A difficult but essential element: how do you know that the jamming had an effect? Unlike a kinetic hit, an EW effect is often invisible. Battle damage assessment (BDA) for EW relies on indirect indicators:
- the enemy radar loses lock, switches to another frequency (an EP response, Electronic Protective Measures), or goes silent;
- enemy message traffic stops or is repeated (a sign of COMJAM effect, Communications EW & SIGINT);
- a missile that has been fired misses, or is not launched at all;
- measured J/S margins (Burn-through and the J/S ratio) and ES feedback (EW: Electronic Support Measures) confirm that the jamming actually reached the target.
Because the effect is reversible and invisible, BDA for EW is a discipline of its own — and one reason why ES (sensing) and EA (disrupting) always work together.