By John Keller
WASHINGTON - Experts at the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., are tapping into commercially developed software and hardware to develop an advanced sonar signal processing system.
DARPA`s Situationally Adaptive Sonar Technologies (SAST) program uses the Rippen software development environment from Orincon Corp. in Washington and the Skybolt II and Skystation II signal processing system from Sky Computers Inc. in Chelmsford, Mass.
Sky`s hardware is a series of 6U VME single-board computers based in the Intel i860 digital signal processing (DSP) chip in a small rugged VME chassis suitable with a real-time sonar data input over a fiber distributed data interface link.
Orincon`s Rippen software, meanwhile, strings applications together for system functionality, provides context-sensitive tools with parameters set for specific applications, and assigns tools to processors and data flow to buses.
The SAST program seeks to improve the way sonar systems process sounds from the water without the "ping" of a transducer. "It is mainly passive, and listens for submarines like fingerprinting," explains Theo Kooij, program manager in DARPA`s tactical technology office.
"We want to look simultaneously at all beams," Kooij says. "We have a collection of geophones, and receive signals on each element of an array. The mathematics is the same as a phased array radar, with waves of varying pressure in the water."
The thrust of SAST is to "use the power of the computer to look everywhere at once instead of in only one direction," he says, explaining that the technology is applicable to a variety of developmental sonar programs, such as the Lockheed Martin Acoustic Rapid COTS Insertion, or ARCI, program (see story page XX).
DARPA experts are seeking this year to upgrade the SAST architecture most likely from the i860 to the Analog Devices 21060 Sharc DSP, Kooij says. The board provider may change from Sky, he says. One company under consideration is Alacron of Nashua, N.H.
DARPA chose the Skybolt II signal processing system from Sky Computers Inc. in Chelmsford, Mass. for its SAST program.
