Characterization of clocks and oscillators

Abstract

For many years following its publication in 1974, "TIME AND FREQUENCY: Theory and Fundamentals," a volume edited by Byron E. Blair and published as NBS Monograph 140, served as a common reference for those engaged in the characterization of very stable clocks and oscillators.Monograph 140 has gradually become outdated, and with the recent issuance of a new military specification, MIL-0-55310B, which covers general specifications for crystal oscilla- tors, it has become especially clear that Monograph 140 no longer meets the needs it so ably served in earlier years.During development of the new military specification, a process involving discussion and input from many quarters, a key author of the specification, John Vig of the US Army Electronics Technology and Devices, urged the National Bureau of Standards (now the National Institute of Standards and Technology, NIST) to issue a revised pubHcation to serve as reference for the characterization of clocks and oscillators.With NIST having agreed to this task, the framers of the military specification used the nomenclature "N^S Monograph 140R" in their document, anticipating a revised (R) volume which had not yet been prepared.Considering the availability of a number of newer books in the time and frequency field, the rewriting of a major volume like Monograph 140 seemed inappropriate.The real need has not been for rework of everything in Monograph 140, but only for those parts which provide reference to definitions and methods for measurement and characterization of clocks and oscilla- tors, subjects which are fully covered in a number of papers distributed through a variety of conference proceedings, books, and journals.For the near term, we concluded that the most effective procedure would be to collect a representative set of these papers into one reference source with introductory comments which permit the reader to quickly access material required to meet particular needs.Thus, we arrived at this particular collection.The editors' challenge has been to select representative papers, to organize them in a convenient manner, and to deal with errata and notation inconsistencies in a reasonable manner.In the longer term, the materi- al in this volume needs to be more completely integrated.This task would profitably await further developments in the area of phase noise measurements.