The Fragile GPS, a Technology Trap
Will Stewart for 4thTriage
In collaboration with Don Hodge
“It WAS just after midday in San Deigo, California, when the disruption started. In the tower at the airport, aircraft controllers peered at their monitors only to find that their system for tracking incoming planes was malfunctioning. At the Naval Medical Center, emergency pagers used for summoning doctors stopped working. Chaos threatened in the busy harbour, too, after the traffic-management system used for guiding boats failed. On the streets, people reaching for their cellphones found they had no signal and bank customers trying to withdraw cash from local ATMs were refused. Problems persisted for another 2 hours.” (1)
What happened? The specific cause was two U.S. Navy ships in the harbour doing a training exercise. They were jamming radio signals.
But isn’t GPS just for finding location? GPS means Global Positioning Satellites. Yes, but this is accomplished by sending down radio waves (with date-time stamps) from at least four satellites. Weak radio signals. How weak? Consultant David Last, former president of the UK's Royal Institute of Navigation thinks “it's like a car headlight 20,000 kilometres away," (1). Unfortunately, the power sources on the satellites can’t increase the signal any more.
Okay. That explains the problems tracking the planes and boats, but what about the cellphones, pagers, and ATMs? The short answer is in two parts: 1) atomic clocks on the satellites; and 2) effeciency in reducing costs. Atomic clocks send down date-time stamps to the nanosecond that the software of the receiving device uses to calculate your distance from at least four satellites – giving you an incredably accurately location fix. Atomic clocks are expensive so good ol’ ingenuity, a love of effeciency, and American “getter-done” spirit took advamtage of those free date-time stamps in the GPS radio signals. ATMs and bank transfers use it (with a 3-nanosecond window of tolerance) to validate the transaction. No validation equals we ain’t doing anything. Cellphones, pagers, and electric power transmission use that date-time stamp to regulate and synchronize their traffic.
There are a lot of devices that use and depend on GPS.
This brings us to the central point of Hambling’s article. You can jam GPS with a $30 device made in China. The range is about a kilometer (.62 miles) if conditions are right. Some truckers and others use this type of device to avoid creating a record of where they went – and how fast. So locally, you (through technology you had no idea was in operation) can be shut down by a cheap device. Can you say “lone wolf nut-job and/or terrorist”? Unintended consequences, collateral damage; call it what you will. Consider it a very small taste of a massive solar flare or an EMP event. Here at least when the jamming stops, you’re back to normal.
Also consider it a warning or reminder that technology which we use but don’t understand has traps/vulnerabilities as well as wonderful benefits. James Burke’s excellent “Connections” series pointed this out 35 years ago. You can view these thought provoking programs at:
There is a second problem besides jamming. It is spoofing. Devices to do this are not yet being manufactured, but they might be produced for $400 to $500. What is spoofing? “Unlike a GPS jammer, which has fairly obvious effects, the spoofer's impact is slow and subtle. ‘The victim usually won't realise they're being spoofed,’ says [Randy] Humphreys [Univ. of Texas at Austin]. ‘It leaves no trace.’" (1) The spoofer collects GPS signals, alters them slightly, and sends them to the receiving device. The accumulating date-time stamp errors can be very significant. Ships, trains, and planes could be led to believe they are at one location when really at another. The biggest threat here comes from insiders who have access to the GPS receiver. Examples could be: stock and securities criminals, fishing boat captains wishing to go into illegal waters, and possibly terrorists.
The key thought is that we are in a window of vulnerability and will be for a significant period of time – a decade and possibly more. We’re travelin’ through “Injin Country”.
Solutions? Well, we have long held that dependence on electronic devices (the GPS in this case) is a critical failure point in a survival situation. Or what may for you suddenly become one.
For spoofing, there isn’t much you can do now. Technology may provide tools to detect it. Otherwise be vigilant and alert for “red flags” - things that don’t seem right.
Our advice for navigation is to have maps, learn to use a compass, and even a sextant. Batteries and electronics are not required. GPS, EMP, and solar flare proof.
For the other stuff, two approaches should become reality in the next decade or two: 1) atomic clocks should become cheaper and more common; and 2) we have a proven backup system that can be installed from the 1940s, LORAN.
“Basic LORAN [LOng RAnge Navigation] is similar to GPS but uses ground-based radio signals rather than from satellites. LORAN operates at a far longer wavelength than GPS signals and is more powerful. Both of these features make it virtually impossible to jam” (1)
LORAN was phased out of use by the Coast Guard but is still in use around the world. It doesn't have complete global coverage, but does beat GPS on some things. It can be used as a second navigation system. It was even tested by the FAA and meets IFR standards. It is still susceptible to EMP, solar flares, power failures, and all the other weaknesses inherent to electronics. Also we feel that while it is much, much more difficult, it too can be jammed or spoofed.
The U.S. is developing LORAN and LORAN-C with our upgraded technology. The European Union is concentrating on their own enhanced version, eLORAN.
Reference Links:
(2) Is Loren-C the Answer to GPS Vulnerability?
(3) GPS Vulnerability Solutions
(4) GPS Vulnerability articles – Crossrate technology, also eLORAN
(5) Global Positioning System Timing Criticality Assessment - Preliminary Performance Results
(6) John A. Volpe National Transportations Center
