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This article introduces the eLoran timing system principle, the characteristics of the eLoran and GNSS systems, and the current development status of eLoran in China. This article elaborates on the significance and scale of this high-precision ground time service system currently being constructed in China and describes the technical methods used in the high-precision ground time service system. Finally, it analyzes and elaborates on the signal and data channels of the eLoran time service system. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geodesy & Geodynamics (1671-5942) is the property of Editorial Board Journal of Geodesy & Geodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article introduces the eLoran timing system principle, the characteristics of the eLoran and GNSS systems, and the current development status of eLoran in China. This article elaborates on the significance and scale of this high-precision ground time service system currently being constructed in China and describes the technical methods used in the high-precision ground time service system. Finally, it analyzes and elaborates on the signal and data channels of the eLoran time service system.

LitPOS (Lithuanian Positioning System), the network of continuously operating GNSS (Global Navigation Satellite System) stations, became operational in July 2007. It provides data both for real-time and post-processing applications. LitPOS stations cover the whole territory of Lithuania. There are 31 of LitPOS GNSS stations in total network. Also LitPOS network includes 3 ASGEUPOS (Poland) and 6 LATPOS (Latvia) stations. LitPOS network data processing and analysis of station’s velocities was done using Bernese 5.2, TSview and CATREF programs. Results of analysis show that North/East velocities of the LitPOS stations are very homogeneous what leads to the conclusion that there are no any significant horizontal deformations of Earth’s crust in the territory of Lithuania. Up components of LitPOS stations velocities fit very well to vertical movements of Earth’s crust as described by the land uplift models of Fennoscandia.

The aim of the paper is to analyse the length of time that ships spend in the Port of Gdansk. It is based on the examination of the time when ships come into and leave the port. Source of data used in the study is public web platform - Marine Traffic. Analysis which was conducted, enables to get information about duration of ships servicing in the port with a division into dimension, load capacity and type of the ship. Due to that information, it is possible to observe the duration of complete service for each vessel, including entering the harbour, reloading and the departure. Gained knowledge would allow to forecast, plan and model future development operations more properly. In addition, due to the method based on counting the number of hours that ships spend in the harbour, it is possible to estimate the amount of pollution emitted to the air.

Modern technical ship systems very often use information and communication technologies. One of the basic requirements of these systems is ensuring time synchronization that aim is to coordinate clocks of all devices working in a computer network. This requirement results from, among others, the necessity to log events with a unified timestamp. To achieve this goal, most frequently expensive time servers are used. This article presents an easy method of time synchronization, which can serve as a reserve or alternative solution to the methods currently used. That is why a proprietary software has been developed, allowing to expand the functionality of a PC so that it can operate as a time server. A time reference in proposed solution would be provided by a GPS receiver. The developed application allows, with the use of the NMEA protocol, to synchronize the current time with the GPS receiver and then, with the help of the SNTP protocol, to distribute it to all network devices operating on the ship.

Copyright of Museologia e Patrimônio is the property of Museologia e Patrimonio and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper I have researched the life of Captain O'Reilly while he was living and working in Brisbane, but particularly focusing upon his astronomical activities. In order to better accomplish this, I needed to learn something about the man himself. I became very impressed with his attributes - competent, capable and courteous - and feel sadness that he was not allowed (dying as he did at 52) a couple more decades of life. He left a fine legacy. In my view he can be regarded as the first Queensland (non-indigenous) astronomer. My thanks go to Steve Hutcheon for his indefatigable research efforts; Bill Kitson, former Senior Curator of the Queensland Museum of Lands, Mapping and Surveying; the descendants of Henry O'Reilly; the State Library of Queensland; and especially the 'Trove' service, which has made so much material from early newspapers and publications so readily accessible on the internet. [ABSTRACT FROM AUTHOR]

With the advent of a new Precision Time Protocol specification, new opportunities abound for clock synchronization possibilities within power grid control systems. The third iteration of the Institute of Electrical and Electronics Engineers Standard 1588 specification provides several new features specifically aimed at complex, wide-area deployments in which situational awareness and control require precise time agreement. This paper describes the challenges faced by existing technology, introduces the new time distribution specification, and provides examples to explain how it represents a game-changing innovation.

A voice enhancement algorithm based on the Empirical Mode Decomposition (EMD) and the improved spectral subtraction is proposed for the low-SNR (Signal Noise Ratio) shortwave time signal. This method is proposed to solve the problem that the shortwave time signal cannot be used for timing in complex noisy environments. The core idea of this method is to use the Hilbert-Huang Transform (HHT) algorithm to make the empirical mode decomposition on the noisy shortwave signal, and to select the intrinsic mode functions containing the shortwave signal information for the signal reconstruction by through the maximum correlation. Then, to make the spectral subtraction on the reconstructed signal to achieve the purpose of noise reduction. The experimental result shows that this method has a better noise reduction than the traditional methods. [ABSTRACT FROM AUTHOR]

The H2020 DEMETRA project provides short latency clock monitoring services to the time users using the Atomium precise point positioning (PPP) software developed by the Royal Observatory of Belgium. In this paper, three recent updates of the current Atomium software are introduced: adding Galileo signals in the PPP computation; the option to constrain the receiver clock; PPP with integer ambiguity resolution. The advantages of these updates are demonstrated: Combining the Galileo and global positioning system (GPS) signals for PPP time transfer will further improve the frequency stability inside the computation batch; PPP with receiver clock constraint is not only used to reduce the short-term noise of the clock measurements but can also be used for some specific applications to a keep continuous clock solution in the computation batch or retrieve correct clock measurements from extremely noisy environments; the integer PPP allows a continuous clock solution, and improves the mid-term and long-term stability of the frequency transfer compared to the current PPP frequency transfer techniques.

SUMMARY We present a new software-based clock synchronization scheme that provides high precision time agreement among distributed memory nodes. The technique is designed to minimize variance from a reference chimer during runtime and with minimal time-request latency. Our scheme permits initial unbounded variations in time and corrects both slow and fast chimers (clock skew). An implementation developed within the context of the message passing interface is described, and time coordination measurements are presented. Among our results, the mean time variance for a set of nodes improved from 20.0 ms under standard Network Time Protocol down to 2.29 μs under our scheme. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The status of the upgraded system for transmission of frequency and time standard signals is described. The signals are transmitted by different means: the global satellite navigation system (GLONASS), ultralong, long, and short wave radio stations for special and other purposes, and the global internet. The areas in which this system is being developed are examined and its structure is described. [ABSTRACT FROM AUTHOR]

The Taosi site in Xiangfen County, Shanxi Province, may be the capital of the King Yao. Archeologists recently discovered a large semi-circular stamped-earth platform, II FJT1, which has a clear and definite pounded-earth central core together with a curved wall perforated by twelve gaps. The platform is said to be an ancient observatory used to determine the seasons by watching the sunrise. Each feature of II FJT1 was precisely measured and the data are reproduced in this paper. An astronomical analysis of slots E2 and E12 was carried out using the azimuths of the slots’ centerlines and the vertical angle of the mountain ridge opposite, above which the sun rises. The results show that at present the sun is close to the two slots but does not exactly enter them at summer and winter solstice sunrise. Using 14C analysis archeologists dated the site to about 2100 BC. Because of the secular change in the obliquity of the ecliptic, at that date on the summer solstice the half-risen sun would have appeared inside slot E12 just to the right of the centerline, and on the winter solstice the sun would have been exactly on the centerline of slot E2. This result provides compelling proof that II FJT1 is an ancient observatory. [ABSTRACT FROM AUTHOR]

With the advent of a new Precision Time Protocol specification, new opportunities abound for clock synchronization possibilities within power grid control systems. The third iteration of the Institute of Electrical and Electronics Engineers Standard 1588 specification provides several new features specifically aimed at complex, wide-area deployments in which situational awareness and control require precise time agreement. This paper describes the challenges faced by existing technology, introduces the new time distribution specification, and provides examples to explain how it represents a game-changing innovation. [ABSTRACT FROM AUTHOR]

We discuss the upper and lower bounds on the accuracy of the time synchronization achieved by the algorithm implemented in TEMPO, the distributed service that synchronizes the clocks of Berkeley UNIX® 4.3BSD systems. We show that the accuracy is a function of the network transmission latency, and depends linearly upon the drift rate of the clocks and the interval between synchronizations. Comparison with other clock synchronization algorithms reveals that TEMPO may achieve better synchronization accuracy at a lower cost. [ABSTRACT FROM AUTHOR]

A probabilistic method is proposed for reading remote clocks in distributed systems subject to unbounded random communication delays. The method can achieve clock synchronization precisions superior to those attainable by previously published clock synchronization algorithms. Its use is illustrated by presenting a time service which maintains externally (and hence, internally) synchronized clocks in the presence of process, communication and clock failures. [ABSTRACT FROM AUTHOR]

The H2020 DEMETRA project provides short latency clock monitoring services to the time users using the Atomium precise point positioning (PPP) software developed by the Royal Observatory of Belgium. In this paper, three recent updates of the current Atomium software are introduced: adding Galileo signals in the PPP computation; the option to constrain the receiver clock; PPP with integer ambiguity resolution. The advantages of these updates are demonstrated: Combining the Galileo and global positioning system (GPS) signals for PPP time transfer will further improve the frequency stability inside the computation batch; PPP with receiver clock constraint is not only used to reduce the short-term noise of the clock measurements but can also be used for some specific applications to a keep continuous clock solution in the computation batch or retrieve correct clock measurements from extremely noisy environments; the integer PPP allows a continuous clock solution, and improves the mid-term and long-term stability of the frequency transfer compared to the current PPP frequency transfer techniques. [ABSTRACT FROM AUTHOR]

Summary: We present a detailed examination of time agreement characteristics for nodes within extreme‐scale parallel computers. Using a software tool we introduce in this paper, we quantify attributes of clock skew among nodes in three representative high‐performance computers sited at three national laboratories. Our measurements detail the statistical properties of time agreement among nodes and how time agreement drifts over typical application execution durations. We discuss the implications of our measurements, why the current state of the field is inadequate, and propose strategies to address observed shortcomings. [ABSTRACT FROM AUTHOR]