New Possibilities in Time-Frequency Standards

Cesium Beam Atomic Time and Frequency Standards

In recognition of the 0ct)ober 1964 declaration of the International Committee of Weights and Measures that the physical measurement of time be based on a particular transition between two hyperfine levels in the ground state of cesium 133, a review of the characteristics of cesium beam atomic frequency standards is presented. This article discusses the general requirements for frequency and ti...

A New Era of Frequency Standards and Optical Frequency Measurement

A New Clock for Improving the Accuracy of Local Frequency and Time Standards

In line with the continually advancing ma turity of the electronics field as a whole, the portion of the field concerned with frequency control has made significant forward strides in recent years. As a result, high-precision fre quency standards employing quartz resonators presently achieve stabilities of a part in 109 per day or better, while atomic standards ex hibit accuracies of one or two...

The Brazilian time and frequency atomic standards program.

Cesium atomic beam clocks have been the workhorse for many demanding applications in science and technology for the past four decades. Tests of the fundamental laws of physics and the search for minute changes in fundamental constants, the synchronization of telecommunication networks, and realization of the satellite-based global positioning system would not be possible without atomic clocks. ...

A new technique for bearing fault detection in the time-frequency domain

This paper presents a new Fast Kurtogram Method in the time-frequency domain using novel types of statistical features instead of the kurtosis. For this study, the problem of four classes for Bearing Fault Detection is investigated using various statistical features. This research is conducted in four stages. At first, the stability of each feature for each fault mode is investigated. Then, res...