Journal ArticleDOI
Statistics of atomic frequency standards
David W. Allan
- Vol. 54, Iss: 2, pp 221-230
TLDR
In this paper, a theoretical analysis of the relationship between the expectation value of the standard deviation of the frequency fluctuations for any finite number of data samples and the infinite time average value of a standard deviation is presented.Abstract:
A theoretical development is presented which results in a relationship between the expectation value of the standard deviation of the frequency fluctuations for any finite number of data samples and the infinite time average value of the standard deviation, which provides an invariant measure of an important quality factor of a frequency standard. A practical and straightforward method of determining the power spectral density of the frequency fluctuations from the variance of the frequency fluctuations, the sampling time, the number of samples taken, and the dependence on system bandwidth is also developed. Additional insight is also given into some of the problems that arise from the presence of "flicker noise" (spectrum proportional to |ω|-1) modulation of the frequency of an oscillator. The theory is applied in classifying the types of noise on the signals of frequency standards made available at NBS, Boulder Laboratories, such as: masers (both H and N15H 3 ), the cesium beam frequency standard employed as the U. S. Frequency Standard, and rubidium gas cells. "Flicker noise" frequency modulation was not observed on the signals of masers for sampling times ranging from 0.1 second to 4 hours. In a comparison between the NBS hydrogen maser and the NBS III cesium beam, uncorrelated random noise was observed on the frequency fluctuations for sampling times extending to 4 hours; the fractional standard deviations of the frequency fluctuations were as low as 5 parts in 1014.read more
Citations
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Journal ArticleDOI
Noise properties of an optical frequency comb from a SESAM-mode-locked 1.5-μm solid-state laser stabilized to the 10−13 level
Stéphane Schilt,Vladimir Dolgovskiy,Nikola Bucalovic,C. Schori,M. C. Stumpf,G. Di Domenico,S. Pekarek,Andreas Oehler,Thomas Südmeyer,U. Keller,Pierre Thomann +10 more
TL;DR: In this article, a detailed investigation of the noise properties of an optical frequency comb generated from a femtosecond diode-pumped solid-state laser operating in the 1.5-μm spectral region is presented.
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Measurement of Submilligram Masses Using Electrostatic Force
Gordon A. Shaw,Julian Stirling +1 more
TL;DR: This work describes a method that scales this mass measurement approach to the submilligram level using an electrostatic force balance (EFB), and shows a substantial reduction in uncertainty relative to those currently available through conventional approaches based on kilogram subdivision for true mass.
Journal ArticleDOI
An Optically Narrowed Diode Laser for Rb Saturation Spectroscopy
TL;DR: In this article, an optically narrowed diode laser has been used to obtain high-resolution Doppler-free spectra of the D2 line of 85Rb and 87Rb at 780 nm.
Journal ArticleDOI
Magic Wavelengths for a Lattice Trapped Rubidium Four-Level Active Optical Clock
TL;DR: In this paper, the authors calculate the ac Stark shift due to lattice trapping laser which dominates the frequency shift of clock transition in a lattice trapped rubidium four-level active optical clock.
Journal ArticleDOI
Time dynamics in the point process modeling of seismicity of Aswan area (Egypt)
Luciano Telesca,Abuo El-Ela Amin Mohamed,Mohamed N. ElGabry,S. El-Hady,Kamal M. Abou Elenean +4 more
TL;DR: The time dynamics of the aftershock-depleted seismicity, investigated by means of the Allan Factor, reveals that the time clustering behavior for events occurred at shallow depths (down to 12.5 meters from the ground) as well as for events occurring at larger depths (from 15 meters down to 27 meters) does not depend on the ordering of the interevent times but mainly on the shape of the probability density functions of the intravent intervals as mentioned in this paper.
References
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Journal ArticleDOI
An Introduction to Fourier Analysis and Generalized Functions.
R. A. Kunze,M. J. Lighthill +1 more
TL;DR: The theory of generalised functions and their Fourier transforms is discussed in this paper. But the analysis of Fourier transform is limited to the case of generalized functions, and it is not suitable for generalised function analysis.
Journal ArticleDOI
Some aspects of the theory and measurement of frequency fluctuations in frequency standards
Leonard S. Cutler,C. L. Searle +1 more
TL;DR: In this article, the effects of finite observation time on the frequency and phase stability of a servo-controlled oscillator with respect to a given quartz oscillator and an atomic reference are analyzed.
Journal ArticleDOI
Atomic timekeeping and the statistics of precision signal generators
TL;DR: In this paper, a detailed analysis of the calibration procedure showed that the third finite difference of the phase is closely related to the clock errors and that quartz crystal oscillators exhibit a "flicker" or |ω|-1type of noise modulating the frequency of the oscillator.
Atomic timekeeping and the statistics of precision signal generators
TL;DR: The method of finite differences of the phase is shown to be a powerful means of classifying the statistical fluctuations of thephase and frequency for signal generators in general and by employing finite differences it is possible to avoid divergences normally associated with flicker noise spectra.
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