The AN/AQS-13 series was a helicopter

dipping sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or ...

system for the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

. These systems were deployed as the primary inner zone

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

(ASW) sensor on

aircraft carrier An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft. Typically, it is the capital ship of a fleet, as it allows a ...

based helicopters for over five decades. Companion versions with the AQS-18 designation were exported to various nations around the globe.

Purpose

Airborne sonar systems provide a light-weight, mobile detection sensor for locating and tracking submarines. Although limited in performance compared to larger, ship-mounted sonars, these helicopter-borne systems have the advantage of rapid deployment/retrieval times, and rapid transition between search areas. Additional advantages over ship sonars include absence of flow noise and engine noise, and the elimination of

Doppler shift The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who d ...

induced by a moving signal source. Deployed from Aircraft Carriers or other ships, these systems enable the aircraft to locate, identify and attack submerged targets within the flight radius from the home ship.

Description

The AQS-13 systems are all primarily

active sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or ...

transmitting in the upper end of the medium frequency sonar range. These systems offered the additional capabilities of voice communication, bathythermography and rudimentary passive sonar. Helicopter borne active sonar has significant advantages over other sensors and is especially effective in the inner zone where noise from the ships of the

carrier battle group A carrier battle group (CVBG) is a naval fleet consisting of an aircraft carrier capital ship and its large number of escorts, together defining the group. The ''CV'' in ''CVBG'' is the United States Navy hull classification code for an airc ...

can interfere with passive sensors. The components of the AQS-13 are informally divided into two groups, the "wet end" and "dry end." The "dry end" involves the processing of the acoustic signals to obtain tactical data. The "wet end" components are those necessary to deploy the acoustic unit into the ocean and retrieve it. These "wet" components include the acoustic elements in a submersible unit, the reel & cable and reeling machine. The

hydrophone A hydrophone ( grc, ὕδωρ + φωνή, , water + sound) is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates an electric potenti ...

and projector elements are housed within the submersible unit or

transducer A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, measurement, and contr ...

. The transducer, also called the "dome", a term borrowed from ship-board sonars, is lowered or "dipped" from the helicopter on a cable by means of the hydraulic reeling machine. The dip depth of the transducer is selected by the operator to achieve the maximum detection probability at the dip location on that particular day as determined by the study of ocean conditions (see

Underwater Acoustics Underwater acoustics is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries. The water may be in the ocean, a lake, a river or a tank. Typ ...

). During active search, the acoustic pulse is emitted from the projector assembly. Echos or "returns" are received by the

, routed through the sonar cable, processed in the aircraft and displayed on a

cathode ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms ( oscilloscope), pictu ...

(CRT) in a

plan position indicator A plan position indicator (PPI) is a type of radar display that represents the radar antenna in the center of the display, with the distance from it and height above ground drawn as concentric circles. As the radar antenna rotates, a radial tra ...

(PPI) format. Returns were also processed and made available to the RO-358 chart recorder in the AQS-13E and earlier systems. This data was made available to the aircraft tactical computer in the AQS-13F. The various functions were selectable by the operator, such as pulse lengths, range scales and other modes to enhance operations for the particular conditions. Sensor elements on the reeling machine monitor the relative angle of the deployed sonar cable and provide flight reference signals to the aircraft stabilization equipment in order to maintain a steady hover position over the submerged transducer. Tactical data of the target is obtained from the acoustic returns, including range, bearing and relative speed. Later versions of the AQS-13 were also capable of processing acoustic signals transmitted to the aircraft from

sonobuoys A sonobuoy (a portmanteau of sonar and buoy) is a relatively small buoy – typically diameter and long – expendable sonar system that is dropped/ejected from aircraft or ships conducting anti-submarine warfare or underwater acoustic resear ...

History

AQS-13

The AQS-13 system was introduced to the US fleet aboard the

Sikorsky SH-3D The Sikorsky SH-3 Sea King (company designation S-61) is an American twin-engined anti-submarine warfare (ASW) helicopter designed and built by Sikorsky Aircraft. A landmark design, it was one of the first ASW rotorcraft to use turboshaft engi ...

anti-submarine warfare helicopter in the mid-1960s. (See

military helicopter A military helicopter is a helicopter that is either specifically built or converted for use by military forces. A military helicopter's mission is a function of its design or conversion. The most common use of military helicopters is transport ...

/maritime helicopters) This was an upgrade from the AQS-10 system carried aboard the SH-3A helicopter. The AQS-13 offered an improved reeling machine and longer cable or "wet-end" than the AQS-10. The "dry-end" components of the system remained essentially the same as the AQS-10. Developed in the 1950s, these components utilized primarily vacuum tube technology. The RO-358

chart recorder A chart recorder is an electromechanical device that records an electrical or mechanical input trend onto a piece of paper (the chart). Chart recorders may record several inputs using different color pens and may record onto strip charts or circu ...

provided a means of recording a permanent record of target data as well as additional means for target evaluation. AQS-13 Dipping sonar

AQS-13A

The AQS-13A system was an upgrade to the basic AQS-13 system incorporated into fleet systems in the late-1960s/early-1970s. The upgrade was primarily to incorporate

built-in test equipment Built-in test equipment (BITE) for avionics primarily refers to passive fault management and diagnosis equipment built into airborne systems to support maintenance processes. Built-in test equipment includes multimeters, oscilloscopes, discharge pr ...

(BITE) circuitry, providing a method for testing system circuitry in the sonar set. Sonar_operator_in_SH-3H_Sea_King_1987

AQS-13B

The AQS-13B system was introduced to the US fleet as standard equipment aboard the Sikorsky SH-3H Sea King helicopter, replacing the SH-3D in the late-1970s. The AQS-13B was a significant upgrade from the AQS-13A. The "dry-end" components were replaced with solid state circuitry in a more compact set of replaceable assemblies. The "wet-end" components were essentially the same as the AQS-13A and the RO-358 was maintained as part of the system. The display remained a standard PPI display. The system was built with the potential to upgrade with an acoustic processor.

AQS-13E

The AQS-13B system was upgraded to the AQS-13E beginning in the late 1970s and early 1980s with the addition of a sonar data computer. This added the capability to process acoustic sonar and

sonobuoy A sonobuoy (a portmanteau of sonar and buoy) is a relatively small buoy – typically diameter and long – expendable sonar system that is dropped/ejected from aircraft or ships conducting anti-submarine warfare or underwater acoustic resea ...

signals digitally while retaining the original analog processing capability. The computer-processed data could be displayed on the system CRT in various formats. Tactical target data derived from the acoustic signals could be transferred electronically from the sonar data computer to the aircraft tactical computer. To enhance target detection, a longer, shaped pulse was used in conjunction with

fast Fourier transform A fast Fourier transform (FFT) is an algorithm that computes the discrete Fourier transform (DFT) of a sequence, or its inverse (IDFT). Fourier analysis converts a signal from its original domain (often time or space) to a representation in th ...

processing by the computer. This enhanced the target selection by weighting each target candidate using frequency and duration information to overcome lower signal return strength.

AQS-13F

The AQS-13F system was introduced to the US fleet as standard equipment aboard the Sikorsky SH-60F Seahawk helicopter, that replaced the SH-3H as the inner-zone ASW platform aboard aircraft carriers in the late-1980s/early-1990s. Key components of the AQS-13F system had origins in the made-for-export AQS-18 sonar developed for the

German Navy The German Navy (, ) is the navy of Germany and part of the unified ''Bundeswehr'' (Federal Defense), the German Armed Forces. The German Navy was originally known as the ''Bundesmarine'' (Federal Navy) from 1956 to 1995, when ''Deutsche Mari ...

for use in the Sea Lynx helicopter. The AQS-13F offered improved acoustic processing, a longer transmit pulse, faster reeling machine, longer cable and increased acoustic transmit power. The processed target data could also be displayed on the aircraft multifunction displays and/or recorded via the aircraft mission tape recorder. Due to the limited funding approved by Congress, the aircraft systems were limited to "off the shelf" technology wherever possible. This resulted in the use of a "dry-end" similar to the AQS-13E, even though more modern technology was available. File:SH-60F dipping sonar.jpg, U.S. Navy SH-60F helicopter with AQS-13F transducer deployed File:Dry-End.jpg, AQS-13F Dry-End Components File:AQS-13F Reeling Machine.jpg, AQS-13F Reeling Machine

Maintainability

AQM-24A

The AQM-21/AQM-24 and AQM-24A Sonar Test Centrals were used at U.S. Navy shore stations and aboard Aircraft Carriers to support the AQS-13 systems. These test benches provided the essential power for operation and simulated aircraft, ocean and target signals in order to test the individual components of the sonar systems.

Manufacturer

The AQS-13 series systems were manufactured by a division of

Bendix Corporation Bendix Corporation is an American manufacturing and engineering company which, during various times in its existence, made automotive brake shoes and systems, vacuum tubes, aircraft brakes, aeronautical hydraulics and electric power systems, av ...

Sylmar, California Sylmar is a suburban neighborhood in the San Fernando Valley and is the northernmost neighborhood within the City of Los Angeles. Historically known for its profusion of sylvan olive orchards, Sylmar can trace its past to the 18th century and th ...

. This division went through multiple ownerships and name changes over the years, including ownership by

Allied Signal AlliedSignal was an American aerospace, automotive and engineering company created through the 1985 merger of Allied Corp. and Signal Companies. It subsequently purchased Honeywell for $14.8 billion in 1999, and thereafter adopted the Honeywell ...

and L-3 Communications L-3 Communications Ocean Systems. and is currently part of L-3Harris.

Export versions

AQS-502

The export version of the AQS-13B sonar used in the

Royal Canadian Navy The Royal Canadian Navy (RCN; french: Marine royale canadienne, ''MRC'') is the Navy, naval force of Canada. The RCN is one of three environmental commands within the Canadian Armed Forces. As of 2021, the RCN operates 12 frigates, four attack s ...

Sikorsky CH-124 Sea King The Sikorsky CH-124 Sea King is a twin-engined anti-submarine warfare (ASW) helicopter designed for shipboard use by Canadian naval forces, based on the US Navy's SH-3. It served with the Royal Canadian Navy (RCN) and Canadian Armed Forces fr ...

helicopter.

AQS-18

The AQS-18 is the export version of the US Navy's AQS-13F. The original AQS-18 was developed for the German Navy from a drawing-board-only plan for an AQS-13D sonar for the US Navy. This version of the AQS-18 was initially deployed in the

Westland Lynx The Westland Lynx is a British multi-purpose twin-engined military helicopter designed and built by Westland Helicopters at its factory in Yeovil. Originally intended as a utility craft for both civil and naval usage, military interest led t ...

helicopter in the early 1980s.

AQS-18(V)

AQS-18(V) Later variations were sold as the AQS-18(V) to countries around the world. Individual variations are distinct to each customer and used aboard various platforms. Earlier versions shared higher degree of commonality with the German AQS-18 and later versions more with the USN's AQS-13F. Users include the

Hellenic Navy The Hellenic Navy (HN; el, Πολεμικό Ναυτικό, Polemikó Naftikó, War Navy, abbreviated ΠΝ) is the naval force of Greece, part of the Hellenic Armed Forces. The modern Greek navy historically hails from the naval forces of vari ...

(Greece) and the Portuguese Navy.

AQS-18(V)-3

The AQS-18 (V)-3 is one export version of the US Navy's AQS-13F helicopter-borne dipping sonar and is used by many friendly nations, including the

Republic of China Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the northeast ...

and the

Republic of Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korean Peninsula and sharing a land border with North Korea. Its western border is formed by the Yellow Sea, while its east ...

. It contains many of the high-performance features of the US Navy version. In high reverberation-limited conditions the sonar system transmits a specially shaped pulse and its

digital signal processor A digital signal processor (DSP) is a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing. DSPs are fabricated on MOS integrated circuit chips. They are widely used in audio si ...

employs

techniques to increase detection capabilities. A high source level provides long range search capabilities, improved

figure of merit A figure of merit is a quantity used to characterize the performance of a device, system or method, relative to its alternatives. Examples *Clock rate of a CPU * Calories per serving *Contrast ratio of an LCD *Frequency response of a speaker * ...

, and a high-speed reeling machine to achieve maximum depth and retrieve the sonar transducer rapidly.

AQS-18A

The AQS-18A was developed in support of the Italian Navy and later sold to various international customers, including the Turkish Navy and the Egyptian Air Force. The system shared a common "wet end" with the US Navy's AQS-13F, but had an improved "dry end" with a more modern processor, operator interface and display. These enhancements allowed for longer acoustic pulses and improved processing techniques resulting in improved tactical performance. The Turkish version was sold aboard the Agusta-Bell AB 212ASW aircraft and the Egyptian version was sold aboard the

Kaman SH-2G Super Seasprite The Kaman SH-2G Super Seasprite is an American ship-based helicopter with anti-submarine, anti-surface threat capability, including over-the-horizon targeting. This aircraft extends and increases shipboard sensor and weapon capabilities agains ...

helicopter.

Users

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Algerian Navy , image = Algerian Naval badge.svg , image_size = 220px , caption = Algerian Naval badge , dates = 1516–18271963–present , country ...

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Australian Navy The Royal Australian Navy (RAN) is the principal naval force of the Australian Defence Force (ADF). The professional head of the RAN is Chief of Navy (CN) Vice Admiral Mark Hammond AM, RAN. CN is also jointly responsible to the Minister of D ...

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Republic of China Navy The Republic of China Navy (ROCN; ), also called the ROC Navy and colloquially the Taiwan Navy, is the maritime branch of the Republic of China Armed Forces (ROCAF). The service was formerly commonly just called the Chinese Navy during World Wa ...

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Republic of Korea Navy The Republic of Korea Navy (ROKN; ko, 대한민국 해군), also known as the ROK Navy or South Korean Navy, is the naval warfare service branch of the South Korean armed forces, responsible for naval and amphibious operations. The ROK Navy in ...

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Portuguese Navy The Portuguese Navy ( pt, Marinha Portuguesa, also known as ''Marinha de Guerra Portuguesa'' or as ''Armada Portuguesa'') is the naval branch of the Portuguese Armed Forces which, in cooperation and integrated with the other branches of the Port ...

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Spanish Navy The Spanish Navy or officially, the Armada, is the maritime branch of the Spanish Armed Forces and one of the oldest active naval forces in the world. The Spanish Navy was responsible for a number of major historic achievements in navigation, ...

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Brazilian Navy ) , colors= Blue and white , colors_label= Colors , march= "Cisne Branco" ( en, "White Swan") (same name as training ship ''Cisne Branco'' , mascot= , equipment= 1 multipurpose aircraft carrier7 submarines6 frigates2 corvettes4 amphibious warf ...

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Italian Navy "Fatherland and Honour" , patron = , colors = , colors_label = , march = ( is the return of soldiers to their barrack, or sailors to their ship after a ...

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Turkish Navy The Turkish Naval Forces ( tr, ), or Turkish Navy ( tr, ) is the naval warfare service branch of the Turkish Armed Forces. The modern naval traditions and customs of the Turkish Navy can be traced back to 10 July 1920, when it was establi ...

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Egyptian Air Force The Egyptian Air Force (EAF) ( ar, القوات الجوية المصرية, El Qūwāt El Gawīyä El Maṣrīya), is the aviation branch of the Egyptian Armed Forces that is responsible for all airborne defence missions and operates all milit ...

References

External links

AN/AQS-13F - Dipping Sonar System webpage
{{DEFAULTSORT:AN AQS-13 Anti-submarine warfare Military sonar equipment of the United States Military electronics of the United States