State of the art—Quartz crystal units and oscillators

Gerber, E.A.; Sykes, R.A.

doi:10.1109/proc.1966.4625

Cited by 36 publications

(2 citation statements)

References 38 publications

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“…In the era of telescopic observations, pendulum clocks served as the standard means of keeping time until the introduction of modern electronics. Quartzcrystal clocks were developed as an outgrowth of radio technology in the 1920s and 1930s [5]. Harold Lyons [6] at the National Bureau of Standards in Washington, D.C. (now the National Institute of Standards and Technology, Gaithersburg, Md.)…”

Section: Clocksmentioning

confidence: 99%

The leap second: its history and possible future

Nelson¹,

McCarthy²,

Malys³

et al. 2001

Metrologia

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This paper reviews the theoretical motivation for the leap second in the context of the historical evolution of time measurement. The periodic insertion of a leap second step into the scale of Coordinated Universal Time (UTC) necessitates frequent changes in complex timekeeping systems and is currently the subject of discussion in working groups of various international scienti c organizations. UTC is an atomic time scale that agrees in rate with International Atomic Time (TAI), but differs by an integral number of seconds, and is the basis of civil time. In contrast, Universal Time (UT1) is an astronomical time scale de ned by the Earth's rotation and is used in celestial navigation. UTC is presently maintained to within 0.9 s of UT1. As the needs of celestial navigation that depend on UT1 can now be met by satellite systems, such as the Global Positioning System (GPS), options for revising the de nition of UTC and the possible role of leap seconds in the future are considered.

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Section: Clocksmentioning

confidence: 99%

The leap second: its history and possible future

Nelson¹,

McCarthy²,

Malys³

et al. 2001

Metrologia

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“…The force-frequency effect in vibrating crystals were first noticed by Bottom for AT-cut and BT-cut quartz crystals [5]. Gerber [6] and Mingins [7] showed that the magnitude of the force-frequency effect is dependent on direction of the applied loads relative to the crystallographic directions of the crystal. Ratajski [8] quantified the force-frequency effect and introduced the force-frequency constant for the circular resonators.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigation of force-frequency effect in crystal resonators

Mohammadi¹

2016

J. vibroeng.

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Piezoelectric resonators are widely applied in frequency control components in electronic devices, digital computers, and telecommunication. The stability of these resonators are affected by force-frequency and temperature-frequency effects. In this paper, a simple laboratory measurement method is introduced for measuring the force-frequency effect in piezoelectric resonators. The method employs the parallel resonance frequency of the resonator. It has been shown that the frequency shift of the parallel resonance frequency is very close to that of series resonance, and can be used instead for similar applications. Accordingly, the frequency shift of an AT-Cut quartz resonator which is subjected to a pair of opposed forces is measured. Also, the frequency shift is calculated by the finite element method. The numerical model and experimental results are in a good accordance. The obtained results can be used for better understanding of the force-frequency effect, its practical measurement to be used in simulation of crystal resonators and sensors behavior. Its industrial application will include design of down-hole sensors with better accuracy and robustness.

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Short-Term Frequency Stability of Precision Oscillators and Frequency Generators

Barber¹

1971

Bell System Technical Journal

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We present in this paper two definitions of short‐term frequency stability: (i) time domain, the expected value of the variance of the fractional frequency fluctuations from nominal frequency, 〈σv2(N, T, τ)〉, in which N is the number of samples, T is the averaging time plus the dead time between samples, and τ is the averaging time; and (ii) frequency domain, the power spectral density of the fractional frequency departure from nominal frequency, Sv(f). We discuss the topics of conversion from the frequency domain to the time domain and conversion among time domain measures. All measurements were made in the time domain, using period counting techniques. An oscillator was offset in frequency by using a specially built quartz crystal unit plated for 10 kHz below the frequency of the other sources. This oscillator was used to obtain the beat frequency required by the period counting approach. Since the use of 〈σv2(2, T, τ)〉 as a measure of short‐term stability has significant advantages over 〈σv2(N, T, τ)〉, the relationship between the two quantities was investigated. For averaging times of one second or less, 〈v2(2, T, τ)〉 and 〈σv2(N, T, τ)〉 were almost equal. The short‐term stability of several quartz crystal oscillators and precision frequency generators was measured. The stability over the shorter averaging times was nearly equal for most of the oscillators. At longer times, the stability of each oscillator was unique. The frequency generators demonstrated similar stability over averaging times of 10 and 100 milliseconds, but were unique elsewhere. The accuracy of all measurements was limited by systematic effects from the environment and the measurement equipment itself.

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State of the art—Quartz crystal units and oscillators

Cited by 36 publications

References 38 publications

The leap second: its history and possible future

The leap second: its history and possible future

Experimental and numerical investigation of force-frequency effect in crystal resonators

Short-Term Frequency Stability of Precision Oscillators and Frequency Generators

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