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We report on the initial use of Galileo signals in the Time and Frequency Department of Physikalisch-Technische Bundeanstalt (PTB). To this end PTB operated five GNSS receivers capable of receiving Galileo Open Service signals with calibrated signal delays for the two frequencies E1 and E5a.
More observations and measurements have been made of propagation phase and frequency shifts of L-band GNSS signals and carriers and standard frequency signals between 60kHz and 20MHz. Fluctuations have been observed which may or may not be attributable to weather, winds, clouds aircraft, ionospheric states, tides, etc. This paper presents new electromagnetic theory and multipath splitting of short-wave...
This paper presents the distribution system providing the UTC(OP) time and frequency reference signals to the microwave time transfer ground terminal (MWL-GT) of the Atomic Clock Ensemble in Space mission (ACES) at SYRTE. UTC(OP) is generated in the first floor of the building B. The MWL-GT will be installed on the top of the building A inside the campus of Observatoire de Paris, which offers the...
The predictability of atomic clock is generally used to characterize its overall performance. Anomalous clock behaviors lead to greater prediction error in traditional prediction method, such as polynomial fitting predictor and Kalman filter predictor. Our previous work developed random pursuit strategy (RPS) to avoid or minimize above the problem. It was further applied to real data of three Hydrogen...
As we all known, the accuracy of time that provided by navigation systems is about tens of nanoseconds. Some applications, such as the time synchronization between ground stations in VLBI, need several nanoseconds or better accuracy of time. This paper provides a possible way for accurate time transfer via communication satellites. Users with simple receive devices can achieve time equivalent to that...
Based on analysis of existing UTC parameters generating method, a new method for generating UTC parameters is proposed. Only changing the way of generating UTC parameters, the timing precision is improved from the level of tens of nanoseconds to nanoseconds when using the proposed method. And the positioning accuracy is also improved. In the paper, influence of the proposed method on BDS positioning...
This paper introduces the design of a near realtime BDS/GPS time transfer method. A Beidou data communication module is assembled into a time transfer receiver. The clock difference computation procedure is modified and a customized protocol is designed for comparison data exchange. The time difference of zero-baseline common-clock by GPS and BDS is compared. The performance of this method is almost...
The performance analysis of TWOTFT with the two terminal equipments at the two remotes sites has been implemented and one way time transfer through optical fiber has been designed and the performance evaluation, demonstration, and verification experiments in short distance have been realized and its uncertainty has been evaluated as roughly 2.1 ns.
This paper reports on the first demonstration of ultra-fast (thermal time constant, τ ∼80 μs) and high resolution (noise equivalent power, NEP ∼656 pW/Hz1/2) infrared detectors based on high quality factor 50-nm thick aluminum nitride (AlN) piezoelectric resonant nano-plates. For the first time, we show that by employing nanoscale (30 nm) aluminum anchors, both high thermal resistance (Rth ∼9.2×10...
Raman lasers with a frequency difference equal to the hyperfine splitting of ground state have been widely used in quantum precision measurements. In this paper, we report a hybrid Raman lasers system combined with the optical injection and optical phase-lock loop. This design not only offers us the convenience to independently adjust the intensity and polarization of Raman lasers, but also suppress...
MEMS atomic vapor cells have a large variety of applications in atomic devices such as chip-scale atomic clocks (CSACs), atomic magnetometers and atomic gyroscopes. We report here on the successful wafer-level hermetic sealing of such cells by Cu-Cu thermocompression bonding. This innovative method is used as an alternative to anodic bonding and allows to overcome some of its limitations. In particular,...
An all-digital sigma-delta modulator (SDM) based RF synthesizer is presented. A multiplier-less architecture for the implementation of the band-pass SDM loop filter is proposed. Furthermore, this architecture enables the adjustment of the loop filter central frequency by exploiting homodyne up- and down-conversion. The RF synthesizer is comprised of a direct digital synthesizer (DDS) and the proposed...
An InP-based photonic integrated circuit was demonstrated for offset locking an on-chip broadly tunable laser to a heterogeneously integrated optical frequency comb oscillator based on a crystalline whispering gallery mode resonator. Optical tuning within 60nm band is demonstrated. The locked laser has excellent spectral purity, sub-kHz linewidth, and good frequency stability.
This paper describes perturbation analysis of nonlinear signal generation in radio frequency (RF) bulk acoustic wave (BAW) devices. Nonlinear constitutive equations with the h form are used where the electric flux density is an independent variable. In conventional ones with the e form, the electric flux density is a dependent variable. This choice makes generated nonlinear fields satisfy Gauss' law...
We report on Whispering Gallery mode resonators based on fluoride materials, MgF2, BaF2, CaF2 and LiF, under Stimulated Brillouin Scattering (SBS). We have simulated various fluoride material under various disc orientation. We have identified the specific orientation [111] in BaF2 as providing a low longitudinal wave velocity variation over the disc periphery, leading to a narrow line Brillouin frequency...
This work focuses on the fabrication of transparent piezoelectric transducers on glass substrates for ultrasonic actuation. Transparent Lead Titanate Zirconate (PZT) thin films are grown on glass following a sol-gel route and InterDigital Electrodes (IDE) are patterned by photolithography. The electrodes design aims to optimize the volume of active piezoelectric material together with the transparency...
Surface acoustic wave (SAW) devices are currently the most exploited acoustic wave devices for high temperature applications due to their straightforward fabrication (few photolithographic steps) and ability for wireless interrogation. However they have some drawbacks like the destructive agglomeration of their electrodes, leading to low power handling, or their low operating frequencies (MHz range)...
We investigated the thermal management design of microfabricated vapor cells by putting forward three wiring patterns. A theoretical model and a simulated analysis were implemented to optimize heating and temperature-measuring wiring patterns on the cell surface. The optimal pattern is able to maintain heating efficiency, optical transparence and weak additional electromagnetic field to ∼nT level...
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