TIMING A LORAN-C CHAIN

Carl F. Lukac and Laura G. Charron

Peer Reviewed

Abstract: Originally developed for marine navigation and now extensively utilized in off-shore air navigation, the Long Range Aid Navigation (LORAN) system has assumed considerable importance in the area of tuning synchronization. LORAN-C chains are maintained by the U.S. Coast Guard. Wherever possible, the chains are monitored by the U.S. Naval Observatory (USNO) and differences, USN0 Master Clock (USN0 MC) minus the chains, are published in Time Service Announcements to enable users to establish and maintain traceability to the USN0 MC. However, the USN0 is within groundwave range of only four of the thirteen chains. Determining the timing relationship between the majority of LORAN-C chains and USN0 MC, therefore, requires dependence upon monitoring stations within groundwave coverage of these chains. The methodology of forming and calibrating remote time scales for individual stations used in determining a time scale for a LORAN-C chain, in particular for LC/9970, is discussed. Portable clock measurements and satellite time transfers are used as the calibration devices. The maximum scatter in values of USN0 MC minus LC/9970 determined by the individual stations forming the MEAN time scale amounts to about 0.15 microsecond.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 29, Number 3
Pages: 235 - 245
Cite this article: Lukac, Carl F., Charron, Laura G., "TIMING A LORAN-C CHAIN", NAVIGATION, Journal of The Institute of Navigation, Vol. 29, No. 3, Fall 1982, pp. 235-245.
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