It's not so easy to find them when they are intermittent and mobile. The prime example is truck drivers who want to briefly disable the GPS tracking systems the

It's not so easy to find them when they are intermittent and mobile. The prime example is truck drivers who want to briefly disable the GPS tracking systems their company put on their trucks. One of these guys was occasionally driving past a major airport... https://gizmodo.com/jamming-gps-signals-is-illegal-dangerous-cheap-and-e-1796778955 https://gizmodo.com/jamming-gps-signals-is-illegal-dangerous... And the penalties seem pretty mild: https://www.fcc.gov/general/jammer-enforcement https://www.fcc.gov/general/jammer-enforcement If one thought the FBI (or a partner or ex-partner) was prone to putting a GPS tracker in one's car, one might grab cheap jammer from a Chinese e-commerce site for $20. This is all for simple omni-directional jammers, whether chirp or wideband. Directional jamming of an aircraft is simple, and let's you put lots of energy on the target and also mask your transmission from surveillance systems. Sophisticated systems don't simply overwhelm the receiver, they trigger decoding errors, and with much less power. The full scope of the problem is masked at present. It is relatively trivial to provide fake GPS signals so as to seduce a target receiver (e.g. mobile phone, plane GPS system) to believe it is somewhere else entirely, or off track by hundreds of meters. If a plane believes it is elsewhere, and transmits that via ADS-B, it could easily cause havok.