Radar signal processing faces the twin burden of A-D conversion and digital signal processing

June 19, 2008
 Systems design -- Radar systems developers face significant design challenges as they consider analog to digital converters, digital to analog converters, and digital signal processing to achieve the optimum balance in their integrated RF sensor systems.

By John Keller

Radar signal processing is one of the most demanding embedded computing applications known in deployed military and aerospace systems. Signal processing demands fall into two general categories -- converting signals from analog to digital, back from digital to analog, and then making sense of signals once they are digitized.

"Radar users today are dealing with an enemy amidst civilian buildings; they want to find him with precision before he moves," explains Rodger Hosking, vice president of signal processing specialist Pentek Inc. in Upper Saddle River, N.J.

"Radar signals and frequency bands are getting wider -- in the hundreds of gigahertz and beyond -- to provide better resolution and precision in positional tracking," Hosking says. "Wider-bandwidth radar signals create two burdens -- digitizing that signal with A-D conversion, and the power of the signal processor that follows. You have to do the processing proportionally faster because you want to do the same kind of algorithm you did before, but at a higher bandwidth, so you need more horsepower."

It is computer horsepower that is the operative phrase when it comes to radar signal processing. "The never-changing requirement from our radar customers is more performance," says Ian Stalker, product marketing manager for Curtiss-Wright Controls Embedded Computing in Leesburg, Va.

"It is the radar developers who are quickest to adopt the highest-performance computing capability," Stalker says. "Radar guys are up against the highest performance and the highest risk. Effectively they have algorithms that consume an unlimited amount of compute power. If we could offer 100 times more power next week, then by Friday they would find a way to use it."

For Curtiss-Wright, the processing technology most in demand from radar systems integrators is the industry-standard VPX high-speed serial switched fabric. "Way over 50 percent of our radar processors are going with VPX," Stalker says. "100 percent of what we do in radar is multiprocessor, and we need some mechanism to communicate between processors. Previously this was the domain of proprietary solutions, but VPX is truly a sea change."

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