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.

Subnanosecond synchronization method based on the synchronous Ethernet network

Abstract: Ethernet networks, which are widely used today in the automation of various radio electronic devices, can be used to transmit time synchronization signals. Existing Ethernet networks can be used to synchronize devices. However, the devices have to support special protocols at the hardware level. A time synchronization algorithm based on the Precision Time Protocol (PTP, IEEE 1588-2008) is considered, which can be used in any data transmission network with a deterministic delay in the transmission line. The use of this protocol in synchronous Ethernet networks allows achieving subnanosecond accuracy of time synchronization between the devices. Hardware and software implementation as well as the results of measuring the synchronization accuracy with multiple system restarts and phase noise measurement are presented.

Design and Hardware Implementation of Improved Precision Time Protocol for High Speed Automotive Wireless Transmission System

Abstract: In this paper, a proposed hardware architecture implementation of more accuracy Precision Time Protocol (PTP) is presented. This approached design can be integrated into the wireless communication system for factory automation (FA) devices. In order to increase the closeness of the PTP harmony, we propose two approaches to improve the accurate synchronization to the nanosecond level by reducing the effects of asymmetric path delays of transmissions between master (MS) and slave (SL). The first one is the PTP protocol implementation at PHY layer to remove the random transmission jitters caused by higher layers. The second one is the full hardware implementation to remove the imbalanced timing made by the uneven hardware designs between MS and SL. Besides, a low overhead 3-frames exchange PTP approach to increase throughput of the transmission system is presented. We also implement successfully the PTP hardware design architecture and the SoPC of PHY-MAC and PTP integration system.

Integration of high-speed visual and tactile sensors with synchronization in a sensor network system

Abstract: In this paper, we propose a data acquisition synchronization scheme for integrating 500-fps class high-speed networked visual and tactile sensors systems. In the proposed scheme, multiple sensor nodes including PCs are connected via Ethernet for data communication and for clock synchronization. The clocks of the PCs are synchronized over the network using Precision Time Protocol (PTP) with negligible errors of around a few microseconds. The trigger of each sensor is locally controlled based on the PC's clock locally provided in the node, and the clocks are globally synchronized over the network. An experimental system comprising a high-speed vision system, a high-speed tactile sensor, and two PCs was constructed, and the experimental results showed that the timing error between the sensor nodes for data acquisition was less than 15 microseconds, which is significantly smaller than the time interval of 2 milliseconds.

Assessment of real-time networks and timing for process bus applications

Abstract: Widespread adoption by electricity utilities of Non-Conventional Instrument Transformers, such as optical or capacitive transducers, has been limited due to the lack of a standardised interface and multi-vendor interoperability. Low power analogue interfaces are being replaced by IEC 61850 9 2 and IEC 61869 9 digital interfaces that use Ethernet networks for communication. These ‘process bus’ connections achieve significant cost savings by simplifying connections between switchyard and control rooms; however the in-service performance when these standards are employed is largely unknown. The performance of real-time Ethernet networks and time synchronisation was assessed using a scale model of a substation automation system. The test bed was constructed from commercially available timing and protection equipment supplied by a range of vendors. Test protocols have been developed to thoroughly evaluate the performance of Ethernet networks and network based time synchronisation. The suitability of IEEE Std 1588 Precision Time Protocol (PTP) as a synchronising system for sampled values was tested in the steady state and under transient conditions. Similarly, the performance of hardened Ethernet switches designed for substation use was assessed under a range of network operating conditions. This paper presents test methods that use a precision Ethernet capture card to accurately measure PTP and network performance. These methods can be used for product selection and to assess ongoing system performance as substations age. Key findings on the behaviour of multi-function process bus networks are presented. System level tests were performed using a Real Time Digital Simulator and transformer protection relay with sampled value and Generic Object Oriented Substation Events (GOOSE) capability. These include the interactions between sampled values, PTP and GOOSE messages. Our research has demonstrated that several protocols can be used on a shared process bus, even with very high network loads. This should provide confidence that this technology is suitable for transmission substations.

Synchronized High-Speed Vision Sensor Network for Expansion of Field of View.

Abstract: We propose a 500-frames-per-second high-speed vision (HSV) sensor network that acquires frames at a timing that is precisely synchronized across the network. Multiple vision sensor nodes, individually comprising a camera and a PC, are connected via Ethernet for data transmission and for clock synchronization. A network of synchronized HSV sensors provides a significantly expanded field-of-view compared with that of each individual HSV sensor. In the proposed system, the shutter of each camera is controlled based on the clock of the PC locally provided inside the node, and the shutters are globally synchronized using the Precision Time Protocol (PTP) over the network. A theoretical analysis and experiment results indicate that the shutter trigger skew among the nodes is a few tens of microseconds at most, which is significantly smaller than the frame interval of 1000-fps-class high-speed cameras. Experimental results obtained with the proposed system comprising four nodes demonstrated the ability to capture the propagation of a small displacement along a large-scale structure.