by John Keller

WASHINGTON — U.S. Navy undersea warfare experts are looking for new ways to process massive amounts of digital data from large sonar systems of the future that will be mounted to the hulls of submarines.

Leaders of the Naval Sea Systems Command (NAVSEA), Advanced Systems and Technology Office (ASTO) in Arlington, Va., are asking industry for new signal processing approaches for future sonar systems that involve thousands of sensor channels. The so-called "large-aperture hull array" sonar project would include:

• outboard and inboard electronics;
• hardware and software for signal conditioning, signal processing, array beamforming, control and display (GUI), as well as test and evaluation data analysis equipment; and
• an advanced development model or prototype.

Navy experts are developing large-aperture hull arrays for submarine sonar systems to supplement — and sometimes replace — existing submarine sonar arrays. This effort involves developing state-of-the-art signal-processing techniques that will take advantage of the large horizontal and vertical apertures that these arrays provide, Navy officials say.

Related initiatives at the NAVSEA ASTO include the CAVES project, which is short for Conformal Acoustic Velocity Sonar. This project is in place to develop an affordable "smart-skin" acoustic sonar receive array, which Navy experts say represents a revolutionary departure from traditional hull array sonar technology.

CAVES seeks to replace existing pressure sensor technology, which that requires tons of expensive outboard signal conditioning and support structures, with an array of fiber-optic accelerometers that will be part of the submarine's hull coating.

Replacing traditional spherical sonar arrays with a conformal bow array would vastly improve submarine structural design, and improve the submarine's stealth characteristics, officials say.

A core goal of the latest large-aperture hull array project revolves around using the vertical distribution of ambient noise to make the most of multipath signal propagation to pinpoint undersea targets. Other objectives are to provide extremely fast data transmission, and to be compatible with the Acoustic Rapid COTS Insertion sonar-processing architecture — better known as ARCI — as well as the electronics aboard future U.S. Virginia-class attack submarines.

Navy experts say they hope this project will result in an affordable, high-performance electronic infrastructure and processing system that will help engineers design a large-aperture hull array into the overall sonar suites of U.S. submarines.

This broad agency announcement will be open for two years, and officials would like to award two contracts no later than 15 February 2003.

To make proposals, or for more information, contact Navy Lt. Michael Carl by phone at 202-781-4924, by fax at 202-781-4653, by e-mail at carlms@navsea.navy. mil, or by post at commander, Naval Sea Systems Command, care of Lt. Michael Carl (SEA 02632), 1333 Isaac Hull Ave. S.E., stop 2050, Washington Navy Yard, D.C., 20376-2050. Text of this broad agency announcement is available on the World Wide Web at http://www2. eps.gov /spg/USN/NAVSEA/NAVSEAHQ/N0002401R6306/SynopsisP.html.