Hydroacoustic Beacon

a stationary underwater acoustic device that radiates acoustic signals. It is used to designate areas that are dangerous for navigation, to mark the location of deep-sea apparatus used in scientific work and in searches, and to indicate the landing site for marine troops.

Hydroacoustic beacons are installed on metal supports on the sea floor or are anchored at a given depth. A hydroacoustic beacon consists of a generator, a power amplifier, an electroacoustic radiator, a signal control mechanism, synchronizing equipment, and a source of electric power. Some hydroacoustic beacons are equipped with an automatic self-flooding submersion device that will operate upon completion of some predetermined task. Electric power feed for hydroelectric beacons can be provided through a cable from the shore (in coastal areas), or the power feed can be self-contained (a battery).

The operating range of hydroacoustic beacons is about 20 km, depending on the purpose of the beacon, the power of the generator, the operating frequency, and the hydrologic conditions. For navigational hydroacoustic beacons an operating frequency of 1050 Hz has been established by an international agreement. Conventional marine hydroacoustic stations are used for the reception of signals from hydroacoustic beacons. Special hydrophones are also used for reception. In such hydrophones the location of the directivity characteristic of the vertical or horizontal plane can be changed within certain limits, so as to assure a maximum signal level for a given task (search for a torpedo, arrival at a landing beacon, and so on).