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High accurate time synchronization is very important for many applications and industrial environments. In a computer network, synchronization of time for connected devices is provided by the Precision Time Protocol (PTP), which in principal allows for device time synchronization down to microsecond level. However, PTP and network infrastructures are vulnerable to cyber-attacks, which can de-synchronize...
In this work, an improved Precision Time Protocol (PTP) used to synchronize clocks in industrial Wireless Local Area Network (WLAN) communication systems is addressed. In order to enhance the accuracy of the PTP synchronization, we first provide an approach to remove the drift factor of frequency of crystal oscillators on the master and slave clocks without any additional message exchanges added to...
The recent breakthrough on power grid technologies was promoted by the emergence of phasor measurement units (PMUs), as they provide direct and high-rate data for analyzing and controlling the network. Time becomes critical however, since offsets in the internal clocks of PMUs render their data unreliable. In this context, the present work describes grid-wide implementation of a Precision Time Protocol...
Prototyping distributed embedded system can be seen as a collection of many requirements covering many domains. System designers and developers need to describe both functional and non-functional requirements. Building distributed systems is a very tedious task since the application has to be verifiable and analyzable. Architecture Analysis and Design Language (AADL) provides adequate syntax and semantics...
Today, local data networks, many last-mile access networks and even some backbone networks are based on packet transmission protocols, especially the Ethernet. Generally, there are several protocols and standards, which could be used for the purpose of clock distribution (synchronization) over packet networks. One of the most accurate protocols is Precision Clock Synchronization Protocol (PTP, IEEE...
Using the Precision Time Protocol (PTP) specified by the IEEE 1588 standard, synchronization of distributed clocks is achieved by propagating the timing information of a preselected master clock throughout the entire network. Based on this directly or indirectly obtained noisy timing information, each slave clock tries to follow as closely as possible the master time. This paper formulates the PTP...
Using IEEE 1588 for highly accurate clock synchronization between nodes of a distributed system has become a widely accepted approach. IEEE 802.3/Ethernet is frequently utilized as communication layer to exchange the Precision Time Protocol (PTP) messages specified in the IEEE 1588 standard. 10/100/1000 MBit Ethernet communication is commonly used by now. In contrast, fiber optics based 10 GBit Ethernet...
Wide-area monitoring (WAM) applications for power distribution rely on accurate global time synchronization. Furthermore, there is interest in replacing current time synchronization methods such as Inter Range Instrumentation Group (IRIG), with distributed time synchronization protocols that utilize the data communication lines eliminating the need for dedicated timing signals within the substation...
Assuring very accurate time synchronization across wide area industrial networks is still an open issue, which even the second version of the Precision Time Protocol (PTPv2) has not been able to solve completely. This is due to the accumulation of many uncertainty contributions when PTP event messages are routed from the master clock to the slave one through multiple network nodes. Peer-to-peer transparent...
The IEEE 1588-2008 Precision Time Protocol (PTP) defined in 2008 opens the possibilities to define profiles for specific application areas. The profiles for power system application and audio/video streaming have an importance beyond their initial application domain and may have to cohabit in the near future. As an example, the smart grid initiative taking place in the power system community will...
In this paper we consider the problem of time synchronization in collaborative environments of robots and intelligent sensors. Due to its superior performance, the Precision Time Protocol (PTP) has been implemented and tested using various topologies of complex, multi-hop networks. Two distinct approaches have been studied. The first one uses boundary clocks, while the second uses a transparent clock...
This paper analyzes the effects on synchronization performances of the accuracy of skew and offset estimates, the short and long-term stability of the unregulated clock, the rate at which timing information is exchanged within the network. The work makes use of a simulated clock based on the state-variable model, for which realistic parameters are obtained from experimental measurements of Allan variance...
Wireless sensor networks are evolving from relatively undemanding applications to applications which have stronger requirements. The coordination of distributed entities and events requires time synchronization. Although a number of methods have been studied for WSNs, some applications require high precision time synchronization. Precision time synchronization enables a variety of extensions of applications...
Precision Time Protocol (PTP) synchronizes clocks of networked elements by exchanging messages containing precise time-stamps. A master clock is carefully chosen to provide the reference clock to the rest elements in the network, called slaves. Using the time-stamps, slave element learns the relation between its own clock and the master clock so that it can synchronize its time to the reference time...
Precision time protocol (PTP) synchronizes clocks of networked elements by exchanging messages containing precise time-stamps. Based on the available timing information, different algorithms can be developed for the clock synchronization. This paper introduces a novel PTP-based method in which clock synchronization is formulated as a probabilistic inference problem and is solved by Kalman filtering...
The IEEE 1588 Precision Time Protocol seems to be a promising way to handle the synchronization requirements of tomorrow's substation automation based on IEC 61850. While a specific working group is tackling the security aspects of the protocols defined by IEC 61850, a secure IEEE 1588 protocol remains mostly uncovered in the specific context of substation automation. In this paper, we are focusing...
In order to improve the time synchronization precision to insure the communication timely, several types of clock synchronization methods were compared, analyzed the IEEE1588 clock synchronization system, discussed the PTP system software programming, introduced some source code transplanting methods, got the root cause of the low precision, provided three major improving methods, tested the improved...
This paper presents a telecom circuit-emulation system that uses the precision time protocol (PTP) aka IEEE1588 v2 for frequency distribution. In particular, a differential clock recovery mechanism is described that uses PTP as its reference clock based at one time on OCXO and at the other time on TCXO. A performance comparison is demonstrated for various test scenarios and compared against the stability...
The Precision Time Protocol (PTP) is an application layer protocol and therefore destined to be implemented in software. Hardware functions, if present, include a high resolution clock that helps to generate precise timestamps for PTP messages. The presented paper describes an IEEE 1588 clock that realizes syntonization and synchronization functions completely in hardware. It combines a three-port...
If all clocks within a distributed system share the same notion of time, the application domain can gain several advantages. Among those is the possibility to implement real-time behavior, accurate time stamping, and event detection. However, with the wide spread application of clock synchronization another topic has to be taken into consideration: the fault tolerance. The well known clock synchronization...
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