The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
D.b. Percival - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Frequency Stability: Frequency-domain estimation of Stability measures
Proceedings of the IEEE, 1991Co-Authors: D.b. PercivalAbstract:The author focuses on the Frequency domain approach, which provides a complete characterization of Frequency. The standard characterization of Frequency Stability in the Frequency domain is the spectral density function (SDF). The author describes SDFs that model sampled Frequency Stability data and that are related to the SDFs of the standard characterization. On the basis of standard techniques in spectral analysis, he outlines a systematic way of estimating SDFs typical of Frequency Stability data. The recommended procedure is to check for broadband bias in the periodogram using a sequence of data tapers and, if bias is in evidence, to design an autoregressive prewhitening filter to prewhiten the data. The author considers the relationship between the Allan variance and the SDF and outlines two nonparametric ways of translating Stability measures between the two domains-one based upon pilot analysis and the other upon J. Rutman's bandpass variance (1978). >
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Theo1 confidence intervals [Frequency Stability measurement applications]
Proceedings of the 2004 IEEE International Frequency Control Symposium and Exposition 2004., 1Co-Authors: T.n. Tasset, David A. Howe, D.b. PercivalAbstract:Theoretical variance #1 (Theo1) has been developed at NIST to improve the estimation of long-term Frequency Stability. Its square-root (Theo1-dev) has two significant improvements over the Allan deviation /spl sigma//sub y/(/spl tau/) (Adev) in estimating long-term Frequency Stability, in that: (1) it can evaluate Frequency Stability at averaging times 50% longer than those of Adev; and (2) it can estimate Frequency Stability with greater confidence than any other estimator. We discuss a method for determining the exact confidence intervals of Theo1, particularly useful for small sample sizes, using analytic techniques. The confidence intervals of Theo1 are narrower and less skewed (more symmetric) than confidence intervals based on chi-square.
Mike Barnes - One of the best experts on this subject based on the ideXlab platform.
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The Influence of Network Factors on Frequency Stability
IEEE Transactions on Power Systems, 2020Co-Authors: John Fradley, Robin Preece, Mike BarnesAbstract:Retaining Frequency Stability is becoming increasingly challenging as the power system incorporates more non-synchronous generation. Assessing the Frequency Stability in a system has been predominantly completed by focusing on the quantity of connected synchronous kinetic energy in the system, or inertia . This traditionally was considered a function of generator construction – network factors typically were not considered. The research in this paper investigates how network topology, power flow, droop gain distribution, and inertia distribution all impact Frequency Stability. A generic four-area model has been created that allows discrete system setups. This research has shown that certain topologies lead to a more severe rate of change of Frequency. A key finding is that the Frequency drop is further increased when there is greater power flow into the area that experiences the disturbance. The extent to which the rate of change of Frequency and Frequency drop are influenced differently is emphasized, highlighting the need to procure different services depending on which metric is of primary significance at a specific location.
Fuhua Yang - One of the best experts on this subject based on the ideXlab platform.
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Frequency Stability of 3D Encapsulated VHF MEMS Resonator
2018 IEEE International Frequency Control Symposium (IFCS), 2018Co-Authors: Fengxiang Wang, Quan Yuan, Jinling Yang, Xiao Kan, Zeji Chen, Fuhua YangAbstract:Frequency Stability of 3D encapsulated VHF MEMS resonators with Q-factor of 10000 are systematically studied. A negating capacitive compensation technique was developed to eliminating the parasitic effect caused by the PCB circuits. The long-term Frequency Stability results of the resonance Frequency variation and the noise floor of Allan Deviation were $\pm 1$ ppm and 26 ppb, respectively, which were comparable to these of the typical quartz resonator. The thermal cycling test between −40 °C and 85 °C for both the long-term operation and the temperature cycling were measured and the results show that the resonant Frequency drifts were less than $\pm$ 1.5 ppm, indicating the high Frequency Stability of the encapsulated disk resonator.
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Frequency Stability of RF-MEMS Disk Resonators
IEEE Transactions on Electron Devices, 2015Co-Authors: Quan Yuan, Wei Luo, Hui Zhao, Bohua Peng, Jinling Yang, Fuhua YangAbstract:This paper systematically investigates the Frequency Stability of a radial-contour-mode micromechanical disk resonators with high quality factor ( $Q$ -factor) and high resonance Frequency. Microelectromechanical system (MEMS)-based oscillator prototype consisting of the resonator and off-chip circuit is realized for Frequency reference. The sustaining circuit is designed using impedance matching networks and two op-amp stages with automatic gain control circuit. The oscillator reaches a short-term Frequency Stability of ±1 ppm and a medium-term Frequency Stability of ±5 ppm over industrial temperature range (−40 °C–85 °C), which outperforms some of the best MEMS oscillators. Meanwhile, the phase noise is −95 dBc/Hz at 10 kHz offset and 149-MHz carrier. This paper also presents a simple and effective compensation scheme by combining built-in microoven and bias voltage tuning, which can achieve a Frequency Stability range of 2 ppm at temperature ranges from 20 °C to 100 °C.
V. Stofanik - One of the best experts on this subject based on the ideXlab platform.
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Improvement of short-term Frequency Stability of the Chip Scale Atomic Clock
2016 IEEE International Frequency Control Symposium (IFCS), 2016Co-Authors: Tomas Bagala, Adam Fibich, Peter Kubinec, V. StofanikAbstract:Utilization of the Chip Scale Atomic Clock (CSAC) today gives great potential for wide range of strategic systems requiring superior long-term Frequency Stability. Compared to CSAC, an OCXO has many drawbacks, e.g. it has larger long-term Frequency instabilities (aging rate), longer warm-up time and higher power consumption. On the other hand, the main disadvantage of the CSAC is the higher phase noise. In this paper we describe a method of improvement of the CSAC SA.45s short-term Frequency Stability (phase-noise) using an external OCXO (MTI 230-0827) syntonized to the CSAC. In the low power mode, the CSAC SA.45s consumes less than 20 mW of power; however it operates as simple TCXO and over a full operating temperature range, the Frequency Stability is limited to ±1 ppm. In the last part of the paper we introduce combined low power clock system that can achieve Frequency Stability ±0.01 ppm over a wide temperature range, while consuming similar power.
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Long-term Frequency Stability improvement of OCXO using CSAC
2016 European Frequency and Time Forum (EFTF), 2016Co-Authors: Tomas Bagala, Adam Fibich, V. StofanikAbstract:In this paper we introduce long-term Frequency Stability improvement of Oven Controlled Crystal Oscillator (OCXO) using Chip Scale Atomic Clock (CSAC). Compared to OCXO, the main disadvantage of the CSAC is their higher phase noise; however the CSAC features with better long-term Frequency Stability, much lower power consumption and much faster warm-up.
Ronghua Huan - One of the best experts on this subject based on the ideXlab platform.
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Micromechanical vibration absorber for Frequency Stability improvement of DETF oscillator
Journal of Micromechanics and Microengineering, 2019Co-Authors: Jianshu Du, Jiuhong Wang, Ronghua HuanAbstract:This article explores a novel way to improve the Frequency Stability of micromechanical double-ended tuning fork (DETF) resonators. The aim of this work is to use a non-linear vibration absorber to improve the Frequency Stability of the oscillator. A vibration absorption device is set up on the oscillator to absorb part of the energy of the oscillator. The influence of the vibration absorber on the Frequency Stability is studied. The short-term Frequency Stability of the DETF oscillator can be improved from 378 ppb to 202 ppb by coupling it to a mechanical vibration absorber.
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Frequency Stability of micromechanical beam oscillator under subharmonic synchronization
2017 19th International Conference on Solid-State Sensors Actuators and Microsystems (TRANSDUCERS), 2017Co-Authors: Ronghua Huan, Xueeyong WeiAbstract:Frequency Stability plays a key role in MEMS oscillator's performance. Synchronization phenomenon has been found useful to improve the short term Frequency Stability. However, to our knowledge, the influence of subharmonic synchronization on Frequency Stability hasn't been reported yet. In this work, a micromechanical clamped-clamped beam oscillator is implemented with a piezoresistive sensing closed loop circuit and works in its nonlinear regime. A subharmonic synchronization is observed when it is subject to an external perturbation, and the short term Frequency Stability along with its contributory factors of perturbation intensity and Frequency detuning is studied for the first time. The experimental results show that the oscillation Frequency Stability is found steady in the subharmonic synchronization region and the short term Frequency Stability can be further slightly improved by using a larger perturbation intensity.
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Frequency Stability improvement for piezoresistive micromechanical oscillators via synchronization
AIP Advances, 2017Co-Authors: Ronghua Huan, Xueyong WeiAbstract:Synchronization phenomenon first discovered in Huygens’ clock shows that the rhythms of oscillating objects can be adjusted via an interaction. Here we show that the Frequency Stability of a piezoresistive micromechanical oscillator can be enhanced via synchronization. The micromechanical clamped-clamped beam oscillator is built up using the electrostatic driving and piezoresistive sensing technique and the synchronization phenomenon is observed after coupling it to an external oscillator. An enhancement of Frequency Stability is obtained in the synchronization state. The influences of the synchronizing perturbation intensity and Frequency detuning applied on the oscillator are studied experimentally. A theoretical analysis of phase noise leads to an analytical formula for predicting Allan deviation of the Frequency output of the piezoresistive oscillator, which successfully explains the experimental observations and the mechanism of Frequency Stability enhancement via synchronization.
