GPS Magical Mystery Tour

That's how David Last, a consultant to the outfit which operates all the aids to navigation in the United Kingdom, described the effects of jamming on GPS and related systems in tests last December conducted on a buoy tender offshore Newcastle, England.

The General Lighthouse Authorities of the U.K. and Ireland ran the tests to determine the effects a cheap GPS jammer anyone can buy over the Internet would have on the GPS navigation system installed on its THV Galatea buoy tender. The results, Last said, were "literally all over the map."

The jammer, which output a signal measured in milliwatts (one thousandth of a watt; by comparison, radio station WETA in Washington transmits 75,000 watts) skewed position results so much that over the course of the tests, the GPS receiver reported that Galatea -- which did not stray far from its position offshore Newcastle -- was anywhere from the northwest coast of Ireland, a distance of about 250 miles, to St. Petersburg, Russia, some 1,200 miles away.

Last told me that the most dramatic results of the Galatea tests showed the jamming crippled not just the ship's main GPS receiver, but multiple systems on the ship, all of which use GPS. It affected the radar system on board the Galatea, which included both a signal from the radar and a signal from an Automatic Identification System. The results were two different locations for nearby ships displayed on the Galatea's screens, Last said. Last reported those results last week at a meeting of the multi-agency U.S. Space Based Position, Timing and Navigation National Executive Committee in Washington.

Other systems on the Galatea crippled by the jamming that depend on GPS included the electronic chart display system, satellite communications systems and emergency distress systems, which rely on GPS for either location or timing, Last told me.

The Galatea was able to get an accurate position from a ground transmitter located 80 miles away in Anthon, using a technology called eLoran, not susceptible to GPS jamming and all but abandoned by the United States.

The Coast Guard started shutting down the Loran stations that transmit the eLoran signal last year, but then-Coast Guard commandant Thad Allen said the service would continue discussions to use eLoran as a backup to GPS. Last said the Newcastle tests proved both the vulnerability of GPS and the need for eLoran as a backup.

And it looks like eLoran is not dead. The 2010 Coast Guard Authorization Act signed by President Obama last Friday directs the Homeland Security Department to establish eLoran as the supplemental navigation system for the United States and the Coast Guard to modernize its Loran stations to transmit the eLoran signal.

At the very least, this should keep the Coast Guard from blowing up any more Loran stations, though I think it still will be a tough fight to make eLoran a reality.