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At the university of Texas at Austin at the university of radio navigation subvert GPS, director of the laboratory in his small confusion with all kinds of equipment in the workshop, to introduce students to the latest experiment of the video. We saw a handheld portable jammer display with a GuGe map: "the device is on a GPS chip and shows a blue dot on the map." Suddenly, the blue dot began to move, as if the smartphone had to be embedded in the car, and it was still in the same place. GPS chips send the wrong location, but credibility, because the progress on the map is done along a normal speed along a street.

To explain the mystery, Todd Humphreys pointed to a prosaic example in the corner of the studio: "it's a deceiver (" usurper"), a GPS simulator, picking out real signals from GPS satellites, and then relaunching them at the same wavelength after modifying the coordinates a little bit. The neighborhood's GPS system will be a priority to collect this faked signal first, because it's more powerful than a satellite of 20 000 kilometers and if I put a good antenna on the roof of this building, I can distort all the GPS in the area, even through the city's plane.

What's practical and practical is that mobile phones are not without flaws, especially in a quiet place where they make a device or their user's noise. Some manufacturers have already proposed a way to solve these inconveniences: the active GSM jammer has to send out a larger signal than a large power relay scrambler, to cut off the receiving, to prevent the use of the phone. These devices can be sold in France, but they are all legally used. Effective? According to Tom's guide, it's best to stay out of the product.

On their site, sellers explains, jammer were employed to neutralize a placed on vehicle GPS signal, without the driver's knowledge or against his will. Therefore, in the United States, they have been around for many years used by truck drivers, want to escape the supervision of their company, such as working in the day of rest of the night. In 2009, near New York's New York airport, the experimental system of a GPS aircraft guide exploded every Thursday for a fixed time. Experts took several weeks to know that the robber the truck is equipped with a jammer, near the airport.

In addition, more basic equipment, only for scrambling GPS signals, is becoming commonplace. These are fairly simple machines that broadcast parasitic signals on the wavelength of satellite use. As a result, the GPS system around them disoriented and stopped working.

In most countries, their use is prohibited, but they can be used on the counters of various European and Asian websites. A small pocket jammer on a cigarette lighter can be charged only 30 euros. The more powerful model cost about 200 euros. Some Chinese websites even sell tripod military superjammers that may disrupt more than a kilometer of GPS. In another type, the hacker group that campaigns to protect the privacy of its citizens has released the instructions from the Internet to create their own cell phone jammer on the Internet.

So far, we've had no major accidents with the use of deception, but Todd humphreys says isolating hacker fun and building handmade equipment. Experimental models with scientific careers are sold on the Internet.

In addition, organized truck thieves began using GPS jammers. Freightwatch, an electronic cargo monitoring expert based in Austin, is working closely on the phenomenon. According to Bill Games, this type of business is very rare in North America and Europe, but in Mexico, especially in Brazil, it's a very popular thing: "first, the thief follows the truck," and in a car, he says, it has a jammer, so the GPS system has lost the trail of the truck before it was stolen, and the driver forced the driver to stop and walk away, always with a jamming car. "

In Austin, Todd humphreys complete more sophisticated equipment, its precise positioning, GPS jammer and development policies are allowed. In addition, he noted that the USRP (universal software radio peripherals) new radio transmitters are very popular with researchers and radio amateurs, and can broadcast signals on GPS frequencies, which can lead to very effective interference. The war of interference has just begun.

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