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Local oscillator induced degradation of medium-term stability in passive atomic frequency standardsAs the performance of passive atomic frequency standards improves, a new limitation is encountered due to frequency fluctuations in an ancillary local oscillator (L.O.). The effect is due to time variation in the gain of the feedback which compensates L.O. frequency fluctuations. The high performance promised by new microwave and optical trapped ion standards may be severely compromised by this effect. Researchers present an analysis of this performance limitation for the case of sequentially interrogated standards. The time dependence of the sensitivity of the interrogation process to L.O. frequency fluctuations is evaluated for single-pulse and double-pulse Ramsey RF interrogation and for amplitude modulated pulses. The effect of these various time dependencies on performance of the standard is calculated for an L.O. with frequency fluctuations showing a typical 1/f spectral density. A limiting 1/sq. root gamma dependent deviation of frequency fluctuations is calculated as a function of pulse lengths, dead time, and pulse overlap. Researchers also present conceptual and hardware-oriented solutions to this problem which achieve a much more nearly constant sensitivity to L.O. fluctuations. Solutions involve use of double-pulse interrogation; alternate interrogation of multiple traps so that the dead time of one trap can be covered by operation of the other; and the use of double-pulse interrogation for two traps, so that during the time of the RF pulses, the increasing sensitivity of one trap tends to compensate for the decreasing sensitivity of the other. A solution making use of amplified-modulated pulses is also presented which shows nominally zero time variation.
Document ID
19910016484
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Dick, G. John
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Prestage, John D.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Greenhall, Charles A.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Maleki, Lute
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
September 6, 2013
Publication Date
May 1, 1990
Publication Information
Publication: The 22nd Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting
Subject Category
Physics (General)
Accession Number
91N25798
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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