By: Mark Lidikay
I recently ran across this device online and thought it would make a good test. Now to start with jamming radio spectrum is illegal because it makes the frequency unusable to everyone with in some radius. If everyone were deciding what they wanted to allow over the air it would not take long before nothing was usable. In testing this device I started out investigating what it did in a manner that did not allow it to radiate. My initial expectation is that it would do nothing at all since some devices sold online have been found to have nothing but an LED. In this case the device was putting out a signal from 1545MHz to 1645MHz which seems to target the GPS, GLONASS and GALILEO bands. The signal was -40dBm (0.0001mw) directly out of the device, this is not a very strong signal. . This could potentially be a problem for a GPS device that was close enough to the jammer except that there are also GPS and other navigation bands allocated from 1164MHz to 1300MHz.
Since the signal was so weak, it was not likely to make it out of the building let alone any distance, so I moved to a test with it’s antenna. The signal measured three feet away was now -95dBm. With my phone/GPS 2 inches from the device, it still worked just fine. The GPS was still able to get a position. Just to eliminate the possibility that the GPS could have stored a position I went out to the the car and tried a short trip around a few blocks. The GPS continued to track just fine. Here again with the signal so weak to begin with, both distance and the body of the car would attenuate it beyond the point of bothering anybody for this short test, which was not interfering with the GPS in the car to begin with.
Perhaps the device might have been effective against some of the first GPS units, before the additional bands were allocated. In theory it could be within maybe 5 or 6 feet. For the current units that use multiple frequencies to pick up the satellites it was completely ineffective.