Special Issue on Time Scale Algorithms

• Main Authors: Matsakis, Demetrios, Tavella, Patrizia
• Other Authors: NAVAL OBSERVATORY WASHINGTON DC
• Format: Text
• Language: English
• Published: 2008
• Subjects: Numerical Mathematics; Navigation and Guidance; *GLOBAL POSITIONING SYSTEM; *ALGORITHMS; FREQUENCY STANDARDS; ARTIFICIAL SATELLITES; ANTARCTIC REGIONS; CLOCKS; REPRINTS; SCALE; TWSTFT(TWO WAY SATELLITE TIME AND FREQUENCY TRANSFER); VITSAS(FIFTH INTERNATIONAL TIME SCALE ALGORITHM SYMPOSIUM); GNSS(GLOBAL NAVIGATION SATELLITE SYSTEMS); Antarctic; Observatorio; Roa; San Fernando; Antarc*; Antarctica
• Online Access: http://www.dtic.mil/docs/citations/ADA492115; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA492115

This special issue of Metrologia presents selected papers from the Fifth International Time Scale Algorithm Symposium (VITSAS), including some of the tutorials presented on the first day. The symposium was attended by 76 persons, from every continent except Antarctica, by students as well as senior scientists, and hosted by the Real Instituto y Observatorio de la Armada (ROA) in San Fernando, Spain, whose staff further enhanced their nation's high reputation for hospitality. Although a timescale can be simply defined as a weighted average of clocks, whose purpose is to measure time better than any individual clock, timescale theory has long been and continues to be a vibrant field of research that has both followed and helped to create advances in the art of timekeeping. There is no perfect timescale algorithm, because every one embodies a compromise involving user needs. Some users wish to generate a constant frequency, perhaps not necessarily one that is well-defined with respect to the definition of a second. Other users might want a clock which is as close to UTC or a particular reference clock as possible, or perhaps wish to minimize the maximum variation from that standard. In contrast to the steered timescales that would be required by those users, other users may need free-running timescales, which are independent of external information. While no algorithm can meet all these needs, every algorithm can benefit from some form of tuning. The optimal tuning, and even the optimal algorithm, can depend on the noise characteristics of the frequency standards, or of their comparison systems, the most precise and accurate of which are currently Two Way Satellite Time and Frequency Transfer (TWSTFT) and GPS carrier phase time transfer. Pub. in Metrologia, v45, 2008.