Atomic Beam Frequency Standards

Mockler, R. C.; Beehler, R. E.; Charles, Snider,

doi:10.1109/ire-i.1960.5006902

Cited by 36 publications

(11 citation statements)

References 21 publications

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“…Another circuit, based on a series of oscillators whose output frequency was locked to another signal 24 , was discovered later, around 1940, but some of the requirements mentioned above were not fulfilled.…”

Section: Development and Use Of Synthesizersmentioning

confidence: 99%

The definition of the ‘atomic’ second

Leschiutta

2005

Metrologia

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When the reference of a unit is changed, the task remains of expressing the new definition in the terms of the previous one. In two centuries, for instance, the definition of the metre was changed six times. Around 1955, the definitions of the second as the SI unit of time were changed from astronomical ones, based on the rotation (or revolution) of the Earth, to a definition stemming from a quantum phenomenon. The expression of the new atomic second in terms of the previous definitions required a number of actions and measurements. The aim of this paper is to review these actions, some of which, fifty years later, are being forgotten for a lack of adequate documentation.

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Section: Development and Use Of Synthesizersmentioning

confidence: 99%

The definition of the ‘atomic’ second

Leschiutta

2005

Metrologia

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“…Improvements Wf're made at all stages, hy better control of the transmitters, by more careful operation of the atomic standards and by ensuring that the measurements at different laboratories were averaged over the same periods. Caesium beam standards having an accuracy of a few parts in 10 10 were made at the National Physical Laboratory, U.K. , the National Bureau of Standards (Mockler, Beehler & Snider, 1960) and at the Laboratoire Suisse de Recherches Hologeres (Kartaschoff) Bonanomi & de Prins, 1960). An analysis of results obtained during the period July 1961 to December 1962 (Morgan Crow & Blair, 1965) showed that the three precise laboratory standards agreed to ± 1 part in 10 10 and that the agreement between seven different standards including commercial models was ±2 parts in 10 10 • An indication of the accuracy now achieved by using VLF transmissions is indicated in Table 1 which gives the measured values of the frequency of the GBR transmitter at the NPL, the NBS and LSRH for a period of 3 months in 1965.…”

Section: The Intercomparison Of Atomic Clocksmentioning

confidence: 99%

Standard Frequency Transmissions in the United Kingdom

Essen

1966

IETE Journal of Research

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Standard frequency transmissions were first made from the NPL, Enaiand, in 1926 to assist E. V. Appleton in his researches on the ionosphere. Subsequently, they were used mainly for the dissemination of a standard of frequency although they have recently contributed to the study of VLF propaaation. Now that they are controlled by atomic standards, standard frequency transmissions can be used to aive an immediate value of frequency accurate to a few parts in 10 11 in any part of the world.

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“…The frequency reference of the NBS standard frequency broadcasts is the USFS which consists of two cesium beam units [Mockler et al, 1960] …”

Section: Role Of Frequency Standards In Nbs Broadcastsmentioning

confidence: 99%

“…Laboratory models of atomic (cesium-beam) frequency standards were developed and built at NBS and in 1960 two such units became the basis of the USFS [Mockler et al, 1960]; continued improve ments followed [Beehler et al, 1962] WWVB (60 kc/s) broadcasts disseminated the USFS with a transmitted accuracy of several parts in 1011 (fractional frequency units) through control by transfer (working) atomic frequency standards. Regularly published corrections relate such values to the USFS as shown in figure 1.…”

Section: Introductionmentioning

confidence: 99%

Control of WWV and WWVH standard frequency broadcasts by VLF and LF signals

Blair¹,

Morgan²

1965

J. RES. NATL. BUR. STAN. SECT. D. RAD. SCI.

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Since 1961 the NBS VLF and LF signals have improved the calibration and frequency control of th e WWV (Mary land) HF broadcasts. Similarly, better co ntrol of the WWVH (Hawai i) HF broadcasls was achieved in early 1963 by monitoring the NBS VLF broadcasts in terms of the WWVH control oscillator. In mid 1963 WWVL (20 kc/s) and WWVB (60 kc/s) were relocated from two sites near Boulder, Colo., to a single site near Ft. Collins, Colo., and the transmitter power for both broadcasts was increased several fold. These higher powered broadcasts resulted in more precise co ntrol of both HF broadcasts. Through the VLF and LF signals the 24-hr average frequency values ofW WV are related to the United States Frequency Standard (USFS) within a few parts in 10". This paper describes the NBS low-frequency broadcasts, the method of using them to co ntrol and calibrate the HF broadcasts, and gives an analysis of the precision of frequency co ntrol obtained at WWV over a 21-month period. An appendix discusses the short-term phase stabilities and diurnal phase shifts observed in the low-frequency signals at WWV and WWVH, and examines the accuracy· limiting effects of propagation path characteristics and background noise levels in suc h received signals.

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Atomic Beam Frequency Standards

Abstract: 10 An unsymmetrical power spectrum can arise when the carrier is frequency modulated with two or more different frequencies (36).

Cited by 36 publications

References 21 publications

The definition of the ‘atomic’ second

The definition of the ‘atomic’ second

Standard Frequency Transmissions in the United Kingdom

Control of WWV and WWVH standard frequency broadcasts by VLF and LF signals

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