Loran on Trial
January 31, 2007 By: GPS World StaffThe Department of Transportation (DoT) has opened a public comment period that could determine the future of the ground-based Long-Range Navigation (LORAN) system. Many consider LORAN the most suitable backup system for GPS, and essential for communications network timing signals and electronic navigation.
The DoT's 2001 Volpe Report assessed GPS vulnerabilities and urged development of a backup system, stating that as GPS penetrates into the civil infrastructure, “it becomes a tempting target that could be exploited by individuals, groups or countries hostile to the United States.” President Bush called for development and maintenance of GPS backup systems in the December 2004 policy statement on space-based positioning, timing and navigation systems, but did not specify the backup system.
DoT is considering “the need to continue to operate or invest in the North American LORAN-C Radionavigation System beyond fiscal year 2007.”
“Future investment decisions,” according to the announcement, “might include: Decommissioning the LORAN-C system, maintaining the LORAN-C system as currently configured, or developing a fully deployed Enhanced LORAN (eLORAN) system.”
The notice was published January 8, with comments due February 7 — although in all likelihood, comments may be accepted after that date. To view the notice and all comments posted so far, go to http://dms.dot.gov/, click “Open Dockets” in the yellow box, scroll down to the “USCG” section at the very bottom of that long page, and select “Long Range Aids to Navigation (LORAN) Program - USCG-2006-24685,” the sixth option in the Coast Guard box.
Support for LORAN and eLORAN comes from wireless carriers, for whom timing signals are crucial to the operation of complex wired and wireless networks. Carriers use GPS for network timing, and require backup in case of GPS outage or jamming. Without backup in such a scenario, network performance could degrade and calls could be dropped when mobile handsets move from one cell site to another, because call handoff relies on highly accurate timing.
Support also comes from the Aircraft Owners and Pilots Association, who need an electronic navigation backup to GPS, and from certain figures within the Federal Aviation Administration.
Attempts to throttle the system reportedly emanate from within the Coast Guard and the Navy, where certain commanding figures seek to reduce operating budgets. The Coast Guard has spent $160 million on Loran modernization since 1997.
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