Improvements in the noise quieting of submarines have reduced the effectiveness of passive sonobuoys in Anti-Submarine Warfare (ASW), causing greater emphasis on active acoustics. However, a sonobuoy with array gain of 24 dB would be a useful asset in the Navys airborne ASW capability. Using velocity sensors can reduce the number of array sensor nodes over omnidirectional hydrophones and reduce the array aperture, needed to provide this much gain in an A-size sonobuoy. Maximum gain is achieved in the real world noise environment, where discrimination against vertical wind-wave noise will improve array performance. The acoustic frequency and array gain will define the array geometry. The large array provides a challenge to package the array in A-size, to deploy it, and maintain the array geometry over the life of the buoy. The Phase I effort will determine the feasibility of developing an innovative free floating high gain array of small inexpensive velocity sensors that can provide over 24dB gain, demonstrate innovative packaging and deployment concepts for the array in an A-size sonobuoy design, evaluate the performance of candidate arrays in realistic noise fields, through modeling, and to select the array design for fabrication and testing in Phase II.
Benefit: The High Gain Array of Velocity Sensors development, as proposed and described in this proposal, gives this system a potential for application to a variety of other government agency and commercial markets. Passive detection of acoustic signals from the array has potential applications in marine mammal detection, drug interdiction and terrorist security systems. The Coast Guard will find it useful in coastline and harbor defense.
Keywords: vector sensor, vector sensor, Horizontal Line Array, passive acoustic sensor, Passive Sonar, Sonobuoy, ASW, underwater acoustics
