AN/AQS-13

These systems were deployed as the primary inner zone anti-submarine warfare (ASW) sensor on aircraft carrier based helicopters for over five decades.

Airborne sonar systems provide a light-weight, mobile detection sensor for locating and tracking submarines.

These systems offered the additional capabilities of voice communication, bathythermography and rudimentary passive sonar.

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.

Echos or "returns" are received by the hydrophone, routed through the sonar cable, processed in the aircraft and displayed on a cathode ray tube (CRT) in a plan position indicator (PPI) format.

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.

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.

To enhance target detection, a longer, shaped pulse was used in conjunction with fast Fourier transform processing by the computer.

[7] Key components of the AQS-13F system had origins in the made-for-export AQS-18 sonar developed for the German Navy for use in the Sea Lynx helicopter.

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.

The export version of the AQS-13B sonar used in the Royal Canadian Navy's Sikorsky CH-124 Sea King helicopter.

In high reverberation-limited conditions the sonar system transmits a specially shaped pulse and its digital signal processor employs fast Fourier transform techniques to increase detection capabilities.

A high source level provides long range search capabilities, improved figure of merit, and a high-speed reeling machine to achieve maximum depth and retrieve the sonar transducer rapidly.