It's almost as ubiquitous as electricity. The Global Positioning System (GPS) is no longer just a convenience for travelers — it’s also used to land aircraft, guide ships, synchronize data on communication networks and manage loads on vast power grids.
We've become so dependent on its precise positioning and timing capabilities that we often take GPS for granted and assume it will always be there when needed.
Yet GPS, originally designed to track military weapons and vehicles, was never meant for so many civilian applications.
Two recent developments show that GPS is vulnerable to security threats that could wreak havoc on not only individual devices, but also on the nation's basic infrastructure.
Small cost, big consequences
The first threat is from what experts fear is becoming a hot trend — the use of cheap GPS jamming devices.
For as little as $30, GPS jammers, or "anti-GPS" devices, are available for personal use and can be as small as a 12-volt car cigarette-lighter power adapter with an antenna attached.
They are touted online as gadgets to protect personal privacy and prevent someone from tracking your movements. However, criminals and car thieves can also use the devices to cover illegal behavior, and such cases have already been reported in the U.K.
"The worry is that factories in China are starting to churn these things out," says Peter Large, vice president at Sunnyvale, Calif.-based Trimble, which develops advanced positioning systems. "If they did start to proliferate, it could have devastating consequences."
GPS jammers work by disrupting frequencies in one of the commonly used GPS bands. Because the GPS signals are weak to begin with (using just 25 watts to send the signals from satellites roughly 12,500 miles away), it's relatively easy to interrupt or interfere with receivers such as portable navigation devices.
Since car and truck fleet operators often equip vehicles with on-board GPS receivers, drivers may use jammers to prevent their bosses from following them.
“We currently lack sufficient capabilities to locate and mitigate GPS jamming,” noted a report issued in November by the government-mandated National Position, Navigation and Timing (PNT) Advisory Board. “It literally took months to locate such a device that was interfering with a new GPS based landing system being installed at Newark Airport, N.J.”
GPS signals will be the basis of the next-generation air-traffic-control system, which manages aircraft in transit. (The current system uses radar and human supervision.)
In addition to guiding road and marine traffic and managing data and power networks, GPS signals also time traffic lights and make sure automated farm equipment accurately plows and harvests fields.
Interfering with any of these systems could cause serious harm.
"It [GPS jamming] could be used as a weapon," emphasizes Trimble's Large.
The National PNT Advisory Board’s report concurred. It recommended that GPS used in national-security capacities, such as for fighter jets and other military equipment, be "hardened" against the threat, and that GPS overall be declared a "critical infrastructure."
"We must quickly develop and field systems that will rapidly locate, mitigate and shutdown the interference," it said. "In addition, laws are needed with the power to arrest and prosecute deliberate offenders."
A British report released this month by the Royal Academy of Engineering reached a similar conclusion.
"The use of GNSS [global navigation satellite services] for a variety of purposes has become so convenient and ubiquitous that there is a strong tendency among users to treat it as a given," it said. "[T]he loss of these services in an individual application will cause only local or isolated inconvenience, but the possibility exists for wider, single mode or common mode failures with more serious consequences.”
GPS jammers are illegal in the U.S and restricted in most of Europe. However, laws in some other countries are less clear.
We’re lost, but we have great Internet access
The jamming issue underscores another concern of GPS companies about the proposed use of nearby frequencies, which they fear could also disrupt GPS service.
Reston, Va.,-based telecommunications startup LightSquared wants to build a network of 40,000 towers across the country to deliver broadband Internet access using the 4G LTE ( Long-Term Evolution ) wireless-data protocols.
The company, which hopes to become a wholesaler of the service to other companies that would in turn sell it to the public, says the goal is to deliver broadband to those who are underserved by traditional DSL and cable services — for example, residents of many rural areas.
The issue arises with GPS because unlike most LTE sevices, which usually operate in the 1.4 MHz to 20 MHz spectrum (or even lower, such as the so-called "white space" relinquished by the now-defunct analog-TV broadcasters), LightSquared wants to use a spectrum range near the existing GPS L1 band. (Consumer GPS devices typically rely on L1 signals, in the 1575.42 MHz wavelength.)
That is what has raised the ire of GPS device makers, emergency response organizations and others.
Initial reports, including one from Garmin, the leading maker of consumer-level GPS receivers, stated that towers such as those that LightSquared is proposing could interfere with or block GPS devices from miles away.
There’s even a lobbying group, the Coalition to SaveOurGPS, which was created this month expressly to oppose LightSquared.
Its 30-odd members include the Aircraft Owners and Pilots Association, the International Air Transport Association and the National Association of Manufacturers, as well as major farm-equipment manufacturers, Trimble, Garmin and TomTom, Garmin’s major rival.
An independent study, due to be filed with the government by June 15, is under way to determine the extent of the problem.
A representative for LightSquared said the company wants to be a good neighbor, and believes it can install filters to forestall any interference.
The GPS community, however, feels that the FCC should continue to protect the GPS spectrum against any possible interference, and that the risks are simply too high to let powerful signals carry voice and data traffic over neighboring wavelengths.
Whether or not LightSquared will be able to proceed with its ambitious plans, one point is increasingly obvious. Given our dependence on GPS, further steps will no doubt need to be taken to protect not only consumer devices but national infrastructure systems as well.