By John Rhea
ARLINGTON, Va. - U.S. Navy officials will begin testing a portable sonar signal processor at sea this month that ostensibly can match performance with the entire rack-mounted anti-submarine warfare console aboard the P-3C maritime patrol turboprop aircraft.
Testing of the 200 MHz Intel Pentium II-based signal processor, which its designers packaged in an attaché case, are scheduled for frigates and destroyers with Carrier Task Force 72 operating in the Pacific using data from the SQR-19 towed arrays.
The new system, like the original model developed 10 years ago, comes from BBN Technologies of Cambridge, Mass., a division of GTE Internetworking. BBN officials demonstrated the system at last month`s Navy League conference in Washington.
The units are part of a family of advanced acoustic processors (AAPs) that all use parallel processing for real-time signal and information processing.
The original version is a VME-based configuration with 6U VME array processor cards for about 640 megaflops of processing power, scalable to the multi-gigaflop range.
Through the use of an open-system architecture and commercial-off-the-shelf (COTS) processors, BBN`s software can run on Windows NT 4.0 and port to almost any laptop computer. The hardware is commercially available at about $20,000, including a flat-panel display, estimates Greg Skarda, a BBN program manager.
BBN is selling the software package, which includes an AAP signal-processing engine, to reuse as much existing software as possible.
For that purpose, company engineers have developed a library of sonar signal processing modules in the C programming language. The package also includes a display-processing engine written in C++ for developing information-processing algorithms and graphic user interfaces.
BBN systems designers are using this new system to tackle a unique sonar problem - accepting data from several different sensors operating in noisy, shallow coastal waters. Experts refer to this as multistatic sonar processing in the littoral environment.
The problem in the past with multistatic sonars operating in littoral environments has been the requirement for high-throughput processing, BBN experts say. This tends to pile up the work on the operators and also makes it hard to distinguish false alarms.
The idea, then, is to pre-process as much data as possible and relieve the load on the operators. The displays shown at Navy League combined alphanumeric and graphic data. Operators can also process sonar data in parallel across several personal computers to increase total processing power in 640-megaflop increments.
BBN designers also developed neural network software for earlier Navy at-sea tests in the Pacific to demonstrate the fusion of acoustic data from shipboard sensors. The tests, conducted last year, aimed at using low-frequency active sonar for shallow-water operations. The job of the software was to pull echoes from submarines out of the acoustic clutter common in shallow waters.
The fused data are also likely to feed into the Navy`s proposed cooperative engagement capability - better known as CEC - to share threat data among ships and aircraft.
In the current post-Cold War period, Navy officials are becoming increasingly concerned about detecting quiet diesel submarines in shallow waters, In this environment, adversaries are likely disperse and operate covertly to elude detection from the air.