Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502369
S. Schediwy, A. Luiten, G. Aben, K. Baldwin, Yabai He, B. Orr, B. Warrington
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.
{"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}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502377
Michaela Nebel, B. Lankl
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.
{"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}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502428
A. Kanj, J. Achkar, D. Rovera
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.
{"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}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502363
Yingxin Luo, Jie Zhang, Bing Ouyang, Ke Deng, Zehuang Lu, Jun Luo
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.
{"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}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502355
John Davis, S. Bhattarai, M. Ziebart
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.
{"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}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502329
T. Ishikawa, H. Itoh
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.
{"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}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502392
V. Zholnerov, A. Vershovskiy, Y. Rozhdestvenskiy
A scheme of a satellite slow-beam microwave atomic clock is presented. A modified Zeeman slower is used for longitudinal cooling of the atomic beam, and a combined CPT-Ramsey registration technique with space domain separation is used for the signal registration.
{"title":"Project of a satellite slow beam atomic clock with CPT-Ramsey registration","authors":"V. Zholnerov, A. Vershovskiy, Y. Rozhdestvenskiy","doi":"10.1109/EFTF.2012.6502392","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502392","url":null,"abstract":"A scheme of a satellite slow-beam microwave atomic clock is presented. A modified Zeeman slower is used for longitudinal cooling of the atomic beam, and a combined CPT-Ramsey registration technique with space domain separation is used for the signal registration.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"6 1","pages":"320-322"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75660785","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}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502395
V. Venkatraman, H. Shea, Y. Petremand, N. D. de Rooij, C. Affolderbach, G. Mileti
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.
{"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}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502402
K. Kalliomaki, T. Mansten, I. Iisakka, T. Fordell, M. Merimaa
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.
{"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}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502404
A. Czubla, R. Osmyk, P. Szterk, W. Adamowicz, M. Marszalec, L. Sliwczynski
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.
{"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}
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