Pub Date : 2015-04-12DOI: 10.1109/FCS.2015.7138962
Songbai Kang, M. Gharavipour, F. Gruet, C. Affolderbach, G. Mileti
We report on the development of a compact laserpumped Rb clock based on the pulsed optical pumping (POP) technique, in view of future industrial applications. The clock Physics Package (PP) is based on a compact magnetron-type microwave cavity of 45 cm3 volume, and our current clock PP has a volume of only 0.8 liters, including temperature control and magnetic shields. This clock PP is completed by a newlydeveloped frequency-stabilized laser head of 2.5 liters overall volume, with an acoustic optical modulator (AOM) integrated within the laser head for switching the laser output power. Due to the highly uniform magnetic field inside the microwave cavity, Ramsey signals with high contrast of up to 35% and with a linewidth of 160 Hz have been demonstrated. A typical shortterm clock stability of 2.4×10-13τ-1/2 is measured. Thanks to the pulsed operation, the light-shift effect has been considerably suppressed as compared to previously demonstrated continuous-wave (CW) clock operation using the same clock PP, which is expected to enable improved long-term clock stabilities down to the 10-14 level or better.
{"title":"Compact and high-performance Rb clock based on pulsed optical pumping for industrial application","authors":"Songbai Kang, M. Gharavipour, F. Gruet, C. Affolderbach, G. Mileti","doi":"10.1109/FCS.2015.7138962","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138962","url":null,"abstract":"We report on the development of a compact laserpumped Rb clock based on the pulsed optical pumping (POP) technique, in view of future industrial applications. The clock Physics Package (PP) is based on a compact magnetron-type microwave cavity of 45 cm3 volume, and our current clock PP has a volume of only 0.8 liters, including temperature control and magnetic shields. This clock PP is completed by a newlydeveloped frequency-stabilized laser head of 2.5 liters overall volume, with an acoustic optical modulator (AOM) integrated within the laser head for switching the laser output power. Due to the highly uniform magnetic field inside the microwave cavity, Ramsey signals with high contrast of up to 35% and with a linewidth of 160 Hz have been demonstrated. A typical shortterm clock stability of 2.4×10-13τ-1/2 is measured. Thanks to the pulsed operation, the light-shift effect has been considerably suppressed as compared to previously demonstrated continuous-wave (CW) clock operation using the same clock PP, which is expected to enable improved long-term clock stabilities down to the 10-14 level or better.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"38 1","pages":"800-803"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81544035","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138926
Droz Fabien, R. Pascal, Boillat Sebastien, S. Batiste
This paper describes the achieved results of a new space Rubidium Atomic Frequency Standard (named Robust-RAFS) through the description of the internal coefficients influence reduction and the positive consequences in term of clock frequency stability and predictability improvements. Performances achievements during uninterrupted operation of several months demonstrate a monotonic behavior, a stability of 1×10-14 @105 sec. and a drift per day of few 10-14.
{"title":"GNSS RAFS latest improvements","authors":"Droz Fabien, R. Pascal, Boillat Sebastien, S. Batiste","doi":"10.1109/FCS.2015.7138926","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138926","url":null,"abstract":"This paper describes the achieved results of a new space Rubidium Atomic Frequency Standard (named Robust-RAFS) through the description of the internal coefficients influence reduction and the positive consequences in term of clock frequency stability and predictability improvements. Performances achievements during uninterrupted operation of several months demonstrate a monotonic behavior, a stability of 1×10-14 @105 sec. and a drift per day of few 10-14.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"16 8 1","pages":"637-642"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82931743","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138858
B. R. Christensen, S. A. Schaffer, M. R. Henriksen, P. Westergaard, Jun Ye, J. Thomsen
The development of simple and reliable high stability clock lasers is of great importance for future state-of-the-art optical clocks [1]-[5] and for future transportable optical clocks [6], [7]. Further development of clock lasers with better stability has so far been hindered by thermal noise in the reference cavity used for laser stabilization and conventional approaches for improvements may be technically challenging. It has been proposed [8]-[11] to improve the stability and reduce the complexity of state-of-the-art laser frequency stabilization by exploiting cavity QED systems consisting of atoms with a narrow optical transition coupled to a single mode of an optical cavity. The laser stabilization performance of a cavity QED system is affected by a number of system parameters such as the finite temperature of the atoms, the number of involved atoms and the laser power [12]-[14]. However, the dynamics of those elements have not yet been fully explored. Here we present a simple cavity QED system consisting of laser cooled strontium-88 atoms coupled to an optical cavity. We relate measurable quantities to the complex transmission coefficient which relates the input field to the output field. The optimal input power for stabilizing a laser to this system is experimentally determined and the optimal shot-noise-limited linewidth of the system is evaluated to 500 mHz. Furthermore, theoretical shot-noise-limited linewidths of similar cavity QED systems are evaluated for a number of different two electron systems.
{"title":"Laser stabilization on velocity dependent nonlinear dispersion of Sr atoms in an optical cavity","authors":"B. R. Christensen, S. A. Schaffer, M. R. Henriksen, P. Westergaard, Jun Ye, J. Thomsen","doi":"10.1109/FCS.2015.7138858","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138858","url":null,"abstract":"The development of simple and reliable high stability clock lasers is of great importance for future state-of-the-art optical clocks [1]-[5] and for future transportable optical clocks [6], [7]. Further development of clock lasers with better stability has so far been hindered by thermal noise in the reference cavity used for laser stabilization and conventional approaches for improvements may be technically challenging. It has been proposed [8]-[11] to improve the stability and reduce the complexity of state-of-the-art laser frequency stabilization by exploiting cavity QED systems consisting of atoms with a narrow optical transition coupled to a single mode of an optical cavity. The laser stabilization performance of a cavity QED system is affected by a number of system parameters such as the finite temperature of the atoms, the number of involved atoms and the laser power [12]-[14]. However, the dynamics of those elements have not yet been fully explored. Here we present a simple cavity QED system consisting of laser cooled strontium-88 atoms coupled to an optical cavity. We relate measurable quantities to the complex transmission coefficient which relates the input field to the output field. The optimal input power for stabilizing a laser to this system is experimentally determined and the optimal shot-noise-limited linewidth of the system is evaluated to 500 mHz. Furthermore, theoretical shot-noise-limited linewidths of similar cavity QED systems are evaluated for a number of different two electron systems.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"23 1","pages":"357-362"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80632608","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138808
A. Kosykh, K. V. Murasov, A. Lepetaev, S. Zavyalov
In the article the realization of the new circuit of differential VCO without varactors in 250 nm CMOS technology has been described. The tuning of VCO is realized as a circuit changing load of oscillator. The control curve for differential VCO without varactors is presented. The results of comparing of phase noise for circuits differential oscillators based on N-channel and P-channel transistors has been described.
{"title":"A 250nm CMOS low phase noise differential VCO circuit without varactors","authors":"A. Kosykh, K. V. Murasov, A. Lepetaev, S. Zavyalov","doi":"10.1109/FCS.2015.7138808","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138808","url":null,"abstract":"In the article the realization of the new circuit of differential VCO without varactors in 250 nm CMOS technology has been described. The tuning of VCO is realized as a circuit changing load of oscillator. The control curve for differential VCO without varactors is presented. The results of comparing of phase noise for circuits differential oscillators based on N-channel and P-channel transistors has been described.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"215 1","pages":"136-138"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79592751","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138880
Charis Basetas, A. Kanteres, P. Sotiriadis
This work discusses hardware implementation considerations for a novel Multi-Step Look-Ahead modulation architecture which improves on the stability and dynamic range of conventional Σ-Δ modulators for all-digital frequency synthesis applications. The basic theoretical concepts of the architecture are analyzed and an appropriate general hardware implementation of the required mathematical operations is presented. It is shown that hardware complexity reduction is possible when noise-shaping filters with convenient coefficients are utilized. Moreover, FPGA and IC implementation examples for a specific noise-shaping filter are given, accompanied by power, area and delay estimations.
{"title":"Hardware implementation aspects of Multi-Step Look-Ahead Σ-Δ modulation-like architectures for all-digital frequency synthesis applications","authors":"Charis Basetas, A. Kanteres, P. Sotiriadis","doi":"10.1109/FCS.2015.7138880","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138880","url":null,"abstract":"This work discusses hardware implementation considerations for a novel Multi-Step Look-Ahead modulation architecture which improves on the stability and dynamic range of conventional Σ-Δ modulators for all-digital frequency synthesis applications. The basic theoretical concepts of the architecture are analyzed and an appropriate general hardware implementation of the required mathematical operations is presented. It is shown that hardware complexity reduction is possible when noise-shaping filters with convenient coefficients are utilized. Moreover, FPGA and IC implementation examples for a specific noise-shaping filter are given, accompanied by power, area and delay estimations.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"21 3","pages":"452-455"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/FCS.2015.7138880","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72463417","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138900
J. Humphries, M. Gallagher, D. Gallagher, A. Weeks, D. Malocha
The universal software radio peripheral (USRP) is a versatile software defined radio (SDR) platform, developed by Ettus Research™, which is intended for a wide variety of applications ranging from communication links to RADAR. We have investigated another application of the USRP by implementing a transceiver capable of interrogating passive, wireless surface acoustic wave (SAW) sensors centered at 915MHz. Interrogation of wideband orthogonal frequency coded (OFC) SAW sensors imposes strict requirements on the timing and synchronization of the transceiver. In the standard mode of operation, samples are generated and streamed between the USRP and host computer, introducing latency and bandwidth limitations due to the sampling bus. To achieve the performance required for this application, the USRP FPGA has been modified to introduce new functionality. Extraction of the sensor temperature is accomplished with a custom matched filter correlator. The system is capable of interrogating multiple sensors and can quickly reconfigure the USRP. Demonstration of the USRP wireless sensor system is achieved by interrogating wireless SAW OFC sensors at 915MHz and extracting the sensor temperature.
{"title":"Interrogation of orthogonal frequency coded SAW sensors using the USRP","authors":"J. Humphries, M. Gallagher, D. Gallagher, A. Weeks, D. Malocha","doi":"10.1109/FCS.2015.7138900","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138900","url":null,"abstract":"The universal software radio peripheral (USRP) is a versatile software defined radio (SDR) platform, developed by Ettus Research™, which is intended for a wide variety of applications ranging from communication links to RADAR. We have investigated another application of the USRP by implementing a transceiver capable of interrogating passive, wireless surface acoustic wave (SAW) sensors centered at 915MHz. Interrogation of wideband orthogonal frequency coded (OFC) SAW sensors imposes strict requirements on the timing and synchronization of the transceiver. In the standard mode of operation, samples are generated and streamed between the USRP and host computer, introducing latency and bandwidth limitations due to the sampling bus. To achieve the performance required for this application, the USRP FPGA has been modified to introduce new functionality. Extraction of the sensor temperature is accomplished with a custom matched filter correlator. The system is capable of interrogating multiple sensors and can quickly reconfigure the USRP. Demonstration of the USRP wireless sensor system is achieved by interrogating wireless SAW OFC sensors at 915MHz and extracting the sensor temperature.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"34 8","pages":"530-535"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/FCS.2015.7138900","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72475996","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138930
P. Defraigne, J. Sleewaegen
Precise Point Positioning (PPP) is a zero-difference single-station technique that has proved to be very effective for time and frequency transfer, enabling the comparison of atomic clocks with a precision of a hundred picoseconds and a one day stability below the 1e-15 level. It was however noted that for some receivers, a frequency difference is observed between the clock solution based on the code measurements and the clock solution based on the carrier phase measurements. These observations reveal some inconsistency between the code and carrier phases measured by the receiver. One explanation of this discrepancy is the time offset that can exist for some receivers between the code and carrier phase latching. This paper explains how a code-phase bias in the receiver hardware can induce a frequency difference between the code and the carrier phase clock solutions. The impact on PPP is then quantified. Finally, the possibility to determine this code-phase bias in the PPP modeling is investigated, and the first results are presented.
{"title":"Correction for code-phase clock bias in PPP","authors":"P. Defraigne, J. Sleewaegen","doi":"10.1109/FCS.2015.7138930","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138930","url":null,"abstract":"Precise Point Positioning (PPP) is a zero-difference single-station technique that has proved to be very effective for time and frequency transfer, enabling the comparison of atomic clocks with a precision of a hundred picoseconds and a one day stability below the 1e-15 level. It was however noted that for some receivers, a frequency difference is observed between the clock solution based on the code measurements and the clock solution based on the carrier phase measurements. These observations reveal some inconsistency between the code and carrier phases measured by the receiver. One explanation of this discrepancy is the time offset that can exist for some receivers between the code and carrier phase latching. This paper explains how a code-phase bias in the receiver hardware can induce a frequency difference between the code and the carrier phase clock solutions. The impact on PPP is then quantified. Finally, the possibility to determine this code-phase bias in the PPP modeling is investigated, and the first results are presented.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"17 1","pages":"662-666"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74622518","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138792
U. Rohde, A. Poddar, E. Rubiola, M. Silaghi
This paper describes oscillator noise measurement techniques, challenges and associated measurement uncertainty. The cross-correlation method used in modern PN measurement equipments, can present erroneous result, depending upon phase-inversion, harmonics, o/p load mismatch, and cable length. This discussion is imperative for low phase noise signal sources, validated with 2.4 GHz SAW oscillator, and discussed steps for mitigating these issues by using filtering/phase-matching N/W.
{"title":"Frequency signal source's PN (phase noise) measurements: Challenges and uncertainty","authors":"U. Rohde, A. Poddar, E. Rubiola, M. Silaghi","doi":"10.1109/FCS.2015.7138792","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138792","url":null,"abstract":"This paper describes oscillator noise measurement techniques, challenges and associated measurement uncertainty. The cross-correlation method used in modern PN measurement equipments, can present erroneous result, depending upon phase-inversion, harmonics, o/p load mismatch, and cable length. This discussion is imperative for low phase noise signal sources, validated with 2.4 GHz SAW oscillator, and discussed steps for mitigating these issues by using filtering/phase-matching N/W.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"54 1","pages":"62-67"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75063771","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138914
Meifang Wu, Pei Wei, Xuhai Yang, Shou-gang Zhang
This paper aims to research and determine GEO satellite clock bias during maneuvering. By analyzing of GEO satellite clock bias data, quadratic polynomials, cubic spline and Lagrange are chose as interpolation methods. The result of the test in this paper shows that in most cases, cubic spline interpolation is the best one of the three interpolation methods. And the accuracy of cubic spline interpolation is at the level of 0.08ns~0.38ns which can meet the actual demand; besides the stability of cubic spline interpolation is obviously better than that of quadratic polynomials and Lagrange interpolations.
{"title":"The method of determination of GEO satellite precise clock bias during maneuvering","authors":"Meifang Wu, Pei Wei, Xuhai Yang, Shou-gang Zhang","doi":"10.1109/FCS.2015.7138914","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138914","url":null,"abstract":"This paper aims to research and determine GEO satellite clock bias during maneuvering. By analyzing of GEO satellite clock bias data, quadratic polynomials, cubic spline and Lagrange are chose as interpolation methods. The result of the test in this paper shows that in most cases, cubic spline interpolation is the best one of the three interpolation methods. And the accuracy of cubic spline interpolation is at the level of 0.08ns~0.38ns which can meet the actual demand; besides the stability of cubic spline interpolation is obviously better than that of quadratic polynomials and Lagrange interpolations.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"10 1","pages":"591-593"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79945146","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}
The capability of one-way time service as an important index of satellite navigation system reflects the ability that a satellite navigation system broadcasts the system time to the clients. In this paper, the performance evaluation method of BD one-way time service is designed standing in the clients' position. The UTC(NTSC)-BDT result via Space signal reception method is obtained in NTSC, the performance of BDT is evaluated reference to UTC (NTSC). The results of BD CV is chose as the reference to evaluate the precision of BD one-way time service. Calculating the root mean square error of residual, The uncertainty of one-way time service is 3.01 ns, the result shows that the precision of BD one-way time service have higher level.
{"title":"The performance evaluation of the BD one-way time service","authors":"Wei Li, Jihai Zhang, Wei Guang, Yongliang Xu, Zhe Gao, Yajing Wei","doi":"10.1109/FCS.2015.7138831","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138831","url":null,"abstract":"The capability of one-way time service as an important index of satellite navigation system reflects the ability that a satellite navigation system broadcasts the system time to the clients. In this paper, the performance evaluation method of BD one-way time service is designed standing in the clients' position. The UTC(NTSC)-BDT result via Space signal reception method is obtained in NTSC, the performance of BDT is evaluated reference to UTC (NTSC). The results of BD CV is chose as the reference to evaluate the precision of BD one-way time service. Calculating the root mean square error of residual, The uncertainty of one-way time service is 3.01 ns, the result shows that the precision of BD one-way time service have higher level.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"81 1","pages":"236-238"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90579553","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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