If you Google long enough to find interesting electronics to splurge on, you're bound to be recommended all sorts of dubious electronics. So I recently tested these little jammer gps that plug directly into a car's cigarette lighter socket. Shipping in the US is under $10, and in my opinion, this device is perfect for opening it up in the name of science.

　　You might be wondering what legal uses this gadget has. As far as I know, no. The only reason you'd want to interfere with the GPS signal around your device is if you're trying to get away from something you shouldn't. Maybe you're driving a tracked company vehicle and want to take a few hours of naps in the parking lot, or maybe you want to turn off the built-in GPS of a stolen car so you have enough time to get to the workshop.

　　However, we won't focus too much on the potential malicious causes of such devices. Hackers never have to be picky about the equipment they research and experiment with, so it's not worth buying. Let's test this iron better from the regular "grey" area and see how it works.

　　Although the GPS satellite orbit altitude of 20,200 kilometers is not as high as that of the communication satellites in the geosynchronous orbit, it is still far from us. Given the distance and size of the antennas on most GPS devices, it's not surprising that the signal received from them is very weak. So much so that it is usually weaker than noise. Only very clever algorithms and a little magic can make your phone hear the whispers of the stars and turn it into something akin to useful information.

　　It's the fragility of this signal that makes it possible to make such a low-cost jammer. To suppress such a signal, not much is needed. Note that the device isn't trying to mimic GPS satellites - it's just broadcasting spam, loud enough that the real satellites can't be heard.

　　The jammer is so harsh that it completely overwhelms the drone signal at 300 meters, even without a directional antenna.

　　Of course, our first thought is to come to a drone competition or exhibition, turn on the jammer, and send everyone the business card of the drone repair shop.

　　It turns out that interfering with WiFi, Bluetooth or Zigbee signals is not difficult at all. All you need is a simple $15 dongle that you can get on Amazon. It connects to a computer or Raspberry Pi. The base antenna has a range of 80 meters. If a signal amplifier is installed, the working distance of the jammer can reach about 120 meters. Signal jammers have been actively used by attackers. For example, car thieves use portable jammer to prevent the car from locking, and GPS jammers to block signals from anti-theft systems (after the car is stolen). Burglars use such jammers to block cellular service during illegal entry into apartments.