Synchronization Accuracy Research Articles

Simulation study of spread spectrum communication on satellite

Abstract All the basic principles and simulation models of the PMF-FFT capture algorithm, overlap-transform interference suppression, digital matched filter capture algorithm, delayed phase-locked loop tracking algorithm and Costas ring carrier synchronization in the starborne spread spectrum communication system are elaborated in detail. The waveforms and spectral variations in each stage of spread spectrum communication are simulated and verified using the Simulink tool. The results show that the model can achieve interference suppression, fast capture tracking of pseudocodes, and accurate synchronization of carriers at -30 dB SNR.

Synchronous LoRa sensor nodes for modal identification in footbridge vibration monitoring

AbstractThis article aims at presenting a preliminary investigation of using long-range and low-cost LoRa (Long Range) technology and two synchronous LoRa sensor nodes for cost-effective footbridge structural health monitoring (SHM). Two sensor nodes with LoRa modules and accelerometers were employed for vibration monitoring and a new attempt was made to use synchronous LoRa nodes for modal identification. In this article, a modal identification method based on a lightweight synchronization concept was proposed. This method is able to identify the fundamental mode of vibrating beam structures. Meanwhile, maximum accelerations can also be tracked periodically from the simultaneously recorded acceleration data by the synchronous LoRa nodes. Specifically, synchronization was achieved through the wireless peer-to-peer (P2P) communication between the two LoRa nodes, with the aim of initializing simultaneous acceleration recordings. The fundamental frequency and the phase information derived from the on-board calculation of the synchronized nodes can then be used to effectively identify the vertical bending mode and torsion mode. A series of laboratory tests were also conducted on a beam structure for the purpose of validation. The test results showed that the fundamental mode of the vibrating beam can be obtained rapidly and accurately using the synchronized LoRa nodes, with an average synchronization accuracy of 4.45 ms. The maximum acceleration data recorded by the LoRa nodes also showed high accuracy when compared with the raw acceleration data collected from a commercial Bluetooth accelerometer node. The fundamental frequencies obtained from both types of nodes also compare reasonably. The proposed modal identification method using two synchronous LoRa sensor nodes provides a basis for the development of a low-cost footbridge SHM system with the integration of IoT techniques. An attempt has been made to perform a preliminary field test on a cable-stayed footbridge, where the fundamental frequency and the mode shape type of the footbridge were successfully identified and its serviceability condition was also found to satisfy the code requirements.

Evaluation of Using RDFT Method for Grid Synchronisation

The proposed work measures the accuracy of synchronization to grid using filtering technique. Where two algorithms of Recursive Discrete Fourier Transform (RDFT) are used, each one turned for a specific frequency. The algorithms are implemented using STM microcontroller. It is shown from the results, that this method can provide accurate calculations and can comply with the domestic standards of synchronisation. The need of such a method can be clear at load-side, as grid waveform can be distorted due to non-linear loads or heavy electronic loads with rectifier filter. Distorting grid with unwanted harmonics can make synchronisation difficult while using Zero Crossing Detectors (ZCD) or Phase Locked Loop (PLL). The RDFT tool, is fast and accurate method to detect waveform by filtering out undesirable perturbation. STM32F4 microcontroller was used to implemented the method and Results were obtained. The results show that using two RDFT method provides high accuracy in comparison to other.

Synchronization evaluation of digital twin for a robotic assembly system using computer vision

Synchronization evaluation of digital twin for a robotic assembly system using computer vision

A Lightweight, Polarization-Camera Equipped Sensor Rig for the Development of Autonomous Surface Vehicles

Abstract Situational Awareness (SITAW) of Autonomous Surface Vessels (ASV) is critical for safe and efficient maritime operations, enabling these vehicles to understand their environment better and make informed decisions. High-quality data sets from relevant maritime environments are needed to advance the development of SITAW, as it is both the backbone of any learning-based method and the development and validation of classical methods. Research vessels such as the full-scale ferry milliAmpere2 provide such data, but there tends to be a considerable labor cost associated with their operation. With this in mind, we have developed a portable sensor rig that makes collecting sensor data significantly easier. The sensor rig is designed for easy transport and operation by a single individual. It can also be temporarily attached to an existing vessel, making it versatile for a wide range of data collection scenarios. The sensor rig is equipped with a Jetson Orin AGX computer, two dual-band GNSS receivers, a high-quality IMU, and two color polarization cameras. Accurate synchronization of all sensors and the computer to UTC is achieved using a microcontroller for triggering and a custom Pulse Per Second (PPS)-enabled Linux kernel on the Jetson. The sensor rig is controlled and monitored by connecting a smartphone to its hosted web app, which provides a live stream from the cameras and information about the sensors. We present a new dataset from the river Nidelva in Trondheim, Norway, to demonstrate the sensor rig’s potential and the benefit of color polarization cameras in the maritime domain. We show how the data from color polarization cameras can be used directly to make the water surface more visibly distinct and remove reflections and sun glare. This new data set consists of synchronized stereo color polarization video, raw IMU data, and raw GNSS data, and it is made publically available to the research community.

A distributed PD detection method for high voltage cables based on high precision clock synchronization

A distributed PD detection method for high voltage cables based on high precision clock synchronization

Keeping Professional Displays in Sync

AbstractWith the high impact of video synchronization inaccuracies on the user experience, it is critical to optimize this aspect of the multi‐media experience especially in multiple‐tile, large‐format displays.

A new dual-thickness semi-transparent beamstop for small-angle X-ray scattering.

An innovative dual-thickness semi-transparent beamstop designed to enhance the performance of small-angle X-ray scattering (SAXS) experiments is introduced. This design integrates two absorbers of differing thicknesses side by side into a single attenuator, known as a beamstop. Instead of completely stopping the direct beam, it attenuates it, allowing the SAXS detector to measure the transmitted beam through the sample. This approach achieves true synchronization in measuring both scattered and transmitted signals and effectively eliminates higher-order harmonic contributions when determining the transmission light intensity through the sample. This facilitates and optimizes signal detection and background subtraction. This contribution details the theoretical basis and practical implementation of this solution at the SAXS station on the 1W2A beamline at the Beijing Synchrotron Radiation Facility. It also anticipates its application at other SAXS stations, including that at the forthcoming High Energy Photon Source, providing an effective solution for high-precision SAXS experiments.

Synchronous Tracking Control Strategy of Dual-Actuator Excited Shaking Table

The electro-hydraulic shaking table in the laboratory is specifically designed to replicate the desired earthquake ground motion for engineering structure, requiring precise synchronization of its dual exciters and accurate tracking of the target signal. The system faces challenges such as control errors and actuator asynchronization due to the nonlinear effects of the shaking table system and the structural model. To address the issues of inadequate tracking and synchronization accuracy, this study introduces a novel strategy for synchronizing the motion of the exciters and establishes a fuzzy logic controller (FLC) for the shaking table to minimize synchronization errors of dual exciters. Furthermore, an adaptive inverse controller (AIC) is developed for the exciters to enhance tracking accuracy. By combining FLC and AIC, this approach leverages the strengths of both control techniques to achieve superior control performance. The proposed control is implemented through MATLAB\Simulink, and numerical analyses are conducted under various conditions. The numerical results demonstrate the effectiveness and feasibility of the proposed control strategy.

An improved derivative‐based phase‐locked loop for single‐phase grid synchronization under abnormal grid conditions

SummaryGenerating a quadrature signal in a single‐phase system using a second‐order generalized integrator (SOGI) requires accurate frequency information. The standard SOGI phase‐locked loop (PLL) includes frequency feedback to the SOGI. However, during grid abnormalities such as voltage sag/swell and phase angle jumps, the SOGI‐PLL faces frequency disturbances that propagate to the phase detector (PD) and affects the quadrature signal generator (QSG). Furthermore, the SOGI‐PLL having two loops dependent on each other creates loop coupling phenomena; either a change in phase or frequency affects each other. SOGI‐PLL is tuning sensitive, as the SOGI block has a gain that needs to be adjusted, increases the complexity, and affects the performance of the system. There is a trade‐off between SOGI gain and PLL parameters that needs to be considered for adequate parameter design to provide accurate grid synchronization while maintaining the stability of the system. To attain better performance, researchers have proposed derivative‐based PLL (DPLL). The conventional DPLL faces challenges to noise and harmonics amplification. This paper presents an improved DPLL for single‐phase grid synchronization under adverse grid conditions. The improved derivative‐based PLL (IDPLL) comprises two improved derivative‐based quadrature signal generator (IDQSG) blocks to extract the phase‐error information for accurately estimating phase and frequency. The detailed mathematical modeling and bode plot for the IDQSG and IDPLL are presented. The proposed IDQSG eliminates the requirement of gain tuning, hence reducing complexity. Moreover, there is no interdependent loop in the IDPLL, which significantly improves the dynamic performance. A hardware setup is developed to evaluate the performance of the system in real‐time. The experimental results are obtained using an field programmable gate array (FPGA)‐based controller.

Characterization of Position Synchronous Control System for Double Hydraulic Cylinder

Background: There are some problems in the synchronous control system of electrohydraulic servo double hydraulic cylinders, such as uncertainty of system parameters, time variation, difference between two subsystems, and unbalanced load disturbance during operation. The above problems cause the output responses of the two cylinders to be inconsistent, resulting in the situation that the output flows of the two cylinders are not synchronized. Objective: Further improve the accuracy of synchronous control while reducing the cost of using synchronous control system. Methods: The AMEsim simulation model of electro-hydraulic servo dual-cylinder synchronous control system is established, and based on this model, the dynamic characteristics, coupling characteristics, and synchronization characteristics of the double-cylinder system are analyzed theoretically and simulated. Results: Analyze and verify the influence of various factors on the synchronization of double hydraulic cylinders, and summarize the influence law of the change of different factors on the output and synchronization accuracy of the double hydraulic cylinder system. Conclusion: This study analyzes the influence of various factors on the synchronization of double cylinders by adjusting the parameters, and summarizes the influence law of the change of different factors on the output and synchronization accuracy of the double cylinder system.

Timing Performance Testing and Regularity Analysis of eLoran System

Accurate time synchronisation is critical in modern communication, navigation, and scientific research. In this context, the eLoran receiver, which is an advanced timing device, has attracted increasing scholarly attention. This study aims to comprehensively analyse the performance and potential applications of eLoran systems for timing monitoring and to specifically explore the relevant indices of two eLoran receivers. To this end, we evaluated the performance of these receivers in receiving time signals through both simulated and empirical data and conducted a regularity analysis to uncover their potential value in practical applications. The findings demonstrate that the eLoran receiver excels at timing monitoring and provides highly accurate time information. An analysis of the timing performance of the eLoran system improved its accuracy and integrity.

Ultra-Low-Power Sensor Nodes for Real-Time Synchronous and High-Accuracy Timing Wireless Data Acquisition.

This paper presents an energy-efficient and high-accuracy sampling synchronization approach for real-time synchronous data acquisition in wireless sensor networks (saWSNs). A proprietary protocol based on time-division multiple access (TDMA) and deep energy-efficient coding in sensor firmware is proposed. A real saWSN model based on 2.4 GHz nRF52832 system-on-chip (SoC) sensors was designed and experimentally tested. The obtained results confirmed significant improvements in data synchronization accuracy (even by several times) and power consumption (even by a hundred times) compared to other recently reported studies. The results demonstrated a sampling synchronization accuracy of 0.8 μs and ultra-low power consumption of 15 μW per 1 kb/s throughput for data. The protocol was well designed, stable, and importantly, lightweight. The complexity and computational performance of the proposed scheme were small. The CPU load for the proposed solution was <2% for a sampling event handler below 200 Hz. Furthermore, the transmission reliability was high with a packet error rate (PER) not exceeding 0.18% for TXPWR ≥ -4 dBm and 0.03% for TXPWR ≥ 3 dBm. The efficiency of the proposed protocol was compared with other solutions presented in the manuscript. While the number of new proposals is large, the technical advantage of our solution is significant.

A modified dispersed frequency and phase consensus algorithm based on differential evolution and credibility weighting matrix

A modified dispersed frequency and phase consensus algorithm based on differential evolution and credibility weighting matrix

A Low-Computational Burden Closed-Form Approximated Expression for MSE Applicable for PTP with gfGn Environment

The Precision Time Protocol (PTP) plays a pivotal role in achieving precise frequency and time synchronization in computer networks. However, network delays and jitter in real systems introduce uncertainties that can compromise synchronization accuracy. Three clock skew estimators designed for the PTP scenario were obtained in our earlier work, complemented by closed-form approximations for the Mean Squared Error (MSE) under the generalized fractional Gaussian noise (gfGn) model, incorporating the Hurst exponent parameter (H) and the a parameter. These expressions offer crucial insights for network designers, aiding in the strategic selection and implementation of clock skew estimators. However, substantial computational resources are required to fit each expression to the gfGn model parameters (H and a) from the MSE perspective requirement. This paper introduces new closed-form estimates that approximate the MSE tailored to match gfGn scenarios that have a lower computational burden compared to the literature-known expressions and that are easily adaptable from the computational burden point of view to different pairs of H and a parameters. Thus, the system requires less substantial computational resources and might be more cost-effective.

High-Accuracy Phase Frequency Detection Technology Based on BDS Time and Frequency Signals.

For the time and frequency signals of Beidou satellites, a high-accuracy phase frequency detection technology based on phase group synchronization is proposed. Using the Beidou receiver and satellite signals as the frequency standard and the measured signals, respectively. The Beidou receiver and the satellite signals are sent to the phase coincidence detector of the different frequencies to generate a phase coincidence point pulse, which is sent to the different frequency phase detector as a control signal to generate the phase differences between the Beidou receiver and satellite signals, and then complete the high-accuracy phase synchronization between the Beidou receiver and satellite signals. Experimental results show that when the delay resolution reaches ps level, the phase synchronization accuracy of the system can reach 10 ps, which has the characteristics of small phase noise, low development cost, simple circuit structure, and high synchronization accuracy compared with the traditional phase synchronization technologies. Therefore, it would be widely used in satellite positioning, astrometry, precision navigation, aerospace, satellite launch, power transmission, communications, radar, and other high-tech fields.

Research on tracking and synchronization control of dual hydraulic cylinders based on improved active disturbance rejection control

To ensure the stability of vertical mold casting machine casting, and improve the quality of casting, for which the electro-hydraulic servo system of the traditional active disturbance rejection control(ADRC) of the nonlinear function is not smooth, a new type of nonlinear function is used. For the ADRC controller, there are too many adjustment parameters and complex engineering tuning, The snake optimization(SO) algorithm is used to adaptively tune the controller parameters, and the error can also be reduced. The simulation results show that compared with the PID controller and the traditional ADRC controller, the ADRC controller based on the Ifal function and SO has a certain jitter suppression effect as well as good tracking and synchronization performance, which can effectively improve the tracking and synchronization accuracy of the dual hydraulic cylinders of the electro-hydraulic servo system.

CRT-Based Clock Synchronization for Millimeter-Wave Communication with Asymmetric Propagation Delays

The rapid advancement of millimeter-wave communication technology has presented new challenges for time synchronization, driven by the need for high-speed and low-latency data transmission. Ethernet synchronization technologies, such as Precise Time Protocol (PTP), have emerged to overcome the limitations of point-to-point architecture and enable precise synchronization across multiple devices. A key drawback of conventional PTP is its reliance on symmetric packet exchange delays, which may not hold in real-world scenarios where there is relative mobility between master and slave nodes, leading to asymmetric propagation delays and clock offset errors. To address this issue, a novel clock synchronization protocol that integrates Chinese Remainder Theory (CRT) has been proposed. This protocol enhances conventional PTP by incorporating distance estimation based on CRT using multi-carrier phase measurement. By combining a coarse estimation of one-way propagation delay from conventional PTP with a fine estimation of remainder distance from CRT, the protocol accurately determines the distance between master and slave nodes, reducing motion errors and enhancing clock synchronization accuracy. Simulation results indicate that the Root Mean Square Error (RMSE) of distance estimation remains below 10−5 m, with a corresponding motion time error of approximately 0.01 picosecond.

Real-World Spatial Synchronization of Event-CMOS Cameras through Deep Learning: A Novel CNN-DGCNN Approach.

This paper presents a new deep-learning architecture designed to enhance the spatial synchronization between CMOS and event cameras by harnessing their complementary characteristics. While CMOS cameras produce high-quality imagery, they struggle in rapidly changing environments-a limitation that event cameras overcome due to their superior temporal resolution and motion clarity. However, effective integration of these two technologies relies on achieving precise spatial alignment, a challenge unaddressed by current algorithms. Our architecture leverages a dynamic graph convolutional neural network (DGCNN) to process event data directly, improving synchronization accuracy. We found that synchronization precision strongly correlates with the spatial concentration and density of events, with denser distributions yielding better alignment results. Our empirical results demonstrate that areas with denser event clusters enhance calibration accuracy, with calibration errors increasing in more uniformly distributed event scenarios. This research pioneers scene-based synchronization between CMOS and event cameras, paving the way for advancements in mixed-modality visual systems. The implications are significant for applications requiring detailed visual and temporal information, setting new directions for the future of visual perception technologies.

The Difference Between Expert Dancers' and Non-Dancers Tapping Timing With and Without an Auditory Stimulus at a Slow Tempo.

Our primary purpose in this study was to determine whether trained dancers differed from untrained non-dancers in their ability to accurately control motor timing during finger and heel tapping tasks, both with and without slow isochronous auditory stimuli. Dancers and non-dancers were instructed to synchronize their taps with isochronous auditory stimuli under three conditions: 30, 40, and 50BPM. After the synchronization phase, participants were asked to continue tapping without the auditory sequences. On the synchronization task, the tapping onset of both groups lagged behind the stimulus onset in all tempo conditions. In all conditions, dancers showed more accurate and stable beat synchronization and continuation than non-dancers. As the tempo condition slowed down (from 50 to 30BPM), synchronization accuracy decreased while synchronization and continuation variability increased. Unlike for novices, dancers showed no difference between the finger and heel tapping synchronization tasks. During the continuous tasks, their timing accuracy was higher for heel than for finger tapping. Collectively, these findings suggest that dance training, which involves synchronizing bodily movements based on rhythm, may lead to an accumulation of experience that enhances specific sensorimotor skills related to synchronizing movements with external stimuli or continuing rhythmic movements temporally.