LORAN-C TIME MANAGEMENT

As of October 1, 1993, the U.S. Coast Guard (USCG) supports and operates fifteen Loran-C chains. With the introduction of the Global Positioning System (GPS) and the termination of the Department of Defense (DOD) overseas need for Loran-C, the USCG will cease operating the three remaining overseas chains by December 31, 1994. Following this date, the USCG Loran-C system will consist of twelve chains. Since 1971, management of time synchronization of the Loran-C system has been conducted under a Memorandum of Agreement between the U.S. Naval Observatory (USNO) and the USCG. The requirement to maintain synchronization with Coordinated Universal Time (UTC) was initially specified as + or - 25 microseconds. This tolerance was rapidly lowered to + or - 2.5 microseconds in 1974. To manage this synchronization requirement, the USCG incorporated administrative practices which kept the USNO appraised of all aspects of the master timing path. This included procedures for responding to timing path failures, timing adjustments and time steps. Conducting these aspects of time synchronization depended on message traffic between the various master stations and the USNO. To determine clock adjustment, the USCG relied upon the USNO's Series 4 and 100 updates so that the characteristics of the master clock could be plotted and controls appropriately applied. In 1987, Public Law 100-223, under the Airport and Airway Improvement Act Amendment, reduced the synchronization tolerance to approximately 100 nanoseconds (ns) for chains serving the National Airspace System (NAS). This action caused changes in the previous administrative procedures and techniques. This paper presents the actions taken by the.

• Supplemental Notes:
  • This article is from 'Proceedings of the Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting (25th) Held in Marina Del Rey, California on 29 November - 2 December 1993', AD-A280 955, p79-91.
• Corporate Authors:

  Coast Guard Radionavigation Div.

  Washington, DC  United States 
• Authors:
  • Justice, C
  • Mason, N
  • Taggart, D
• Publication Date: 1993-12-2

Language

• English

Media Info

• Pagination: 13 p.

Subject/Index Terms

• TRT Terms: Alternatives analysis; Control; Global Positioning System; Loran; Management; Passenger terminals; Railroad stations; Specifications; Time
• Identifier Terms: United States Coast Guard
• Uncontrolled Terms: Observatories; Requirements; Systems management
• Old TRIS Terms: Overseas
• Subject Areas: Administration and Management; Marine Transportation; Public Transportation; Terminals and Facilities;

Filing Info

• Accession Number: 00666468
• Record Type: Publication
• Source Agency: National Technical Information Service
• Files: TRIS
• Created Date: Oct 3 1994 12:00AM