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IEEE 802.1 Audio/Video Bridging and Time-Sensitive Networking
Published in Richard Zurawski, Industrial Communication Technology Handbook, 2017
Wilfried Steiner, Norman Finn, Matthias Posch
The purpose of a clock synchronization protocol is to bring local clocks in the end stations and bridges into close agreement, such that at any point in real-time, two nonfaulty clocks in end points or switches will read approximately the same local computer-time. The clock synchronization protocol of TSN/AVB is standardized as IEEE 802.1AS and is significantly overlapping with the IEEE 1588 standard. We give an overview of IEEE 802.1AS and currently discussed improvements to it in the following. A more detailed introduction to IEEE 802.1AS is given by Garner et al. in [3].
Time-Triggered Communication
Published in Richard Zurawski, Networked Embedded Systems, 2017
TT Ethernet is based on a uniform 64-bit binary time-format that is based on the physical second. Fractions of a second are represented as 24 negative powers of two (down to about 60 ns), and full seconds are presented in 40 positive powers of two (up to about 30,000 years). This time format has been standardized by the object management group (OMG) in the smart transducer interface standard [EHK+05]. The time format of TT Ethernet is closely related to the time-format of the General Positioning System (GPS) time, but has a wider horizon. The similarity to the GPS time-format facilitates external clock synchronization using a GPS receiver.
Timing Synchronization System on RF-Driven Neutral Beam Injection System
Published in Fusion Science and Technology, 2022
Y. Li, C. D. Hu, Y. Z. Zhao, Q. L. Cui, X. L. Shu, Y. H. Xie, W. Liu
Network time synchronization refers to synchronizing the clock of each node to a stable and high-precision time source through the network so that the whole system can achieve clock consistency. At present, the network clock synchronization system generally uses the Network Time Protocol (NTP); the synchronization accuracy can reach only millisecond level. NTP is a protocol based on TCP/IP and User Data Protocol (UDP) network transmission and adopts the method of application layer synchronization for network time synchronization. The synchronization protocol is mainly defined by RFC 1305, “Network Time Protocol (Version 3) Specification, Implementation and Analysis.” It can solve the time synchronization problem between devices on complex network topologies. For some systems with low time synchronization accuracy requirements, using NTP for time synchronization is more economical and practical, and the implementation method is relatively simple.
Design and FPGA based Implementation of IEEE 1588 Precision Time Protocol for Synchronisation in Distributed IoT Applications
Published in Australian Journal of Electrical and Electronics Engineering, 2022
Aamir Sohail Nagra, Irfan Allahi, Muhammad Adeel Pasha, Shahid Masud
Time or clock synchronisation is an important aspect in distributed networks to maintain the correctness and predictability of the system. Clock drifts in geographically sparse networks can cause serious issues in systems that rely on ordered sequential events occurring at specified time instants. To address this requirement, time synchronisation protocols are utilised within a network. These protocols ensure that each node has the same reference time stamp for predictable communication. IEEE 1588 protocol was introduced in 2008 to provide an effective method and high precision for clock synchronisation in wired distributed networks. The high bandwidth and reliability of Ethernet protocol make it the most popular network communication for LAN. In order to provide timing synchronisation in Ethernet, the industry has developed a Network Time Protocol (NTP) to improve the timing synchronisation between different network devices. Traditional NTP can only provide millisecond-level time precision and cannot meet the accuracy requirements of modern high-speed applications in instruments and industrial process controls (Wallner, Wasicek, and Grosu 2016; Allahi et al. 2018).
Precise Clock Management Technology of Electric Power Meter
Published in IETE Journal of Research, 2021
Shangmin Qi, Yongchao Wang, Wei Zhang, Ning Li, Shenghui Guo, Darong Huang
With the increasing complexity of the power system network structure and the increasing degree of automation of the power system, the demand for the uniformity of the clock of the electricity information collection system is more and more urgent [1–4]. The traditional on-site manual time synchronization or infrared handheld time correction method is time-consuming and labour-intensive. Therefore, a series of new technologies in the power system have been proposed and applied, such as the Phasor Measurement Unit (PMU) system. This system is used to provide phasor information with a global synchronous time stamp and provide data for dynamic state estimations as well as online steady-state analysis of power systems [5–6]. As an important part of the synchronous phasor measurement system, the clock synchronization technology provides stable and high-precision standard clock synchronization signals to ensure the unity and coordination of the phasor measurement system. In the current power systems, there are two main ways to achieve clock synchronization in the wide-area network, broadcast clock synchronization and the use of high-precision GPS timing module clock synchronization in the entire network. Broadcast clock synchronization is currently widely used in substation automation systems, and the cost is also low [7,8]. However, due to the delay errors in the propagation process, it is difficult to ensure the timing accuracy of the broadcast clock synchronization method, which limits the application of new technologies such as synchronous phasor measurement of the entire network in the power systems [9]. In recent years, with the development and popularization of GPS technology, the use of high-precision GPS timing module-based clock synchronization methods in the entire network has been rapidly developed in synchronous phasor measurement of power systems [10–12].