Готові списки джерел за темами / Frequency transfer

Добірка наукової літератури з теми "Frequency transfer"

Автор: Grafiati
Опубліковано: 14 березня 2023

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Статті в журналах з теми "Frequency transfer"

1

Yukun Luo, Yukun Luo, Shuhua Yan Shuhua Yan, Aiai Jia Aiai Jia, Chunhua Wei Chunhua Wei, Zehuan Li Zehuan Li, Enlong Wang Enlong Wang, and and Jun Yang and Jun Yang. "Revisiting the laser frequency locking method using acousto-optic frequency modulation transfer spectroscopy." Chinese Optics Letters 14, no. 12 (2016): 121401–5. http://dx.doi.org/10.3788/col201614.121401.

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2

Sun, Oliver M., and Robert Pinkel. "Energy Transfer from High-Shear, Low-Frequency Internal Waves to High-Frequency Waves near Kaena Ridge, Hawaii." Journal of Physical Oceanography 42, no. 9 (April 11, 2012): 1524–47. http://dx.doi.org/10.1175/jpo-d-11-0117.1.

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Abstract Evidence is presented for the transfer of energy from low-frequency inertial–diurnal internal waves to high-frequency waves in the band between 6 cpd and the buoyancy frequency. This transfer links the most energetic waves in the spectrum, those receiving energy directly from the winds, barotropic tides, and parametric subharmonic instability, with those most directly involved in the breaking process. Transfer estimates are based on month-long records of ocean velocity and temperature obtained continuously over 80–800 m from the research platform (R/P) Floating Instrument Platform (FLIP) in the Hawaii Ocean Mixing Experiment (HOME) Nearfield (2002) and Farfield (2001) experiments, in Hawaiian waters. Triple correlations between low-frequency vertical shears and high-frequency Reynolds stresses, 〈uiw∂Ui/∂z〉, are used to estimate energy transfers. These are supported by bispectral analysis, which show significant energy transfers to pairs of waves with nearly identical frequency. Wavenumber bispectra indicate that the vertical scales of the high-frequency waves are unequal, with one wave of comparable scale to that of the low-frequency parent and the other of much longer scale. The scales of the high-frequency waves contrast with the classical pictures of induced diffusion and elastic scattering interactions and violates the scale-separation assumption of eikonal models of interaction. The possibility that the observed waves are Doppler shifted from intrinsic frequencies near f or N is explored. Peak transfer rates in the Nearfield, an energetic tidal conversion site, are on the order of 2 × 10−7 W kg−1 and are of similar magnitude to estimates of turbulent dissipation that were made near the ridge during HOME. Transfer rates in the Farfield are found to be about half the Nearfield values.
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3

Takiguchi, Hiroshi, Yasuhiro Koyama, Ryuichi Ichikawa, Tadahiro Gotoh, Atsutoshi Ishii, Thomas Hobiger, and Mizuhiko Hosokawa. "VLBI Measurements for Frequency Transfer." Proceedings of the International Astronomical Union 5, H15 (November 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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4

Panfilo, Gianna, and Thomas E. Parker. "A theoretical and experimental analysis of frequency transfer uncertainty, including frequency transfer into TAI." Metrologia 47, no. 5 (September 8, 2010): 552–60. http://dx.doi.org/10.1088/0026-1394/47/5/005.

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5

Zhang, Hongyuan, Haoyun Wei, Honglei Yang, and Yan Li. "Active laser ranging with frequency transfer using frequency comb." Applied Physics Letters 108, no. 18 (May 2, 2016): 181101. http://dx.doi.org/10.1063/1.4948593.

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6

Zhang, Zhehao, and 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, no. 11 (May 26, 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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Li, Qi, Liang Hu, Jinbo Zhang, Jianping Chen, and Guiling Wu. "Fiber Radio Frequency Transfer Using Bidirectional Frequency Division Multiplexing Dissemination." IEEE Photonics Technology Letters 33, no. 13 (July 1, 2021): 660–63. http://dx.doi.org/10.1109/lpt.2021.3086299.

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Zhang, Xiang, Liang Hu, Xue Deng, Qi Zang, Jie Liu, Dongdong Jiao, Jing Gao, et al. "All-Passive Cascaded Optical Frequency Transfer." IEEE Photonics Technology Letters 34, no. 8 (April 15, 2022): 413–16. http://dx.doi.org/10.1109/lpt.2022.3164406.

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9

Jaekel, Marc-Thierry, and Serge Reynaud. "Time-Frequency Transfer with Quantum Fields." Physical Review Letters 76, no. 14 (April 1, 1996): 2407–11. http://dx.doi.org/10.1103/physrevlett.76.2407.

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10

Pufall, M. R., W. H. Rippard, S. Kaka, T. J. Silva, and S. E. Russek. "Frequency modulation of spin-transfer oscillators." Applied Physics Letters 86, no. 8 (February 21, 2005): 082506. http://dx.doi.org/10.1063/1.1875762.

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Дисертації з теми "Frequency transfer"

1

Butler, Brandon. "Reliable data transfer via frequency transmission." Thesis, Butler, Brandon (2017) Reliable data transfer via frequency transmission. Honours thesis, Murdoch University, 2017. https://researchrepository.murdoch.edu.au/id/eprint/40398/.

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Анотація:
Reliable single directional frequency data transfer is a method of electronic communication that is a potential alternative to a bi-directional or wired method. It is intended to determine whether or not single directional data transfer can be designed to perform at the same reliability level as other methods of data transmission. The reason for researching this is to see whether, two-way communication is necessary. Upon finding results to this question it will be determined if single directional frequency data transfer can be as power efficient as bi directional data transfer. It will also look into the overall performance of the method and how it can deal with inhibiting factors that will be introduced to simulate real world external variations in the signal. How reliable single directional frequency transfer is, will be determined through experiments that are tasked at finding the maximum transmission rate of the devices made and the distance that data transmission can be conducted over. The investigation will require the design of an experimental apparatus that will allow results to be found in the maximum possible transmission rate and distance transmission can cover. The experimental apparatus will consist of two possessors, one for encoding a message, the other for decoding a message. The apparatus will also require an integrated radio frequency transmitter circuit as well as a receiver radio frequency integrated circuit. The processors will need to be coded with a new protocol that will allow the incorporation of three forward error correction techniques. This is so that a basic, intermediate and advanced method of forward error correction can be compared when gathering results. Throughout this research consideration into all aspects that can possibly improve the energy efficiency of the electrical apparatus will be addressed an implemented. By creating an experimental apparatus that is competitive against other data transmission methods in terms of energy efficiency. With an energy efficient experimental apparatus, then results found could be a close representation of the likely outcomes if single directional data transmission was to be implemented on a larger scale.
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2

Ilvedson, Corinne Rachel 1974. "Transfer function estimation using time-frequency analysis." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50472.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1998.
Includes bibliographical references (p. 135-136).
Given limited and noisy data, identifying the transfer function of a complex aerospace system may prove difficult. In order to obtain a clean transfer function estimate despite noisy data, a time-frequency analysis approach to system identification has been developed. The method is based on the observation that for a linear system, an input at a given frequency should result in a response at the same frequency, and a time localized frequency input should result in a response that is nearby in time to the input. Using these principles, the noise in the response can be separated from the physical dynamics. In addition, the impulse response of the system can be restricted to be causal and of limited duration, thereby reducing the number of degrees of freedom in the estimation problem. The estimation method consists of finding a rough estimate of the impulse response from the sampled input and output data. The impulse response estimate is then transformed to a two dimensional time-frequency mapping. The mapping provides a clear graphical method for distinguishing the noise from the system dynamics. The information believed to correspond to noise is discarded and a cleaner estimate of the impulse response is obtained from the remaining information. The new impulse response estimate is then used to obtain the transfer function estimate. The results indicate that the time-frequency transfer function estimation method can provide estimates that are often less noisy than those obtained from other methods such as the Empirical Transfer Function Estimate and Welch's Averaged Periodogram Method.
by Corinne Rachel Ilvedson.
S.M.
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3

Lawson, James. "High frequency electromagnetic links for wireless power transfer." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/54841.

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This thesis investigates inductive links used in wireless power transfer systems. Inductive power transfer can be used as a power delivery method for a variety of portable devices, from medical implants to electric vehicles and is gaining increased interest. The focus is on high quality factor coils and MHz operation, where accurate measurements are difficult to achieve. Fast models of all pertinent aspects of inductive power transfer systems for constant cross section coils are developed. These models are used to optimise a new coil winding pattern that aims to increase efficiency in volume constrained scenarios. Measurement systems are developed to measure coil Q factors in excess of 1,000. The prototype measurement systems are verified against models of that system, as well as finite element simulations of the coil under test. Shielding of inductive power transfer systems is then investigated. A structure typically used at GHz frequencies, the artificial magnetic conductor, is miniaturised as an alternative to conventional ferrite backed ground plane shielding. Finite element simulation shows this structure significantly improves link efficiency. The artificial magnetic conductor prototype does not result in a gain in efficiency expected, however it does display the properties expected of an artificial magnetic conductor, including increased coupling factor. Finally, an unconventional inductive power transfer system is presented where transmitter and receiver are up to 6m away from each other and of radically different size. This system provides mW level power to remote devices in a room, for example thermostats or e-ink displays. Conventional approaches to design do not consider the distortion of the magnetic field caused by metallic objects in the room. It was found that treating the system as a decoupled receiver and transmitter provides a better prediction of received power in real world environments.
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4

Foreman, Seth M. "Femtosecond frequency combs for optical clocks and timing transfer." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273700.

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5

Zhao, Rui. "Double resonant high-frequency converters for wireless power transfer." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22958/.

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This thesis describes novel techniques and developments in the design and implementation of a low power radio frequency (40kHz to 1MHz) wireless power transfer (WPT) system, with an application in the wireless charging of autonomous drones without physical connection to its on-board Battery Management System (BMS). The WPT system is developed around a matrix converter exploiting the benefits such as a small footprint (DC-link free), high efficiency and high power density. The overall WPT system topology discussed in this thesis is based on the current state-of-the-art found in literature, but enhancements are made through novel methods to further improve the converter's stability, reduce control complexity and improve the wireless power efficiency. In this work, each part of the system is analysed and novel techniques are proposed to achieve improvements. The WPT system design methodology presented in this thesis commences with the use of a conventional full-bridge converter. For cost-efficiency and to improve the converters stability, a novel gate drive circuit is presented which provides self-generated negative bias such that a bipolar MOSFET drive can be driven without an additional voltage source or magnetic component. The switching control sequences for both a full-bridge and single phase to single phase matrix converter are analysed which show that the switching of a matrix converter can be considered to be the same as a full-bridge converter under certain conditions. A middleware is then presented that reduces the complexity of the control required for a matrix converter and enables control by a conventional full-bridge controller (i.e. linear controller or microcontroller). A novel technique that can maximise and maintain in real-time the WPT efficiency is presented using a maximum efficiency point tracking approach. A detailed study of potential issues that may affect the implementation of this novel approach are presented and new solutions are proposed. A novel wireless pseudo-synchronous sampling method is presented and implemented on a prototype system to realise the maximum efficiency point tracking approach. Finally, a new hybrid wireless phase-locked loop is presented and implemented to minimise the bandwidth requirements of the maximum efficiency point tracking approach. The performance and methods for implementation of the novel concepts introduced in this thesis are demonstrated through a number of prototypes that were built. These include a matrix converter and two full WPT systems with operating frequencies ranging from sub-megahertz to megahertz level. Moreover, the final prototype is applied to the charging of a quadcopter battery pack to successfully charge the pack wirelessly whilst actively balancing the cells. Hence, fast battery charging and cell balancing, which conventionally requires battery removal, can be achieved without re-balance the weight of the UAV.
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6

Marra, Giuseppe. "Transfer of optical frequency combs over optical fibre links." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/350220/.

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Анотація:
In just over a decade the optical frequency comb technique has completely transformed the field of frequency metrology. These devices have made the measurement of the frequency of light a much easier and affordable task when compared to with earlier techniques. With both research and technology development on these devices becoming more mature, optical frequency combs have been affecting other science areas. Applications are already found in spectroscopy, attosecond physics and astrophysics and more science and engineering areas can be expected to be affected in the near future. The dissemination over optical fibre of optical frequency combs between research labs, or between research labs and industry, could facilitate and accelerate this process. In particular, with optical frequency standards currently exhibiting a fractional accuracy better than 10^-17 and optical frequency combs making this accuracy available across a wide spectrum, new experiments could be devised in a wide range of research fields if ultra accurate microwave and optical frequencies were to be made available beyond the walls of metrology laboratories. However, before the work presented in this thesis, limited research was undertaken to test how accurately an optical frequency comb could be transferred over optical fibre. Environmentally-induced noise in the fibre, dispersion issues and other processes taking place during the propagation and detection of the optical signal could all degrade its quality to a level incompatible with the desired applications. The experiments described here demonstrate that optical frequency combs can be disseminated over optical links, from several-km to many tens of km-long, whilst preserving the stability and accuracy of its mode frequency spacing and mode frequency to a level compatible with the majority of the most demanding frequency metrology applications.
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7

Boaventura, Alírio de Jesus Soares. "Efficient wireless power transfer and radio frequency identification systems." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17374.

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Анотація:
Doutoramento em Engenharia Eletrotécnica
In the IoT context, where billions of connected objects are expected to be ubiquitously deployed worldwide, the frequent battery maintenance of ubiquitous wireless nodes is undesirable or even impossible. In these scenarios, passive-backscatter radios will certainly play a crucial role due to their low cost, low complexity and battery-free operation. However, as passive-backscatter devices are chiefly limited by the WPT link, its efficiency optimization has been a major research concern over the years, gaining even more emphasis in the IoT context. Wireless power transfer has traditionally been carried out using CW signals, and the efficiency improvement has commonly been achieved through circuit design optimization. This thesis explores a fundamentally different approach, in which the optimization is focused on the powering waveforms, rather than the circuits. It is demonstrated through theoretical analysis, simulations and measurements that, given their greater ability to overcome the built-in voltage of rectifying devices, high PAPR multi-sine (MS) signals are capable of more efficiently exciting energy harvesting circuits when compared to CWs. By using optimal MS signals to excite rectifying devices, remarkable RF-DC conversion efficiency gains of up to 15 dB with respect to CW signals were obtained. In order to show the effectiveness of this approach to improve the communication range of passive-backscatter systems, a MS front-end was integrated in a commercial RFID reader and a significant range extension of 25% was observed. Furthermore, a software-defined radio RFID reader, compliant with ISO18000-6C standard and with MS capability, was constructed from scratch. By interrogating passive RFID transponders with MS waveforms, a transponder sensitivity improvement higher than 3 dB was obtained for optimal MS signals. Since the amplification and transmission of high PAPR signals is critical, this work also proposes efficient MS transmitting architectures based on space power combining techniques. This thesis also addresses other not less important issues, namely self-jamming in passive RFID readers, which is the second limiting factor of passive-backscatter systems. A suitable self-jamming suppression scheme was first used for CW signals and then extended to MS signals, yielding a CW isolation up to 50 dB and a MS isolation up 60 dB. Finally, a battery-less remote control system was developed and integrated in a commercial TV device with the purpose of demonstrating a practical application of wireless power transfer and passive-backscatter concepts. This allowed battery-free control of four basic functionalities of the TV (CH+,CH-,VOL+,VOL-).
No contexto da internet das coisas (IoT), onde são esperados bilhões de objetos conectados espalhados pelo planeta de forma ubíqua, torna-se impraticável uma frequente manutenção e troca de baterias dos dispositivos sem fios ubíquos. Nestes cenários, os sistemas radio backscatter passivos terão um papel preponderante dado o seu baixo custo, baixa complexidade e não necessidade de baterias nos nós móveis. Uma vez que a transmissão de energia sem fios é o principal aspeto limitativo nestes sistemas, a sua otimização tem sido um tema central de investigação, ganhando ainda mais ênfase no contexto IoT. Tradicionalmente, a transferência de energia sem-fios é feita através de sinais CW e a maximização da eficiência é conseguida através da otimização dos circuitos recetores. Neste trabalho explora-se uma abordagem fundamentalmente diferente, em que a otimização foca-se nas formas de onda em vez dos circuitos. Demonstra-se, teoricamente e através de simulações e medidas que, devido à sua maior capacidade em superar a barreira de potencial intrínseca dos dispositivos retificadores, os sinais multi-seno (MS) de elevado PAPR são capazes de excitar os circuitos de colheita de energia de forma mais eficiente quando comparados com o sinal CW tradicional. Usando sinais MS ótimos em circuitos retificadores, foram verificadas experimentalmente melhorias de eficiência de conversão RF-DC notáveis de até 15 dB relativamente ao sinal CW. A fim de mostrar a eficácia desta abordagem na melhoria da distância de comunicação de sistemas backscatter passivos, integrou-se um front-end MS num leitor RFID comercial e observou-se um aumento significativo de 25% na distância de leitura. Além disso, desenvolveu-se de raiz um leitor RFID baseado em software rádio, compatível com o protocolo ISO18000-6C e capaz de gerar sinais MS, com os quais interrogou-se transponders passivos, obtendo-se ganhos de sensibilidade dos transponders maiores que 3 dB. Uma vez que a amplificação de sinais de elevado PAPR é uma operação crítica, propôs-se também novas arquiteturas eficientes de transmissão baseadas na combinação de sinais em espaço livre. Esta tese aborda também outros aspetos não menos importantes, como o self-jamming em leitores RFID passivos, tido como o segundo fator limitativo neste tipo de sistemas. Estudou-se técnicas de cancelamento de self-jamming CW e estendeu-se o conceito a sinais MS, tendo-se obtido isolamentos entre o transmissor e o recetor de até 50 dB no primeiro caso e de até 60 dB no segundo. Finalmente, com o objetivo de demonstrar uma aplicação prática dos conceitos de transmissão de energia sem fios e comunicação backscatter, desenvolveu-se um sistema de controlo remoto sem pilhas, cujo protótipo foi integrado num televisor comercial a fim de controlar quatro funcionalidades básicas (CH+,CH-,VOL+,VOL-).
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8

Hopper, David J. "Investigation of laser frequency stabilisation using modulation transfer spectroscopy." Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/16667/1/David_John_Hopper_Thesis.pdf.

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Анотація:
Optical frequency standards are necessary tools for accurate measurement of time and length. In practice these standards are stabilised laser systems locked to a known frequency reference. These references are typically the resonant frequencies of the atoms of an absorption medium that have been theoretically calculated to a high degree of accuracy. This thesis describes a combination of experimental and theoretical research performed on modulation transfer spectroscopy (MTS)--a technique used to frequency stabilise a laser in order to produce an accurate frequency reference--with emphasis placed on developing techniques and procedures to overcome the limitations found in existing MTS stabilised laser systems. The focus of the thesis is to generate a highly accurate frequency reference by researching the system parameters that will increase the signal to noise ratio and improve the accuracy of the reference through refinement of the signal structure. The early theoretical interpretation of MTS was effectively a low absorption approximation that occurs at low pressures. This approximation ignores the depletion of beam energy through absorption and is a distinct limitation of the theoretical model in its ability to accurately predict the influence of a range of system parameters on signal strength and structure. To overcome this limitation a 3-D (or volumetric) analysis was developed and is presented here for the first time. This volumetric model is a measure of two depleted beams interacting collinearly in an absorbing medium of iodine and is described to accurately predict the signal maximum as a function of pressure for all wavelengths. This model was found to be more accurate in predicting the influence of system parameters on the signal strength and structure, including that of pump beam intensity, pressure, saturation parameter, cell length and modulation parameters. The volumetric model is a novel approach to MTS theory but is more complex computationally than the traditional low pressure model and therefore more difficult to implement in many situations. To overcome this problem a hybrid model was developed as a combination of the low pressure and volumetric models. The comparison between the rigorous volume model and the hybrid model indicate that there is a deviation in the signal strength at high pressures. However, the agreement was very good in the pressure regimes that are commonly used to realise actual frequency references. Comparison of the hybrid model to experimental data was performed over a range of different wavelengths (532 nm, 543.5 nm, 612 nm and 633 nm) and found to be in close agreement. This gives confidence in the model to accurately predict signal strength and structure in any situation. Three mechanisms have been identified that limit the accuracy of frequency references due to the creation of residual amplitude modulation (RAM) where it shifts the frequency of the reference. The influence of RAM is included in the hybrid model as a ratio of the amplitude modulated and frequency modulated components of the saturating beam. These RAM production mechanisms result from the modulation of the saturating beam, the overlap of the beams in the medium, and the differential absorption of the sidebands in the medium. While the first mechanism has been previously reported the latter two are discussed here in detail for the first time. RAM generated by the modulators used (acousto-optic or electro-optic modulators) was typically of the order of 10% to 12%, depending on the excursion of the created sidebands. RAM generated by an asymmetric beam overlap with the modulators used was found to be as large as 30%. A combination of these two independent mechanisms can be used to provide a "RAM-free" state of the system by using one to cancel the effects of the other. The third RAM generation process--medium induced RAM--is difficult to remove but through a careful combination of absorption related parameters--namely, pump intensity, cell length, pressure and detector phase--the effects of RAM can be removed, leading to a distortion free MTS signal. Further investigation into the predictions provided by the hybrid model shows that there is a complex relationship between cell length and the optimum pressure required for maximum signal strength, such that longer cell lengths will not necessarily improve the signal strength. This is contrary to conventional thinking and is important in the MTS design process to reduce unnecessary costs and improve the signal to noise ratio and frequency accuracy. Optimisation of frequency stabilised laser systems using MTS are generally performed using trial and error. Comparison of these optimum parameter values to those predicted by the hybrid model show that for popular wavelengths such as 532 nm they are similar. In addition, the hybrid model is able to predict the frequency shifts that arise within the system parameters used and has shown that existing systems being used at 532 nm, 633 nm and 778 nm could improve their signal to noise ratio and accuracy through a variation in the parameters. A methodology based on the hybrid model is presented that can be used to calculate the optimum parameters for maximum signal strength and a "RAM-free" state for any wavelength. This systematic approach can therefore be used to guide the design of actual frequency stabilised laser systems prior to and during the design process.
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9

Hopper, David J. "Investigation of laser frequency stabilisation using modulation transfer spectroscopy." Queensland University of Technology, 2008. http://eprints.qut.edu.au/16667/.

Повний текст джерела
Анотація:
Optical frequency standards are necessary tools for accurate measurement of time and length. In practice these standards are stabilised laser systems locked to a known frequency reference. These references are typically the resonant frequencies of the atoms of an absorption medium that have been theoretically calculated to a high degree of accuracy. This thesis describes a combination of experimental and theoretical research performed on modulation transfer spectroscopy (MTS)--a technique used to frequency stabilise a laser in order to produce an accurate frequency reference--with emphasis placed on developing techniques and procedures to overcome the limitations found in existing MTS stabilised laser systems. The focus of the thesis is to generate a highly accurate frequency reference by researching the system parameters that will increase the signal to noise ratio and improve the accuracy of the reference through refinement of the signal structure. The early theoretical interpretation of MTS was effectively a low absorption approximation that occurs at low pressures. This approximation ignores the depletion of beam energy through absorption and is a distinct limitation of the theoretical model in its ability to accurately predict the influence of a range of system parameters on signal strength and structure. To overcome this limitation a 3-D (or volumetric) analysis was developed and is presented here for the first time. This volumetric model is a measure of two depleted beams interacting collinearly in an absorbing medium of iodine and is described to accurately predict the signal maximum as a function of pressure for all wavelengths. This model was found to be more accurate in predicting the influence of system parameters on the signal strength and structure, including that of pump beam intensity, pressure, saturation parameter, cell length and modulation parameters. The volumetric model is a novel approach to MTS theory but is more complex computationally than the traditional low pressure model and therefore more difficult to implement in many situations. To overcome this problem a hybrid model was developed as a combination of the low pressure and volumetric models. The comparison between the rigorous volume model and the hybrid model indicate that there is a deviation in the signal strength at high pressures. However, the agreement was very good in the pressure regimes that are commonly used to realise actual frequency references. Comparison of the hybrid model to experimental data was performed over a range of different wavelengths (532 nm, 543.5 nm, 612 nm and 633 nm) and found to be in close agreement. This gives confidence in the model to accurately predict signal strength and structure in any situation. Three mechanisms have been identified that limit the accuracy of frequency references due to the creation of residual amplitude modulation (RAM) where it shifts the frequency of the reference. The influence of RAM is included in the hybrid model as a ratio of the amplitude modulated and frequency modulated components of the saturating beam. These RAM production mechanisms result from the modulation of the saturating beam, the overlap of the beams in the medium, and the differential absorption of the sidebands in the medium. While the first mechanism has been previously reported the latter two are discussed here in detail for the first time. RAM generated by the modulators used (acousto-optic or electro-optic modulators) was typically of the order of 10% to 12%, depending on the excursion of the created sidebands. RAM generated by an asymmetric beam overlap with the modulators used was found to be as large as 30%. A combination of these two independent mechanisms can be used to provide a "RAM-free" state of the system by using one to cancel the effects of the other. The third RAM generation process--medium induced RAM--is difficult to remove but through a careful combination of absorption related parameters--namely, pump intensity, cell length, pressure and detector phase--the effects of RAM can be removed, leading to a distortion free MTS signal. Further investigation into the predictions provided by the hybrid model shows that there is a complex relationship between cell length and the optimum pressure required for maximum signal strength, such that longer cell lengths will not necessarily improve the signal strength. This is contrary to conventional thinking and is important in the MTS design process to reduce unnecessary costs and improve the signal to noise ratio and frequency accuracy. Optimisation of frequency stabilised laser systems using MTS are generally performed using trial and error. Comparison of these optimum parameter values to those predicted by the hybrid model show that for popular wavelengths such as 532 nm they are similar. In addition, the hybrid model is able to predict the frequency shifts that arise within the system parameters used and has shown that existing systems being used at 532 nm, 633 nm and 778 nm could improve their signal to noise ratio and accuracy through a variation in the parameters. A methodology based on the hybrid model is presented that can be used to calculate the optimum parameters for maximum signal strength and a "RAM-free" state for any wavelength. This systematic approach can therefore be used to guide the design of actual frequency stabilised laser systems prior to and during the design process.
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10

Heikkinen, Jouko. "TELEMETRY AND RADIO FREQUENCY IDENTIFICATION." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/607334.

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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada
Comparison of short-range telemetry and radio frequency identification (RFID) systems reveals that they are based on very similar operating principles. Combining the identification and measurement functions into one transponder sensor offers added value for both RFID and telemetry systems. The presence of a memory (e.g. FRAM) in the transponder, required for ID information, can also be utilized for storing measurement results. For passive transponders low power consumption is one of the main objectives. Wireless power transfer for passive transponder sensors together with above aspects concerning a combined telemetry and identification system are discussed.
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Книги з теми "Frequency transfer"

1

Ramaswamy, Ramkumar. On the characteristic frequency of a filter. Norwich, N.Y.]: Knovel, 2011.

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2

Chakraborty, D. R. Estimation of nonlinear heat and momentum transfer in the frequency domain by the use of frequency co-spectra and cross-bispectra. Pune: Indian Institute of Tropical Meteorology, 2002.

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3

Zhang, H. Analysing the transfer functions of nonlinear systems in the frequency domain. Sheffield: University of Sheffield, Dept. of Automatic Control and Systems Engineering, 1992.

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4

Miller, R. L. Dynamic modelling of an electromechanical valve using frequency response data. Monterey, Calif: Naval Postgraduate School, 1986.

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5

Q, Pan J., and United States. National Aeronautics and Space Administration., eds. Frequency analysis via the method of moment functionals. [Washington, D.C: National Aeronautics and Space Administration, 1990.

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6

Pinelli, Thomas E. NASA/DoD aerospace knowledge diffusion research project: summary report to phase 3 faculty and student respondents including frequency distributions. Hampton, VA: Langley Research Center, 1991.

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7

S, Melis Theodore, United States. Bureau of Reclamation., and Geological Survey (U.S.), eds. Magnitude and frequency data for historic debris flows in Grand Canyon National Park and vicinity, Arizona. Tucson, Ariz: U.S. Dept. of the Interior, U.S. Geological Survey, 1995.

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8

M, Wang C., and National Institute of Standards and Technology (U.S.), eds. Calibration service of optoelectronic frequency response at 1319 nm for combined photodiode/RF power sensor transfer standards. Boulder, Colo: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1999.

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9

Zink, L. R. NO?□heterodyne frequency measurements with a tunable diode laser, a CO laser transfer oscillator, and CO?□laser standards. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, 1987.

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10

Zink, L. R. NOb2s heterodyne frequency measurements with a tunable diode laser, a CO laser transfer oscillator, and COb2s laser standards. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, 1987.

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Частини книг з теми "Frequency transfer"

1

Frisch, Hélène. "Asymptotic Results for Partial Frequency Redistribution." In Radiative Transfer, 563–81. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-95247-1_26.

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2

Jonscher, A. K. "Surface Transport in Time and Frequency Domains." In Energy Transfer Dynamics, 112–35. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-71867-0_12.

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3

Defraigne, Pascale. "GNSS Time and Frequency Transfer." In Springer Handbook of Global Navigation Satellite Systems, 1187–206. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-42928-1_41.

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4

Glisson, Tildon H. "Transfer Functions and Frequency-Domain Analysis." In Introduction to Circuit Analysis and Design, 539–82. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-9443-8_15.

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5

Svehla, Drazen. "First Phase Clocks and Frequency Transfer." In Geometrical Theory of Satellite Orbits and Gravity Field, 53–63. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-76873-1_4.

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6

Xie, Bin, Changqing Liao, Xian Li, and Zihao Ding. "Color Transfer Based on Frequency Tuning." In Exploration of Novel Intelligent Optimization Algorithms, 345–52. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-4109-2_31.

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7

Lin, Huang-Tien. "Precise Time and Frequency Transfer: Techniques." In Handbook of Metrology and Applications, 1–26. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1550-5_24-1.

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8

Yang, Zhichao, Digbijoy N. Nath, Yuewei Zhang, Sriram Krishnamoorthy, Jacob Khurgin, and Siddharth Rajan. "III-Nitride Tunneling Hot Electron Transfer Amplifier (THETA)." In High-Frequency GaN Electronic Devices, 109–57. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-20208-8_5.

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9

Fang, Zujie, Haiwen Cai, Gaoting Chen, and Ronghui Qu. "Optical Phase Locked Loop and Frequency Transfer." In Optical and Fiber Communications Reports, 235–66. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-5257-6_8.

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10

Blower, Gordon. "Transfer Functions, Frequency Response, Realization and Stability." In Linear Systems, 139–72. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-21240-6_5.

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Тези доповідей конференцій з теми "Frequency transfer"

1

CITRO, M. "PHARMACOLOGICAL FREQUENCY TRANSFER." In Proceedings of the International School of Biophysics. WORLD SCIENTIFIC, 1998. http://dx.doi.org/10.1142/9789812816887_0038.

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2

Rieck, Carsten, Rudiger Haas, Per Jarlemark, and Kenneth Jaldehag. "VLBI frequency transfer using CONT11." In 2012 European Frequency and Time Forum (EFTF). IEEE, 2012. http://dx.doi.org/10.1109/eftf.2012.6502358.

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3

Petit, Gerard, Amale Kanj, Aurelie Harmegnies, Sylvain Loyer, Jerome Delporte, Flavien Mercier, and Felix Perosanz. "GPS frequency transfer with IPPP." In 2014 European Frequency and Time Forum (EFTF). IEEE, 2014. http://dx.doi.org/10.1109/eftf.2014.7331533.

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4

Defraigne, P., W. Aerts, A. Harmegnies, G. Petit, D. Rovera, and P. Uhrich. "Advances in multi-GNSS time transfer." In 2013 Joint European Frequency and Time Forum & International Frequency Control Symposium (EFTF/IFC). IEEE, 2013. http://dx.doi.org/10.1109/eftf-ifc.2013.6702126.

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5

Parker, Thomas E., and Gianna Panfilo. "Experimental Analysis of Frequency Transfer Uncertainty." In 2007 IEEE International Frequency Control Symposium Joint with the 21st European Frequency and Time Forum. IEEE, 2007. http://dx.doi.org/10.1109/freq.2007.4319228.

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6

Xuhai, Yang, Hu Zhenyuan, Guo Ji, Li Xiaohui, Li Zhigang, and Yuan Haibo. "Method of common-view time transfer with transfer mode based on geostationary satellite." In 2012 IEEE International Frequency Control Symposium (FCS). IEEE, 2012. http://dx.doi.org/10.1109/fcs.2012.6243622.

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7

Smotlacha, Vladimir, Josef Vojtech, and Alexander Kuna. "Optical infrastructure for time and frequency transfer." In 2013 Joint European Frequency and Time Forum & International Frequency Control Symposium (EFTF/IFC). IEEE, 2013. http://dx.doi.org/10.1109/eftf-ifc.2013.6702170.

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8

Hu, Liang, Guiling Wu, Jianguo Shen, Huang Huang, and Jianping Chen. "Distributed time transfer using optical fiber links." In 2013 Joint European Frequency and Time Forum & International Frequency Control Symposium (EFTF/IFC). IEEE, 2013. http://dx.doi.org/10.1109/eftf-ifc.2013.6702146.

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9

Schediwy, Sascha, Andre Luiten, Guido Aben, Kenneth Baldwin, Yabai He, Brian Orr, and Bruce Warrington. "Microwave frequency transfer with optical stabilisation." In 2012 European Frequency and Time Forum (EFTF). IEEE, 2012. http://dx.doi.org/10.1109/eftf.2012.6502369.

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10

Kroese, Bethany, Gabriele Giorgi, and Christoph Gunther. "Relativistic corrections for intersatellite frequency transfer." In 2018 European Frequency and Time Forum (EFTF). IEEE, 2018. http://dx.doi.org/10.1109/eftf.2018.8409041.

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Звіти організацій з теми "Frequency transfer"

1

Tang, J. Non-Markovian electron transfer reactions with frequency-dependent friction. Office of Scientific and Technical Information (OSTI), December 1993. http://dx.doi.org/10.2172/10141924.

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2

Trudnowski, D. J. Frequency domain transfer function identification using the computer program SYSFIT. Office of Scientific and Technical Information (OSTI), December 1992. http://dx.doi.org/10.2172/10106833.

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3

Till, Andrew T. Linear-Multi-Frequency-Grey Preconditioning for Radiative Transfer SN Calculations. Office of Scientific and Technical Information (OSTI), August 2013. http://dx.doi.org/10.2172/1090639.

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4

Trudnowski, D. J. Frequency domain transfer function identification using the computer program SYSFIT. Office of Scientific and Technical Information (OSTI), December 1992. http://dx.doi.org/10.2172/6971318.

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5

Slinker, S., and A. W. Ali. Electron Momentum Transfer Collision Frequency in N(2), O(2) and Air. Fort Belvoir, VA: Defense Technical Information Center, July 1985. http://dx.doi.org/10.21236/ada157030.

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6

Bailey, J. W. W-320 waste retrieval sluicing system transfer line flushing volume and frequency calculation. Office of Scientific and Technical Information (OSTI), November 1997. http://dx.doi.org/10.2172/10148004.

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7

Wolfe, C. R., J. D. Downie, and J. K. Lawson. Measuring the spatial frequency transfer function of phase measuring interferometers for laser optics. Office of Scientific and Technical Information (OSTI), June 1996. http://dx.doi.org/10.2172/281674.

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8

Bailey, J. W. W-320 waste retrieval sluicing system transfer line flushing volume and frequency calculation. Office of Scientific and Technical Information (OSTI), April 1997. http://dx.doi.org/10.2172/16874.

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9

Hale, Paul D., and C. M. Wang. Calibration service of optoelectronic frequency response at 1319 nm for combined photodiodeRF power sensor transfer standards. Gaithersburg, MD: National Institute of Standards and Technology, 1999. http://dx.doi.org/10.6028/nist.sp.250-51.

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10

Zink, L. R. NO₂ Heterodyne frequency measurements with a tunable diode laser, a CO laser transfer oscillator, and CO₂ laser standards,. Gaithersburg, MD: National Bureau of Standards, 1987. http://dx.doi.org/10.6028/nbs.tn.1308.

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