A Digital Servo for Frequency and Time Scale Conversion

Kartaschoff, P.; Brandenberger, H.

doi:10.1109/freq.1966.199643

Cited by 5 publications

(5 citation statements)

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“…This minimum time implies, however, that the frequency fluctuations of the microwave oscillator contribute to the error sigiial only if they occur on a time scale that esceeds twice the modulation period, according to the sampling theorem [23]. Faster fluctuations could give rise to amplification of the error signal and oscillation of the servo system [23]. This limitation emphasizes the necessity for a very frequencystable local oscillator which serves as a "fly wheel" during the cycles of frequency meas1 irement.…”

Section: Freqiiency Control Of Tho L26-g)hz Oscillatormentioning

confidence: 96%

“…Note, that for the generation of the error signal a t least one full modulation period is required. This minimum time implies, however, that the frequency fluctuations of the microwave oscillator contribute to the error sigiial only if they occur on a time scale that esceeds twice the modulation period, according to the sampling theorem [23]. Faster fluctuations could give rise to amplification of the error signal and oscillation of the servo system [23].…”

Section: Freqiiency Control Of Tho L26-g)hz Oscillatormentioning

confidence: 98%

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A 12‐GHz Standard Clock on Trapped Ytterbium Ions

et al. 1991

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Abstract. The ground-state hyperfine transition Amp = 0 of trapped Yb+ ions has been meauiircd BS 12W2812 119.6 (0.4) Hz. The frequency instability of a microwave, controlled by this resonnncc, is rhnracterised by the standard deviation 2 -(r/sec)-l/*, where r i a the time sepnrlttion of probes. The performance of this frequency staiidurd or "clock" esceeds the stability of commercial ce4um rlorks tind still offers mnjor potential for improvement. 'l'imc keeping is based at present on a continuous measurement of the hyperfine splittiiig of the ground state of cesium atoms whose results control a 9.19-GHz oscillator.liemarkably small imprecision of the oscillator frequency -less than 10-l' -has been achieved in this way [l]. It seems, however, that fnrther progress is impeded by fundamental limitations :(i) The line width of the signal is determined by the separation of the two microwave fields in Rainsey's arrangement, whose length cannot esceed a few meters, since otherwise errors from dispersion and temperature effects become intolerable.(ii) Comparison of the microwave phases at the positions of the beamin the separated fields is hardly to achieve a t a higher level of precision.Ions confined in an electromagnetic

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Section: Freqiiency Control Of Tho L26-g)hz Oscillatormentioning

confidence: 96%

Section: Freqiiency Control Of Tho L26-g)hz Oscillatormentioning

confidence: 98%

A 12‐GHz Standard Clock on Trapped Ytterbium Ions

et al. 1991

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“…Time series from atomic clocks are typically represented by the phase deviation (we use bold symbols for stochastic quantities) x(t), or by the normalized frequency deviation y(t) [6]:…”

Section: The Dynamic Allan Variancementioning

confidence: 99%

Identifying Nonstationary Clock Noises in Navigation Systems

Galleani

Tavella

2008

International Journal of Navigation and Observation

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The stability of the atomic clocks on board the satellites of a navigation system should remain constant with time. In reality, there are numerous physical phenomena that make the behavior of the clocks a function of time, and for this reason we have recently introduced the dynamic Allan variance (DAVAR), a measure of the time-varying stability of an atomic clock. In this paper, we discuss the dynamic Allan variance for phase and frequency jumps, two common nonstationarities of atomic clocks. The analysis of both numerical simulations and experimental data proves that the dynamic Allan variance is an effective way of characterizing nonstationary behaviors of atomic clocks.

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“…The reception of signals of the US Global Positioning System (GPS) satellites has become the routine time and frequency comparison method (Lewandowsky and Thomas 1991, Levine 1999. Before this had happened the properties of some primary clocks, of the kind discussed in section 2 and operated in different laboratories at that time, could not be verified (Kartaschoff 1978). In the present context it may be helpful to include a very brief description of GPS to facilitate the understanding of the different uses of the signals.…”

Section: Time and Frequency Comparisons Of Remote Standardsmentioning

confidence: 99%

Frequency standards and frequency measurement

Bauch

Telle

2002

Rep. Prog. Phys.

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Recent years have brought major breakthroughs in the development, operation and mutual comparison of frequency standards in the microwave as well as in the optical frequency domain. Several cold-atom fountains have been developed, using caesium as well as rubidium atoms. Some of them have been compared among each other. Mutual agreement of the order of one part in 10 15 was demonstrated for two caesium fountains operated side by side but also for two operated simultaneously in the US and Germany. Ultra-narrow resonances of optical transition lines were observed using single trapped ions, and a maximum line quality factor in excess of 10 14 was reported. Measurements of frequencies in the optical range of atomic transitions in neutral hydrogen and calcium, as well as in ions of indium, mercury, strontium and ytterbium, were performed. The last-named achievements were to a large extent enabled by the use of Kerr-effect mode-locked Ti:sapphire femtosecond lasers and techniques of broadening the output spectrum of these lasers to an octave-wide comb.This paper reviews the current status in these fields, with similar emphasis on the standards and on the feasibility to transfer the properties of the standards from a local laboratory to a broader community.

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A Digital Servo for Frequency and Time Scale Conversion

Cited by 5 publications

References 0 publications

A 12‐GHz Standard Clock on Trapped Ytterbium Ions

A 12‐GHz Standard Clock on Trapped Ytterbium Ions

Identifying Nonstationary Clock Noises in Navigation Systems

Frequency standards and frequency measurement

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