Loran-C Signal Stability Study. Northeast and Southeast U.S

摘要

The suitability of Loran-C as a precision aid to navigation in the harbor-harbor entrance (HHE) areas of the continental U.S. involves an assessment of the stability of the signals of the existing Loran-C system along with an examination of stability improvement methods. The final efforts were begun in early 1981 with the deployment of Loran data collection sets (the so-called 'harbor monitors') in select harbor areas. In this report, the harbor monitor data collected at 14 sites located along the northeast U.S. and southeast U.S. (N.E.U.S./S.E.U.S.) coast is presented. Extensive analyses are conducted to obtain a model of the Loran signal variations and extend the results to allow the determination of system performance throughout the region. The report shows the 'HHE level' performance requirements can be met, at most with a moderate set of system improvements, in almost all major harbor areas. The effects of adverse system geometry, unfortunately, exclude the achievement of adequate performance in the major ports of the east coast of Texas. An analysis shows how the addition of another chain, requiring the installation of one more transmitting station would solve the problems along the Texas coast. The report also shows that the repeatable accuracy of existing Loran-C is better than 40-meters. 2-drms, in 50% of the N.E.U.S./S.E.U.S. coverage area. It is better than 80-meters in over 90% of the same coverage area. This means that GPS, at the 100-meter, 2-drms accuracy levels presently being planned for release to the public, does not qualify as a bona fide replacement for Loran-C.