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Passive wireless surface acoustic wave (SAW) sensors are used to measure temperature, pressure and torque, identify the railway vehicle at high speed, etc. with a resolution of about 1%. Most frequently, the information bearer in such sensors is a time delay of the SAW estimated at the receiver. The basic principle utilized in such a technique combines advantages of the precise piezoelectric sensors,...
In the process of designing resonant temperature sensors, getting minimal dimensions is required to decrease calorific capacity and response time. In this view, we investigated new shapes of sensing elements essentially obtained by modifying an initial resonator's design. This design consists in plane parallel circular disk plates in NLC-cut for energy trapping by electrodes mass loading. Then, the...
The scope of this paper is to investigate the motional parameters and the frequency spectrum of small size resonators designed to be used as thermal sensors on a wide range of temperature from ambient down to cryogenic temperatures. Different electrodes configurations are used to trap the vibration.
Gallium phosphate, GaPO4, is a piezoelectric crystal material homeotypic to quartz which features outstanding thermal stability up to 970°C, higher coupling than quartz and good temperature compensation for resonant applications. We report results in the research and development for high-temperature micro balance including thermo gravimetric analysis and for affinity sensor applications in aqueous...
This work is aimed at the study of a potential possibilities of microwave Bulk Acoustic Wave resonators for temperature measurements. The resonators under study had non-standard high overtone BAW resonator configuration: a thin piezoelectric film ZnO with electrodes was deposited onto the surface of the substrate made of the (100) oriented YAG plate with the thickness 480… 980 µm. The new technical...
Techniques are proposed that allow systems that use multiple oscillators to correct the effects of occasional frequency jumps, or of changes in drift rates in any of the oscillators. Existing methods of drift prediction may readily be adapted to suppress drift changes in individual oscillators. In addition, previously unreported jump detection schemes are shown to be capable of suppressing large jumps,...
This paper describes a new method for power law noise identification, based on the lag 1 autocorrelation function, that can determine the dominant noise type for all common noise processes, from phase or frequency data, for all averaging factors, in a consistent and analytic manner.
Theo1 is the first new species of variance that addresses a particularly difficult measurement problem, namely, obtaining reliable estimation of frequency stability for sample periods that are long compared to the length of a data run. Theo1 has statistical properties that are like the Allan variance (Avar), but Theo1 also has two advantages over other estimators of frequency stability: (1) it can...
The dual-mixer time-difference (DMTD) multiplication technique used in frequency stability measurement of precision frequency sources shows potential for achieving a frequency stability measurement floor as low as a few parts in 1015 at 1 s in terms of Allan deviation (ADEV) at 5 MHz at ambient temperature. The paper discusses the optimization of the DMTD multiplier using the frequency stability floor...
The paper describes a new type of instrument for measuring phase and frequency, that was presented for the first time in 2001 [2]. After recalling in the introduction the principles of operation, the paper explains in some detail the component elements and the latest enhanced versions of the instrument, which now allow the comparison of clock signals with sub-picosecond precision.
This paper reports on progress at NPL in extending the range and utility of optical frequency combs. To enable measurements to be made at locations other than our own laboratory, a transportable comb system is being built whilst to extend the spectral range to cover the telecommunications bands we are also building a comb based on a Cr:forsterite laser.
The use of entangled states can provide an increased sensitivity in quantum-limited spectroscopic measurements, leading to an uncertainty that is inversely proportional to the number of particles instead of the usual square-law dependence [1].
Recebt advances concerning two-photon Ramsey fringes in SF6 at 30 THz obtained with a 1m separation between the two interaction zones are presented. The experiment is referenced to a primary standard, the Hydrogen maser / Cs fountain located at BNM-SYRTE, Observatoire de Paris, via a femtosecond laser frequency comb generator. This results in an absolute frequency measurement of the central fringe...
We report on a high stability optical frequency source based on a Nd:YAG laser. A stable local oscillator is an essential component of an optical frequency standard and the techniques acquired through this research will inform the development of wavelength specific standards referenced to atomic absorptions. Light sources with a high degree of coherence are also of interest to the space-science community,...
We have measured the frequencies of the hyperfine components of the transition 4d10 5s 2S1/2 → 4d9 5s22D3/2 in 107Ag and 109Ag, by Doppler-free two-photon laser spectroscopy of a thermal atomic beam and heterodyne calibration with respect to a molecular iodine line near 520THz. We deduce the value of 1 040 706 327 (3) MHz for the centre of gravity of a mixture of natural abundance. For the isotope...
The differential calibrations of GPS Common-View time-receiving equipment have been made for over twenty years. Until recently, TWSTFT calibrations have been rare due to a lack of suitable equipment. Now, the Technical University of Graz is providing such a calibration service, and this paper describes a simultaneous differential calibration of the IEN/PTB time link by GPS CV and TWSTFT. The GPS calibration,...
Using Precise Point Positioning (PPP) we show the potential for comparing frequency standards with time stabilities of under 300 ps in flicker phase noise for time periods of 1 to 10 d. This leads to comparisons at 1 part in 1015 or better at 10 d. We compare short baseline PPP results with 2 hour data from the NIST Measurements System. We compare results from the NIST - USNO baseline with hourly...
There are now four types of navigation satellite available for time and frequency transfer: GPS, GLONASS, WAAS and EGNOS. This paper describes briefly a new time-transfer receiver TTS-3, based on a Javad Legacy plate, which allows observations of these satellites simultaneously in multi-channel, multi-frequency mode. The following codes are used: C/A-code for GPS, WAAS, EGNOS and GLONASS, P-code for...
Most of the GPS links between timing laboratories that contribute to TAI are performed by single channel GPS timing receivers. These are based in the original NBS and JPL designs, and can perform and store 48 tracks per day.
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