What are the two types of ECM?

The correct answer identifies the two fundamental types of Electronic Countermeasures (ECM) as Passive and Active.

Active ECM involves emitting signals to disrupt or deceive enemy radar systems. This can be accomplished through techniques such as jamming, where a competing signal is transmitted to interfere with the enemy’s ability to detect or track targets. It actively engages with the enemy's systems, making it a direct method of neutralizing threats.

On the other hand, Passive ECM does not involve emitting signals but instead relies on techniques that exploit the enemy’s radar. This includes actions like using radar-absorbing materials or electronic deception, such as providing false signatures to mislead detection systems. It essentially allows assets to operate without actively revealing their presence, thereby enhancing stealth.

This distinction between active and passive methods is crucial for understanding how naval forces protect themselves and engage in operations while minimizing vulnerability to enemy sensors.