Reliable Acoustic Path Vertical Line Array
Navy SBIR 2008.2 - Topic N08-171
NAVSEA - Mr. Dean Putnam - email@example.com
Opens: May 19, 2008 - Closes: June 18, 2008
N08-171 TITLE: Reliable Acoustic Path Vertical Line Array
TECHNOLOGY AREAS: Sensors, Battlespace
ACQUISITION PROGRAM: IWS5 Undersea Systems; non ACAT
The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.
OBJECTIVE: Develop component level and system level technologies for reliable acoustic path vertical line arrays.
DESCRIPTION: In recent years the U.S. Navy has researched the utility of deep water (i.e., 6 km depth, 3 deg C temperature) acoustic sensing technologies that exploit the reliable acoustic path (RAP)  using vertical line arrays (VLAs) of vector sensors [2,3]. The first RAP VLA array was large and deployed over the side of a research vessel . The sensing nodes consisted of a pressure hydrophone, a triaxial pressure-gradient hydrophone, and an electronics housing all contained within a free-flooding plastic frame having a diameter and length of 13-in x 41-in. The measured acoustic signals were routed to a central node that served as a data recorder. Future arrays will be smaller and deployed from tactical naval platforms using existing packaging modalities (i.e., sonobuoy, torpedo, etc.). A target form factor for future array sensing elements and associated electronics is desired to be less than an AN/SSQ-53 DIFAR wet-end transducer [i.e., a cylinder having nominal dimensions of 5-in (D) x 5-in (L)]. The reduction in form factor is substantial and will require novel sensor and preamplifier designs to ensure that the electronic noise floor of the system is well below the ambient noise level at depth . Moreover, it is envisioned that future arrays will operate autonomously with persistence to support ambient noise and anti-submarine warfare studies over the frequency range from a few hertz to several kilohertz. Data will be recorded and processed in situ then relayed to platforms of opportunity via suitable means (i.e., acoustic modems or equivalent technologies). This feature is new relative to the existing system which only employed a data recorder . It is the intention of this SBIR topic to solicit technical concepts to support development of RAP VLAs at the component and system level. Component level technologies include miniature low noise vector sensors, array electronics and telemetry, DC power generation and distribution, and transducers to support communication between the array and the host platform. System level technologies include end-to-end array design, conventional and advanced signal processing techniques suitable for a deep water vector sensor line array, packaging and deployment concepts, and communication modalities.
PHASE I: Perform analytical modeling studies of the component or system to ensure that it is suitable for RAP VLA operation. If possible, perform proof-of-concept experiments to supplement the modeling studies.
PHASE II: Refine the models during Phase I, then fabricate and test prototype components and systems.
PHASE III: Integrate components and systems into a full-up array which will be deployed at-sea for a full-scale demonstration test.
PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The technology developed herein is applicable to researchers engaged in ocean ambient noise surveys, deep water acoustic propagation studies, bio-acoustic monitoring of marine life, and seismic surveys in support of geophysical prospecting.
2. J. Nickles, G. Edmonds, R. Harriss, F. Fisher, W. S. Hodgkiss, J. Giles and G. D'Spain, "A Vertical Array of Directional Acoustic Sensors," Proceedings of Mastering the Oceans Through Technology (Oceans 92), Oct. 1992.
3. J. McEachern, J. McConnell, J. Jamieson, and D. Trivett, "ARAP - Deep Ocean Vector Sensor Research Array," Conference Proceedings, IEEE / Oceans 2006, Sept. 2006.
KEYWORDS: Reliable acoustic path; vertical line array; vector sensor; array processing; ocean ambient noise; deep water acoustic propagation