Showing papers on "Clock synchronization published in 1974"
TL;DR: A procedure for synchronizing the local clocks in an N -node network is explored, termed "discrete control correction," which utilizes buffer contents and rates to derive correction signals to the local VCXO's.
Abstract: Synchronization plays an important role in digital communication networks. A procedure for synchronizing the local clocks in an N -node network is explored in this concise paper. The procedure, termed "discrete control correction," utilizes buffer contents and rates to derive correction signals to the local VCXO's. The system is formulated as a second-order matrix difference equation, which is examined for stability. A two-node network is analyzed as an example, and stability bounds are determined for the control parameters.
19 citations
TL;DR: This concise paper details the synchronization philosophy and instrumentalities adopted in The Dataroute, a TransCanada digital data network established in April 1973, a hierarchical master-slave system with a two-level hierarchy at locations physically distant from one another.
Abstract: This concise paper details the synchronization philosophy and instrumentalities adopted in The Dataroute [1], a TransCanada digital data network established in April 1973. The synchronization system discussed is a hierarchical master-slave system with a two-level hierarchy at locations physically distant from one another. A discussion of the alarm transmission in The Dataroute is also presented. Alarms in The Dataroute are displayed locally, and facilities are provided for their transmission to a regional center and a national center for real-time action as well as for management purposes, and report generation on demand.
8 citations
TL;DR: The conclusion was arrived at that the more stations included in a network, the shorter the time elapsed before the frame pulse phase disturbances are settled down to a steady state, although this tendency is rather gradual.
Abstract: An integrated telephone network requires synchronization of digital signal streams arriving at each switching system with its switching points. A new synchronization control system for this purpose was already proposed by one of the authors and the final clock rate and stability criterion were discussed in the preceding material. Continuing with this discussion, impulse responses of the proposed control system applied to mesh networks are mathematically analyzed under the condition that all of the clock pulse generators have respective clock rate derivations from their nominal value. The conclusion was arrived at that the more stations included in a network, the shorter the time elapsed before the frame pulse phase disturbances are settled down to a steady state, although this tendency is rather gradual. The dynamic response of the synchronization control system applied to mesh networks, a ring network, a chain network, and an assumed worldwide network are computer simulated in linear and three-value clock rate control modes and the characteristic of the control system is clarified.
6 citations
01 Jan 1974
TL;DR: The relativistic conversion between coordinate time and atomic time is reformulated to allow simpler time calculations relating analysis in solar-system barycentric coordinates (using coordinate time) with earth-fixed observations (measuring earth-bound proper time or atomic time).
Abstract: The relativistic conversion between coordinate time and atomic time is reformulated to allow simpler time calculations relating analysis in solar-system barycentric coordinates (using coordinate time) with earth-fixed observations (measuring earth-bound proper time or atomic time.) After an interpretation of terms, this simplified formulation, which has a rate accuracy of about 10 to the minus 15th power, is used to explain the conventions required in the synchronization of a world wide clock network and to analyze two synchronization techniques-portable clocks and radio interferometry. Finally, pertinent experiment tests of relativity are briefly discussed in terms of the reformulated time conversion.
5 citations
TL;DR: Effects of clock drift on the performance of a discretetime control system for synchronizing all the clocks in a digital communications network are shown by a detailed analysis of the dynamic behavior of the simple case of a two-node network.
Abstract: Effects of clock drift on the performance of a discretetime control system for synchronizing all the clocks in a digital communications network are shown by a detailed analysis of the dynamic behavior of the simple case of a two-node network. With a unidirectional frequency drift of one or both oscillators, it is shown that the buffer stores eventually overflow. A more general linear control scheme is also discussed.
4 citations
01 Jan 1974
TL;DR: In this article, accurate baseline determinations and clock synchronization results obtained from the Quasar Patrol observations at X band with the Goldstone-Haystack baseline were presented, and data from stations at Greenbank, West Virginia, and Onsala, Sweden were used.
Abstract: Accurate baseline determinations and clock synchronization results obtained from the Quasar Patrol observations at X band with the Goldstone-Haystack baseline are presented. In addition, data from stations at Greenbank, West Virginia, and Onsala, Sweden were used. It was estimated that clock accuracy was on the order of 16 cm.
2 citations
TL;DR: In this paper, a semi-real time system for synchronizing the Deep Space Net station clocks by radio interferometry was successfully demonstrated on August 30, 1972, using an approximate maximum likelihood estimation procedure for processing the data.
Abstract: A prototype of a semi-real time system for synchronizing the Deep Space Net station clocks by radio interferometry was successfully demonstrated on August 30, 1972. The system utilized an approximate maximum likelihood estimation procedure for processing the data, thereby achieving essentially optimum time sync estimates for a given amount of data, or equivalently, minimizing the amount of data required for reliable estimation. Synchronization accuracies as good as 100 ns rms were achieved between Deep Space Stations 11 and 12, both at Goldstone, Calif. The accuracy can be improved by increasing the system bandwidth until the fundamental limitations due to baseline and source position uncertainties and atmospheric effects are reached. These limitations are under 10 ns for transcontinental baselines.
2 citations
TL;DR: In this paper, the clock paradox is reformulated using Moller's mathematical formalism but comparing adjacent unresynchronized natural clocks rather than coordinate clocks, and the relative behavior of natural clocks in the two systems is seen to depend in the first instance on their initial synchronization, but regardless of initial synchronisation, on the return trip the “rest” clock experiences a uniform and continuous increase in time relative to adjacent “moving” clocks.
Abstract: Moller's analysis of the clock paradox in The Theory of Relativity is reformulated using Moller's mathematical formalism but comparing adjacent unresynchronized natural clocks rather than coordinate clocks. The relative behavior of natural clocks in the two systems is seen to depend in the first instance on their initial synchronization, but regardless of initial synchronization, on the return trip the “rest” clock is shown to experience a uniform and continuous increase in time relative to adjacent “moving” clocks. There is no sudden, discontinuous increase when using unresynchronized natural clocks as there is when using coordinate clocks.
2 citations
01 Jan 1974
TL;DR: In this paper, a treatment of relativistic clock synchronization effects due to the rotation of the earth is given, where the point of view of an earth fixed coordinate system is used which offers insight to many problems.
Abstract: A treatment is given of relativistic clock synchronization effects due to the rotation of the earth. Unlike other approaches, the point of view of an earth fixed coordinate system is used which offers insight to many problems. An attempt is made to give the reader an intuitive grasp of the subject as well as to provide formulae for his use. Specific applications to global timekeeping, navigation, VLBI, relativistic clock experiments, and satellite clock synchronization are discussed. The question of whether atomic clocks are ideal clocks is also treated.
1 citations
01 Mar 1974
TL;DR: In this article, a semi-real time system for synchronizing the Deep Space Net station clocks by radio interferometry was successfully demonstrated on August 30, 1972, using an approximate maximum likelihood estimation procedure for processing the data.
Abstract: A prototype of a semi-real time system for synchronizing the Deep Space Net station clocks by radio interferometry was successfully demonstrated on August 30, 1972. The system utilized an approximate maximum likelihood estimation procedure for processing the data, thereby achieving essentially optimum time sync estimates for a given amount of data, or equivalently, minimizing the amount of data required for reliable estimation. Synchronization accuracies as good as 100 ns rms were achieved between Deep Space Stations 11 and 12, both at Goldstone, Calif. The accuracy can be improved by increasing the system bandwidth until the fundamental limitations due to baseline and source position uncertainties and atmospheric effects are reached. These limitations are under 10 ns for transcontinental baselines.