Abstract: A simple mechanical device is provided which generates acoustic signals at ne or more specified depths. The device consists of a spring loaded piston placed in a wall of a housing, the spring loading biasing the piston away from the housing. The piston is subjected to a pressure differential between the exterior and interior of the housing such that the piston moves against the spring force and into the housing as the pressure differential, corresponding to a depth of the housing beneath a water surface, increases. As the piston moves further into the housing, it contacts a series of latches, each latch being used to detain spring loaded striker. The latches are spaced along the travel path of the piston such that each striker is associated with a specific piston movement, or depth. When the piston contacts a latch, the striker is released and strikes against a ledge within the housing, creating one of the acoustic signals.

Abstract: A simple, mechanical device is provided which produces an acoustic signal a specified depth. The device consists of a shear plug in an exterior wall of the device housing which prevents the movement of a spring biased piston. The plug is subjected to increasing differential pressure between the exterior and interior of the housing as the depth of the device beneath the water surface increases. At a known pressure differential, corresponding to a specified depth, the shear plug fails, allowing for the actuation of the piston. The spring biased piston strikes against a ledge in the device, creating the acoustic signal.