According to the announcement of Turkey's Aselsan Defense Company, the Pakistan Navy's Agosta 90B class submarine mid-term upgrade (MLU) project completed the factory acceptance test (FAT), the most important of which was the installation of a Turkey-made Zargana torpedo countermeasure system, by firing ZOKA acoustic jammers and decoys to deflect incoming acoustic self-guided torpedoes, which can be described as weaving an underwater ecstasy array, thereby protecting the safety of the submarine.
The Pakistan Navy has a total of 5 conventional submarines in service, all belonging to the French Agosta series, of which 2 Aresta 70, equipped with troops in the early 1980s, 3 Argista 90B, in 1994, the Pakistani side signed a contract to introduce 3, the first boat "Khalid" was built by the French DCN in the Cherbourg Shipyard, and entered service in 1999. The second Saad was assembled in Karachi using components built at the Cherbourg shipyard and entered service in 2003. The third Hamza was fitted with an additional MESMA AIP system to extend underwater endurance and entered service in 2008. The first two boats were also fitted with AIP units in subsequent modifications. Because of India's obstruction, Pakistan signed a contract with Turkey's STM Company in 2016 to modernize three Agosta Agosta 90B submarines in the medium term. The Turkish side provided structural planning for design engineering and procurement, upgraded at the Pakistani shipyard, and provided logistical support and training services by Turkey, retrofitted all sonar kits, periscope systems, command and control systems, radar and electronic warfare systems, retrofitting torpedo countermeasure systems and acoustic measurement sensors made domestically made by Turkey. STM delivered its first upgraded submarine, hamza Hamza, in 2020.
The submarine's underwater enemy is the enemy's acoustic self-guided torpedo and sonar, and when the submarine is attacked by the enemy, it is necessary to get rid of the locking attack of the torpedo; or when the enemy anti-submarine platform is being detected and tracked, it needs to get rid of its positioning of the submarine itself. This makes it necessary for submarines to use underwater acoustic countermeasures to protect themselves. Underwater acoustic confrontation is an important part of underwater electronic warfare, which is to use the principle of hydroacoustics to weaken or hinder the effective detection and attack of the enemy's hydroacoustic weapons and equipment, so that the enemy's acoustic self-guided torpedo or sonar fails or is confused, and at the same time to ensure the safety of their own ships. The equipment used is called underwater acoustic countermeasure equipment, which is generally divided into soft kill and hard kill 2 kinds, of course, this equipment can also be equipped on surface ships, but larger and more perfect. Soft killing equipment includes different types of air curtain shells, sound decoys, sound jammers, wake simulators, etc., and hard killing equipment includes rocket depth bombs, detonation sound decoys, anti-torpedo torpedoes and other types. Turkey's Zargana torpedo countermeasures system is a soft-kill device that fires ZOKA acoustic jammers and acoustic decoys. An acoustic jammer is a wideband noise generator that emits high-power noise to mask ship/boat noise, while acoustic decoys can trick incoming torpedoes by simulating the submarine's movements and acoustic behavior.
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Because the underwater acoustic countermeasure systems of various countries are related to the survival of surface ships and submarines, the possibility of technology transfer is very small, and the Turks can only rely on themselves. Before 2000, Turkey did not have any related systems, until 2006 ASESAN company made a lot of investment in the field of underwater acoustic system technology, and in a very short period of time in the field of torpedo countermeasure systems achieved important technical results, in 2007 ASELSAN and the Turkish Ministry of Defense signed a contract to develop a submarine acoustic decoy system, thereby developing a HIZIR torpedo countermeasure system for surface ships and a ZARGANA torpedo countermeasure system for submarines in a relatively short period of time. In 2014 ASALSAN also started developing an anti-torpedo torpedo with the support of TÜBİTAKTEYDEB (Turkish Council for Scientific and Technological Research, Technology and Innovation Funding Scheme) to achieve hard kills.
The ZARGANA submarine torpedo countermeasure system consists of a tactical development simulator (ground), a decision support system, a launcher (starboard/starboard), and a scalable effector (acoustic jammer/acoustic decoy). Tactical development simulators are used to develop and validate countermeasures that provide the highest survival rate in different threat scenarios on the ground; these tactics are then installed on a decision support system on a submarine or surface platform, which can also be integrated into a submarine fire control system. When the system uses data obtained from submarine sensors/systems to detect actual torpedo threats through its detection, positioning, and classification functions, the system uses scenarios and algorithms stored in its database to provide tactical advice to the operator based on the threat situation, including evasion maneuvers for submarines or surface platforms, as well as acoustic decoys, jammers, and launch modes and timing, and operating parameters. This requires a sufficient understanding of enemy submarines to be able to develop better countermeasures.
The launcher of the ZARGANA submarine torpedo countermeasure system, which is generally installed inside the submarine hull in a group of 6 jamming shells or acoustic decoys, has participated in several weapons exhibitions, but its first practical appearance was on January 30, 2020, when a Turkish 209T1/1400 Plewitze-class submarine S-356 Anafitara was photographed as having two sets of 6-in-pack white launchers installed on the side of the hull while passing through Istanbul. The transmitter has a rapid response capability, flexible configuration of the launch unit according to user needs, up to 24 launch tubes on both sides of the hull, with high redundancy, single/continuous launch capability, and bubble-free emission to reduce noise.
The scalable effectors used in the ZARGANA submarine torpedo countermeasure system include a longer ZOKA acoustic jammer and a shorter acoustic decoy. Both are modular in design and can be manufactured in different types and sizes according to user requirements. ZOKA acoustic jammer is a broadband high-power acoustic noise generator, may be composed of reconnaissance receiving components and release interference components, can operate in active, passive or active and passive combination mode, can receive the enemy underwater acoustic equipment emitted by the sound wave signal, automatic analysis of the signal operating frequency, pulse duration, pulse period and other related parameters, and then control the transmitter to transmit the corresponding broadband high level interference sound waves, in order to cover up the submarine's noise, so that the enemy torpedo completely confused and lost the target. The Turks claim that the ZOKA acoustic jammer is capable of covering all operating frequency bands of modern acoustic self-guided torpedoes. ZOKA acoustic decoy is directly generated by the noise generator or amplified by the submarine recording, through the transducer to emit high-fidelity simulation of the submarine's noise and simulated dynamic characteristics, so that the enemy torpedo is lured to the direction of the decoy to detonate, in order to preserve the submarine or deceptive sonar tracking, but also can be released in a specific formation mode, which can greatly improve the submarine's survivability in the torpedo attack.
Pakistan and India are definitely the powder kegs of South Asia, and its three armed forces, especially the navy and the enemy, in order to counteract the Indian Navy, Pakistan needs submarines as asymmetric weapons to deter a large number of Indian naval ships, and India also has nuclear submarines and catfish-class conventional submarines, in this case Pakistan's older Agosta 90B submarine will be greatly threatened. After equipping the ZARGANA submarine torpedo countermeasure system, the Pakistani submarine can obtain a stronger survivability with its assistance, thus gaining a hard-won advantage in underwater confrontation!