Active Sonobuoys

Target detection of a very quiet diesel submarine or a submarine in attack mode, is very difficult, especially in extreme environmental conditions. In these situations, it is critical to localize the target quickly and accurately. This is when active sonobuoys are used. The released acoustic energy ("ping") from an active sonobuoy and the resultant return signal enable accurate positioning of the submarine in both range and bearing. When two or more fixes are obtained, the speed and the course of the submarine can be established.

The following 'A' size sonobuoys can be air-launched from fixed or rotary-wing aircraft, since they all employ a parachute to retard their descent and provide descent stability. These sonobuoys are also easily deployable from the deck of a surface vessel. Descent of the sonobuoy is stabilized and slowed by a parachute. They also all employ a battery, which is energized upon entry into salt water. As with the passive sonobuoys, once energized, a mechanism for inflating a float with CO2 gas is activated, suspending the sonobuoy. The sensors are then released to specified depths. These sonobuoys use a transducer to introduce acoustic energy into the water ("ping") and use the transducer to receive the return echoes, which are then amplified and frequency modulated for VHF transmission. All of the sonobuoys scuttle after a preset length of operation.

AN/SSQ-47B Range Only

This active sonobuoy, sometimes also referred to as a "Pinger" sonobuoy automatically commences to generate pings at periodic intervals after water entry. During the interval between pings, these sonobuoys receive omnidirectional acoustic data in the same frequency band as the radiated signal and transmit this data over one of twelve selectable RF channels. There are six different ping frequencies that can be specified for these sonobuoys. The sonobuoys are manufactured to the ping frequency specified by the customer. This sonobuoy is manually set prior to deployment to operate at 60 or 800 feet. These sonobuoys provide target range information, but not direction, for detected targets.
 Download AN/SSQ-47B Data Sheet

AN/SSQ-62B/D DICASS

The AN/SSQ-62 Directional Command Activated Sonobuoy System (DICASS) is currently the primary active sonobuoy used internationally. DICASS permits the operator to pinpoint a target's position in range and bearing. The AN/SSQ-62D version has been in service for a decade and offers operation on one of four acoustic frequencies (6.5, 7.5, 8.5, and 9.5 kHz) and the selection of one of two depth families. The effective source level of this sonobuoy varies with the acoustic channel between 199 and 201 dB.

AN/SSQ-62E DICASS

The current generation of the DICASS family of active sonobuoys is the AN/SSQ-62E. This sonobuoy is in use by the United States and several other countries. The major advantage of the AN/SSQ-62E over the AN/SSQ-62D is that it permits each sonobuoy to transmit on any of four acoustic channels and their respective RF channels. Optional thermal battery technology allows DICASS sonobuoys to be shipped and stored in a relatively unrestricted manner.
 Download AN/SSQ-62E DICASS Data Sheet