Time and Frequency: Theory and Fundamentals


Book Description

The document is a tutorial Monograph describing various aspects of time and frequency (T/F). Included are chapters relating to elemental concepts of precise time and frequency; basic principles of quartz oscillators and atomic frequency standards; historical review, recent progress, and current status of atomic frequency standards; promising areas for developing future primary frequency standards; relevance of frequency standards to other areas of metrology including a unified standard concept; statistics of T/F data analysis coupled with the theory and construction of the NBS atomic time scale; an overview of T/F dissemination techniques; and the standards of T/F in the USA. The Monograph addresses both the specialist in the field as well as those desiring basic information about time and frequency. The authors trace the development and scope of T/F technology, its improvement over periods of decades, its status today, and its possible use, applications, and development in days to come.







NBS Monograph


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NBS Technical Note


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Computer Network Time Synchronization


Book Description

Carefully coordinated, reliable, and accurate time synchronization is vital to a wide spectrum of fields—from air and ground traffic control, to buying and selling goods and services, to TV network programming. Ill-gotten time could even lead to the unimaginable and cause DNS caches to expire, leaving the entire Internet to implode on the root servers. Written by the original developer of the Network Time Protocol (NTP), Computer Network Time Synchronization: The Network Time Protocol on Earth and in Space, Second Edition addresses the technological infrastructure of time dissemination, distribution, and synchronization—specifically the architecture, protocols, and algorithms of the NTP. This system has been active in one form or another for almost three decades on the Internet and numerous private networks on the nether side of firewalls. Just about everything today that can be connected to a network wire has support for NTP. This book: Describes the principal components of an NTP client and how it works with redundant servers and diverse network paths Provides an in-depth description of cryptographic and other critical algorithms Presents an overview of the engineering principles guiding network configuration Evaluating historic events that have taken place since computer network timekeeping started almost three decades ago, the author details a number of systems and drivers for current radio, satellites, and telephone modem dissemination and explains how we reckon the time, according to the stars and atoms. The original 16 chapters of the first edition have been rewritten, updated, and enhanced with new material. Four new chapters cover new algorithms and previously uncovered concepts, including timekeeping in space missions. Praise for the first edition: "... For those that need an exhaustive tome on all of the minutiae related to NTP and synchronization, this is the source. ... definitive ... this book should be considered the last word on the topic." —Ben Rothke on Slashdot.org "... the bible of the subject... contains enough information to take you just as far as you want to go....Dr. Mills is the original developer of NTP." —Books On-Line




NBS Special Publication


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Frequency Standards and Metrology


Book Description

Since the previous Symposium, several exciting new developments and advances have occurred in the field of frequency standards and metrology. These include the first results on the long-tenn stability of a millisecond Pulsar, for which data 14 integrated over several years now show a stability of around 10- . Improvements in the understanding of various biases in Cesium beam standards promise accuracies in the low 14s for primary standards and in the low 13s for short commercial tubes, for which long tenn stabilities in low 14s have already been shown to be obtainable by accuracy improvement. Beams using optical pumping for state selection and for detection have been operated with excellent results, and more are being realized. Other new frequency standards which have appeared include a macroscopic rf trap with Mercury ions, which perfonns in the low 15s in one day, the sub millimeter metastable Magnesium beam, which has shown a short tenn stability 19 in the low 12s in one second and promises an accuracy of 10- , and the cold Hydrogen masers, which have such high stabilities that they cannot be measured with existing local oscillators. Prospects for future developments include laser manipulation of neutrals and spectroscopy of single ions at rest in a trap. Both these groups of techniques have great potential for unprecedented accuracy and short-and long-tenn stability, and new superior frequency standards are expected to be realizable in this way in the not too distant future.