Jumat, 21 Mei 2010
LORAN (LOng RAnge Navigation) is a terrestrial radio navigation system using low frequency radio transmitters that uses multiple transmitters (multilateration) to determine the location and speed of the receiver. The current version of LORAN in common use is LORAN-C, which operates in the low frequency portion of the EM spectrum from 90 to 110 kHz. Many nations use the system, including the United States, Japan, and several European countries. Russia uses a nearly identical system in the same frequency range, called CHAYKA. LORAN use was in steep decline, with GPS being the primary replacement, however, there currently are attempts to enhance and re-popularize LORAN, mainly to serve as a backup and land-based alternative to GPS and other GNSS systems.
In November 2009, the U.S. Coast Guard announced that LORAN-C is not needed for Maritime navigation. This decision left the fate of LORAN and eLORAN in the U.S. to the Secretary of the Department of Homeland Security. Per a subsequent announcement, the U.S. Coast Guard, in accordance with the DHS Appropriations Act, was to terminate the transmission of all U.S. LORAN-C signals effective 2000 UTC, 8 February 2010. At that time, the U.S. LORAN-C signal would be unusable and permanently discontinued. "The decision to cease transmission of the LORAN-C signal reflects the president’s pledge to eliminate unnecessary federal programs." This termination does not affect U.S. participation in the Russian-American or Canadian LORAN-C chains. U.S. participation in these chains will continue temporarily in accordance with international agreements. The Canadian government has announced that operation of Canadian chains will cease on or before 1 October 2010.