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Precision Time Protocol

About: Precision Time Protocol is a research topic. Over the lifetime, 604 publications have been published within this topic receiving 6006 citations. The topic is also known as: PTP & IEEE 1588.


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Patent
17 Feb 2010
TL;DR: In this article, a set of rules on node placement, such as Boundary Clock (BC) nodes and Sync-E nodes, a clock selection algorithm, a holdover algorithm, and the like are presented.
Abstract: The present disclosure relates to Ethernet synchronization systems and methods that combines Synchronous Ethernet (Sync-E) and Precision Time Protocol (PTP) IEEE 1588 algorithms. The present invention includes systems and methods for Ethernet networks and node configurations that include a set of rules on node placement, such as Boundary Clock (BC) nodes and Sync-E nodes, a clock selection algorithm, a holdover algorithm, and the like. Advantageously, the present invention provides an architecture that allows practical and real-world useful clock propagation through placement of BCs and Sync-E nodes for best performance. Practical experience and theoretical design are embodied in the present invention to define a very specific set of rules on how to build a network capable of providing accurate and reliable synchronization. The present invention includes clock selection that unifies Sync-E and 1588 algorithms.

62 citations

Journal ArticleDOI
TL;DR: To eliminate sawtooth errors that are peculiar to the 1PPS signals and optimally steer the clock errors each M seconds, the use of a ramp-predictive finite-impulse-response (FIR) filter that is known to be optimal for clock models on large averaging horizons is proposed.
Abstract: In this paper, we discuss optimal synchronization of local clocks using Global Positioning System (GPS) one-pulse-per-second (1PPS) timing signals. To eliminate sawtooth errors that are peculiar to the 1PPS signals and optimally steer the clock errors each M seconds, we propose the use of a ramp-predictive finite-impulse-response (FIR) filter that is known to be optimal for clock models on large averaging horizons. A low-pass filter is used to smooth the hold filter output between the optimally predicted points. A GPS-locked crystal clock has been investigated in detail in terms of the time interval error, Allan deviation, and precision time protocol (PTP) variance. A high-efficiency implementation of the proposed synchronization algorithm is experimentally demonstrated.

59 citations

Journal ArticleDOI
TL;DR: A new distributed architecture to measure synchrophasors in power substations, inspired by the standards IEC 61850 is proposed and suitably modified to have high performance also in terms of response time in presence of step change conditions.
Abstract: This paper proposes a new distributed architecture to measure synchrophasors in power substations, inspired by the standards IEC 61850 The new scheme is implemented in the process bus, where a high performance merging unit (MU), synchronized by precision time protocol (PTP), according to the standard IEEE 1588-2008, sends the sampled values (SVs) to an intelligent electronic device (IED) enabled to behave as a phasor measurement unit (PMU) The synchrophasors are evaluated in the IED through an algorithm based on the Taylor Fourier Transform and suitably modified to have high performance also in terms of response time in presence of step change conditions Different tests and considerations are presented to evaluate the various elements of uncertainty that a distributed architecture can introduce and, finally, to ensure the feasibility of the proposed approach

58 citations

Proceedings ArticleDOI
29 Aug 2009
TL;DR: The result established a method for nodes in a network to maintain their clocks to within a 200 nanosecond offset from the reference clock of a master node, which provides compatibility between heterogeneous systems in WSNs.
Abstract: 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. The IEEE 1588 precision time protocol (PTP) provides a standard method to synchronize devices in a network with sub-microsecond precision. This paper deals with precision time synchronization using IEEE 1588 over wireless sensor networks. Precision time synchronization using IEEE 1588 provides compatibility between heterogeneous systems in WSNs. This paper also presents experiments and performance evaluation of precision time synchronization in WSNs. Our result established a method for nodes in a network to maintain their clocks to within a 200 nanosecond offset from the reference clock of a master node.

56 citations

Journal ArticleDOI
TL;DR: The suitability of PTPv2 to synchronize sampling in a digital process bus is evaluated, with preliminary results indicating that steady-state performance of low-cost clocks is an acceptable 300 ns but that corrections issued by grandmaster clocks can introduce significant transients.
Abstract: Transmission smart grids will use a digital platform for the automation of high-voltage substations. The IEC 61850 series of standards, released in parts over the last ten years, provide a specification for substation communication networks and systems. These standards, along with IEEE Std 1588-2008 Precision Time Protocol version 2 (PTPv2) for precision timing, are recommended by both the IEC Smart Grid Strategy Group and the National Institute of Standards and Technology Framework and Roadmap for Smart Grid Interoperability Standards for substation automation. IEC 61850, PTPv2, and Ethernet are three complementary protocol families that together define the future of sampled-value (SV) digital process connections for smart substation automation. A time synchronization system is required for an SV process bus; however, the details are not defined in IEC 61850-9-2. PTPv2 provides the greatest accuracy of network-based time transfer systems, with timing errors of less than 100 ns achievable. The suitability of PTPv2 to synchronize sampling in a digital process bus is evaluated, with preliminary results indicating that steady-state performance of low-cost clocks is an acceptable 300 ns but that corrections issued by grandmaster clocks can introduce significant transients. Extremely stable grandmaster oscillators are required to ensure that any corrections are sufficiently small that time synchronizing performance is not degraded.

55 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202126
202045
201936
201839
201732
201654