Signal Stoppers

Physical Security

​Illustration by Carl Wiens​​​

Signal Stoppers

GPS, owned by the federal government as a national resource, was originally developed in 1973 by the U.S. Department of Defense to overcome the limitations of previous navigation systems. In 1983, after Korean Air Lines Flight 007 was shot down after straying into the USSR’s prohibited airspace, President Ronald Reagan issued a directive making GPS freely available for civilian use. Initially, the highest quality GPS signal was reserved for military use, with the signal available for civilian use intentionally degraded—a move known as selective availability. However, President Bill Clinton ordered that selective availability be turned off in 2000.

Since then, GPS has been periodically improved, and now provides location and time information in all weather conditions anywhere on earth, as long as there is an unobstructed line of sight to four or more GPS satellites. Nonetheless, GPS signals are faint, which makes it relatively easy for a GPS jamming device to swamp the circuitry in the receiving hardware so it cannot detect the GPS signal. As one expert described it, trying to use jammed GPS is like trying to spot a firefly in the distance with a searchlight shining in your eyes. 

For the Federal Communications Commission (FCC), GPS jamming is a serious issue. Last June, the agency issued a $34.9 million fine, the largest monetary penalty in agency history, against the Chinese electronics manufacturer and online retailer C.T.S. Technology for allegedly marketing 280 models of signal jamming devices to U.S. consumers for more than two years. 

“Jamming devices pose tangible threats to the integrity of U.S. communications infrastructure. They can endanger life and property by preventing individuals from making 911 or other emergency calls or disrupting the basic communications essential to aviation and marine safety,” the FCC said in the fine notice.

The fine came after an extensive undercover operation conducted by the FCC’s own enforcement bureau. The agency has charged that devices made by C.T.S. Technology not only jammed the communications signals as advertised, but blocked communications beyond the scope of those listed in their advertisements and marketing materials, which is potentially more harmful. The agency also alleged that C.T.S. Technology misled consumers:  the company claimed on its website that certain signal jammers were approved by the FCC for consumer use.

“These apparent violations are egregious, escalated over more than two years, and continue as of the date of this action. We therefore propose the maximum penalty permitted by statute,” the FCC said. An FCC spokesman demurred when asked about the current status of the action: “I can’t speak to any active enforcement actions [or] investigations under way, but can confirm the FCC is vigilant in pursuing jamming enforcement,” he told Security Management. 

As the C.T.S. Technology case shows, GPS jammers can be purchased over the Internet, often for a modest price. Since jamming technology generally does not discriminate between modes of communication, the same jammer can prevent a cell phone from making or receiving calls; prevent a Wi-Fi enabled device from connecting to the Internet; prevent a GPS unit from receiving correct location positioning signals; and prevent a first responder from locating someone needing assistance in an emergency.

While the GPS jammers purchased over the Internet are mainly for land use, GPS manipulation is also on the rise on the high seas. Over the past two years, there has been a 59 percent increase in the number of ships transmitting incorrect positioning information, which allows these ships to obscure their locations, according to a recent report by the data and analytics firm Windward. 

Many of these seaborne GPS manipulators are fishing vessels, and they do so for economic or competitive reasons, says Windward CEO Ami Daniel. (Chinese fishing vessels account for 44 percent of these GPS manipulators, the report found.) Some of these boats may have exceeded their catch quota and want to fish without anyone knowing. Others may have found a great fishing spot and don’t want competitors finding out where it is. 

And some vessels manipulate GPS data for criminal reasons, such as a smuggling mission. One common method of manipulation at sea is to cross the cables that relay positioning information, so that the latitude cable is actually reporting the ship’s longitude, and vice-versa, Daniel explains. Nonetheless, such manipulation on the high seas is especially troubling because of the reach of global seaborne commerce—roughly 90 percent of the world’s trade is transported by sea. “The oceans remain one of the last Wild West frontiers,” he says. 

Other GPS manipulations have come to light recently. In the last few years, South Korean officials have reported that the North Korean government is using large-scale GPS jammers to interfere with South Korean GPS military and civilian receivers on land and at sea. On a smaller scale, criminals in the United States have hijacked trucks filled with high-value goods by jamming GPS and mobile phone signals, so drivers cannot specify their location and call for help during the attack.

And there’s always the possibility that terrorists could try to disable the GPS signal for an entire American city. Given this and other concerns, development efforts for a back-up system continue. The Defense Advanced Research Projects Agency (DARPA) has been developing a single-chip timing and inertial measurement unit (TIMU) that uses tiny gyroscopes and accelerometers to track position without the aid of satellites or radio towers. The TIMU prototype is smaller than a penny and works by measuring orientation, acceleration, and time.

In the meantime, the FCC is still on the hunt for GPS jammers. Any security practitioners or executives who suspect that their company or operations may have experienced GPS signal jamming can call the FCC’s jammer tip line at 1-855-55-NOJAM.