GPS.gov says interference can come from radio emissions in nearby bands, intentional or unintentional jamming, and naturally occurring space weather. Telling which one you have shapes the response, because only one of the three is an attack, and the fix and the reporting path differ for each.
The three causes
The official GPS.gov page on spectrum and interference names the sources in one sentence, and it is a useful frame.
- Nearby band emissions. A transmitter working in a neighbouring frequency band can leak into the GPS band. The US executive branch has set power limit criteria for transmitters in bands near GPS to limit this.
- Jamming. This can be intentional, or unintentional, such as a faulty device that radiates noise.
- Space weather. Natural activity in the space environment can degrade signals with no human involved.
Spoofing, where a device sends fake signals that look real, is a different problem from all three. It is not about drowning the signal but about replacing it, and it is covered by different defences.
Clues that help you tell them apart
None of these are proof, but they guide the first hour.
- Many unrelated devices fail at the same moment and place. That points to a local emitter or a jammer.
- Failure follows you as you move, then clears. A moving source, such as a vehicle carrying a jammer, fits that pattern.
- Failure is wide, hits sites far apart, and matches a known space weather event. That points away from a local device. Check space weather reports for the time window.
- Position jumps to a plausible but wrong place. That is a spoofing symptom rather than a jamming one, since a jammed receiver tends to lose its fix.
Treat these as hints. Collect timestamps, locations, receiver models and logs before drawing conclusions.
What the rules say about jammers
GPS.gov states that consumers cannot legally use signal jammers within the United States, and that the FCC is cracking down on the marketing, sale and use of illegal cellphone and GPS jamming devices. A cheap gadget in a delivery truck can disturb receivers around it, so "it only affects me" is not a safe assumption.
Who to tell
Civilian users who suspect radio interference should report it to the US Coast Guard Navigation Center and the FCC, per GPS.gov. The page also notes that the US Space Force Joint Commercial Operations publishes daily unclassified heat maps showing intentional interference and spoofing worldwide. Those maps are a quick way to check whether your region has known activity. Outside the United States, your national spectrum regulator is the likely contact, which you should confirm locally.
Build for loss, not just detection
Any system that needs time or position from satellites should have a plan for the signal being unavailable. Log receiver status. Alert when the number of tracked satellites drops sharply. Decide ahead of time what the system does without a fix, and test that path on purpose.
Quick check
Is jamming the same as spoofing?
No. Jamming blocks or drowns the signal. Spoofing sends fake signals that look genuine. They need different defences.
Can space weather cause GPS problems?
GPS.gov lists naturally occurring space weather as one source of interference, alongside nearby band emissions and jamming.
Sources
Last reviewed: 19 October 2026.
