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Einstein’s Concept of Clock Synchronization Conflicts with the Second Relativity Postulate
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作者 Steven D. Deines 《Journal of Modern Physics》 2024年第7期985-1000,共16页
Einstein defined clock synchronization whenever photon pulses with timetags traverse a fixed distance between two clocks with equal time spans ineither direction. Using the second relativity postulate, he found clocks... Einstein defined clock synchronization whenever photon pulses with timetags traverse a fixed distance between two clocks with equal time spans ineither direction. Using the second relativity postulate, he found clocksmounted on a rod uniformly moving parallel with the rod’s length cannot besynchronized, but clocks attached to a stationary rod can. He dismissed thisdiscrepancy by claiming simultaneity and clock synchronization were not commonbetween inertial frames, but this paper proves with both Galilean and Lorentztransformations that simultaneity and clock synchronization are preservedbetween inertial frames. His derivation means moving clocks can never besynchronized in a “resting” inertial frame. Ultraprecise atomic clocks intimekeeping labs daily contradict his results. No algebraic error occurred inEinstein’s derivations. The two cases of clocksattached to a rod reveal three major conflicts with the currentsecond postulate. The net velocity between a photon source and detector plusthe “universal” velocity c is mathematically equivalent toEinstein’s clock synchronization method. As the ultraprecise timekeepingcommunity daily synchronizes atomic clocks on the moving Earth withultraprecise time uncertainty well below Einstein’s lowest limit ofsynchronization, the theoretical resolution of the apparent conflict isaccomplished by expanding the second relativity postulate to incorporate thenet velocity between the photon source and detector with the emitted velocity c as components of the total velocity c. This means the magnitudeof the total photon velocity can exceed the speed limit (299792458 m/s) set by the standard velocity c. . 展开更多
关键词 Special Relativity SIMULTANEITY Clock Synchronization Photon Speed Lorentz Transformation Galilean Transformation
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An Improved Kalman Filter Positioning Method in NLOS Environment 被引量:4
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作者 Zhanjun Hao Beibei Li Xiaochao Dang 《China Communications》 SCIE CSCD 2019年第12期84-99,共16页
In the precision positioning system, NLOS(Non Line of Sight) propagation and clock synchronization error caused by multiple base stations are the main reasons for reducing the reliability of communication and position... In the precision positioning system, NLOS(Non Line of Sight) propagation and clock synchronization error caused by multiple base stations are the main reasons for reducing the reliability of communication and positioning accuracy. So, in the NLOS environment, it has an important role to eliminate the clock synchronization problem in the positioning system. In order to solve this problem, this paper proposes an improved Kalman filter localization method NLOS-K(Non Line of Sight-Kalman filter). First, the maximum likelihood estimation algorithm is used to iterate. Then, the Kalman filter algorithm is implemented and the Kalman gain matrix is redefined. The clock drift is compensated so that the clock between the master and slave base stations remains synchronized. The experimental results show that in the non-lineof-sight environment, compared with other algorithms, the positioning accuracy error of the improved algorithm is about 5 cm, and the accuracy compared with other algorithms is 97%. In addition, the influence of bandwidth and spectral density on the method is analyzed, and the accuracy and stability of positioning are improved as a whole. 展开更多
关键词 NLOS clock synchronization Kalman filtering maximum likelihood estimation spectral density
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How to Define the Equality of Durations in Measurement of Time 被引量:2
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作者 赵峥 田贵花 +1 位作者 刘辽 高思杰 《Chinese Physics Letters》 SCIE CAS CSCD 2006年第12期3165-3168,共4页
We develop the research on measurement of time worked by Poincarh, Einstein, Landau and other researchers. Based on the convention that the velocity of light is isotropic and is a constant in empty spacetime, we not o... We develop the research on measurement of time worked by Poincarh, Einstein, Landau and other researchers. Based on the convention that the velocity of light is isotropic and is a constant in empty spacetime, we not only answer the question about the definition of the synchronization of rate of clocks located at different places, but also find the solution to the issue of how to define the equality of two durations in measurement of time. 展开更多
关键词 CLOCK RATE SYNCHRONIZATION TRANSITIVITY
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New Synchronization Algorithm and Analysis of Its Convergence Rate for Clock Oscillators in Dynamical Network with Time-Delays 被引量:1
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作者 甘明刚 于淼 +1 位作者 陈杰 窦丽华 《Journal of Beijing Institute of Technology》 EI CAS 2010年第1期58-65,共8页
New synchronization algorithm and analysis of its convergence rate for clock oscillators in dynamical network with time-delays are presented.A network of nodes equipped with hardware clock oscillators with bounded dri... New synchronization algorithm and analysis of its convergence rate for clock oscillators in dynamical network with time-delays are presented.A network of nodes equipped with hardware clock oscillators with bounded drift is considered.Firstly,a dynamic synchronization algorithm based on consensus control strategy,namely fast averaging synchronization algorithm (FASA),is presented to find the solutions to the synchronization problem.By FASA,each node computes the logical clock value based on its value of hardware clock and message exchange.The goal is to synchronize all the nodes' logical clocks as closely as possible.Secondly,the convergence rate of FASA is analyzed that proves it is related to the bound by a nondecreasing function of the uncertainty in message delay and network parameters.Then,FASA's convergence rate is proven by means of the robust optimal design.Meanwhile,several practical applications for FASA,especially the application to inverse global positioning system (IGPS) base station network are discussed.Finally,numerical simulation results demonstrate the correctness and efficiency of the proposed FASA.Compared FASA with traditional clock synchronization algorithms (CSAs),the convergence rate of the proposed algorithm converges faster than that of the CSAs evidently. 展开更多
关键词 clock synchronization convergence rate dynamical network robust optimal design
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A clock synchronization method based on IEEE 1588 and its implementation on Ethernet 被引量:1
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作者 许万 《Journal of Chongqing University》 CAS 2008年第2期145-150,共6页
We presented a clock synchronization method that contained a clock adjusting algorithm and a frequency compensated clock to achieve precise synchronization among distributed clocks based on IEEE 1588 protocol.Further,... We presented a clock synchronization method that contained a clock adjusting algorithm and a frequency compensated clock to achieve precise synchronization among distributed clocks based on IEEE 1588 protocol.Further,we presented its application on Ethernet and implementation of the frequency compensated clock in a field programmable gate array(FPGA) as experiments.The results indicate that this method can support sub-microsecond synchronization with inexpensive standard crystal oscillators. 展开更多
关键词 clock synchronization clock adjustment frequency compensation IEEE 1588
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A Control Scheme Based on Online Delay Evaluation for a Class of Networked Control Systems 被引量:1
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作者 马向华 谢剑英 魏震 《Journal of Donghua University(English Edition)》 EI CAS 2004年第4期124-130,共7页
A control scheme that integrates control technology with communication technology to solve the delay problem is introduced for a class of networked control systems: Networked Half-Link Systems (NHLS). Concretely, we u... A control scheme that integrates control technology with communication technology to solve the delay problem is introduced for a class of networked control systems: Networked Half-Link Systems (NHLS). Concretely, we use the master-slave clock synchronization technology to evaluate the delays online, and then the LQ optimal control based on delays is adopted to stabilize the controlled plant. During the clock synchronization process, the error of evaluated delays is inevitably induced from the clock synchronization error, which will deteriorate the system performances, and even make system unstable in certain cases. Hence, the discussions about the clock error, and the related control analysis and design are also developed. Specifically, we present the sufficient conditions of controller parameters that guarantee the system stability, and a controller design method based on the error of delays is addressed thereafter. The experiments based on a CANbus platform are fulfilled, and the experimental results verify the previous analytic results finally. 展开更多
关键词 Networked Control Systems NCS Networked Half-Link Systems NHLS Clock Synchronization Optimal Control Based on Delays CANbus.
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A new synchronization scheme based on time division multiplexing and wavelength division multiplexing technology for practical quantum key distribution system
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作者 钟平平 张华妮 +4 位作者 王金东 秦晓娟 魏正军 陈帅 刘颂豪 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第5期73-79,共7页
Three clock synchronization schemes for a quantum key distribution system are compared experimentally through the outdoor fibre and the interaction physical model of the the clock signal and the the quantum signal in ... Three clock synchronization schemes for a quantum key distribution system are compared experimentally through the outdoor fibre and the interaction physical model of the the clock signal and the the quantum signal in the quantum key distribution system is analysed to propose a new synchronization scheme based on time division multiplexing and wavelength division multiplexing technology to reduce quantum bits error rates under some transmission rate conditions, The proposed synchronization scheme can not only completely eliminate noise photons from the bright background light of the the clock signal, but also suppress the fibre nonlinear crosstalk. 展开更多
关键词 quantum key distribution clock synchronization wavelength division multiplexing timedivision multiplexing
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Scalable Clock Synchronization Analysis:A Symmetric Noncooperative Output Feedback Tubes-MPC Approach
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作者 Ting Wang Xiaoquan Xu Xiaoming Tang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2020年第6期1604-1626,共23页
In the cyber-physical environment,the clock synchronization algorithm is required to have better expansion for network scale.In this paper,a new measurement model of observability under the equivalent transformation o... In the cyber-physical environment,the clock synchronization algorithm is required to have better expansion for network scale.In this paper,a new measurement model of observability under the equivalent transformation of minimum mean square error(MMSE)is constructed based on basic measurement unit(BMU),which can realize the scaled expansion of MMSE measurement.Based on the state updating equation of absolute clock and the decoupled measurement model of MMSElike equivalence,which is proposed to calculate the positive definite invariant set by using the theoretical-practical Luenberger observer as the synthetical observer,the local noncooperative optimal control problem is built,and the clock synchronization system driven by the ideal state of local clock can reach the exponential convergence for synchronization performance.Different from the problem of general linear system regulators,the state estimation error and state control error are analyzed in the established affine system based on the set-theoryin-control to achieve the quantification of state deviation caused by noise interference.Based on the BMU for isomorphic state map,the synchronization performance of clock states between multiple sets of representative nodes is evaluated,and the scale of evaluated system can be still expanded.After the synchronization is completed,the state of perturbation system remains in the maximum range of measurement accuracy,and the state of nominal system can be stabilized at the ideal state for local clock and realizes the exponential convergence of the clock synchronization system. 展开更多
关键词 Affine system clock synchronization model predictive control output feedback
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Heuristics Scheduling Algorithm on the Links Scheduling of Satellite-Ground Clock Synchronization and Ephemeris Uploading in COMPASS System
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作者 张忠山 闫俊刚 +1 位作者 谭跃进 王沛 《Journal of Donghua University(English Edition)》 EI CAS 2016年第3期462-466,共5页
The execution process of satellite-ground clock synchronization and ephemeris uploading in the system is analyzed,as well as their characterized operation and their relationship.Based on the analysis of the scheduling... The execution process of satellite-ground clock synchronization and ephemeris uploading in the system is analyzed,as well as their characterized operation and their relationship.Based on the analysis of the scheduling goal and constraint character,a heuristics rule-based multi-stage link scheduling algorithm was put forward.The algorithm distinguishes the on-off-frontier satellites from the others and schedules them by turns.The paper presented the main flow as well as the detailed design of the rule.Finally based on the current COMPASS global system,some typical resources and constraints are selected to generate an instance.Then the comparison analysis between the heuristics scheduling algorithm and three other traditional scheduling strategies are carried out.The result shows the validity and reasonability of the multi-stage strategy. 展开更多
关键词 heuristics algorithm COMPASS system CROSSLINKS satelliteground clock synchronization and ephemeris uploading SCHEDULING
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Iterative quantum algorithm for distributed clock synchronization
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作者 王洪福 张寿 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第10期110-114,共5页
Clock synchronization is a well-studied problem with many practical and scientific applications.We propose an arbitrary accuracy iterative quantum algorithm for distributed clock synchronization using only three qubit... Clock synchronization is a well-studied problem with many practical and scientific applications.We propose an arbitrary accuracy iterative quantum algorithm for distributed clock synchronization using only three qubits.The n bits of the time difference between two spatially separated clocks can be deterministically extracted by communicating only O(n) messages and executing the quantum iteration process n times based on the classical feedback and measurement operations.Finally,we also give the algorithm using only two qubits and discuss the success probability of the algorithm. 展开更多
关键词 clock synchronization iterative algorithm
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Maximum Likelihood Estimation of Clock Synchronization Error in OFDM System
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作者 崔小准 胡光锐 陈豪 《Journal of Donghua University(English Edition)》 EI CAS 2004年第4期1-3,共3页
The performance degradation of an orthogonal frequency division multiplexing (OFDM) systems due to clock synchronization error is analyzed and a pilot-aided maximum likelihood (ML) estimating method is proposed to cor... The performance degradation of an orthogonal frequency division multiplexing (OFDM) systems due to clock synchronization error is analyzed and a pilot-aided maximum likelihood (ML) estimating method is proposed to correct it. The proposed algorithm enables clock synchronization error estimation from a pilot whose duration is only two symbol periods. The study shows that this method is simple and exact. The clock synchronization error can be corrected almost entirely. 展开更多
关键词 Orthogonal frequency-division multiplexing clock synchronization error maximum likelihood estimator
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A scheme for implementing quantum clock synchronization algorithm in cavity QED
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作者 吴琴琴 匡乐满 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第11期2593-2599,共7页
In this paper, we propose a scheme for implementing the quantum clock synchronization (QCS) algorithm in cavity quantum electrodynamic (QED) formalism. Our method is based on three-level lader-type atoms interacti... In this paper, we propose a scheme for implementing the quantum clock synchronization (QCS) algorithm in cavity quantum electrodynamic (QED) formalism. Our method is based on three-level lader-type atoms interacting with classical and quantized cavity fields. Atom-qubit realizations of three-qubit and four-qubit QCS algorithms are explicitly presented. 展开更多
关键词 quantum clock synchronization algorithm three-level atoms cavity QED
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A method for measuring the clock offset of two hosts in the network
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作者 Xingye Yu +1 位作者 Yang 《Journal of University of Science and Technology Beijing》 CSCD 2003年第1期65-68,共4页
In order to detect the performance parameters of the network, for example, the network delay or delay jitter, the clock synchronization relations between the two hosts at two ends along the network must be calculated ... In order to detect the performance parameters of the network, for example, the network delay or delay jitter, the clock synchronization relations between the two hosts at two ends along the network must be calculated in advance. Then with the correct temporal relations between the two hosts, multimedia transmission along the network and display can occur by the proper order. A refined method based on Paxson's algorithm is proposed and testified. More accurate results can be attained by the method. By the way, the method can be used in a more complicated environment. Furthermore, an end-to-end network performance tester based on the proposed algorithm is designed and implemented. 展开更多
关键词 end-to-end measurement network delay clock synchronization
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A study on synchronization error accumulation over hop count for synchronization scheme of two-way packet exchange
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作者 徐朝农 Xu Yongjun +1 位作者 Wang Zhiguang Wang Feng 《High Technology Letters》 EI CAS 2012年第2期179-185,共7页
Two-way packet exchange synchronization scheme has been widely used in wireless sensor networks. However, due to the fact that its synchronization error accumulates rapidly over hop count, its applications are greatly... Two-way packet exchange synchronization scheme has been widely used in wireless sensor networks. However, due to the fact that its synchronization error accumulates rapidly over hop count, its applications are greatly restricted. In this paper, the factors that cause the accumulation of synchronization error over hop count are investigated. Theoretical analysis shows that two factors including the clock drift and the asymmetry of two-way packet exchange, have distinct influences on synchronization error between two adjacent nodes. Further, the clock frequency order along synchronization path is found to be vital to the accumulation of synchronization error. The above three factors jointly determine the accumulation of synchronization error over hop count in wireless network. Theoretic results are also verified by three fine-grained experiments on wireless sensor network testbed. The conclusions can be used to decrease synchronization error for large-scale wireless network by careful network deployment. 展开更多
关键词 wireless sensor networks(WSN) clock drift time synchronization clock synchronization ACCUMULATION
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A Survey on Clock Synchronization in the Industrial Internet 被引量:2
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作者 党凡 孙熙凯 +2 位作者 刘克彬 许逸凡 刘云浩 《Journal of Computer Science & Technology》 SCIE EI CSCD 2023年第1期146-165,共20页
Clock synchronization is one of the most fundamental and crucial network communication strategies.With the expansion of the Industrial Internet in numerous industrial applications,a new requirement for the precision,s... Clock synchronization is one of the most fundamental and crucial network communication strategies.With the expansion of the Industrial Internet in numerous industrial applications,a new requirement for the precision,security,complexity,and other features of the clock synchronization mechanism has emerged in various industrial situations.This paper presents a study of standardized clock synchronization protocols and techniques for various types of networks,and a discussion of how these protocols and techniques might be classified.Following that is a description of how certain clock synchronization protocols and technologies,such as PROFINET,Time-Sensitive Networking(TSN),and other well-known industrial networking protocols,can be applied in a number of industrial situations.This study also investigates the possible future development of clock synchronization techniques and technologies. 展开更多
关键词 clock synchronization industrial communication Industrial Internet wireless sensor network
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A Secure Clock Synchronization Scheme for Wireless Sensor Networks Against Malicious Attacks 被引量:1
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作者 ZHANG Xuxin LIU Yanzhang ZHANG Ya 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2021年第6期2125-2138,共14页
This paper studies the secure and accurate clock synchronization problem for sensor networks with time-varying delays and malicious attacks.A novel clock synchronization scheme based on the attack detection mechanism,... This paper studies the secure and accurate clock synchronization problem for sensor networks with time-varying delays and malicious attacks.A novel clock synchronization scheme based on the attack detection mechanism,attack compensation,and maximum consensus protocol is proposed.The proposed scheme starts with the detection of the malicious attacks and the clock data under attacks is eliminated.On the basis,software clock parameters are updated so that all the nodes in the network can have the same software skew and offset,so the clock synchronization can be achieved.Furthermore,it is theoretically proved that the proposed scheme can achieve the attack detection correctly,and further can guarantee a secure and accurate clock synchronization.In addition,extensive simulations are also conducted to validate the effectiveness of the proposed scheme. 展开更多
关键词 Clock synchronization communication delays CONSENSUS malicious attacks wireless sensor networks
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A high-precision synchronization circuit for clock distribution
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作者 路崇 谭洪舟 +1 位作者 段志奎 丁一 《Journal of Semiconductors》 EI CAS CSCD 2015年第10期108-116,共9页
In this paper, a novel structure of a high-precision synchronization circuit, HPSC, using interleaved delay units and a dynamic compensation circuit is proposed. HPSCs are designed for synchronization of clock distrib... In this paper, a novel structure of a high-precision synchronization circuit, HPSC, using interleaved delay units and a dynamic compensation circuit is proposed. HPSCs are designed for synchronization of clock distribution networks in large-scale integrated circuits, where high-quality clocks are required. The application of a hybrid structure of a coarse delay line and dynamic compensation circuit performs roughly the alignment of the clock signal in two clock cycles, and finishes the fine tuning in the next three clock cycles with the phase error suppressed under 3.8 ps. The proposed circuit is implemented and fabricated using a SMIC 0.13 μm 1P6M process with a supply voltage at 1.2 V. The allowed operation frequency ranges from 200 to 800 MHz, and the duty cycle ranges between [20%, 80%]. The active area of the core circuits is 245 × 134 μm2, and the power consumption is 1.64 mW at 500 MHz. 展开更多
关键词 HPSC clock synchronization circuit SMD dynamic compensation circuit binary search interleaveddelay units
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Effects of Quantum Noise on Quantum Clock Synchronization
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作者 谢端 彭进业 《Communications in Theoretical Physics》 SCIE CAS CSCD 2012年第8期213-219,共7页
In laboratory environment, the channel apparatus will generate particular dominant quantum noise. The noise then will give rise to some errors during synchronization. In this work, the accuracies of one qubit transpor... In laboratory environment, the channel apparatus will generate particular dominant quantum noise. The noise then will give rise to some errors during synchronization. In this work, the accuracies of one qubit transport protocol and entangled states transport protocol in the presence of noise have been studied. With the help of three important and familiar noise models, the quantum noise will degrade the accuracy has been proved. Due to the influence of quantum noise, the accuracy of entangled qubits decrease faster than that of one qubit. The entangled states will improve the accuracy in noise-free channel, and will degrade the accuracy in noise channel. 展开更多
关键词 quantum communication quantum clock synchronization quantum noise synchronization accuracy
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Clock auto-synchronization method for BESIII ETOF upgrade
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作者 王思宇 曹平 +1 位作者 刘树彬 安琪 《Chinese Physics C》 SCIE CAS CSCD 2015年第12期57-61,共5页
An automatic clock synchronization method implemented in a field programmable gate array (FPGA) is proposed in this paper. It is developed for the clock system which will be applied in the end-cap time of flight (E... An automatic clock synchronization method implemented in a field programmable gate array (FPGA) is proposed in this paper. It is developed for the clock system which will be applied in the end-cap time of flight (ETOF) upgrade of the Beijing Spectrometer (BESIII). In this design, an FPGA is used to automatically monitor the synchronization circuit and deal with signals coming from the external clock synchronization circuit. By testing different delay time of the detection signal and analyzing the signal state returned~ the synchronization windows can be found automatically by the FPGA. The new clock system not only retains low clock jitter which is less than 20ps root mean square (RMS), but also demonstrates automatic synchronization to the beam bunches. So far, the clock auto-synchronizing function has been working successfully under a series of tests. It will greatly simplify the system initialization and maintenance in the future. 展开更多
关键词 BESIII endcap time-of-flight clock synchronization
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Accuracy for superposition of squeezed states in lossless and dissipative channel
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作者 XIE Duan PENG JinYe 《Science China Chemistry》 SCIE EI CAS 2013年第3期593-599,共7页
The analysis of accuracy for superposition of squeezed states (SSSs) in lossless and loss case has been performed in this study. In lossless case, time accuracies of SSSs with mean photon number ns have a scaling of... The analysis of accuracy for superposition of squeezed states (SSSs) in lossless and loss case has been performed in this study. In lossless case, time accuracies of SSSs with mean photon number ns have a scaling of ns-2 in two limits of large and small squeezing. With the help of photon loss model, the dissipative channel will degrade accuracies has been proved. In the limit of large squeezing, the accuracy will slowly decrease with the reduction of transmittance η. In the limit of small squeezing, time accuracy scales as 1/(η4n2) and will decrease much faster along with η decreases. 展开更多
关键词 time accuracy quantum clock synchronization superposition of squeezed states
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