Jamming versus spoofing: why the quiet one is worse
A jammer announces itself — you lose lock and you know it. A spoofer lets the receiver keep working while it reports a position that was chosen for you.
Jamming is loud
A jammer raises the noise floor until the receiver can no longer pull the satellite signal out of it. GNSS signals arrive at roughly −130 dBm, below the thermal noise floor; a few watts from a nearby transmitter buries them completely.
The saving grace is that jamming announces itself. You lose lock, the receiver reports it, and your flight controller can act — return to home, hold on inertial, land. It is a failure you can plan around.
Spoofing is quiet, and worse
A spoofer transmits counterfeit satellite signals that look correct. The receiver locks onto them, reports a healthy fix with good C/N₀ and plenty of satellites, and hands your autopilot a position that someone else chose.
Nothing looks wrong. There is no alarm to act on, because from the receiver's point of view everything is nominal. That is what makes spoofing the more dangerous of the two: your failure mode is not losing navigation, it is trusting navigation that is lying to you.
Why a CRPA answers both
Both attacks share a weakness: they come from somewhere. Real satellites are spread across the sky, thousands of kilometres up, arriving from many directions at once. A jammer or a spoofer is a transmitter at one location, so its energy arrives from one direction.
An adaptive array reads that difference geometrically. It combines the signal from each element so that gain collapses in the attacker's direction while the satellites are still received normally. The same mechanism that suppresses interference also suppresses a counterfeit constellation.
What ≤20 dB residual means
Our anti-spoofing models quote residual spoofing signal C/N₀ at ≤20 dB at the output. In practice: whatever the spoofer transmits, what survives to the receiver is pushed down to a level too weak to win the correlation against genuine satellites. It is a suppression figure, not a detection flag — the false constellation is attenuated before it can reach the navigation solution, rather than being flagged after it already has.