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.

Trusted GNSS-Based Time Synchronization for Industry 4.0 Applications

Abstract: The protection of satellite-derived timing information is becoming a fundamental requirement in Industry 4.0 applications, as well as in a growing number of critical infrastructures. All the industrial systems where several nodes or devices communicate and/or coordinate their functionalities by means of a communication network need accurate, reliable and trusted time synchronization. For instance, the correct operation of automation and control systems, measurement and automatic test systems, power generation, transmission, and distribution typically require a sub-microsecond time accuracy. This paper analyses the main attack vectors and stresses the need for software integrity control at network nodes of Industry 4.0 applications to complement existing security solutions that focus on Global Navigation Satellite System (GNSS) radio-frequency spectrum and Precision Time Protocol (PTP), also known as IEEE-1588. A real implementation of a Software Integrity Architecture in accordance with Trusted Computing principles concludes the work, together with the presentation of promising results obtained with a flexible and reconfigurable testbed for hands-on activities.

Substation device clock synchronization improving method

Abstract: The invention discloses a substation device clock synchronization improving method. The method comprises following steps of step 1, calculating the frequency offset of a local clock; solving the maximum likelihood estimation value of the frequency offset eta of the local clock; step 2, calculating the phase offset of the local clock; calculating the average value of N times of clock synchronization phase offsets phik as a phase offset value phi; step 3, compensating the crystal oscillator natural frequency of the local clock; and step 4, compensating the local clock. For that when the network load of an intelligent substation is relatively high, network transmission round-trip delays are asymmetric, correction of the local clock through one-time clock synchronization according to a conventional precision time protocol PTP is relatively high in error, the invention provides the substation device clock synchronization improving method; and according to the method, through adoption of a statistics method, after many times of time synchronization, the optimum solutions of the frequency offset and phase offset errors of the local clock are calculated, and further compensation is carried out.

Time synchronous method in residential ethernet system

Abstract: A time synchronization method in a residential Ethernet system is provided to synchronize time of day information of respective node devices in a timing master in the residential Ethernet system to minimize transmission delay. A PTP(Precision Time Protocol) message frame for synchronizing times in respective nodes in a residential Ethernet system includes a preamble field(31), a DA(Destination Address) field(32), an SA(Source Address) field(33), a type field(34), a PTP message field(35), and an error correction field(36). The preamble field consists of eight-byte data. The DA field consists of 6-byte data and represents a source MAC(Media Access Control) data. The type field consists of 2-byte data and defines a data type. The PTP message field includes a PTP message to be transmitted. The error correction field consists of 4-byte data and checks an error in a transmission frame.

PTP interworking 802.15.4 using 6LoWPAN

Abstract: Network Time Protocol (NTP) and Precision Time Protocol (PTP) have been used for time synchronization in many year. These protocols are not appropriated for IP over 802.15.4 like heterogeneous network because these are using Ethernet. To cope with this difficulty, we proposed IP over 802.15.4 time synchronization using 6LoWPAN (IPv6 over Low power Wireless Personal Area Networks) we could get accurate and precision time synchronization due to sending single packet. We implement IP over 802.15.4 FPGA board.

Transparent clock characterization using IEEE 1588 PTP timestamping probe

Abstract: As new application areas like SmartGrids and 4G cellular mobile backhaul networks emerge, requirements on precision of the frequency and time synchronization increase. IEEE 1588v2 Precision Time Protocol (PTP) offers sub-microsecond synchronization precision using conventional Ethernet networks. In practical network scenarios the PTP performance is greatly reduced due to varying queuing latencies introduced by the network's switching and routing devices. This drawback has been overcome with the introduction of network devices with a Transparent Clock (TC) functionality defined in the IEEE 1588v2 PTP standard. As different vendors use proprietary implementations of the TC mechanism, it becomes essential to characterize TC's accuracy. Literature survey revealed that so far two measurement techniques have been proposed for that purpose, however, a comprehensive study of the measurement's error with regards to hardware imprecisions have not yet been published. In this paper we provide a thorough mathematical analysis with respect to hardware limitations of the TC measurement techniques and based on this analysis measurement calibrations are introduced. Moreover, we propose a new measurement setup that requires less expensive hardware yet maintains similar precision to prior art techniques. The new setup is provided with a detailed proof of concept and an experimental verification through measurements.