Not much, based on this updated report from the Department of Homeland Securty.
DHS prepared a classified report on Global Positioning System vulnerabilities in November 2012 and the unclassified version, released last week, leaves much to worry about, including the fact that “Detecting, locating and disabling sources of GPS disruption remain a challenge.”
The department suggests manual backups for GPS, which I imagine includes old-fashioned compasses and maps, but observed that “human skills for using manual techniques could erode due to lack of training and practice as GPS becomes more ubiquitous.”
GPS signals sit at the core of the Federal Aviation Administration’s Next Generation Air Transportation System, provide timing signals for wired and wireless networks, guide precision munitions, help mariners navigate tough harbor approaches and are key to precision farming operations.
But nowhere in the report does DHS suggest an automatic back-up system for the simple reason that one does not exist, even though the Department of Transportation’s John A. Volpe National Transportation Systems Center warned about the dangers of GPS jamming and called for development of an automatic back-up system in a report published 13 years ago.
The Volpe report suggested a terrestrial backup GPS system based on an improved version of the WW II Long Range Navigation System, known as Loran, but the United States abandoned Loran due to the manning costs incurred by the Coast Guard, which literally blew up the tower of the Port Clarence, Alaska, station in 2010.
South Korea, which has a lot of experience with GPS jamming by North Korea, plans to start installing a Loran system in 2016 with full operation planned by 2018 -- a better approach than a compass or map.