$30 GPS Jammer Can Wreak Havok

An anonymous reader writes "A simple $30 GPS jammer made in China can ruin your day. It doesn't just affect your car's navigation — ATM machines, cell phone towers, plane, boat, train navigation systems all depend upon GPS signals that are easily blocked. These devices fail badly — with no redundancy. These jammers can be used to defeat vehicle tracking products — but end up causing a moving cloud of chaos. The next wave of anti-GPS devices include GPS spoofers to trick or confuse nearby devices."

Weak spot in FAA's "NextGen" system

[elrous0]

What's even more disturbing is that the FAA is currently looking to move away [nytimes.com] from traditional radar and even human air traffic controllers [theatlantic.com], as part of their "NextGen" system [faa.gov]. GPS is just fine as long as there is a redundancy in the system. But the idea of abandoning radar as if GPS were a time-tested system is a little scary.

Old news

[GPSguy]

The ability to white-noise (or pink-noise) jam GPS has been around and employed for, literally, years. And, most of the first of these I saw came from China, too. GPS is a relatively fragile system, at least n the L1-C/A world: GPS satellites have limited power budgets so signal levels are low on the ground. Receivers have high gain. Multipath in urban environments can confuse receivers. Emitting a random noise signal over the range of L1 frequencies isn't that hard, and doesn't take much power... or antenna height... to cause problems.

The article makes all of these points. Read it and take note of the fragility of the system. That's its downfall, not a $30 device.

Re:WANT!

[gad_zuki!]

You probably don't want one. A few years ago I bought a cell phone jammer from a company in Hong Kong. The build quality was terrible and I was only able to jam phones within a 2 or 3 foot radius at best. Most of the time the phone would drop signal and then find its way back onto the network in 30 or so seconds. I managed just once to drop a stranger's loud call on the train after dozes on attempts.

Turns out cell phones are designed to find ways around interference. Afterall, my jammer was just like having to deal with 100 nearby cell phones trying to make calls. Some phones have no problem with this.

The real issue is that when you're dealing with potentially illegal items with no brands, there's no incentive to make the product work correctly. I wouldn't be surprised if these jammers sucked also.

Re:Vulnerable

[justthisdude]

A quick GPS history lesson: GPS signals are spread-spectrum in order to make them harder to jam from a distance. The military goal was not to make it un-jammable, merely to force a functioning jammer to be so large that it could be found and (ahem) stopped. So GPS was built upon the assumption of radiation-seeking missiles to protect it. To deter jamming, they spread the main signal SO widely that it was hard for them to even acquire themselves (back in the day). For acquisition they built a less spread "finder" signal. This is spread over only about a MHz and can be easily acquired. It gives some accuracy, but also gives a timing code to find the second code which is spread over more bandwidth around the same frequency. As an afterthought, they released the first stage (the narrow one) to the public. This first stage is what we all use and love.