2012 European Frequency and Time Forum最新文献

{"title":"Microwave frequency transfer with optical stabilisation","authors":"S. Schediwy, A. Luiten, G. Aben, K. Baldwin, Yabai He, B. Orr, B. Warrington","doi":"10.1109/EFTF.2012.6502369","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502369","url":null,"abstract":"In this paper we present a novel frequency dissemination technique which uses an all-optical interferometer to sense length fluctuations with high precision, and then utilises this information to simultaneously stabilise a transmitted optical and signal and a microwave signal.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"47 1","pages":"211-213"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80794777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cramer-Rao-Bounds for cross-spectrum measurements of oscillator phase noise","authors":"Michaela Nebel, B. Lankl","doi":"10.1109/EFTF.2012.6502377","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502377","url":null,"abstract":"The cross-spectrum method is one of the best ways to measure the phase noise of an oscillator. Basically, the phase noise of a device-under-test oscillator is measured using two identical measurement circuits each with a reference oscillator which are synchronized by a phase-locked loop. In this paper, the exact Cramer-Rao-Bounds for the estimation of the oscillator phase noise power spectral density are given and efficient estimators are determined using the maximum-likelihood approach. Furthermore, our measurement system is presented where we discuss crucial points in the practical implementation. Finally, several measured results are shown where we also present a possibility to use an a-priori measurement of the system's background noise to improve the measurement precision or to reduce the measurement time.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"35 1","pages":"253-259"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82213229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of OP TWSTFT stations in colocation based on combined use of code and carrier phase data","authors":"A. Kanj, J. Achkar, D. Rovera","doi":"10.1109/EFTF.2012.6502428","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502428","url":null,"abstract":"The TWSTFT carrier phase technique permits to improve the short term stability of the two-way links. The basic idea of this method is to calculate the offset between the frequencies of the two remote clocks in comparison. The frequency of the local oscillator on-board and Doppler coefficients are also determined. By applying the carrier phase method using the two OP ground stations in a common clock mode, a frequency stability of 1×10−12 is reached at 1 s while with the OP satellite simulator, a value of 4×10−13 is achieved.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"1 1","pages":"477-482"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89509802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of an optical reference cavity with flexible thermal expansion tuning properties","authors":"Yingxin Luo, Jie Zhang, Bing Ouyang, Ke Deng, Zehuang Lu, Jun Luo","doi":"10.1109/EFTF.2012.6502363","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502363","url":null,"abstract":"An ultra-stable optical cavity is designed as the frequency reference of a clock laser for an Al+ optical clock by finite element analysis (FEA). The cavity has a structure with fused silica (FS) mirrors contacted to FS rings and re-entrant inside the ULE spacer. This design yields a low thermal noise limit and a flexible tuning range of the total coefficient of thermal expansion (CTE) which is suitable for applications with ULE materials that have various zero-crossing temperatures of CTE from 5 °C to 35 °C, and for applications for cavities with various dimensions and configurations.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"362 1","pages":"182-185"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74156829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a Kalman filter based GPS satellite clock time-offset prediction algorithm","authors":"John Davis, S. Bhattarai, M. Ziebart","doi":"10.1109/EFTF.2012.6502355","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502355","url":null,"abstract":"An enhanced deterministic model along with a stochastic model for describing clock noise is used to compute predictions of the time-offset of individual GPS satellites from the IGS rapid timescale. These are determined with significantly lower prediction uncertainties than may currently be obtained using the IGS ultra-rapid predictions. At prediction length of one day IGS prediction errors are commonly of the order of several ns for all GPS satellite clocks. In comparison the new techniques offers to limit prediction errors at the order of 1 ns for prediction lengths of one day in the newer generation Block IIR and IIF satellites. The factors contributing to the uncertainties in the IGS predictions are discussed. The application of a Kalman filter based prediction algorithm is shown to produce close to optimal predictions.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"49 1","pages":"152-156"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90924655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The space optical clocks project: Development of high-performance transportable and breadboard optical clocks and advanced subsystems","authors":"S. Schiller, A. Görlitz, A. Nevsky, S. Alighanbari, S. Vasilyev, C. Abou-Jaoudeh, G. Mura, T. Franzen, U. Sterr, S. Falke, C. Lisdat, E. Rasel, A. Kulosa, S. Bize, J. Lodewyck, G. Tino, N. Poli, M. Schioppo, K. Bongs, Y. Singh, P. Gill, G. Barwood, Yuri B. Ovchinnikov, J. Stuhler, W. Kaenders, C. Braxmaier, R. Holzwarth, A. Donati, S. Lecomte, D. Calonico, F. Levi","doi":"10.1109/EFTF.2012.6502414","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502414","url":null,"abstract":"The use of ultra-precise optical clocks in space (“master clocks”) will allow for a range of new applications in the fields of fundamental physics (tests of Einstein's theory of General Relativity, time and frequency metrology by means of the comparison of distant terrestrial clocks), geophysics (mapping of the gravitational potential of Earth), and astronomy (providing local oscillators for radio ranging and interferometry in space). Within the ELIPS-3 program of ESA, the “Space Optical Clocks” (SOC) project aims to install and to operate an optical lattice clock on the ISS towards the end of this decade, as a natural follow-on to the ACES mission, improving its performance by at least one order of magnitude. The payload is planned to include an optical lattice clock, as well as a frequency comb, a microwave link, and an optical link for comparisons of the ISS clock with ground clocks located in several countries and continents. Undertaking a necessary step towards optical clocks in space, the EU-FP7-SPACE-2010-1 project no. 263500 (SOC2) (2011–2015) aims at two “engineering confidence“, accurate transportable lattice optical clock demonstrators having relative frequency instability below 1×10−15 at 1 s integration time and relative inaccuracy below 5×10−17. This goal performance is about 2 and 1 orders better in instability and inaccuracy, respectively, than today's best transportable clocks. The devices will be based on trapped neutral ytterbium and strontium atoms. One device will be a breadboard. The two systems will be validated in laboratory environments and their performance will be established by comparison with laboratory optical clocks and primary frequency standards. In order to achieve the goals, SOC2 will develop the necessary laser systems - adapted in terms of power, linewidth, frequency stability, long-term reliability, and accuracy. Novel solutions with reduced space, power and mass requirements will be implemented. Some of the laser systems will be developed towards particularly high compactness and robustness levels. Also, the project will validate crucial laser components in relevant environments. In this paper we present the project and the results achieved during the first year.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"28 1","pages":"412-418"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87264849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control algorithm of UTC(MIKE)","authors":"K. Kalliomaki, T. Mansten, I. Iisakka, T. Fordell, M. Merimaa","doi":"10.1109/EFTF.2012.6502402","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502402","url":null,"abstract":"The Finnish realization of coordinated universal time, designated UTC(MIKE), is derived from a single active hydrogen maser at the Centre for Metrology and Accreditation (MIKES). The frequency of a hydrogen maser typically drifts with time, leading to an approximately parabolic phase shift. At MIKES, a programmable delay generator is used to negate the phase drift of the maser. An improved control algorithm for the phase compensation has lead to a ten-fold improvement in time stability compared to our previous results. With time-transfer based on precise point positioning, we have been able to keep UTC(MIKE) within ±6 ns of UTC during the past year even though our only link to primary frequency standards is through the CCTF-K001. UTC and Circular T. Moreover, improved predictability has lowered the time deviation (TDEV) of UTC(MIKE) to a level below 500 ps when data from the past 10 months is considered.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"68 1","pages":"365-367"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83870590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of a chip-scale Rb plasma discharge light source: Effects of RF drive frequency and cell impedance","authors":"V. Venkatraman, H. Shea, Y. Petremand, N. D. de Rooij, C. Affolderbach, G. Mileti","doi":"10.1109/EFTF.2012.6502395","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502395","url":null,"abstract":"We report on the performance improvements achieved on our previously demonstrated proof-of-concept chip-scale dielectric barrier discharge (DBD) Rb lamp [1], (1) with change in the plasma regime of operation by changing RF drive frequency and (2) with an improved electrode design, for optical pumping in a chip-scale Double-Resonance (DR) atomic clock. Our realized microfabricated planar DBD Rb lamp now has externally deposited Al electrodes, allowing for efficient power coupling to the discharge volume and was tested at different RF drive frequencies ranging from 2 MHz to 500 MHz. Currently the light source can emit up to 380 µW of optical power on the Rb D2 line depending on input conditions.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"1 1","pages":"332-334"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82943258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optical fiber time and frequency transfer inside urban telecom network in Warsaw - Results of initial tests","authors":"A. Czubla, R. Osmyk, P. Szterk, W. Adamowicz, M. Marszalec, L. Sliwczynski","doi":"10.1109/EFTF.2012.6502404","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502404","url":null,"abstract":"In this paper, the initial results of optical fiber time and frequency transfer at the optical distance up to about 40 km inside urban telecom network have been presented. The applied optical methods have been shortly described. The results of optical measurements have been compared with GPS CV method and specifications of compared clocks. In practice, it was obtained a similar effect if compared clocks were standing very close to each other.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"12 1","pages":"371-374"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81857340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of the motional capacitance of the electric equivalent circuit of quartz-crystal tuning fork using L-shaped bar model with torsion spring and in consideration of electric field distribution","authors":"T. Ishikawa, H. Itoh","doi":"10.1109/EFTF.2012.6502329","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502329","url":null,"abstract":"We derived the motional capacitance of quartz-crystal tuning fork using L-shaped bar model with torsion spring and in consideration of both electric field distribution and the width of electrodes. If the width and the length of electrodes are taken into consideration, the calculated values of motional capacitance of the tuning fork with 100µm in thickness are good agreement with the measured ones under three boundary conditions; free-free bar, clamped-free bar, and L-shaped bar models.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"12 1","pages":"41-48"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74525718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}