USCG R&D Differential Loran-C Study

D. S. Taggart

Abstract: The U.S. Coast Guard Research and Development Center (R&DC) is currently engaged in a project to develop techniques for the operation of real time differential Loran-e system in harbor areas that require improved navigational performance. Present project efforts are dedicated to the generation of an automated marine band VH F-FM digital and synthesized voice update message. Variations induced in the Loran- e signals can be attributed to changing propagation speeds (seasonal), different transmitter characteristics, weather conditions, chain control procedures and diurnal effects. The project is divided into five separate tasks. The first task includes the development of hardware and software to output the automated synthesized voice and digital update message. The second task is concerned with the development of a redundant network of monitors for a specific harbor. The third task will address the survey of the subject harbor. The fourth task is concerned with the modification of the Johns Hopkins University Applied Physics Laboratory (JHU/APL) Precision Intracoastal Loran-e Translocator (PILOT) to allow automated input of the digital updates. The fifth task is dedicated to investigation of problems that will most likely be encountered should the system become operational. Areas to be addressed in this final task include: the message format, the update interval, the generation of the update TD values, differences between various receiver types and the addition of differential information on nautical charts (reference TDs, waypoint locations and TDs, VHF-FM update channel and frequency of messages, etc.). Anticipating the implementation of NAVSTAR GPS, the Coast Guard is also involved with Differential GPS. Much of the knowledge gained during the development of.the Differential Loran-e system will be directly applicable to the development of a GPS Differential network.
Published in: Proceedings of the 1985 National Technical Meeting of The Institute of Navigation
January 15 - 17, 1985
San Diego, CA
Pages: 25 - 33
Cite this article: Taggart, D. S., "USCG R&D Differential Loran-C Study," Proceedings of the 1985 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1985, pp. 25-33.
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