The ECM arsenal at a glance, ordered by what it attacks:
- Noise jamming attacks the SNR: barrage (wide, thin), spot (narrow, thick), swept-spot (thick, in turn), side lobe (through the antenna's back door — directional information becomes worthless).
- Deceptive jamming attacks the tracker's gates: RGPO/RGPI (range), VGPO (Doppler), inverse gain / cross-eye / cross-pol / blinking (angle) — and DRFM made the lies coherent and kinematically consistent.
- Cover pulses erase the real echo instead of offering a false one — economical and inconspicuous.
- Decoys (towed, expendable active) move the transmitter away from the platform and thereby defeat home-on-jam and Doppler discrimination.
- Chaff passively offers a larger radar target (λ/2 dipoles) but is betrayed by its Doppler; flares offer a hotter IR target but are filtered out on spectrum, kinematics and image — both live on as layers in a package.
- DIRCM jams the IR seeker directly through its own optics; stealth deprives the sensor of its signal at the source (the fourth root!); counter-IR tactics deprive it of contrast, geometry and time.
Two common threads to remember. One: every ECM technique exploits an assumption made by the sensor — and every EPM measure (next chapter) breaks an assumption made by the jammer. Two: nothing works on its own; the modern self-protection package is layered (warning → manoeuvre → expendables → active means), and the direction of it all starts with listening: ESM, EW: Electronic Support Measures.