GPS jamming drowns the weak satellite signal in noise. The receiver notices that it no longer has a position — inconvenient, but at least you know something is wrong.
In practiceSince 2022 there has been large-scale GPS interference over the Baltic Sea region and around Kaliningrad, attributed to Russia, which also affects civil aviation. Pilots then switch to other navigation aids; military units deliberately train to operate without GPS.
Jamming drowns the GNSS signal in noise — the navigation counterpart of noise jamming against radar (Noise jamming). The aim is denial: the receiver loses its lock and can no longer determine position or time. The forms:
| Type | How it works | Characteristic |
|---|---|---|
| Wideband noise | noise across the whole band (e.g. all of L1) | simple, reliable; hits C/A, P(Y), M and Galileo at once |
| Narrowband / CW | energy on a single frequency | power-efficient, but can be suppressed by filtering |
| Chirp / swept | a tone sweeping rapidly across the band | the "personal privacy device"; cheap and widespread |
| Matched-spectrum | noise shaped like the code's band | maximum J/S per watt; more advanced |
| Pulsed | short, powerful pulses | can strike in between the receiver's integrations |
The effects increase with the J/S ratio: first accuracy decreases and satellites drop out, then the position fix breaks, and finally time disappears as well. As with radar, there is a burn-through range (Overpowering the jamming signal): close enough to the jammer there is no reception, and only at a greater distance does the satellite signal win again.
Operationally, GNSS jamming has become ubiquitous: in conflict zones whole regions are disrupted structurally, with noticeable consequences even for civil aviation. For the attacker the trade-off is the same as for any jammer (Radar Jamming): transmitting gives away your position and makes you a target for home-on-jam weapons (Home-on-jamming) and anti-radiation munitions.