Compact, Isolating Elastomeric Suspension for Vehicle Acoustic Vector Sensor

The increasing use of small platforms such as unmanned underwater vehicles, which cannot support large hydrophone arrays, is driving the development of compact sensors which also work at lower signal-to-noise ratios. The acoustic vector sensor incorporates 3-axis accelerometers whose output can be integrated to give local fluid particle velocity information, so a single AVS can give unambiguous bearing information. Multiple vector sensors in arrays of moderate size can improve spatial resolution. For this sensor to respond with fidelity, it must be essentially adrift in the medium, hence mounting on a moving vehicle is necessarily a compromise. Also, there will always be a compromise between exposure of the sensor to the free field and its isolation from hydrodynamic loads. Finally, any type of mounting will be prone to transmitting some ownship noise into the sensor. KaZaK sees the problem in terms of vibration isolation and impedance matching, and proposes to address it by means of advanced materials: Reducing transmissibility of noise and accelerations with very soft “springs” embodied in an innovative 3-axis series shear mount, and surrounding the sensor with material of good impedance match to the medium and which lends itself to shaping for low drag and flow induced noise.