Pub Date : 2014-10-02DOI: 10.1109/CPEM.2014.6898563
M. Abgrall, S. Bize, B. Chupin, J. Guéna, P. Laurent, P. Rosenbusch, P. Uhrich, G. Rovera
This paper presents the new method implemented since October 2012 to realize UTC(OP) at LNE-SYRTE, in Observatoire de Paris (OP), France. This time scale is based on a H-Maser steered by the LNE-SYRTE atomic fountains. We describe the algorithm and we discuss the results obtained over almost 2 years of operation. Since the implementation of the new method, the departure of UTC(OP) from UTC remained well below 10 ns.
{"title":"Performances of UTC(OP) based on LNE-SYRTE atomic fountains","authors":"M. Abgrall, S. Bize, B. Chupin, J. Guéna, P. Laurent, P. Rosenbusch, P. Uhrich, G. Rovera","doi":"10.1109/CPEM.2014.6898563","DOIUrl":"https://doi.org/10.1109/CPEM.2014.6898563","url":null,"abstract":"This paper presents the new method implemented since October 2012 to realize UTC(OP) at LNE-SYRTE, in Observatoire de Paris (OP), France. This time scale is based on a H-Maser steered by the LNE-SYRTE atomic fountains. We describe the algorithm and we discuss the results obtained over almost 2 years of operation. Since the implementation of the new method, the departure of UTC(OP) from UTC remained well below 10 ns.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121549081","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 : 2014-06-23DOI: 10.1109/EFTF.2014.7331461
K. Hosaka, H. Inaba, S. Okubo, D. Akamatsu, M. Yasuda, A. Onae, F. Hong
We have evaluated an ultra-stable laser system, which is based on the linewidth transfer method. In this system, a Nd:YAG laser at 1064 nm stabilised to a high finesse Fabry- Pérot etalon is employed as a master laser. Beat signals between the high-speed controllable optical frequency comb locked to the master laser and another ultra-stable laser operated at 1.5 μm are observed to investigate the frequency stability. The frequency stability measured by the fractional Allan deviation is about 2 × 10-15 at 1 s averaging time, which almost coincides with the estimated thermal noise limit on the optical cavity. Furthermore, using the system, the 1S0-3P0 transitions in ytterbium and strontium atoms are observed. We have demonstrated that linewidth transfer technique based on the optical frequency comb combining with the narrow linewidth laser serves as a useful ultra-stable local oscillator for optical clocks.
{"title":"Evaluation of an ultra-stable laser system based on a linewidth transfer method for optical clocks","authors":"K. Hosaka, H. Inaba, S. Okubo, D. Akamatsu, M. Yasuda, A. Onae, F. Hong","doi":"10.1109/EFTF.2014.7331461","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331461","url":null,"abstract":"We have evaluated an ultra-stable laser system, which is based on the linewidth transfer method. In this system, a Nd:YAG laser at 1064 nm stabilised to a high finesse Fabry- Pérot etalon is employed as a master laser. Beat signals between the high-speed controllable optical frequency comb locked to the master laser and another ultra-stable laser operated at 1.5 μm are observed to investigate the frequency stability. The frequency stability measured by the fractional Allan deviation is about 2 × 10-15 at 1 s averaging time, which almost coincides with the estimated thermal noise limit on the optical cavity. Furthermore, using the system, the 1S0-3P0 transitions in ytterbium and strontium atoms are observed. We have demonstrated that linewidth transfer technique based on the optical frequency comb combining with the narrow linewidth laser serves as a useful ultra-stable local oscillator for optical clocks.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115637716","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 : 2014-06-23DOI: 10.1109/EFTF.2014.7331441
Luiz Vicente Gomes Tarelho, Guilherme de Andrade Garcia, A. C. Baratto, Rodolfo Saboia Lima de Souza, Elizabeth Vilcanaupa Raymundo, S. Junqueira
This paper describes the determination of ionospheric and tropospheric effects on satellite communications between Inmetro ground station and GPS constellation satellites This is made with the use of a geodesic receiver to collect data and with post processing softwares for PPP implementations. The satellite communication link is used for time and frequency maintenance of Local Time Scale UTC (INXE) and for key comparison promoted by BIPM. Relative differences in the plasma density of ionosphere and the atmospheric conditions can be inferred from the different delays imposed to the propagating signal and there are some highlighted effect differences during daytime and nighttime signal behavior.
{"title":"Evaluation of environmental effects on GPS signals by submitting rinex files to online PPP software","authors":"Luiz Vicente Gomes Tarelho, Guilherme de Andrade Garcia, A. C. Baratto, Rodolfo Saboia Lima de Souza, Elizabeth Vilcanaupa Raymundo, S. Junqueira","doi":"10.1109/EFTF.2014.7331441","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331441","url":null,"abstract":"This paper describes the determination of ionospheric and tropospheric effects on satellite communications between Inmetro ground station and GPS constellation satellites This is made with the use of a geodesic receiver to collect data and with post processing softwares for PPP implementations. The satellite communication link is used for time and frequency maintenance of Local Time Scale UTC (INXE) and for key comparison promoted by BIPM. Relative differences in the plasma density of ionosphere and the atmospheric conditions can be inferred from the different delays imposed to the propagating signal and there are some highlighted effect differences during daytime and nighttime signal behavior.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117034052","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 : 2014-06-23DOI: 10.1109/EFTF.2014.7331423
Z. Abdallah, A. Rumeau, A. Fernandez, O. Llopis, J. Maxin, G. Pillet, L. Morvan, G. Cibiel
The photodiode impact on the phase noise of an optical link, and particularly its ability to convert the laser amplitude noise into microwave phase noise, is studied and modeled. The model involves a nonlinear RC cell which describes a photogeneration delay which is a function of the optical power. The whole system is then implemented on a microwave CAD software, and the link gain and phase noise performance are computed.
{"title":"Photodiode nonlinear modeling and its impact on optical links phase noise","authors":"Z. Abdallah, A. Rumeau, A. Fernandez, O. Llopis, J. Maxin, G. Pillet, L. Morvan, G. Cibiel","doi":"10.1109/EFTF.2014.7331423","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331423","url":null,"abstract":"The photodiode impact on the phase noise of an optical link, and particularly its ability to convert the laser amplitude noise into microwave phase noise, is studied and modeled. The model involves a nonlinear RC cell which describes a photogeneration delay which is a function of the optical power. The whole system is then implemented on a microwave CAD software, and the link gain and phase noise performance are computed.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129690200","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 : 2014-06-23DOI: 10.1109/EFTF.2014.7331559
Songbai Kang, C. Affolderbach, F. Gruet, M. Gharavipour, C. Calosso, G. Mileti
A compact magnetron-type microwave cavity has previously been developed for a high performance Rb atomic clock based on conventional continuous-wave double-resonance (DR) interrogation. This magnetron-type cavity shows a homogenous microwave field distribution while having a cavity volume of only 35 cm3. So it is interesting for realizing a high performance Rb cell clock based on pulsed optical pumping (POP) technique with a reduced physics package size. In this proceeding we report on the evaluation of pulsed optical pumping with our magnetron-type cavity. Using the pulsed technique and optical detection, high-contrast Ramsey fringes were observed. The central fringe of the Ramsey signal has a linewidth of 160 Hz and contrast of 35%. Under these conditions, the shot-noise limit is estimated at a level around 2×10-14 τ-1/2 which shows the great potential of a POP clock based on the compact magnetron-type cavity. The Rabi oscillation result also indicates an acceptable uniform field distribution inside the cavity for a high-performance POP clock. Some optimizations of pumping and detection power for improving the contrast are also presented.
{"title":"Pulsed optical pumping in a Rb vapor cell using a compact magnetron-type microwave cavity","authors":"Songbai Kang, C. Affolderbach, F. Gruet, M. Gharavipour, C. Calosso, G. Mileti","doi":"10.1109/EFTF.2014.7331559","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331559","url":null,"abstract":"A compact magnetron-type microwave cavity has previously been developed for a high performance Rb atomic clock based on conventional continuous-wave double-resonance (DR) interrogation. This magnetron-type cavity shows a homogenous microwave field distribution while having a cavity volume of only 35 cm3. So it is interesting for realizing a high performance Rb cell clock based on pulsed optical pumping (POP) technique with a reduced physics package size. In this proceeding we report on the evaluation of pulsed optical pumping with our magnetron-type cavity. Using the pulsed technique and optical detection, high-contrast Ramsey fringes were observed. The central fringe of the Ramsey signal has a linewidth of 160 Hz and contrast of 35%. Under these conditions, the shot-noise limit is estimated at a level around 2×10-14 τ-1/2 which shows the great potential of a POP clock based on the compact magnetron-type cavity. The Rabi oscillation result also indicates an acceptable uniform field distribution inside the cavity for a high-performance POP clock. Some optimizations of pumping and detection power for improving the contrast are also presented.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"311 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129050948","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 : 2014-06-23DOI: 10.1109/EFTF.2014.7331447
F. Mirsaitov, E. Safonova, V. Boloznev
The sensor is designed for in-flight aeroengine turbine blade vibration monitoring. The sensor operation and construction are similar to liquid rocket engine flame parameters sensors, which were presented on 20'th European Frequency and Time Forum. Three dimensional (3D) electromagnetic (EM) field structure and its fluctuation depending on regular, vibrating and damaged blade travel states have been researched in quasi-static approximation. Probing frequency varied from 4 to 40 GHz, and range from 28 to 37 GHz was accepted as preferable. Field structure impact on antenna current flow, its vector admittance, and reflectivity have been found out. Furthermore, computational EM simulation by FEKO software tool was applied. Then autodyne frequency response form was found out. During regular turbine rotation radio frequency (RF) spectrum is sampled. Sampling rate F is a multiplication of rotation frequency (hundreds of hertz) to number of blades (approximately one hundred hertz). Estimated samples amplitudes are stipulated by response form and modulated by vibration process.
{"title":"Microwave autodyne vibrosensor in aeroengine diagnostics","authors":"F. Mirsaitov, E. Safonova, V. Boloznev","doi":"10.1109/EFTF.2014.7331447","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331447","url":null,"abstract":"The sensor is designed for in-flight aeroengine turbine blade vibration monitoring. The sensor operation and construction are similar to liquid rocket engine flame parameters sensors, which were presented on 20'th European Frequency and Time Forum. Three dimensional (3D) electromagnetic (EM) field structure and its fluctuation depending on regular, vibrating and damaged blade travel states have been researched in quasi-static approximation. Probing frequency varied from 4 to 40 GHz, and range from 28 to 37 GHz was accepted as preferable. Field structure impact on antenna current flow, its vector admittance, and reflectivity have been found out. Furthermore, computational EM simulation by FEKO software tool was applied. Then autodyne frequency response form was found out. During regular turbine rotation radio frequency (RF) spectrum is sampled. Sampling rate F is a multiplication of rotation frequency (hundreds of hertz) to number of blades (approximately one hundred hertz). Estimated samples amplitudes are stipulated by response form and modulated by vibration process.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123222660","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 : 2014-06-23DOI: 10.1109/EFTF.2014.7331429
T. Laroche, Julien Garcia, E. Courjon, S. Ballandras, W. Daniau
A comprehensive model for computing the electrical response of surface acoustic wave (SAW) devices is proposed in this paper. Based on a mixed-matrix analysis, it allows for the prediction of any SAW device admittance/impedance at any temperature. In that purpose, the temperature dependences of the wave velocity of course but also of the reflexion coefficient, directivity, conductance and capacitance are established using polynomial developments. The interest of this approach is illustrated for SAW devices on directive crystal cuts for which dramatic changes of the SAW parameters versus temperature may occur, such as the (YXlt)/48.5°/26.7° Langasite (LGS) cut. First assessment elements are shown to illustrate the importance of accurately designing SAW devices operating on extended temperature range.
{"title":"A comprehensive model of the electrical response of SAW devices submitted to thermal perturbation","authors":"T. Laroche, Julien Garcia, E. Courjon, S. Ballandras, W. Daniau","doi":"10.1109/EFTF.2014.7331429","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331429","url":null,"abstract":"A comprehensive model for computing the electrical response of surface acoustic wave (SAW) devices is proposed in this paper. Based on a mixed-matrix analysis, it allows for the prediction of any SAW device admittance/impedance at any temperature. In that purpose, the temperature dependences of the wave velocity of course but also of the reflexion coefficient, directivity, conductance and capacitance are established using polynomial developments. The interest of this approach is illustrated for SAW devices on directive crystal cuts for which dramatic changes of the SAW parameters versus temperature may occur, such as the (YXlt)/48.5°/26.7° Langasite (LGS) cut. First assessment elements are shown to illustrate the importance of accurately designing SAW devices operating on extended temperature range.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124164159","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 : 2014-06-23DOI: 10.1109/EFTF.2014.7331463
M. Čížek, R. Smíd, V. Hucl, J. Lazar, O. Cíp
The presented work deals with a novel application of digital signal processing and software-defined radio algorithms for keeping an optical frequency comb in long-term stable operation. We are using a two-stage stabilization scheme. A frequency-locked loop (FLL) pre-stabilizes the offset frequency and steers it into the capture range of a phase-locked loop (PLL) that consequently takes control. Such combination of FLL and PLL together with additional control logics is also able to handle situations when the PLL unexpectedly goes out of lock and so it is capable of keeping the optical frequency comb in a long-time stable operation. The stability of the resulting system was investigated. Allan deviations from data measured during 8 days of operation were computed. The resulting long-term stability of the setup is better than 1.6 × 10-11.
{"title":"Digital system for keeping optical frequency comb in long-term stable operation","authors":"M. Čížek, R. Smíd, V. Hucl, J. Lazar, O. Cíp","doi":"10.1109/EFTF.2014.7331463","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331463","url":null,"abstract":"The presented work deals with a novel application of digital signal processing and software-defined radio algorithms for keeping an optical frequency comb in long-term stable operation. We are using a two-stage stabilization scheme. A frequency-locked loop (FLL) pre-stabilizes the offset frequency and steers it into the capture range of a phase-locked loop (PLL) that consequently takes control. Such combination of FLL and PLL together with additional control logics is also able to handle situations when the PLL unexpectedly goes out of lock and so it is capable of keeping the optical frequency comb in a long-time stable operation. The stability of the resulting system was investigated. Allan deviations from data measured during 8 days of operation were computed. The resulting long-term stability of the setup is better than 1.6 × 10-11.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125607947","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 : 2014-06-23DOI: 10.1109/EFTF.2014.7331422
D. Howe, A. Hati, C. Nelson
We discuss frequency synthesizer needs and recent phase noise results of a multi-level frequency divider that are consistent with the phase noise of new high-accuracy optical atomic standards. Optical atomic standards achieve extremely low frequency uncertainties in less than hundreds of seconds due to their unprecedented phase stability and accuracy. The desire for low white-FM noise that ordinarily required days of averaging for laboratory standards to attain full accuracy has been shifted to a need for low flicker-FM noise to maintain long-term frequency uncertainty with only seconds of averaging. This imposes new requirements for low levels of phase noise realizable by laser stabilization by a hi-Q optical cavity of a phase-coherent optical frequency comb. The multi-level frequency divider serves as a tool for synthesizing many low-phase noise frequencies.
{"title":"Ultra-low phase noise frequency synthesis from optical atomic frequency standards","authors":"D. Howe, A. Hati, C. Nelson","doi":"10.1109/EFTF.2014.7331422","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331422","url":null,"abstract":"We discuss frequency synthesizer needs and recent phase noise results of a multi-level frequency divider that are consistent with the phase noise of new high-accuracy optical atomic standards. Optical atomic standards achieve extremely low frequency uncertainties in less than hundreds of seconds due to their unprecedented phase stability and accuracy. The desire for low white-FM noise that ordinarily required days of averaging for laboratory standards to attain full accuracy has been shifted to a need for low flicker-FM noise to maintain long-term frequency uncertainty with only seconds of averaging. This imposes new requirements for low levels of phase noise realizable by laser stabilization by a hi-Q optical cavity of a phase-coherent optical frequency comb. The multi-level frequency divider serves as a tool for synthesizing many low-phase noise frequencies.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131653259","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 : 2014-06-23DOI: 10.1109/EFTF.2014.7331549
M. Witkowski, S. Bilicki, B. Nagórny, Bartosz Przewiezlikowski, R. Munoz-Rodriguez, P. Żuchowski, R. Ciuryło, M. Zawada
We present an experimental set-up of two species mercury-rubidium magneto-optical trap (MOT). The preliminary studies of interactions in mercury MOT and mercury-rubidium MOT are presented. In bosons with the s2 configuration the clock transition 1S0-3P0 is strictly forbidden. The commonly used method to overcome this problem is to induce a coupling with 3P0 state with a state which is optically accessible. In the mercury-rubidium MOT, the presence of cold Rb atoms might be used to tune the probability of the 1S0-3P0 clock transition in mercury.
{"title":"Experimental set-up for study of collisions of cold mercury atoms for optical frequency clocks","authors":"M. Witkowski, S. Bilicki, B. Nagórny, Bartosz Przewiezlikowski, R. Munoz-Rodriguez, P. Żuchowski, R. Ciuryło, M. Zawada","doi":"10.1109/EFTF.2014.7331549","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331549","url":null,"abstract":"We present an experimental set-up of two species mercury-rubidium magneto-optical trap (MOT). The preliminary studies of interactions in mercury MOT and mercury-rubidium MOT are presented. In bosons with the s2 configuration the clock transition 1S0-3P0 is strictly forbidden. The commonly used method to overcome this problem is to induce a coupling with 3P0 state with a state which is optically accessible. In the mercury-rubidium MOT, the presence of cold Rb atoms might be used to tune the probability of the 1S0-3P0 clock transition in mercury.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130696568","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：