Better RADAR Tools: Firms are developing a new kind of X-ray vision.

August 24, 1998|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

Adolescent boys aren't the only people who have wished, at some moment in their lives, for X-ray vision.

Contractors would love to see through walls to the studs, pipes and wires behind them. Police officers would be safer if they could see through closed doors. And drivers would relax some if they could see the curbs, posts and tricycles their mirrors can't reflect.

X-rays are too dangerous and costly. But recent advances in low-power radar technologies are driving the development of new tools and gizmos that may soon fulfill these wishes and more, at affordable prices.

Their inventors believe the potential market can be measured in the billions of dollars. And some of the first applications are getting closer to commercial production.

At the Georgia Tech Research Institute, Gene Greneker's "radar flashlight" can detect human breathing through eight inches of cinder block. "With the interest we have had on this, we could have already sold a thousand if we had them," he said.

Zircon Corp., a privately held, California-based company that has sold 20 million old-fashioned electronic stud finders, is pumping big money into development of a new, improved radar version.

"It would give me a window into the wall," said Zircon spokesman Neil Cohen. "I would be able to see all the objects back there - determine their size and shape and what the material is."

Amerigon Inc. of Monrovia, Calif., is working on a radar system that can warn drivers before they back into a wall or a child. The systems may become cheap enough, at roughly $100, to be commonplace in new cars.

Conventional radar (an acronym for "radio detection and ranging") is World War II-era technology. It sends out pulses of radio-frequency signals that travel at the speed of light. Where the signals encounter a ship or airplane, they bounce back. By listening for that echo, and timing the signal's return, radar can calculate the target's distance.

Most radar systems today send out continuous signals, and listen for small changes in the reflected signals' frequency caused by the target's motion (the Doppler effect). From that, they can calculate distance and speed.

But long-range radar systems are expensive and power-hungry. The new short-range radars are relatively cheap, and can run on batteries.

Greneker's radar flashlight uses new, high-speed, digital signal processing to filter out irrelevant patterns in the radar echo. It listens only for the very slight, rhythmic changes typical of chest movements in a breathing human.

"First we detect the presence of something, then we determine whether it's the target we're after," he said. "It is sensitive enough to detect through an eight-inch cinder-block wall, a wood door, or plywood," Greneker said. "It occurred to us it might be very useful for police applications."

With an effective range of less than 40 feet, it could detect suspects hiding in closets, or the whereabouts of hostages in a house. Under some conditions, rescue workers could locate survivors in avalanches or collapsed buildings.

Greneker is working now to reduce the radar's electronics to a set of tiny chips, so that the entire system will fit inside a cylinder the size of a large police flashlight.

"We think it has to be very simple," he said. A pair of lights may be enough. "If it's green, there's nobody being detected - no human respiration. If there's a red light, it sees something that you need to be aware of."

Greneker believes a prototype will be ready for field testing in eight months. A commercial product selling for $500 to $1,000 could be available in a year.

At Zircon, engineers are working with a different radar technology, called micropower impulse radar (MIR).

MIR was developed at the Lawrence Livermore National Laboratory to measure atomic particle collisions in nuclear fusion research. Instead of a continuous signal, MIR sends out millions of low-power radar impulses each second, at random frequencies. It then listens only for specific impulses that return at precise instants - timing that indicates they have bounced off objects encountered at a preset distance.

That detection perimeter, or radar "bubble," suggests many potential uses, including home security. And the whole thing can be produced on a $10 circuit board the size of a credit card.

Lawrence Livermore's patents for MIR, and by implication the 26 licenses it has sold to manufacturers, have been challenged - with some partial but preliminary success - before the U.S. Patent Office. An Alabama inventor, Larry D. Fullerton, founder of Time Domain Corp. of Huntsville, claims to hold an earlier patent for the same technology.

But Zircon is pressing ahead with development. "We really understand what's going on with this technology, and we've got a four-year lead on anybody else," Cohen said. Even if the patent challenge is successful, "we would aggressively pursue bringing something to market."

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