Relationships Between U.S. Naval Observatory, Loran-C and the Defense Satellite Communication System
Abstract
Department of Defense (DoD) Directive 5160.51 of 31 August 1971 states that "All DoD component... refer time and time interval to the standards established by the (U.S. Naval) Observatory." To obtain the required traceability, the most widely used system for time dissemination has been the navigational system of the U.S. Coast Guard Loran-C. When the only chain available for timing was the East Coast chain, monitored by the Observatory, there was no problem in publishing comparisons of that chain to the U.S. Naval Observatory's Master Clock (USNO MC) with a fair degree of reliability. By 1981, however, thirteen chains, covering a substantial portion of the Northern Hemisphere, were in use. The question of how the time comparisons were to be obtained, the chains calibrated, and the results published for chains not directly monitored by USNO then arose. During this same period, the number of links permitting time transfers point-to-point over the Defense Satellite Communication System (DSCS) were being expanded. In addition, at some selected sites, Loran-C montoring equipment was installed. It was now possible to have values of USNO MC - DS-CS Monitoring Site and thus to be able to determine USNO MC minus Loran - C. This paper addresses, in general terms, the methods used in forming time scales for distant sites montoring Loran-C. Particular emphasis will be given to the time transfers obtained via the DSCS and on how the data provided by this system is used to calibrate these remote time scales. The errors involved will be discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1981
- Accession Number
- ADA497395
Entities
People
- Laura G. Charron
Organizations
- United States Naval Observatory