» Hydrophone

Closed-Form Underwater Acoustic Direction-Finding with Arbitrarily Spaced Vector Hydrophones at Unknown Locations

arjun — Mon, 10 Nov 2008 19:06:55 +0000

Abstract This paper introduces a novel ESPRIT-based closed form source localization algorithm applicable to arbitrarily spaced three-dimensional arrays of vector hydrophones, whose locations need not be known. Each vector hydrophone consists of two or three identical but orthogonally oriented velocity hydrophones plus one pressure hydrophone, all spatially co-located in a point-like geometry. A velocity hydrophone measures one Cartesian component of the incident sonar wavefield’s velocity vector, whereas a pressure hydrophone measures the acoustic wavefield’s pressure. Velocity-hydrophone technology is well established in underwater acoustics and a great variety of commercial models have long been available. ESPRIT is realized herein by exploiting the nonspatial interrelations among read more

A New Multilayer Planar PVDF Standard Hydrophone and its Applications

arjun — Mon, 10 Nov 2008 18:53:41 +0000

Abstract A new type of PVDF hydrophone, the multilayer planar PVDF hydrophone, is described in this paper. The hydrophone disturbs measured acoustic fields very little and has a high sensitivity. The noise equivalent pressure of the hydrophone is 45 dB re 1 μ Pa per Hz bandwidth.The working freqency range og hyrophon is 20kHz ~4MHz.In the range of 100kHz ~ 1MH,the hydrophone has a flat frequency response with sensitivity -205 dB & 1.5 dB (0 dB = 1 V/pPa). In this range, the hydrophone has been used for five years as a standard one. Two other applications (measurements of noise spectra and ultrasonic imaging) are also reported. Download Share and Enjoy: read more

DEVELOPMENT OF A COST-EFFECTIVE SHOCK WAVE HYDROPHONE

arjun — Mon, 10 Nov 2008 18:43:38 +0000

Abstract The design of a new wideband, quantitative shock wave hydrophone is presented. The sensor not only has a wideband (>SOMHz) and linear (up to 100MPa) response, but it also operates in a measurement environment in which the hydrophone element’s sensitivity changes as a function of shock wave exposure. Thin films of polyvinylidene difluoride (PVDF) were used in a disposable hydrophone configuration. A self-monitoring feature, based on the change in hydrophone electrode resistance as the electrode materials are removed by shock wave action, indicates that the hydrophone element needs to be replaced. Development efforts include: 1) reducing the manufacturing costs; 2) determining the relationship between electrode resistance and hydrophone sensitivity; 3) developing a read more