GPS risksThe increasing risks of GPS systems

Published 22 November 2011

During a recent meeting of the National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board, participants described how U.S. infrastructure is increasingly at risk due to the widespread use of GPS systems and the presence of interdependencies between different sectors

U.S. critical infrastructure sectors are increasingly at risk from a growing dependency on GPS for positioning, navigation, and timing (PNT) services,” warned Brandon Wales, the director of the DHS’ Homeland Infrastructure Threat and Risk Analysis Center.

One of the major problems, said Wales, is that GPS reliance in many of the nation’s critical systems is either not fully understood and often taken for granted, describing GPS as a “largely invisible utility.”

“You’ve got a highly accurate, very robust system, that has proven to be highly reliable, embedded in a lot of systems that people are not fully aware of,” he said.

Disruptions in GPS service can be caused by naturally occurring phenomenon, such as space weather events, unintentionally by interference between GPS signals and radio frequencies, or intentionally by jamming or “spoofing” devices.

Spoofing is the process of creating a false GPS signal which replaces correct readings, leading devices to display incorrect times or locations. Spoofing could potentially be used to disrupt power grids or by criminals under house arrest looking to fool monitoring devices.

Cases of GPS interference are on the rise according to participants at the meeting. A recent study on the problem at Taiwan’s Kaohsiung International Airport found an average of 177 jamming and spoofing incidents a day. In early 2010, investigators at Newark Liberty International Airport discovered that a series of outages in the airports Ground Based Augmentation System (GBAS), which provides GPS data to aid in aircraft approach and departure, was caused by a $33 dollar jammer being used by a truck driver.

Jamming devices are prohibited by federal law but are widely available on the Internet.

In February the Federal Communications Commission announceda crackdown and awareness campaign against the use of the devices.

Incidents of jamming are more likely than those of spoofing, said Wales, but spoofing is judged to be more dangerous. Disruptions caused by jamming devices are easily identified due to the loss of a GPS signal, whereas a spoofed device could provide incorrect readings for a much longer period before the issue is detected.

Spoofing countermeasures are readily available according to Logan Scott, president of LS Consulting, who also presented at the meeting. “Most receivers have a lot of the [necessary] parts in place [to identify interference].” Simple software upgrades can make many devices spoof resistant and manufacturers should integrate spoof-detection to set themselves apart from their competition, he said.

In January DHS is planning to release its 2011 risk-analysis entitled “National Risk Estimate: Risks to United States Critical Infrastructure from Global Positioning System Disruptions,” which analyzes the potential for disruption in the communications, emergency services, energy, and transportation sectors. A draft is currently being reviewed by the Assistant Secretary for the Office of Infrastructure Protection and the PNT Executive Steering Group.