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We tested the performance of metal-semiconductor point-contact diodes as frequency mixers in the near infrared region. We performed preliminary experiments in order to phase-lock two diode laser at 850 nm some hundred GHz apart. We used GaSb, InAs and InSb as semiconductor layer. The frequency bridge between the two lasers was covered by a Gunn diode frequency locked to a 1 GHz SAW oscillator. The...
Fifty years ago next October, the Ve Congrés International de Chronométrie was held in Paris. In its proceeding there is a paper by L. Essen which shows a drawing of a caesium-beam frequency standard then under construction. Measurements in the paper were referred to quartz ring oscillators. The caesium apparatus was still for the future. here I draw comparisons with that time. I also collate new...
This paper develops the effective method of sapphire loaded cavity (SLC) microwave oscillator frequency stabilization proposed two years ago [1]. The method uses the dual-mode temperature frequency control based on two orthogonal “whispering gallery” (WG) modes and differs from similar approaches by applying of output microwave frequency division to form a control signal. The desired resonant spectrum...
Atomic fountain frequency standard have the potential to reach a frequency stability of about 10−14τ−1/2, if the interrogation oscillator frequency noise which degrades the stability via the “Dick effect” ([2, 7]) is made negligible. In this aim a Sapphire Cryogenic Oscillator (SCO) is used as very low noise frequency source σy(τ) ≤ 1 – 2 × 10−15 1 s ≪ τ ≪ 1000 s. In this paper, we describe a low...
The 35kg active Space Hydrogen Maser (SHM-35) developed at the Observatory of Neuchâtel is one core element of the ACES experiment (Atomic Clock Ensemble in Space). ACES is an European experiment on the International Space Station (ISS) comprising the SHM-35 and the cold atom caesium clock PHARAO locked to each other. The resulting ultrastable clock provides an optimised time scale and allows for...
The time scale synchronization algorithms are very important because they provide registering or removal of signal delay in the propagation medium. The algorithm choice influences the technical realization of synchronization system as a whole. Different algorithms result in different transformation of the source errors into measurement errors, as well. The preliminary analysis has shown that there...
Electrodes on the surface of an elastic substrate have important effects on the surface acoustic wave (SAW) propagation, and related changes like wave velocity and mode shapes due to the presence of electrodes should be considered in the analysis so the information available to practical applications can be accurate and adequate. Because the essential characteristics of surface acoustic wave propagation...
Thermoluminescence spectral characteristics of a Ge-doped quartz crystal show the presence of a temperature-glow peak at 200 EC. This peak is not observable in conventionally grown quartz undoped with Ge. Results have been compared and discussed with the near infrared spectral characteristics of natural and conventionally grown quartz crystals.
This paper presents the low-loss natural single phase unidirectional transducer (NSPUDT) SAW filters, which use SAW propagation direction reversal without the reversal of NSPUDT directivity. In this design the input and output NSPUDTs are placed in parallel acoustic tracks. SAW transmission between these tracks and propagation direction reversal are provided by a double reflection from the inclined...
In this paper we report the method used to dissolve the Langasite and Langatate crystals. Then the characterization of chemical impurities like Al, Fe, Na, Li… incorporated in the crystal during the pooling or coming from strating oxides (La2O3, Ga2O3, Ta2O3 and SiO2) is discussed. Finally, the comparison with the quartz crystal material has been done as well in the IR range as in term of chemical...
The paper is devoted to experimental study of non-linearity of HFF crystal units and its influence on the quartz filter intermodulations. On statistical treatment of the measurement data the regression coefficients linking the crystal parameters non-linearity with the intermodulation level have been defined. The origin of the crystal non-linearity was explored through standard fabrication process...
Thin films of ZnO have been grown using sol-gel technique. The precursor materials for sol preparation include zinc acetate or zinc nitrate. Characterization was done using optical absorption, ellipsometry, X-ray diffraction, photoluminescence and scanning electron microscopy.
The general understanding describes the ageing of quartz crystals as a change of the frequency over time for all vibration modes in the same size and direction. In reality, a different ageing behaviour of fundamental mode and overtone modes can be noticed. This effect depends on the blank design and on the electrode design.
We present in this paper the progress report of the building of two cryogenic sapphire oscillators (CSO) at LPMO. A description of our original resonator configuration is discussed. The measurement of a short-term frequency instability better than 2 · 10−14 for short integration times is presented. We also demonstrated an exceptional long term frequency stability of better than 5 · 10−14 over one...
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,...
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...
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.
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,...
The time and frequency reference in the three laboratories of Besançon is based on Cesium clocks for absolute accuracy and long-term stability at the LAOB, on a H-maser for medium and long term stability at the LCEP, and on a liquid-He whispering gallery sapphire oscillator for best spectral purity and short-term stability at LPMO. These standards are located at three different sites, at a few hundreds...
Long-term phase stability of GPS receivers is important in time-keeping applications. MIKES and Nokia Mobile Phones have studied in co-operation the performance of medium price commercial GPS receivers both in the short term and long-term sense. MIKES has run five GPS receivers of two manufacturers for over five years. An automatic measurement system has collected data from those receivers and from...
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