In 2002, AML Oceanographic was approached to create a sound velocity sensor specifically designed for deployment with a helicopter dipping sonar system in support of ASW activities.
Dipping sonar allows the helicopter to listen for underwater electronic signals while in 'hover' or stationary mode. The active sonar package can detect and maintain contact with underwater targets through a transducer lowered into the water. The system provides target identification clues through active echo-ranging and determines a target's range and bearing relative to the helicopter. Sound velocity was required for determining the SV profile through the water column and for acoustic beam steering.
The project presented some design challenges in order to integrate and operate the sound velocity sensor on the helicopter deployed sonar head. These included:
The potential for EMI (electromagnetic interference) or RFI (radio frequency interference) on helicopter deployments is a strong concern. EMI or FGI are unwanted disturbances that affect an electrical circuit due to electromagnetic radiation emitted from an external source. The disturbance may interrput, obstruct or otherwise degrade or limit the effecctive performance of the circuit. A custom aluminium enclosure was designed to protect the sensor electronics from this harsh environment, thus assuring optimal performance of the SV sensor.
