Which mechanism is employed by an active sonobuoy?

The mechanism of an active sonobuoy involves the use of a transducer to radiate sonar pulses. Active sonobuoys are designed to emit sound waves into the water. When these pulses are transmitted, they travel through the water and can bounce off any objects, such as submarines, returning echoes that are then detected by the same transducer or another receiving component. This method enables the identification and localization of submerged objects by analyzing the time it takes for the echoes to return and the characteristics of those echoes.

By using sonar pulses, the active sonobuoy can provide real-time data on the presence and movements of underwater vessels, making it essential for anti-submarine warfare. The other options do not accurately reflect the primary function of active sonobuoys. For instance, while detecting sound emissions and analyzing sound frequency are part of passive systems or the broader sonar function, they do not capture the active element that defines the specific operation of active sonobuoys. Additionally, while sonobuoys may transmit data through radio frequencies, the main characteristic that distinguishes an active sonobuoy is its capability to initiate sound waves, which is not represented in those other options.