By John Keller
LAKEHURST, N.J. - U.S. Navy researchers are trying to find better ways of observing and measuring undersea conditions in shallow coastal waters in efforts to improve anti-submarine warfare (ASW) operations in sonically difficult areas near land and inside harbors and coves.
One of their approaches is to use data from existing sensors-principally air-deployed sonobuoys with active sonar and temperature-measuring capabilities-to determine the most effective ways of searching for hostile submarines in littoral areas.
Toward this goal, experts at the Naval Air Warfare Center Aircraft Division in Lakehurst, N.J., awarded a $25 million contract in December to Signal Systems Corp. in Severna Park, Md., to study how to use sensors the Navy has available in the fleet today to help map the sonic environment of coastal waters in rapidly changing conditions.
Signal Systems experts are working under a Small Business Innovative Research (SBIR) phase III contract to deliver real-time single-channel signal processing of the Navy AN/SSQ-101 air-deployable active receiver (ADAR) A-size, expendable, nonrepairable sonobuoy.
The ADAR is an acoustic data receiver capable of in-buoy beamforming and transmission of received real-time acoustic signals back to any monitoring unit(s). The primary mission is to receive active search signals such as long-range echo detection of quiet, slow-moving submarines.
The ADAR sonobuoy system is from the ERAPSCO joint venture of Sparton Corp. in Jackson, Mich., and UnderSea Sensor Systems Inc. (USSI) in Columbia City, Ind. The SBIR programs involved in the Signal Systems contract are the “Air Antisubmarine Warfare Environmental Characterization using Existing Tactical Sensors,” and “Continuous Active Sonar.”
In this research project, Signal Systems experts will make use of data from the ADAR sonobuoy, as well as from the AN/SSQ-36B air-launched expendable bathythermograph (AXBT) conductivity, temperature, and depth probe sonobuoy.
Navy officials say they consider technology that Signal Systems will develop to be an alternative to the Tactical Acoustic Measurement and Decision Aid (TAMDA), and specifically will focus on active sonar in littoral ocean areas.
TAMDA uses an expendable environmental-measurement sonobuoy and a tactical decision aid for antisubmarine warfare aircraft weapon system software. The sonobuoy measured littoral environmental variables not necessary for deep open-ocean ASW operations, while the tactical decision aid helped with preflight planning and in-flight near-real-time updates from sonobuoy data or retrieved from other environmental databases.
The idea of such a system is to measure and compensate for ocean variables such as temperature layers, depth, and angle of the ocean bottom, the presence of fish and other undersea wildlife in the area, sunken obstructions, sediment depth, and noise from shipping to gauge the effective range of active sonar sensors such as sonobuoys.
With detailed marine data, Navy officials can optimize the patterns of sonobuoy fields to make the most of their ASW systems in littoral waters.
Signal Systems engineers will provide exploratory studies, an analysis for system integration, a customizing prototype to platform needs, test and evaluation, production buys, support and training as necessary.
Work will be in Severna Park, Md., and will be finished in December 2011. For more information contact Signal Systems online at www.signalsystemscorp.com.
