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With the development of digitization of substation, the future trend of on-line monitoring system of substation power equipment is adopting the IEC61850 standard to realize seamless communication. However, the change of distance and node make synchronization precission of samples transmission become a problem. An implementation method based on the IEEE1588 standard is proposed, by use of DP83640 Ethernet...
Time synchronization is the basis of real-time connecting in distributed battle simulation systems, which is an important issue for battle simulation. The time management of HLA and approaches of time synchronization in distributed battle simulation systems are introduced, and then grounded on the analysis of time synchronization on real-time connecting, the approach of RTXTimer-based time synchronization...
There is an increasing demand on accurate time synchronization for protection and control equipment for the electrical power supply system. Today, with the proliferation of Ethernet networks in the substation automation systems, mainly driven by other standards as IEC 61850, time distribution over these networks appears to be especially appealing. NTP was already specified in IEC 61850 as time distribution...
The IEEE 1588 standard is widely established and accepted for clock synchronization in Ethernet networks. High accuracy IEEE 1588 implementations require a well-coordinated hardware/software co-design. Processing of sophisticated control algorithms for the time speed of local clocks within synchronization slaves are particularly important. Hence, IEEE 1588 implementations should be tested with respect...
The key point of the existing Ethernet test and measurement is that the method needs to achieve precision clock synchronization between different terminals. In this paper, an improved method was proposed with consideration of the time drift and propagation delay, expressing master-slave synchronization as a linear relationship and inducting the line of least squares fitting algorithm that traded as...
EtherCAT is a real-time Ethernet protocol conceived for industrial environments, which is characterised by high communication efficiency. It is provided with a suitable mechanism, known as distributed clock, that enables synchronised operations to be carried out with precise timings. This can be profitably adopted, for instance, in motion control applications. In this paper, the accuracy of the distributed...
Communication redundancy and time synchronization are two important requirements commonly found in industrial systems. However, achieving high redundancy performance in combination with highly accurate time synchronization at all times is a challenging task. EtherCAT is a high performance, functionality rich communication technology offering both advanced redundancy features and accurate time synchronization...
It requires accurate synchronization among the MCU, servo controllers and sensors in CNC systems for time stamping of data and motion control. This paper presents the design and implementation of time synchronization for CNC systems which employ switched Ethernet as its communication module. The method adopts the clock of switches as the master clock instead of that of MCU which usual is. To obtain...
This paper focuses on the synchronization between master clock and slave clock in the Distributed clock of EtherCAT. It supports very accurate synchronization function which let local slaves follow reference time under the degree of few nano second differences. However, there exists the propagation delay between reference clock and slave clock. To remove the delay, EtherCAT uses the static compensation...
We study a performance improvement technique for the IEEE 1588 time synchronization system for Ethernet mobile backhaul. We propose and demonstrate the queuing delay estimation method by using dedicated probing packets to mitigate time synchronization deterioration caused by queuing delay in a packet switch. The demonstration results by numerical simulation show that the proposed method is effective...
Hardware-timestamping is essential for achieving tight synchronization in networking applications. This mechanism is selectively used on few high-cost tailored systems. Actual muP-based implementations fail on deterministic timestamp retrieval and insertion inside the message. This problem degrades significantly the synchronization between network nodes. This paper describes the analysis, implementation,...
Assisted-GNSS (A-GNSS) is an innovative technology intended to allow the use of GNSS (Global Navigation Satellite Systems) signals indoor or in environments in which the GNSS signal in space (SIS) is heavily attenuated or masked. Aiding is provided in the form of data that can be broadcast to the users via a variety of means, but primarily via the ubiquitous wireless telephone. ESA has tasked the...
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 article addresses issues with the design and implementation of systems using the IEEE 1588 standard, which provides a new synchronization scheme for next-generation telecommunications networks. With a focus on achieving high accuracy in the real network environments, key features introduced in the new version of the standard and the exact causes and practical handling of time errors are discussed...
We propose a simple and precise time distribution technique utilizing multipoint control protocol in EPON, and also experimentally demonstrate time transfer within plusmn100 ns and frequency synchronization within plusmn10-10.
In the three years since the introduction of the LXI specification, test system designers have quickly embraced the technology and have rapidly integrated the platform into new and existing system designs. Instrument manufacturers are motivated to satisfy the initial demand for LXI-based products as quickly as possible. The result has been an influx of instruments that meet the minimum Class C requirements...
Time and frequency alignment is critical for ensuring QoS for applications such as voice, real-time video, wireless hand-off, and data over a converged access medium. To satisfy the accuracy of time synchronization, propagation delay measurement is required between time-sensitive devices. There is existing network technology for time synchronization, such as network time protocol (NTP), IEEE 1588...
Effects of improved channel estimation are studied for a proposed IEEE 802.11n OFDM MIMO system. Three channel estimation methods are considered: maximum likelihood (ML), time-domain truncation (TDT) and model-based (MB). TDT and MB are particularly useful when the channel delay spread is short. For an MMSE receiver, MB shows a 1-2.5 dB improvement over ML on the packet error rate performance for...
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