Small diameter, low frequency multimode hydrophone

Claim 1

A small diameter, low frequency, multimode hydrophone for receiving relatively low frequency, plane-wave acoustic signals impinging thereon, comprising: piezoelectric means, for converting each said relatively low frequency, plane-wave acoustic signal to a plurality of quadrantal electrical signals, each of said electrical signals being proportional to said plane-wave acoustic signal as received by separate quadrants of said hydrophone, said piezoelectric means further comprising a plurality of piezoelectric cylindrical segments; inert means, bonded to said piezoelectric means, for reducing the propagation speed of sound within said multimode hydrophone thereby permitting said small diameter hydrophone to be formed, said inert means being bonded to said piezoelectric means, said inert means further comprising a corresponding plurality of inert cylindrical segments of identical size and shape as said piezoelectric cylindrical segments, interspersed alternately between said plurality of piezoelectric cylindrical segments, each said inert cylindrical segment being bonded to adjacent piezoelectric cylindrical segments thereby forming a generally cylindrical thin wall tube of relatively small diameter having at least two piezoelectric cylindrical segments per quadrant; electrical conductor means, connected to said piezoelectric means within each quadrant of said hydrophone, for producing and transmitting said quadrantal electrical signals; and signal processing means, attached to said conductor means, for receiving said quadrantal electrical signals and producing an omnidirectional signal and two spatially orthogonal directional signals containing a decade range of frequency and bearing information therefrom.