Topic
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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17 Apr 2013
TL;DR: In this paper, a method and a device for selecting a clock source from the master clock equipment is presented. But the method comprises the following steps that: slave clock equipment receives a PTP (precision time protocol) message which is transmitted by master clock devices; after the PTP message is received, a hop count passed by the PTLT message is obtained; and according to the hop count obtained, the clock source is selected from the clock devices.
Abstract: The invention discloses a method and a device for selecting a clock source. The method comprises the following steps that: slave clock equipment receives a PTP (precision time protocol) message which is transmitted by master clock equipment; after the PTP message is received, a hop count passed by the PTP message is obtained; and according to the hop count passed by the PTP message, the clock source is selected from the master clock equipment. When the PTP message passes through an IP (internet protocol) and/or MPLS (multiple protocol label switching) network for frequency synchronization, by analyzing the TTL (time to live) value of the message, the slave clock equipment can obtain the hop count passed by the message, the hop count is used as a reference factor for a BMC (best master clock) algorithm, the slave clock equipment can select the clock source more optimally for synchronization, and the synchronization performance and the synchronization accuracy of the slave clock equipment are improved.
5 citations
01 Sep 2014
TL;DR: A solution inspired by the Precision Time Protocol (PTP) for achieving this lockstep transmission and preliminary results showing the precision with which the masters can synchronize the masters on a software prototype are presented.
Abstract: For a distributed embedded system (DES) to operate continuously in a dynamic environment, it must be flexible and highly reliable. This applies in particular to its communication subsystem. The Flexible Time-Triggered Replicated Star for Ethernet (FTTRS) aims at providing such a subsystem by means of a highly-reliable switched-Ethernet architecture based on the Flexible Time-Triggered paradigm (FTT), a master/slave communication paradigm where the master periodically polls the slaves using so-called trigger messages (TMs). In particular, FTTRS interconnects nodes by redundant communication paths provided by two switches, each embedding an FTT master that manages the communication. This allows FTTRS to tolerate the failure of one switch without interrupting the communication as long as the masters are replica determinate, i.e., provide identical service to the slaves. The master replica determinism entails the masters broadcasting their TMs in a lockstep fashion: when one master broadcasts a TM, the other should do the same quasi-simultaneously. In this paper we present a solution inspired by the Precision Time Protocol (PTP) for achieving this lockstep transmission and preliminary results showing the precision with which we can synchronize the masters on a software prototype.
5 citations
20 Apr 2009
TL;DR: To eliminate sawtooth errors peculiar to the 1PPS signals and optimally steer the clock errors each M seconds, a ramp predictive finite impulse response (FIR) filter that is known to be optimal for clock models on large averaging horizons is proposed.
Abstract: We discuss optimal synchronization of local clocks by the Global Positioning System (GPS) one pulse per second (1PPS) timing signals. To eliminate sawtooth errors peculiar to the 1PPS signals and optimally steer the clock errors each M seconds, we propose using 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 demonstrated experimentally.
5 citations
TL;DR: A solution has been designed that distributes the clock from the IEEE 1588 timing card to all FlexRIO devices and increases the functionality of the NIRIO EPICS Device Support and can be included with the nominal device support that is a generic EPICS driver for every device type in the CODAC CORE System.
5 citations
01 Nov 2016
TL;DR: This paper proposes to use Timed Colored Petri Nets (TCPN) to model PTP and formally represent with temporal dimension and will verify the model by means of simulation techniques.
Abstract: Precision Time Protocol (PTP) is clock synchronization protocol that is used in computer networks. It is one of the most widely used clock synchronization protocol in the domains where the high degree of precision is required. Accuracy of the PTP goes in the sub-microsecond range. A lot of works have been done for verification and simulation of the protocol. There are still lacks of formal model representations of the PTP in temporal interactions aspects. This paper proposes to use Timed Colored Petri Nets (TCPN) to model PTP and formally represent with temporal dimension. We will verify the model by means of simulation techniques.
5 citations