Jamming and spoofing both attack satellite navigation, but they do opposite things — and they need opposite responses. Jamming denies: it drowns the signal so your receiver gets nothing. Spoofing deceives: it feeds fake signals so your receiver reports a confident, wrong answer. Knowing which one you're facing changes everything about what you do next.
Jamming: denial
A jammer simply transmits noise across the GPS band, far stronger than the faint signals coming from satellites. The receiver is swamped and loses its fix entirely. The symptom is obvious: the tracker goes offline or blank, position stops updating, the device reports no lock. Jammers are cheap — around £30 — which is exactly why they're the tool of choice for stealing plant and vehicles. If an asset's tracking simply disappears, jamming is the prime suspect.
Spoofing: deception
Spoofing is the clever cousin. Instead of drowning the signal, it transmits counterfeit satellite signals so the receiver locks onto them and calculates a false position — or a false time. The dangerous part is that nothing looks broken: the device shows a confident location that simply isn't real. Spoofing takes more skill and kit than jamming, so it's rarer in everyday theft and more associated with conflict zones, aviation and shipping — but it's worth knowing it exists.
Why the difference matters to you
For plant and fleet operators, the threat you'll almost always meet is jamming — an asset going dark as a prelude to theft, or an operator killing the signal to go unmonitored. Spoofing matters more where a wrong-but-plausible position could be used to mask a route or mislead. The practical point: if your tracking shows nothing, think jamming; if it shows something that's clearly wrong — a jump, an impossible location, a time error — consider spoofing.
How each looks on the radio
The two are very different to an RF engineer. Jamming is unmistakable — the noise floor across the GPS band lifts dramatically, a brute-force signature anyone with a spectrum analyser sees instantly. Spoofing is subtle, because the counterfeit signals sit at roughly normal power and look like the real thing; catching it means examining the consistency of the signals themselves, not just the noise level.
It's not just GPS
"GNSS" covers GPS plus Galileo, GLONASS and BeiDou. A jammer or spoofer may hit one band or several, and many modern receivers use more than one system — which can help, since knocking out all of them at once is harder than knocking out one.
No position vs wrong position
A tracker showing no position is most likely being jammed. A tracker showing a wrong but believable position may be spoofed. Either way, the receiver has stopped telling you the truth — and confirming which it is takes measuring the signal, not guessing from the symptom.
See GPS jammer detection →When to investigate
If assets are going dark, or positions look wrong in ways you can't explain, an RF investigation can establish which attack it is, measure it, and document it. Knowing whether you're being denied or deceived is the first step to doing anything about it.