Short Term Frequency Instability Effects in Networks of Coupled Oscillators

Network Time Protocol (Version 3) Specification, Implementation and Analysis

“…The clock filter and selection algorithms are designed so that the clock synchronization subnet self-organizes into a hierarchical-master-slave configuration [MIT80]. With respect to timekeeping accuracy and stability, the similarity of NTP to digital telephone systems is not accidental, since systems like this have been studied extensively [LIN80], [BRA80]. What makes the NTP model unique is the adaptive configuration, polling, filtering, selection and correctness mechanisms which tailor the dynamics of the system to fit the ubiquitous Internet environment.…”

“…In order to avoid the tedious calculations [BRA80] necessary to estimate errors in each specific configuration, it is useful to assume the mean measurement errors accumulate approximately in proportion to the measured delay and dispersion relative to the root of the synchronization subnet. Appendix H contains an analysis of errors, including a derivation of maximum error as a function of delay and dispersion, where the latter quantity depends on the precision of the timekeeping system, frequency tolerance of the local clock and various residuals.…”

Network Time Protocol (version 1) specification and implementation

“…From the analytical point of view, the system of distributed NTP peers operates as a set of coupled phase-locked oscillators, with the update algorithm functioning as a phase detector and the logical clock as a voltagecontrolled oscillator. This similarity is not accidental, since systems like this have been studied extensively [3], [4] and [5].…”

“…In order to avoid the tedious calculations [4] necessary to estimate errors in each specific configuration, it is useful to assume the errors accumulate approximately in proportion to the minimum total roundtrip path delay between each server and the primary reference source to which it is synchronized. This is called the synchronization distance.…”

A temperature compensated CMOS ring oscillator for wireless sensing applications

“…These building blocks are used as beating heart of applications such as disk drive read channels [3], clock recovery circuits for serial data communications [4]. Stable frequency is imperative in order to minimize interference in adjacent frequency bands, as far as many communications applications are concerned [5]. A popular method for realizing digital-output VCOs in CMOS technology is a subclass of the CMOS relaxation oscillator family, such as the structure of ring oscillator.…”