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Conference proceedings front matter may contain various advertisements, welcome messages, committee or program information, and other miscellaneous conference information. This may in some cases also include the cover art, table of contents, copyright statements, title-page or half title-pages, blank pages, venue maps or other general information relating to the conference that was part of the original...
Synchronization of a Wireless Sensor Network is a crucial task and is based on a precise syntonization of all clocks within the network. The synchronization precision is usually closely connected to the positioning accuracy in networks for the purpose of localization. This paper introduces a concept, how the clocks of low-complexity stationary receivers can be adjusted to the same frequency with the...
End-to-end latency is critical to many distributed applications and services that are based on computer networks. There has been a dramatic push to adopt wireless networking technologies and protocols (such as WiFi, ZigBee, WirelessHART, Bluetooth, ISA100.11a, etc.) into time-critical applications. Examples of such applications include industrial automation, telecommunications, power utility, and...
In sensor network, ISO/IEC/IEEE 21451 standards attach significance for its provided communication and information models which facilitate the access of smart sensor to a network. As a distributed system, many applications and protocols in ISO/IEC/IEEE 21451 sensor network require common clock through time synchronization. Ensuring the security of time synchronization sets significant foundation to...
Distributed cyber-physical systems (CPS) are increasingly provided with an accurate and precise common sense of time using a variety of well established time distribution methods such as GNSS, IEEE 1588 and others. Less attention has been paid to the effective use of time in CPS and techniques and components to support such use. This paper reviews these topics and discusses critical components that...
In this paper an architecture for High-Availability Cyber-Physical Production Systems with sub-microsecond synchronization capabilities is presented. The proposed CPPS nodes are based on cost-affordable components. These CPPS can deal with most of the challenges set by Industry for a massive adoption of the distributed computing philosophy in critical systems like Smart-Grids or Advanced Manufacturing...
The micro grid is a cluster of electricity generators, energy storage systems, and loads that can operate connected, as well as disconnected, from the distribution grid. In this paper the time related characteristics of Cyber Physical Systems (CPCs) to be used for (IEC 61850-based) automation of micro grids are investigated. Specific constrains are taken into account as, for instance: the use of heterogeneous...
The precision time protocol (PTP) is fundamentally recommended in smart substations, which could potentially result in further weakening the power system. However, defects of domestic PTP devices restrict the spread of the application of PTP in smart substations. In this paper, the computation of the PTP offset in different clock modes from the two editions of 1588 standards is analyzed theoretically...
Wide Area Protection (WAP) system is a protection system based on wide area synchronized power grid information through network communication. It can determine fault location and clear fault selectively and quickly. This paper first lists several problems solved by WAP technology, and Guizhou Duyun WAP project is taken as an example to illustrate the engineering experience in this area. Considering...
The receiver system is an important part of FAST (Five-hundred-meter Aperture Spherical Radio Telescope) and plays a key role in determining the performance of the telescope. The receiver design requires synchronization among the digital instruments and accurate timestamp, because time synchronization of astronomical data before and after it is recorded and processed is of vital importance for the...
This article discussed the time synchronization performance monitoring system in the scope of 1588v2 telecom profile and presented three monitoring system modes: Master-slave monitoring (node-by-node monitoring), Passive-node monitoring on loop topology network (segmental monitoring), and multicast + unicast monitoring (full-path monitoring). The article detailed three monitoring modes' implementation,...
Differ to the IEEE 1588v2, ITU-T G.8275.1 network has two different synchronization planes, frequency source and time source. We think that the best clock selection principle should originate from co-action of the frequency and PTP. Compared with the current G.8275.1 schemes, good synchronization performances have been obtained by using G.8275.1+ which is revised by ChinaUnicom.
The phenomenon of timing loop appeared in the 1588 networks during the laboratory-testing at Chinaunicom. This article focused on the origin of timing loop, and drew a conclusion that passive state would not prevent the timing loop effectively in the 1588 networks. Remedial measures were presented in the article. It was proposed that the function of path trace attribute should be applied upon the...
Many network applications like motion control or precise monitoring of machines need precise knowledge about the time synchronization accuracy. But time synchronization accuracy depends on the performance of PTP nodes, network topology, environmental conditions and various other factors. This makes the determination of synchronization accuracy a complex task. A mechanism for determining the worst...
This paper describes research into improving IEEE 1588 synchronization accuracy when using 1000BASE-T, Gigabit Ethernet over copper wiring. It describes the possible sources of error in such a system, such as path asymmetries and non-deterministic delays, and proposed solutions for them. The methods described improve synchronization accuracy by enhancing the accuracy of timestamps of both ingress...
With the increasing deployment of large-scale distributed packet networks in the industry, highly reliable and precise clock synchronization gains even more importance to ensure timeliness of the exchanged datagrams. Design for reliability, robustness and availability should optimally be taken into account for the architecture of the synchronization subsystem as high-level redundancy schemes are limited...
IEEE 1588 is a promising way of time synchronization in control systems that include IT. Intermediate devices such as network switches are needed when the control systems are built on a multi-hop network for wide area operations. However, the introduction of switches causes conflicts between the reply packets from the devices in a switch, and thus, the delays on the backward and forward paths would...
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