Acoustic Sounders
SONOBUOYS
The United States Navy maintains a superior global Anti-Submarine Warfare (ASW) capability with the ability to detect, localize, identify, and track potential hostile submarines. This is provided by the capabilities of sonobuoys. Sonobuoys are used to determine environmental conditions for determination of best search tactics, to communicate with friendly submarines, and to conduct search, localization, tracking, and, as required, attack of designated hostile platforms. Sonobuoys provide both a deployable acoustical signal source and reception of underwater signals of interest. These received signals are transmitted to any monitoring unit(s) that then processes the signal for analysis, classification of any target, and recording on magnetic tape media for replay and post event analysis. Both the initial detection of submarines and the localization of detected targets is usually done with passive sonobuoys, if possible, so as to deny for as long as possible the submarine becoming aware that an adversary aircraft is present. By use of established tactics, the sonobuoys allow for short and long range detection of surface ships and submarines, thereby, allowing for prosecution of identified hostile targets. Other specialized sonobuoys can detect electric fields, magnetic anomalies or the light emitted by microscopic organisms disturbed by the passage of a submarine [bioluminescence]. Active sonobuoys are used to localize targets quickly and accurately in extreme environmental conditions, against a very quiet submarine, or in an attack mode. The released acoustic energy enables an accurate location from the sonobuoy in both range and bearing to the submarine. When two or more ?fixes? are obtained the speed and the course of the target can be established. Active buoys use a transducer to introduce acoustic energy into the water and to manipulate the return echoes that are amplified and for VHF radio transmission. These buoys are designed for deeper depths than passive buoys. Sonobuoys may be classified by size ( A, B, C,etc.) and type (active, passive or measurement). Most American sonobuoys are A-size length 36 inches, diameter 4 7/8 inches. The A-size sonobuoy weight varies by manufacturer and buoy type, but will not exceed 39 pounds. Some other countries are using half size or A/2 as a standard configuration. All sonobuoys currently in inventory are normally launched from standard A-size tubes via pneumatics, free fall, or a Cartridge Actuated Device (CAD). When launched from aircraft they employ a parachute to retard their descent and provide descent stability. Shipboard personnel may also launch them by hand or Over the Side (OTS). All are powered by either salt water activated magnesium or silver chloride, lithium chemistry, or thermal batteries and are designed to scuttle at some point after usable or selected life expires. Additional information available at "http://www.fas.org/man/dod-101/sys/ship/weaps/sonobuoys.htm" [Summary provided by the Military Analysis Network]