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This paper describes research into improving IEEE 1588 synchronization accuracy when using 1000BASE-T, Gigabit Ethernet over copper wiring. It describes the possible sources of error in such a system, such as path asymmetries and non-deterministic delays, and proposed solutions for them. The methods described improve synchronization accuracy by enhancing the accuracy of timestamps of both ingress...
In smart grids, the deviation of frequency and phase angle serves as an important indicator of abnormal events, the detection of which is critical to maintain reliable and stable operations of the power grid. However, the high cost and low accessibility of current power grid monitoring systems restrict their large-scale deployment over highly distributed microgrids. In this paper, we present a practical...
We present an evaluation of the accuracy of an adherence monitoring add-on device (SmartTurbo v2.0, Nexus6 Limited, Auckland, New Zealand) designed to fit a commercial inhalation device (Turbuhaler®, dry powder inhaler, AstraZeneca). The evaluation has been based on simulated reallife placebo usage by 11 patients and carried out during a 12 day period. The simulated usage covered low and high inhalation...
In order to reduce the cost and acquire the microsecond-level time synchronization, this paper has proposed the DF-NTP (Double filter NTP) and analyzed the algorithm of NTP (network time protocol) and the causes of synchronization error. The precision of time synchronization can be raised through filtrating the delay in the forward-backward path and reducing the influence of uncertain delay. The experimental...
Nowadays, the growing presence of distributed energy resources (DER) makes the management of the distribution grid more complex, thus requiring distributed monitoring and controlling capabilities. The deployment of locally distributed intelligent devices over a large area involves a high performance network infrastructure (typically based on heterogeneous communication technologies) in order to provide...
The Linking Open Data (LOD) initiative has motivated numerous institutions to publish their data on the Web and to interlink them with those of other data sources. The structure makes it easier for both the users and the web applications to share the decentralized linked data. Since the data over the web changes frequently, maintaining link integrity to keep data consistency becomes a challenging...
According to the characteristics of smart substation, this text discusses the test process, contents and methods of smart substation secondary system. The emphases and difficulties of the test are also discussed.
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...
Utilizing service oriented architectures to enhance seamless collaborations and information sharing among nodes in mobile ad hoc networks with limited communication capability is a challenging task. In this paper a novel tree-based service discovery mechanism, able to achieve high accuracy in the process of service discovery, is proposed, which affords wireless communication overheads nearly linear...
Many large industrials operate internal co-generation systems to provide a substantial portion of their own power as well as to use the resulting output heat as part of their industrial process. Depending on the amount of co-generation, on loss of connection to the main grid or instability of the grid, these industrials may have the option of supplying all internal electrical loads from the co-generation...
Wide-area monitoring (WAM) applications for power distribution rely on accurate global time synchronization. Furthermore, there is interest in replacing current time synchronization methods such as Inter Range Instrumentation Group (IRIG), with distributed time synchronization protocols that utilize the data communication lines eliminating the need for dedicated timing signals within the substation...
Stride-related parameters of sprinters, such as split times (i.e. which is speed-related), foot contact times, stance times, stride/step length, and stride/step frequency, etc. are important factors which affect athletes' performances. Traditionally, this information is captured by biomechanics researchers and coaches using optical-based systems. However, these systems are expensive, time consuming...
We develop a novel technique to obtain the constellation diagram from asynchronously sampled data measured by using the delay-detection technique, and demonstrate the constellation monitoring of 10.7-Gsymbol/s DQPSK and D8PSK signals and the BER estimation.
The mass-target real time localization system has great potential applications. However, the indoor results in a complex radio environment; the people moving results in the time vary channel; and the mass people in the monitoring area cause the interference and collision. Therefore, there is a great challenge for deploying the low cost RF devices to implement high accurate localization system. In...
Time synchronization is the basic of distributed system, and also is one of the key techniques for solving time offset in space TT&C network. According to the low precision and the bad stability of time synchronization in Internet, this paper designs the scheme of time synchronization in space TT&C network, and proposes the server selection algorithm; finally, the paper proves that the algorithm...
One-way network delay is a critical parameter in VoIP as it allows the application to assess the perceived quality. However, it is well known that it is very difficult to measure one-way delay of the VoIP packets traversing the network. This is because the Internet architecture is based on the end-to-end principle in which the endpoints are connected to the network independently, typically without...
We present a 3-tier UWB-based indoor localization system. It consists of a large number of energy-scavenging-based cost-effective transmit-only tags, a small number of battery powered hubs as relay stations and a few base stations. This hierarchical scheme is driven by the energy available at each node. Localization is based on the arrival time of the UWB pulses at reference nodes.We describe how...
Time synchronization in wireless sensor networks (WSNs) is essential to coordinate activities distributed among different nodes. In recent years many protocols have been proposed to achieve high-accuracy synchronization. However, up to now only few researchers focused their attention on the issue of trading the number of periodic synchronization events for target accuracy. In fact, the synchronization...
To study and gain a better understanding of the power system dynamics, the concept of building a frequency monitoring network (FNET) was proposed in 2000 [1] and has been realized in 2003. The FNET system consists of many high dynamic precision frequency and phasor estimation devices, also known as frequency disturbance recorders (FDR). These FDRs can be used at any 110 V or 220 V wall outlet and...
A high bandwidth critical path monitor (1 sample/ cycle at 4-5 GHz) capable of providing real-time timing margin information to a variable voltage/frequency scaling control loop is described. The critical path monitor tracks the critical path delay to within 1 FO2 inverter delay with a standard deviation less than 3 FO2 delays over process, voltage, temperature, and workload. The CPM is sensitive...
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