[time-nuts] LORAN-C discontinuation in US
stanley_reynolds at yahoo.com
Thu Mar 12 22:39:40 EDT 2009
More info here:
(change xx to tt , sorry many ads on this linked site)
Since 1999, Congress has allocated $160 million to begin the eLORAN improvements, according to a presentation by USCG Capt. Curt Dubay to the U.S. Space-Based PNT Executive Committee last October. Of the 24 U.S. LORAN-C stations; 19 have been updated and modernized to transmit the extra data services required for eLORAN, but a monitoring network has not yet been installed.
No funds have been allocated since FY06, however, and a full eLoran
system would cost up to $400 million more with an expected annual
allocation of $15–$25 million, Dubay said. Annual LORAN operations and
maintenance costs (as of FY06) are $45 million, a figure expected to
decline to a projected $22 million a year upon implementation of full
eLORAN system architecture with reduced staffing at automated stations.
Improvements have included the following:
• upgrade existing station transmitting equipment to new solid state transmitters and associated timing equipment (atomic clocks)
• transition to time of arrival (TOA) positioning techniques, similar to pseudorange-based navigation used in GPS
• incorporate new messaging channel to increase position and time accuracy (differential Loran, integrity, and time messages)
• support operation of modern all-in-view equipment (improves fix geometry for better accuracy and extended coverage).
Modernization of LORAN improves the system’s positioning accuracy from between 0.25 and 1 nautical mile to between about 3 and 20 meters."
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