Underwater sound generator esp. for fisheries - has long tube filled with oil with pulsations sounding at end of/or along whole length

摘要

In its simplest form, the sound generator consists of a long flexible tube (1) with, at its far end, a short length of pipe (2) terminated by a membrane (3), which is the sound source. Oil under pressure from pump (10) is admitted to the tube through a rotary intermittent valve (4) and released through a second similar valve (6) opening out of phase with the first via common drive (8). The rapid pulsations engendered in the oil generate the sound at the membrane. In a second form the flexible tube has an outer sleeve with short, narrow slits-some longitudinal some circumferential-along its length. The pulsating inner pipe (1) pumps water in and out of the slits, producing sound along the whole length of the tube.