New Littoral Undersea Surveillance System Completes Successful Sea Test

The Advanced Deployable System (ADS) is a passive acoustic undersea surveillance system designed for rapid deployment in littoral areas for the detection, classification, localization, and tracking of both underwater and surface targets. Unlike earlier deepwater systems that take months to deploy, ADS can be installed within significantly shorter time frames in response to quickly evolving political and military situations along coastal areas of interest. The key sensors are battery-powered disposable hydrophone arrays that can be deployed from ships of opportunity. Lightweight fiber-optic cables interconnect the arrays at sea and bring data ashore in real time. Because of its modular configuration, the same basic equipment can be used to create sensor fields of varying shape and density for area search, or be configured as a trip-wire or barrier, as shown above.

In March 1998, ADS accomplished a key milestone when a complete, integrated ADS system was deployed for the first time. For this major event, which occurred in Puget Sound, Washington, the Space and Naval Warfare Systems Command (SPAWAR) successfully deployed two fiber-optically-cabled underwater acoustic sensor arrays and performed real-time signal processing of the acoustic data ashore. This test was intended as the first opportunity to bring together all segments of the ADS program to plan, deploy, and operate an integrated and functional, mini-system. The three primary ADS sub-systems are:

The Underwater Segment, consisting of the Wet-End Hardware deployed on the sea floor to collect and transmit acoustic data. Both the arrays and the fiber-optic cabling are included here.

The Mission Support Segment,comprising:

  • the Installation Sub-system

  • the Mission Planning Sub-system

  • the Wet-End Inspection and Repair Equipment

The Processing and Analysis System, which records, processes, and displays data from the array and reports contacts to users.

In the Puget Sound test, two arrays were deployed near major shipping channels for both car ferries and cargo ships serving the Port of Seattle. Lockheed Martin Federal Systems and their major subcontractor, Raytheon Systems Company of Mukilteo, Washington, designed and manufactured the underwater hardware, and the Raytheon research vessel Sensor streamed the arrays from the towed deployment vehicle (TDV). The TDV is capable of deploying multiple arrays and their corresponding trunk cables in a single load, which permits a significant area to be “wired for sound” in a single rapid evolution. A shore-based digital signal processing system, housed in a flyaway van, processed acoustic data from the two nodes in real time and successfully detected and tracked a wide variety of surface ships in the Puget Sound test area. The Applied Physics Laboratory of Johns Hopkins University outfitted the processing van. The digital analysis system itself was developed by a consortium of university laboratories and contractors.

The Puget Sound test successfully demonstrated that the current ADS design could be rapidly mobilized, reliably deployed, and effectively operated to perform its mission. While further design work remains, the results show that ADS is ready to proceed with planning and development for its final two developmental tests: the Multi-Node Test and the Fleet Exercise Test. During these events, a more ambitious ADS sensor field will be deployed against surface and subsurface targets, including mining operations. The ADS program is expected to put operational systems into production around fiscal year 2003.

George Shepard, GTE Corporation, and John Thornton,
PMW183, Space and Naval Warfare Systems Command