Articoli di riviste: "Time and frequency transfer"

1

Jaekel, Marc-Thierry, e Serge Reynaud. "Time-Frequency Transfer with Quantum Fields". Physical Review Letters 76, n. 14 (1 aprile 1996): 2407–11. http://dx.doi.org/10.1103/physrevlett.76.2407.

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Huang, Min-Chih, e Cheng-Han Tsai. "Pressure transfer function in time and time-frequency domains". Ocean Engineering 35, n. 11-12 (agosto 2008): 1203–10. http://dx.doi.org/10.1016/j.oceaneng.2008.04.005.

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Bourgoin, A., M. Zannoni, L. Gomez Casajus, P. Tortora e P. Teyssandier. "Relativistic modeling of atmospheric occultations with time transfer functions". Astronomy & Astrophysics 648 (aprile 2021): A46. http://dx.doi.org/10.1051/0004-6361/202040269.

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Context. Occultation experiments represent unique opportunities to remotely probe the physical properties of atmospheres. The data processing involved in modeling the time and frequency transfers of an electromagnetic signal requires that refractivity be properly accounted for. On theoretical grounds, little work has been done concerning the elaboration of a covariant approach for modeling occultation data. Aims. We present an original method allowing fully analytical expressions to be derived up to the appropriate order for the covariant description of time and frequency transfers during an atmospheric occultation experiment. Methods. We make use of two independent powerful relativistic theoretical tools, namely the optical metric and the time transfer functions formalism. The former allows us to consider refractivity as spacetime curvature while the latter is used to determine the time and frequency transfers occurring in a curved spacetime. Results. We provide the integral form of the time transfer function up to any post-Minkowskian order. The discussion focuses on the stationary optical metric describing an occultation by a steadily rotating and spherically symmetric atmosphere. Explicit analytical expressions for the time and frequency transfers are provided at the first post-Minkowskian order and their accuracy is assessed by comparing them to results of a numerical integration of the equations for optical rays. Conclusions. The method accurately describes vertical temperature gradients and properly accounts for the light-dragging effect due to the motion of the optical medium. It can be pushed further in order to derive the explicit form of the time transfer function at higher order and beyond the spherical symmetry assumption.

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Raupach, Sebastian M. F., e Gesine Grosche. "Chirped frequency transfer: a tool for synchronization and time transfer". IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 61, n. 6 (giugno 2014): 920–29. http://dx.doi.org/10.1109/tuffc.2014.2988.

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Skoda, Pavel, e Emilie Camisard. "Time and frequency transfer over optical networks". Proceedings of the Asia-Pacific Advanced Network 35 (10 giugno 2013): 20. http://dx.doi.org/10.7125/apan.35.3.

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Śliwczyński, Łukasz, Przemysław Krehlik e Marcin Lipiński. "Optical fibers in time and frequency transfer". Measurement Science and Technology 21, n. 7 (20 maggio 2010): 075302. http://dx.doi.org/10.1088/0957-0233/21/7/075302.

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Rickard, Mark A., Andrei V. Pakoulev, Nathan A. Mathew, Kathryn M. Kornau e John C. Wright. "Frequency- and Time-Resolved Coherence Transfer Spectroscopy". Journal of Physical Chemistry A 111, n. 7 (febbraio 2007): 1163–66. http://dx.doi.org/10.1021/jp0677804.

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Zhang, Zhehao, e Lin Pan. "Galileo Time Transfer with Five-Frequency Uncombined PPP: A Posteriori Weighting, Inter-Frequency Bias, Precise Products and Multi-Frequency Contribution". Remote Sensing 14, n. 11 (26 maggio 2022): 2538. http://dx.doi.org/10.3390/rs14112538.

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Galileo satellites can broadcast signals on five frequencies, namely E1, E5A, E5B, E5 (A+B), and E6. The multi-frequency integration has become an emerging trend in Global Navigation Satellite System (GNSS) data processing. This study focused on the precise time transfer based on Galileo five-frequency uncombined precise point positioning (PPP), including the performance comparison of PPP time transfer with a priori and a posteriori weighting strategies, with different inter-frequency bias (IFB) dynamic models, and with the precise satellite products from different analysis centers, as well as the contribution of multi-frequency observations for time transfer. Compared with the a priori weighting strategy, the short-term frequency stability of time transfer adopting the Helmert variance component estimation method can be improved by 28.9–37.6% when the average time is shorter than 100 s. The effect of IFB dynamic models on Galileo five-frequency PPP time transfer is not obvious. When employing the post-processed precise satellite products from seven analysis centers, the accuracy of time transfer can be better than 0.1 ns, while an accuracy of 0.253 ns can be obtained in the real-time mode. At an average time of approximately 10,000 s, the post-processed time transfer with Galileo five-frequency PPP can provide a frequency stability of 3.283 × 10−14 to 3.459 × 10−14, while that in real-time mode can be 3.541 × 10−14. Compared with dual-frequency PPP results, the contribution of multi-frequency combination to the accuracy and frequency stability of time transfer is not significant, but multi-frequency PPP can achieve more reliable time transfer results when the signal quality is poor.

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Ge, Yulong, Xinyun Cao, Fei Shen, Xuhai Yang e Shengli Wang. "BDS-3/Galileo Time and Frequency Transfer with Quad-Frequency Precise Point Positioning". Remote Sensing 13, n. 14 (9 luglio 2021): 2704. http://dx.doi.org/10.3390/rs13142704.

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In this work, quad-frequency precise point positioning (PPP) time and frequency transfer methods using Galileo E1/E5a/E5b/E5 and BDS-3 B1I/B3I/B1C/B2a observations were proposed with corresponding mathematical models. In addition, the traditional dual-frequency (BDS-3 B1I/B3I and Galileo E1/E5a) ionospheric-free (IF) model was also described and tested for comparison. To assess the proposed method for time transfer, datasets selected from timing labs were utilized and tested. Moreover, the number of Galileo or BDS-3 satellites, pseudorange residuals, positioning accuracy and tropospheric delay at receiver end were all analyzed. The results showed that the proposed quad-frequency BDS-3 or Galileo PPP models could be used to time transfer, due to stability and accuracy identical to that of dual-frequency IF model. Furthermore, the quad-frequency models can provide potential for enhancing the reliability and redundancy compared to the dual-frequency time transfer method.

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Levine, Judah. "A review of time and frequency transfer methods". Metrologia 45, n. 6 (dicembre 2008): S162—S174. http://dx.doi.org/10.1088/0026-1394/45/6/s22.

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Schäfer, W., e T. Feldmann. "Perspectives of Time and Frequency Transfer via Satellite". Journal of Physics: Conference Series 723 (giugno 2016): 012038. http://dx.doi.org/10.1088/1742-6596/723/1/012038.

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Wang, Jia-Lun, Shi-Yu Huang e Chia-Shu Liao. "Time and frequency transfer system using GNSS receiver". Radio Science 49, n. 12 (dicembre 2014): 1171–82. http://dx.doi.org/10.1002/2014rs005460.

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He, Zaimin, Lan Li, Runzhi Zhang, Juan Hou, Gongwei Xiao, Wei Guang, Jihai Zhang e Xiangyi He. "Research on Single-Frequency PPP-B2b Time Transfer". IEEE Instrumentation & Measurement Magazine 26, n. 6 (settembre 2023): 42–47. http://dx.doi.org/10.1109/mim.2023.10217029.

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Zhang, Runzhi, Lan Li, Xueqing Li, Hongjiao Ma, Gongwei Xiao e Jihai Zhang. "Research on Quad-Frequency PPP-B2b Time Transfer". IEEE Instrumentation & Measurement Magazine 27, n. 1 (febbraio 2024): 57–62. http://dx.doi.org/10.1109/mim.2024.10423730.

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Takiguchi, Hiroshi, Yasuhiro Koyama, Ryuichi Ichikawa, Tadahiro Gotoh, Atsutoshi Ishii, Thomas Hobiger e Mizuhiko Hosokawa. "VLBI Measurements for Frequency Transfer". Proceedings of the International Astronomical Union 5, H15 (novembre 2009): 225. http://dx.doi.org/10.1017/s1743921310008926.

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AbstractWe carried out the intercomparison experiments between VLBI, GPS and DMTD to show the VLBI can measure the right time difference. We produced the artificial change using by line stretcher. At the artificial change part, VLBI and DMTD show good agreement, less than 10ps. The quantity and sense of VLBI results match well with DMTD results. Consequently, the geodetic VLBI technique can measure the right time difference.

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Xiao, Xia, Fei Shen, Xiaochun Lu, Pengli Shen e Yulong Ge. "Performance of BDS-2/3, GPS, and Galileo Time Transfer with Real-Time Single-Frequency Precise Point Positioning". Remote Sensing 13, n. 21 (20 ottobre 2021): 4192. http://dx.doi.org/10.3390/rs13214192.

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Single-frequency (SF) receivers are much cheaper than that of dual-frequency (DF). Even though DF precise point positioning (PPP) is nowadays applied in the time community, the cost of equipment is one of the key considerations for time users. Furthermore, the hardware delay calibration of single-frequency devices is simpler than that of dual-frequency devices. In addition, there is no literature to study real-time SF PPP time transfer. In this contribution, the possibility of time transfer using SF PPP was studied. The Un-combined SF PPP was employed for time transfer with ionospheric-constraint using real-time precise products. In this case, 18 multi-GNSS experiment (MGEX) stations and one time lab station were used to study real-time SF PPP time transfer using GPS, Galileo and BDS-2/3 satellites with 20-day. The results suggested that real-time single-frequency PPP can meet time transfer. the standard deviation (STD) of the clock difference obtained from GPS-only, Galileo-only and BDS-2/3 single-frequency PPP are about (0.51, 0.54, 0.91) ns, respectively. The frequency stability of real-time single-frequency PPP can achieve (1E-12, 1E-13, 1E-13) level at short-term and (1E-13, 1E-13, 1E-14) level at long-term, respectively, for BDS-2/3, Galileo-only and GPS-only based.

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Chen Faxi, 陈法喜, 李博 Li Bo e 郭宝龙 Guo Baolong. "基于光纤频率传递的高精度时间传递方法". Acta Optica Sinica 42, n. 15 (2022): 1506002. http://dx.doi.org/10.3788/aos202242.1506002.

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Huang, Wantao, Peng Zhang e Dong Hou. "Multiple-Access Time and Frequency Transfer over Fiber and Free-Space Link Based on Optical Frequency Comb". Applied Sciences 14, n. 20 (17 ottobre 2024): 9477. http://dx.doi.org/10.3390/app14209477.

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We have demonstrated a multiple-access transfer of time and frequency signal over a fiber and free-space link based on an optical frequency comb (OFC). With this transfer technique, two time–frequency signals were disseminated separately from a master site to two slave sites over a 3.9 km fiber and 100 m free-space link for 10,000 s. The timing fluctuations and instabilities of the time and frequency transfer were measured, estimated, and discussed. The experimental results show that the total root-mean-square (RMS) timing fluctuation of the transfer from site A to B is about 119 ps, with a fractional frequency instability on the order of 3.3 × 10−11 at 1 s and 2.8 × 10−14 at 2000 s. The RMS timing fluctuation of the transfer from site A to C is about 59.5 ps, with a fractional frequency instability on the order of 3.0 × 10−11 at 1 s and 2.6 × 10−14 at 2000 s. These results indicate that the multiple-access transfer technique proposed in this paper can provide important support for the application of a large-scale time–frequency synchronization network.

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Jefferts, S. R., M. A. Weiss, J. Levine, S. Dilla, E. W. Bell e T. E. Parker. "Two-way time and frequency transfer using optical fibers". IEEE Transactions on Instrumentation and Measurement 46, n. 2 (aprile 1997): 209–11. http://dx.doi.org/10.1109/19.571814.

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Imaoka, A., e M. Kihara. "Accurate time/frequency transfer method using bidirectional WDM transmission". IEEE Transactions on Instrumentation and Measurement 47, n. 2 (aprile 1998): 537–42. http://dx.doi.org/10.1109/19.744202.

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Imaoka, A., e M. Kihara. "Accurate time/frequency transfer method using bidirectional WDM transmission". Electronics Letters 31, n. 16 (3 agosto 1995): 1361–62. http://dx.doi.org/10.1049/el:19950933.

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Sun Yanguang, 孙延光, 徐敏 Xu Min, 陈亚晴 Chen Yaqing, 吴瑞 Wu Rui, 桂有珍 Gui Youzhen, 程楠 Chen Nan, 应康 Ying Kang, 杨飞 Yang Fei e 蔡海文 Cai Haiwen. "Research Progress on Free-Space Laser Time-Frequency Transfer". Laser & Optoelectronics Progress 57, n. 17 (2020): 170004. http://dx.doi.org/10.3788/lop57.170004.

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Siltanen, Samuel, Tapio Lokki e Lauri Savioja. "Frequency Domain Acoustic Radiance Transfer for Real-Time Auralization". Acta Acustica united with Acustica 95, n. 1 (1 gennaio 2009): 106–17. http://dx.doi.org/10.3813/aaa.918132.

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Kiasaleh, K., e W. C. Lindsey. "Time and frequency transfer between master and slave clocks". IEEE Transactions on Communications 38, n. 10 (1990): 1900–1912. http://dx.doi.org/10.1109/26.61463.

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Lahaye, François, Giancarlo Cerretto e Patrizia Tavella. "GNSS geodetic techniques for time and frequency transfer applications". Advances in Space Research 47, n. 2 (gennaio 2011): 253–64. http://dx.doi.org/10.1016/j.asr.2010.05.032.

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Defraigne, Pascale, e Quentin Baire. "Combining GPS and GLONASS for time and frequency transfer". Advances in Space Research 47, n. 2 (gennaio 2011): 265–75. http://dx.doi.org/10.1016/j.asr.2010.07.003.

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Shi, J. L., C. L. Ho, M. Li e C. S. Liao. "Two-Way Time and Frequency Transfer Using SONET/SDH". International Journal of Modelling and Simulation 22, n. 4 (gennaio 2002): 225–30. http://dx.doi.org/10.1080/02286203.2002.11442243.

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Zhang, Pengfei, Rui Tu, Xiaochun Lu, Yuping Gao e Fan Lihong. "Performance of global positioning system precise time and frequency transfer with integer ambiguity resolution". Measurement Science and Technology 33, n. 4 (10 gennaio 2022): 045005. http://dx.doi.org/10.1088/1361-6501/ac3a30.

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Abstract The Global Positioning System (GPS) carrier-phase technique is a widely used spatial tool for remote precise time and frequency transfer. However, the performance of traditional GPS time and frequency transfer has been limited because the ambiguity parameter is still the float solution. This study focuses on the performance of GPS precise time and frequency transfer with integer ambiguity resolution and discusses the corresponding mathematical model. Fractional-cycle bias (FCB) products were estimated using an ionosphere-free combination. The results show that the satellite wide-lane (WL) FCB products are stable, with a standard deviation (STD) of 0.006 cycles. The narrow-lane (NL) FCB products were estimated over 15 min with a STD of 0.020 cycles. More than 98% of the WL and NL residuals are smaller than 0.25 cycles, which helps to fix the ambiguity into integers during the time and frequency transfer. Subsequently, the performance of time transfers with integer ambiguity resolution at two time links between international laboratories was assessed in real-time and post-processing modes and compared. The results show that fixing the ambiguity into an integer in the real-time mode significantly decreases the convergence time compared with the traditional float approach. The improvement is ∼49.5%. The frequency stability of the fixed solution is notably better than that of the float solution. Improvements of 48.15% and 27.9% were determined for the IENG–USN8 and WAB2–USN8 time links, respectively.

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Liu, Qin, Shenglong Han, Jialiang Wang, Zitong Feng, Wei Chen, Nan Cheng, Youzhen Gui, Haiwen Cai e Shensheng Han. "Simultaneous frequency transfer and time synchronization over a 430 km fiber backbone network using a cascaded system". Chinese Optics Letters 14, n. 7 (2016): 070602. http://dx.doi.org/10.3788/col201614.070602.

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Cheng Nan, 程楠, 陈炜 Chen Wei, 刘琴 Liu Qin, 徐丹 Xu Dan, 杨飞 Yang Fei, 桂有珍 Gui Youzhen e 蔡海文 Cai Haiwen. "Time Synchronization Technique for Joint Time and Frequency Transfer via Optical Fiber". Chinese Journal of Lasers 42, n. 7 (2015): 0705002. http://dx.doi.org/10.3788/cjl201542.0705002.

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Juncheng Guo, 郭俊成, 卢麟 Lin Lu, 吴传信 Chuanxin Wu, 张宝富 Baofu Zhang, 魏恒 Heng Wei e 赵晓宇 Xiaoyu Zhao. "Time Delay Measurement of Optical Fiber Link Using Time-Frequency Joint Transfer". Acta Optica Sinica 39, n. 9 (2019): 0906003. http://dx.doi.org/10.3788/aos201939.0906003.

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Cerretto, Giancarlo, Andrea Perucca, Patrizia Tavella, Álvaro Mozo, Ricardo Píriz e Miguel Romay. "Network time and frequency transfer with GNSS receivers located in time laboratories". IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 57, n. 6 (giugno 2010): 1276–84. http://dx.doi.org/10.1109/tuffc.2010.1548.

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Zhang, Pengfei, Rui Tu, Yuping Gao, Ju Hong, Junqiang Han e Xiaochun Lu. "Comparison of Multi-GNSS Time and Frequency Transfer Performance Using Overlap-Frequency Observations". Remote Sensing 13, n. 16 (7 agosto 2021): 3130. http://dx.doi.org/10.3390/rs13163130.

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The modernized GPS, Galileo, and BeiDou global navigation satellite system (BDS3) offers new potential for time transfer using overlap-frequency (L1/E1/B1, L5/E5a/B2a) observations. To assess the performance of time and frequency transfer with overlap-frequency observations for GPS, Galileo, and BDS3, the mathematical models of single- and dual-frequency using the carrier-phase (CP) technique are discussed and presented. For the single-frequency CP model, the three-day average RMS values of the L5/E5a/B2a clock difference series were 0.218 ns for Galileo and 0.263 ns for BDS3, of which the improvements were 36.2% for Galileo and 43.9% for BDS3 when compared with the L1/E1/B1 solution at BRUX–PTBB. For the hydrogen–cesium time link BRUX–KIRU, the RMS values of the L5/E5a/B2a solution were 0.490 ns for Galileo and 0.608 ns for BDS3, improving Galileo by 6.4% and BDS3 by 12.5% when compared with the L1/E1/B1 solution. For the dual-frequency CP model, the average stability values of the L5/E5a/B2a solution at the BRUX–PTBB time link were 3.54 × 10−12 for GPS, 2.20 × 10−12 for Galileo, and 2.69 × 10−12 for BDS3, of which the improvements were 21.0%, 45.1%, and 52.3%, respectively, when compared with the L1/E1/B1 solution. For the BRUX–KIRU time link, the improvements were 4.2%, 30.5%, and 36.1%, respectively.

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Xu, Wei, Chao Yan e Jian Chen. "Investigation of Precise Single-Frequency Time and Frequency Transfer with Galileo E1/E5a/E5b/E5/E6 Observations". Remote Sensing 14, n. 21 (26 ottobre 2022): 5371. http://dx.doi.org/10.3390/rs14215371.

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With the rapid upgrade of global navigation satellite system (GNSS) single-frequency (SF) receivers and the increasing market demand for low-cost hardware, SF precise point positioning (PPP) technology has been widely applied in the time and frequency field. The five-frequency signals provided by the whole constellation of Galileo bring more opportunities for the application of SF PPP in time and frequency transfer. In this contribution, using Galileo’s multi-frequency observations, three SF PPP time and frequency transfer models, i.e., the un-combined (UC) model, the ionosphere-free-half (IFH) model, and the ionosphere-weighted constraints (IWCs) model are established. SF PPP time and frequency transfer performance with Galileo E1, E5a, E5b, E5, and E6 multi-frequency observations is evaluated using four links (947.7 km to 1331.6 km) with five external high-precision atomic clocks stations. The results show that the time and frequency transfer performance of SF-UC and SF-IWC is better than that of SF-IFH, and the timing accuracy of SF-UC and SF-IWC is similar. SF PPP time and transfer performance with E5, E5a, E5b, and E6 signals is improved compared with traditional E1 signal. Among them, the frequency stability of E5 improves the most (about 58%), and that of E6 improves the least (about 14%). In addition, the difference in frequency stability between SF and double-frequency (DF) PPP decreases gradually with an increase in average time, and the frequency stability difference between SF and DF PPP can reach 2 × 10−16 in 120,000 s, indicating that SF PPP has the potential to achieve DF PPP frequency stability. Considering the possible frequency data loss during actual observation, the cost of the GNSS SF receiver, and the advantages of Galileo multi-frequency observations, SF PPP can also meet the long-time time and frequency transfer requirements, and the SF-IWC model based on Galileo E5 observations is more recommended.

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Li, Changsheng, Wenjie Dong, Libo Ding, He Zhang e Hang Sun. "Transfer Characteristics of the Nonlinear Parity-Time-Symmetric Wireless Power Transfer System at Detuning". Energies 13, n. 19 (5 ottobre 2020): 5175. http://dx.doi.org/10.3390/en13195175.

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The nonlinear parity-time-symmetric wireless power transfer (NPTS-WPT) system is more robust against transfer distance than the traditional WPT system. Current studies mainly focus on the situation in which the transmitter (Tx) and the receiver (Rx) are completely matched. Our study focuses on the transfer characteristics of the NPTS-WPT system under detuning between the Tx and the Rx. First, the mathematical model of the detuned system is established, and then the model is solved using Shengjin’s formula. Then, the exact analytical solutions for the operating frequency, the amplification factor of the operational amplifier (OP Amp) and the transfer efficiency at detuning are obtained. It was noted, for the first time, that even though the Tx and the Rx were completely matched, a frequency jump could occur when the distance between the Tx and Rx coils slowly changed. Our study found that when the degree of detuning of the system changed, the operating frequency of the system could jump. By investigating the amplification factor of the OP Amp, the reason for the frequency jump when the system was detuned was explained. Our study also revealed that detuning did not imply a decreased transfer efficiency, and the over-detuning can improve the transfer efficiency sometimes. Finally, an experimental system was constructed, and the correctness of the theory was validated using the experimental system.

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Barsoum, N. N. "Time Domain Transfer Function of the Induction Motor". Studies in Engineering and Technology 1, n. 2 (22 aprile 2014): 1. http://dx.doi.org/10.11114/set.v1i2.393.

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Small signal stability of electrical machines at frequency domain has been shown by toque coefficients and eigenvalue of motional impedance matrix in state space form. The relation of damping, synchronizing and total synchronizing torque coefficients with the eigenvalue or the roots of the characteristic equation of the perturbed machine shows that the instability occurs at 2 different modes. Static mode represented by real root at over load condition, and dynamic mode represented by complex root at the condition when the total synchronizing coefficient exhibits zero value within the negative range of the damping torque coefficient. However, small signal instability details at time domain are not given in the literatures. This paper discusses with figures the time domain signals of the induction motor perturbation variables under hunting condition, and presents the differences observed between inverse Laplace transform and Fourier transform in time domain response, based on the transform of the transfer function from the frequency domain, The figures demonstrate and confirm the machine small signal stability performance given in frequency domain.

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Jiang, Z., e W. Lewandowski. "Accurate GLONASS Time Transfer for the Generation of the Coordinated Universal Time". International Journal of Navigation and Observation 2012 (25 settembre 2012): 1–14. http://dx.doi.org/10.1155/2012/353961.

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The spatial techniques currently used in accurate time transfer are based on GPS, TWSTFT, and GLONASS. The International Bureau of Weights and Measures (BIPM) is mandated for the generation of Coordinated Universal Time (UTC) which is published monthly in the BIPM Circular T. In 2009, the international Consultative Committee for Time and Frequency (CCTF) recommended the use of multitechniques in time transfer to ensure precision, accuracy, and robustness in UTC. To complement the existing GPS and TWSTFT time links, in November 2009 the first two GLONASS time links were introduced into the UTC worldwide time link network. By November 2011, 6 GLONASS time links are used in the UTC computation. In the frame of the application in the UTC computation, we establish the technical features of GLONASS time transfer: the short- and long-term stabilities, the calibration process, and in particular the impact of the multiple GLONASS frequency biases. We then outline various considerations for future developments, including the uses of P-codes and carrier-phase information.

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Qin Liu, Qin Liu, Wei Chen Wei Chen, Dan Xu Dan Xu, Nan Cheng Nan Cheng, Fei Yang Fei Yang, Youzhen Gui Youzhen Gui, Haiwen Cai Haiwen Cai e and Shensheng Han and Shensheng Han. "Bidirectional erbium-doped fiber amplifiers used in joint frequency and time transfer based on wavelength-division multiplexing technology". Chinese Optics Letters 13, n. 11 (2015): 110601–5. http://dx.doi.org/10.3788/col201513.110601.

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Wang, Pingli, Guangli Wang, Yuping Gao, Hongbing Cai e Na Liu. "Comparison of VLBI and GNSS common view for time transfer". International Journal of Metrology and Quality Engineering 10 (2019): 15. http://dx.doi.org/10.1051/ijmqe/2019014.

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With the rapid development of optical clock, the stability and system uncertainty of optical clocks has reached a 1.0e–18 level. Optical clocks will likely constitute the next generation of time-frequency standards for redefining the SI second. Because time and frequency transfer services that rely on satellite systems are not always reliable and currently available technologies are insufficient for comparing the next generation of frequency standards, high-precision time and transfer techniques are strongly desired. Very Long Baseline Interferometry (VLBI) is one of the space geodetic techniques that measure the arrival time delays between multiple stations utilizing radio signals from distant celestial radio sources. Not only can VLBI obtain the angle position measurement of the radio source with sub-millisecond accuracy and the station coordinate measurement with millimeter accuracy, but also, it can provide high-precision information regarding inter-station atomic clock differences. Therefore, it is theoretically feasible to use the VLBI technology to do the remote time transfer. Because of this characteristic of VLBI technology, VLBI has significant application potential in the field of remote time transfer. To confirm the suitability of VLBI to time-frequency transfer for future practical applications, the results of VLBI and GPS common view time transfer were compared using a Kunming-Urumqi baseline. The performance characteristics of time transfer based on VLBI are then analyzed. Experimental results show that VLBI technology can accurately measure the variation of clock differences between stations as same as the GPS common view time comparison technology. It briefly describes the challenges of future VLBI technology for practical applications of time transfer.

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Xin Sun, Qiming Hou, Zhong Ren, Kun Zhou e Baining Guo. "Radiance Transfer Biclustering for Real-Time All-Frequency Biscale Rendering". IEEE Transactions on Visualization and Computer Graphics 17, n. 1 (gennaio 2011): 64–73. http://dx.doi.org/10.1109/tvcg.2010.58.

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41

Ascarrunz, F. G., S. R. Jefferts e T. E. Parker. "Earth station errors in two-way time and frequency transfer". IEEE Transactions on Instrumentation and Measurement 46, n. 2 (aprile 1997): 205–8. http://dx.doi.org/10.1109/19.571813.

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42

Geršl, J., P. Delva e P. Wolf. "Relativistic corrections for time and frequency transfer in optical fibres". Metrologia 52, n. 4 (17 luglio 2015): 552–64. http://dx.doi.org/10.1088/0026-1394/52/4/552.

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43

Fujieda, M., T. Gotoh, F. Nakagawa, R. Tabuchi, M. Aida e J. Amagai. "Carrier-phase-based two-way satellite time and frequency transfer". IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 59, n. 12 (dicembre 2012): 2625–30. http://dx.doi.org/10.1109/tuffc.2012.2503.

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44

Yoshimura, K., M. Imae, M. Urazuka, T. Morikawa, T. Yoshino, S. Kobayashi e T. Igarashi. "Research activities on time and frequency transfer using space links". Proceedings of the IEEE 74, n. 1 (gennaio 1986): 157–60. http://dx.doi.org/10.1109/proc.1986.13427.

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45

Giorgetta, Fabrizio R., William C. Swann, Laura C. Sinclair, Esther Baumann, Ian Coddington e Nathan R. Newbury. "Optical two-way time and frequency transfer over free space". Nature Photonics 7, n. 6 (28 aprile 2013): 434–38. http://dx.doi.org/10.1038/nphoton.2013.69.

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46

Pireaux, Sophie, Pascale Defraigne, Laurence Wauters, Nicolas Bergeot, Quentin Baire e Carine Bruyninx. "Influence of ionospheric perturbations in GPS time and frequency transfer". Advances in Space Research 45, n. 9 (maggio 2010): 1101–12. http://dx.doi.org/10.1016/j.asr.2009.07.011.

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47

Pireaux, S., P. Defraigne, L. Wauters, N. Bergeot, Q. Baire e C. Bruyninx. "Higher-order ionospheric effects in GPS time and frequency transfer". GPS Solutions 14, n. 3 (16 dicembre 2009): 267–77. http://dx.doi.org/10.1007/s10291-009-0152-1.

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48

Nalcaci, Erhan, Canan Basar-Eroglu e Michael Stadler. "Visual evoked potential interhemispheric transfer time in different frequency bands". Clinical Neurophysiology 110, n. 1 (gennaio 1999): 71–81. http://dx.doi.org/10.1016/s0168-5597(98)00049-5.

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49

Defraigne, Pascale, Nicolas Guyennon e Carine Bruyninx. "GPS Time and Frequency Transfer: PPP and Phase-Only Analysis". International Journal of Navigation and Observation 2008 (8 luglio 2008): 1–7. http://dx.doi.org/10.1155/2008/175468.

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To compute precise point positioning (PPP) and precise time transfer using GPS code and phase measurements, a new software named Atomium was developed by the Royal Observatory of Belgium. Atomium was also adapted to perform a phase-only analysis with the goal to obtain a continuous clock solution which is independent of the GPS codes. In this paper, the analysis strategy used in Atomium is described and the clock solutions obtained through the phase-only approach are compared to the results from the PPP mode. It is shown that the phase-only solution improves the stability of the time link for averaging times smaller than 7 days and that the phase-only solution is very sensitive to the station coordinates used. The method is, however, shown to perform better than the IGS clock solution in case of changes in the GPS receiver hardware delays which affects the code measurements.

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Talaei, Saeid, Xinqun Zhu, Jianchun Li, Yang Yu e Tommy H. T. Chan. "Transfer learning based bridge damage detection: Leveraging time-frequency features". Structures 57 (novembre 2023): 105052. http://dx.doi.org/10.1016/j.istruc.2023.105052.

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