Short answer
Techniques and equipment that maintain GNSS reception in the presence of deliberate or accidental RF interference. The main hardware approach is a CRPA (controlled reception pattern antenna); software approaches include narrow-band filtering, AGC compression detection, and pulse blanking.
Detailed explanation
GNSS signals at the user antenna are extraordinarily weak — about −128 dBm at GPS L1, well below thermal noise. A trivially-small jammer (sub-watt at 1 km range) can overwhelm this signal and prevent any GNSS receiver from acquiring or tracking. Anti-jamming is the collection of hardware and software techniques that maintain useable reception despite such interference.
Hardware anti-jamming: CRPA arrays (steer nulls toward jammers), high dynamic range LNAs (don't compress under strong in-band signals), saturation-resistant front-ends, narrow-band notch filters (remove specific known interferers like FM repeaters), and pulse blanking (drop sample windows that contain pulse jammers).
Software anti-jamming: AGC monitoring (detect interference by watching for unusual compression), narrow-band excision in the frequency domain, multi-constellation cross-validation, and Kalman filter weighting based on per-satellite C/N₀.
Operational anti-jamming: physical antenna placement (avoid line-of-sight to ground-level jammers, use roof masking), inertial coast-through during jamming events, and switching to alternate PNT sources (eLoran, INS) when GNSS is denied. The DSP-based CRPA is the highest-payoff hardware investment for high-value platforms.
Where you'll see this
Anti-Jamming CRPA
Browse product lineRelated terms
CRPA
An adaptive antenna array (typically 4, 7, 11, 16, or 32 elements) that electronically steers nulls toward jamming sources and / or steers beams toward GNSS satellites in real time. The standard anti-jamming hardware for military and high-value civilian GNSS receivers.
Anti-spoofing
Detection and rejection of false GNSS signals — typically broadcast by an attacker who wants to misdirect a receiver to a false position or time. Distinct from anti-jamming; spoofing attacks use plausible-looking signals, not raw noise, so the receiver has to authenticate rather than just power through.
LNA
An amplifier with very low added noise (typical NF 1–2.5 dB at L-band) placed as close to the antenna element as possible. Sets the cascaded noise figure of the entire receiver chain and lets the antenna drive long cable runs without C/N₀ loss.