weapon knowledge丨talking about towed sonar
2024-09-22
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talking about towed sonar
■ french general cheng shangjinxin
schematic diagram of towed sonar underwater operation. drawn by zhou kai
according to foreign media reports, in may this year, at the asian defense services exhibition held in malaysia, a turkish company demonstrated two types of small towed sonars that can be deployed on unmanned surface ships - low-frequency active towed array sonar and passive towed sonar, showing a broader prospect for the use of towed sonar.
the principle of sonar detection is similar to that of radar, except that sound waves are emitted and received instead of electromagnetic waves. it is mainly used for searching, warning, tracking and monitoring submarines, surface ships, mines and torpedoes. it can also be used for underwater navigation and positioning, shipwreck detection and underwater short-range communication. the reason why sonar often uses low-frequency sound waves is that low-frequency sound waves have less energy attenuation when propagating in water, can propagate farther, and can better "penetrate" anechoic tiles to detect target submarines.
the core component of towed sonar is the transducer array. the transducer is a component used to realize the mutual conversion of electrical energy and acoustic energy in order to better transmit signals. the transducer array arranges and combines multiple transducers according to a certain rule to obtain better detection effects. simply put, a towed sonar is a sonar system in which part of the device is left at the tail of the carrier platform, and the other part of the device includes the transducer array towed in the water. from a distance, it looks like a long tail, towing behind the tail of the carrier platform, so it is called a towed sonar.
towed sonar started late but has developed rapidly because it has a series of advantages: the core components are far away from the carrying platform and are relatively less affected by the noise of the carrying platform; by controlling the speed of the carrying platform and the length of the tow cable, the sonar can be operated at the optimal depth, with better detection effects.
towed sonar also has shortcomings. for example, the transducer array, tow cable and retractable device take up a relatively large space on the carrier platform; when the transducer array is placed in the water and works, the swing amplitude is large, which has a certain impact on the maneuverability of the carrier platform.
according to the structural characteristics of the transducer array, towed sonar can be divided into towed body sonar and towed linear array sonar. among them, towed linear array sonar is more advanced, with more transducers and longer tow cables, so the detection distance is deeper and farther.
according to the working mode, towed linear array sonars can be divided into passive and active and passive types. the ones installed on submarines are generally passive towed linear array sonars, while the ones installed on surface ships can be passive towed linear array sonars or active and passive sonars.
according to the purpose of use, it can be divided into tactical and surveillance types. tactical towed linear array sonars are generally one or two hundred meters long and are mainly used for passive surveillance tasks, mainly used to indicate targets and guide ship-borne helicopters for anti-submarine operations; surveillance towed linear array sonars are generally more than 1,000 meters long, have low operating frequencies, and slow towing speeds, and are mainly used for ultra-long-range underwater surveillance tasks.
at present, the navies of more and more countries have begun to use towed linear array sonar as the main equipment for anti-submarine detection, and are developing towards higher resolution, larger detection range, and stronger anti-interference capability.
the united states' tb-29a towed linear array sonar and the united kingdom's kraitarray towed linear array sonar belong to this type of sonar.
the two types of sonars from the united states and the united kingdom also reflect another direction of the future development of such sonars - small and easy to use. as low-frequency thin-line array sonars, they can not only significantly reduce the weight, power consumption and manufacturing cost of the sonar towed body, but also make deployment and recovery more convenient.
of course, this type of sonar has its limitations. due to the small size of the transducer array, it is not only easily affected by waves, but also not suitable for use in offshore environments with complex sea conditions.
(source: china military network-liberation army daily)
