrios Matsakis, Judah Levine, Michael A. Lombardi
Metrological traceability requires an unbroken chain of calibrations that relate to a reference, with each calibration having a documented measurement

Improving packet synchronization in an NTP server

Author(s)
Andrew N. Novick, Michael A. Lombardi, Kevin Franzen, John Clark
A computer or dedicated client can use the Network Time Protocol (NTP) to synchronize an internal clock to a server that is synchronized by a 1 pulse-per-second

Timekeeping in the Americas

Author(s)
Michael A. Lombardi, Jose M. Lopez
Time and its measurement belong to the most fundamental core of physics, and many scientific and technological advances are directly or indirectly related to

Practical Limitations of NTP Time Transfer

Author(s)
Andrew N. Novick, Michael A. Lombardi
The Network Time Protocol (NTP) is commonly utilized to synchronize computer clocks in packet-switched, wide area networks (WANs) such as the public Internet

International Comparisons of Network Time Protocol Servers

Author(s)
Michael A. Lombardi, Judah Levine, Jose M. Lopez, Francisco Jimenez, John Bernard, Marina Gertsvolf, Harold Sanchez, Oscar G. Fallas, Liz C. Hernandez Ferero, Ricardo de Carvalho, Mario Fittipaldi, Raul Solis, Franklin Espejo
This paper describes a recently designed system that measures the time transmitted by network time protocol (NTP) servers located in North, Central, and South

Improvements in SIM Time Network and SIM Time Scale Performance

Author(s)
Michael A. Lombardi, J. Mauricio Lopez-Romero, Nelida Diaz-Munoz, E. de Carlos-Lopez, Marina Gertsvolf, Ricardo de Carvalho
We report recent results achieved within the Sistema Interamericano de Metrología (SIM) regarding the multinational cooperation program in the field of time and

Frequency Measurement

Author(s)
Michael A. Lombardi
An overview of frequency metrology, with emphasis on estimating accuracy and stability, oscillator types, and measurement instrumentation. It describes how to

Time Measurement

Author(s)
Michael A. Lombardi
An overview of time metrology, with emphasis on time interval measurements, and time synchronization. It covers the evolution of clocks and timekeeping, time

The SIM time scale

Author(s)
Michael A. Lombardi, J. Mauricio Lopez-Romero, Nelida Diaz-Munoz, E. de Carlos-Lopez
Time measurement is of great importance for science, technology and commerce. Among the seven base units of the International System (SI), the second can be

Replicating UTC(NIST) at Remote Sites

Author(s)
Michael A. Lombardi, Andrew N. Novick, J. Mauricio Lopez-Romero, Rodrigo Ramos
The National Institute of Standards and Technology (NIST) is deploying disciplined oscillators that are referenced to the UTC(NIST) time scale through common

The Need for a Robust, Precise Time and Frequency Alternative to GNSS

Author(s)
Michael A. Lombardi, Mitch Narins, Per Enge, Ben Peterson, Sherman Lo, Yu-Hsuan Chen, Dennis Akos
Positioning, Navigation, and Timing (PNT) services are key enablers of both essential safety and security applications and economically beneficial capacity and