Anti-Submarine Warfare: "ASW - Tracking the Threat" 1982 US Navy Training Film 35798DN (Patreon)

more at http://quickfound.net/

Originally a public domain film from the US Navy, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.

The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

https://en.wikipedia.org/wiki/Anti-submarine_warfare

Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/

Anti-submarine warfare (ASW, or in older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, or other submarines to find, track, and deter, damage, or destroy enemy submarines.

Successful anti-submarine warfare depends on a mix of sensor and weapon technology, training, and experience. Sophisticated sonar equipment for first detecting, then classifying, locating, and tracking the target submarine is a key element of ASW. To destroy submarines, both torpedoes and naval mines are used, launched from air, surface, and underwater platforms. ASW also involves protecting friendly ships...

The military submarine is still a threat, so ASW remains a key to obtaining sea control. Neutralizing the SSBN has been a key driver and this still remains. However, non-nuclear-powered submarines have become increasingly important. Though the diesel-electric submarine continues to dominate in numbers, several alternative technologies now exist to enhance the endurance of small submarines. Previously the emphasis had been largely on deep water operation but this has now switched to littoral operation where ASW is generally more difficult.

Anti-submarine warfare technologies

There are a large number of technologies used in modern anti-submarine warfare:

Sensors

Acoustics particularly in active and passive sonar, sonobuoys, and fixed hydrophones aid in the detection of radiated noise. Sonar can be mounted on the hull or in a towed array.

Pyrotechnics in the use of markers, flares and explosive devices

Searchlights

Radar, for surfaced parts

Hydrodynamic pressure wave (wake) detection

Laser detection and ranging of surfaced vessels; airborne and satellite

Electronic countermeasures and acoustic countermeasures such as noise and bubble makers

Passive acoustic countermeasures such as concealment and design of sound-absorbing materials to coat reflecting underwater surfaces

Magnetic anomaly detection (MAD)

Active and (more commonly) passive infra-red detection of surfaced parts.

In modern times forward looking infrared (FLIR) detectors have been used to track the large plumes of heat that fast nuclear-powered submarines leave while rising to the surface. FLIR devices are also used to see periscopes or snorkels at night whenever a submariner might be incautious enough to probe the surface.

The active sonar used in such operations is often of "mid-frequency", approximately 3.5 kHz. Because of the quietening of submarines, resulting in shorter passive detection ranges, there has been interest in low frequency active for ocean surveillance. However, there have been protests about the use of medium and low frequency high-powered active sonar because of its effects on whales. Others argue the high power level of some LFA (Low Frequency Active) sonars is actually detrimental to sonar performance in that such sonars are reverberation limited.

Weapons

B57 nuclear bomb

Naval Mines

Torpedoes (acoustic or wake homing, wire-guided)

Depth charges

Rockets

Mk 101 Lulu

Anti-submarine missiles

Anti-submarine mortar

Anti-submarine net

Nuclear depth bomb

Ramming

WE.177