In his small workshop cluttered with devices of all kinds, Todd Humphreys, director of the Radionavigation Laboratory at the University of Texas in Austin, shows his students the video of a recent experiment. We see a smartphone held at arm’s length whose screen shows a Google map: “The device is located with its GPS chip and indicates its position with a blue dot on the map.” Suddenly, the blue dot starts to move, as if the smartphone had just been in a car, while it is still in the same place. The GPS chip transmits a wrong position, but credible, because the progression on the map is at a normal pace, along a street.
To explain this enigma, Todd Humphreys points to an ordinary-looking case in a corner of the studio: “It’s a spoofer (” usurper “), a GPS jammer simulator that picks up authentic signals from GPS satellites , then re-emits them on the same wavelength after having slightly modified the coordinates The neighborhood GPS systems will first pick up the false signal from the spoofer, because it is more powerful than that of a satellite located 20 000 kilometers from If I installed one on the roof of this building with a good antenna, I could distort all the GPS in the neighborhood, and even those planes passing over the city. ”
According to Todd Humphreys, a spoofer used for malicious purposes by hackers, gangsters or terrorists could cause chain disasters, since GPS systems now play a vital role in many sectors of activity: land transport, air and shipping, container management, agricultural machinery guidance, electronic communications and even banks, which use satellite signals as a universal clock to date financial transactions to one hundredth of a second.