[1] It includes two separate active sonar systems to detect and classify mine-like objects on the surface, in the volume, or on the bottom of the sea.
VDS operations are necessary in deep water due to refraction of the sonar from the various temperature layers present in the ocean; with the sonar positioned in the same thermal layer as the suspected mines the error induced by refraction is minimized.
It provides the operator 180 degrees of selectable coverage via electronic switching of sonar stave arrays circling the towed body.
Characteristics include approximate size and shape measurements, ringing patterns caused by metallic objects, and aspect changes as the ship and towed body circle the target.
The initial contract was for installation on four MCM-1 Avenger class minesweepers for $14 million,[3] and later an available option was awarded to upgrade an additional ten units plus a battle spare.