About Quartz Crystal Resonator Noise: Recent Study

The first step, before investigating physical origins of noise in resonators, is to investigate correlations between external measurement parameters and the resonator noise. Tests and measurements are mainly performed on an advanced phase noise measurement system, recently set up. The resonator noise is examined as a function of the sensitivity to the drive level, the temperature operating point and the tuning capacitor.Comment: 20th International Conference on Noise and Fluctuations, Pisa : Italie (2009

Extraction des contours de la texture musculaire animale à l'aide d'algorithmes linéaires et morphologiques

Nous décrivons dans cet article une combinaison d'opérateurs linéaires classiques d'extraction de contour et d'opérateurs morphologiques permettant d'apporter une solution à des problèmes liés à l'acquisition d'images par un processeur de vision. A l'aide de ces algorithmes, implantés sur notre Processeur d'Images Vidéo d'Evaluation, nous avons pu obtenir une binarisation correcte de la trame conjonctive d'une coupe transversale microscopique de muscle sur support photographique vue à travers une caméra vidéo standard

Losses in high quality quartz crystal resonators at cryogenic temperatures

International audienceMeasurement of the mechanical losses of quartz crystal is a topic of interest for communities dealing with the gravitational wave detectors and also the time and frequency domain. About the latter, the authors describe Q-factor measurements of quartz crystal resonators at cryogenic temperatures under 10 K, thanks to a cryocooler-based experimental set-up. A Q-factor of 325 millions at 4 K, on the fifth overtone of the quasilongitudinal mode at 15.9 MHz, has been recorded. As shown, the acoustic wave trapping is suspected to limit the Landau-Rumer regime below 6 K [Landau and Rumer, Phys. Z. Sowjetunion 11, 18 (1937)]

Development of a 10 MHz Oscillator Working with an LGT Crystal Resonator : Preliminary results

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Quartz crystals resonators exhibiting extremaly high Q-factor at cryogenic temperatures

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Recent Investigations on BAW Resonators at Cryogenic Temperatures

International audienceThis work presents the results of investigations on different aspects of cryogenic operation of BAW resonators. For the quartz crystal resonators the losses mechanisms, the temperature sensitivity, the amplitude-frequency effect are described for liquid helium temperatures. The corresponding problems are discussed. To overcome some of these problems, the possible solution of operation at higher modes is considered. Some of these higher modes exhibit outstanding quality factors. The highest (for BAW resonators) quality factor value and quality factor-frequency product are measured for the 11th and 13th overtones respectively. In addition, two LGT resonators have been characterized in a wide temperature range. Finally, some preliminary results on utilization of cryogenic quartz resonators as a part of a frequency stabilization closed loop system are given

Some considerations on acoustic resonator phase noise modeling and recent short-term stability experimental results

International audienceThis paper presents a critical review of different acoustic resonator models exposed in the past, in the light of recent experimental results. Among the few models attempting to explain the 1/f behavior of the quartz crystal resonator, the 1/f quantum noise theory of P. Handel and the thermal boson theory of M. Planat, are recalled. The latest published experimental results are analyzed taking into account these models. In the case of Handel's model, the noise depends on the resonator volume under the electrodes and the unloaded quality factor of the resonator. Handel's model is supposed to give an order of magnitude of the lowest possible noise level, but now some experimental results are under its prediction. An approach using the vibrating volume of the resonator is proposed to renew the lowest noise level estimation and found to be compatible with the latest experimental results

The effect of power-drive level on the calibration of the bridge instrument for the measurement of the quartz stability

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The effect of power-drive level on the calibration of the bridge instrument for the measurement of the quartz stability

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