Also found in: Acronyms.
Those countermeasures that require transmissions from friendly sources. Active countermeasures can be electromagnetic, IR (infrared), electro-optical, or microwave. Among electromagnetic active countermeasures, the most common are deception jamming, self-protection jamming, and stand-off jamming. This is in contrast to passive countermeasures such as chaff dispensing. Also called active detection systems.