Anactive protection system (APS) is a system designed to actively prevent certain anti-tank weapons from destroying a vehicle.
Countermeasures that either conceal the vehicle from or disrupt the guidance of an incomingguided missile threat are designatedsoft-kill active protection measures. Countermeasures that physically strike an incoming threat to damage or destroy it and thereby limit its ability to penetrate armor are designatedhard-kill active protection measures.
Soft-kill measures are designed to defeat guided weapons either by concealing the protected vehicle from them (for example, with asmoke screen) or by disrupting their guidance with radiation (for example, with adazzler). Some systems use laser dazzlers to blind the operator or sensors ofsemi-automatic command to line of sight (SACLOS)anti-tank guided missiles (ATGMs), such as the JD-3 of theType 99 tank. Others use powerful infrared emitters to mask the IR tracking flare present on many SACLOS ATGMs, such as theShtora-1.
Soft-kill measures can be divided intoon-board countermeasures, such as dazzlers, which are fixed to the platform andexpendable countermeasures, such as smoke grenades, which are ejected upon use.
Soft-kill measures may be used preemptively, but are more commonly employed in reaction to detected threats.
Hard-kill measures kinetically attack threatening missiles or other munitions, usually at very close range to the protected vehicle.Explosively formed penetrators (EFPs) or high explosive fragmentation countermeasures are typically used. The exact mechanisms of many APS systems have not been published.The action of these countermeasures may lead to:
There are many examples of hard kill countermeasures. The RussianArena system utilizes aDoppler radar to detect incoming threats and fires munition to eliminate the threat. The IsraeliTrophy system fires a multiple explosively formed penetrator (MEFP) to destroy the threat. An American system known asQuick Kill detects incoming threats using anActive Electronically Scanned Array, which assesses the threat, and deploys a smaller rocket countermeasure. Another American system, known asIron Curtain, utilizes two sensors to reduce false alarms and defeat threats inches from their target by firing a kinetic countermeasure designed to minimize collateral damage. The RussianAfganit active protection system of theArmata AFVs features a millimeter-wavelength radar to detect and track incominganti-tank munitions. It can reportedly interceptarmour-piercing fin-stabilized discarding sabotkinetic energy penetrators in addition tohigh-explosive anti-tank (HEAT) munitions.[1][2]
Mountains and neighboring vehicles reflectradio waves, thus creatingradar clutter, which adversely affects radar-detection and radar-lock performance.[citation needed]
The trajectories oftop attack ATGMs like theFGM-148 Javelin (US) andTrigat (Germany) plunge down onto their targets. Not all active protection systems are designed to fire at the extreme elevations necessary to protect against such munitions. RPGs fired at a steep downward angle from elevated positions can pose a similar threat.
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