Ultra-wideband makes waves

Finding a needle in a haystack isn't child's play anymore, thanks to X-rays, radar detectors and metal detectors. But how about finding a person behind a wall of a burning, smoke-filled building? Or pinpointing the location of a lost soldier in a foggy valley?

Those are some of the government uses of ultra-wideband technology that its advocates envision. Assuming talks between industry and the Federal Communications Commission ultimately end with the go-ahead to sell ultra-wideband operating products, the public may find the technology arrives none too soon.

The public airways are already jammed with thousands of signals — from commercial and government broadcasts via TV, radio and satellite, to shortwave radios and cell phones. Ultra-wideband will add to the noise even while it operates across the frequency spectrum — but without, say its advocates, further crowding or interfering with existing signals (see related story).

Most people agree that the technology, once unharnessed from federal regulations designed to safeguard the integrity of broadcast frequencies, will revolutionize communications.

Current bandwidth limitations will no longer restrict the amount of signals that may be broadcast, making ultra-wideband an excellent technology for supporting wireless local-area networks that can transmit data, voice and video.

Time Domain Corp. will soon be demonstrating a wireless tactical operations center for the Army's Space and Missile Defense Command. Such capability would free a deploying unit from the wires and cables it must rely on, said Kevin Davis, business development manager at Time Domain.

Ultra-wideband can also be used to build sensors that track people and objects to within a few feet of their exact locations, according to Robert Fontana, president of Multispectral Solutions Inc.

Fontana said his company produced an ultra-wideband "geolocator" about two years ago for the military. With it, officials were able to track the soldier's exact location from about a kilometer away. Though such tracking can now be done using satellites, ultra-wideband technology has a major advantage: Successful use is not dependent upon daylight and clear skies, according to Fontana. To date, the technology has found application mostly as radar.

The pulses, bounced back and interpreted by the transmitter, produce images far more precise than traditional radar, which relies on high-frequency radio waves. Engineers are using the technology to determine the soundness of bridges by looking for structural weaknesses. Archeologists use it to look into the ground before sticking in a shovel. The Army and Air Force use ultra-wideband radar systems in setting up perimeters and detecting land mines.

The FCC, which is charged with safeguarding the integrity of radio frequencies, is studying ultra-wideband to determine its potential for disrupting other communications.

John Reed, senior engineer with the FCC's Office of Engineering and Technology, said the military already uses some ultra-wideband systems that transmit over GPS frequencies, apparently without problems. how it works Cutting through the noise Think of the airwaves as tens of thousands of multilane intersecting highways with the traffic — communications signals — to match.

The government regulates the airwaves in much the same way it regulates traffic, and for the same reason: to avoid chaos and disaster. Everyone operates in specific frequencies — their lanes, so to speak — and if everybody obeys the rules of the road, then traffic moves safely and smoothly.

Ultra-wideband lets you to drive in everyone's lane regardless of flow, direction or density because instead of cruising along like the others in a specific frequency, you're driving the equivalent of a bullet. Your signals reach receivers in short, fast bursts or pulses. Each pulse carries a unique signature that enables it to be picked up and interpreted by receivers. Because data is transmitted in pulses, only microseconds apart, they can cross other frequencies without disrupting them.

"The narrower the pulses, the more spreading you have [across the spectrum]. That reduces the potential [for] interference with other frequencies," said John Reed, senior engineer at FCC's Office of Engineering and Technology.