Aselsan developed the ZOKA Torpedo Countermeasure family (comprising both stationary and self-propelled jammers and target emulator decoys) with up-to-date signal processing capability under the DAKA (Acoustic Decoy System for Submarines) Project. ZOKA effectors are capable of operating effectively against any torpedo threat that has acoustic homing capability operating in active, passive or combined modes. Two types of ZOKA effectors, jammers and decoys, are used in HIZIR-Torpedo Countermeasure System for Surface Ships and ZARGANA-Torpedo Countermeasure System for Submarines. The system offers considerably reduced reaction time compared with signal tube ejection thanks to being fully integrated into the submarines’ combat management system.
ZOKA jammers transmit wide band high-level noise to saturate acoustic operating frequency bands of all existing torpedoes. In this way, jammers mask the noise of submarines against passive torpedoes and reduce the detection range of echo signals reflecting from the submarine by increasing the noise level against active torpedoes. ZOKA decoys deceive and confuse the torpedo by simulating the acoustic and dynamic characteristics of the platform and attract the torpedo to themselves. ZOKA decoys have separate receive and transmit sections. A hydrophone is towed from the stern of the decoy. Having separate receive and transmit units allow decoy to perform noise generation and echo generation of torpedo active pulses at the same time. The combined use of ZOKA decoys and jammers has been highly effective against acoustic torpedoes.
ZOKA effectors with various lengths have mobile capability in vertical and/or horizontal plane and can be launched from surface ship launchers, submarine signal ejectors and submarine outboard launchers. Some 280 ZOKA decoys and four ZARGANA TCMS were manufactured for the AY-class submarines, with a further 360 and eight respectively for the PREVEZE- and GUR-classes. All three classes can launch the LAPIN, MERCAN, CIPURA and CACA (10x50cm and 10x100cm) decoys though signal ejector tubes: PREVEZE- and GUR-class boats, however, use the ZARGANA launcher for the 12.5x120cm self-propelled LIPSOZ target emulator and ESKINA jammer.