By John McHale
REDONDO BEACH, Calif. - TRW engineers are developing a weather-piercing camera to help aircraft pilots land in bad weather. Engineers are using automated production lines, deconvolution algorithms, and a focal plane array (FPA) of 1,000 receivers.
The passive millimeter wave (PMMW) camera senses in the millimeter wave portion of the electromagnetic spectrum - a portion that is invisible to the human eye - and produces images in real time that enable pilots to discern runways, obstacles, and the horizon through fog, smoke, and clouds.
The sensor`s receivers are of monolithic millimeter wave integrated circuits (MMICs) developed at TRW in Redondo Beach, Calif., says Merit Shoucri, TRW`s business area manager. TRW is lead contractor in a consortium with experts at the NASA Langley Research Center in Hampton, Va.
Each of these circuits, formed on a sliver of gallium arsenide (GaAs), replaces bulky, heavy, and costly components, resulting in a compact device.
Aperture deconvolution (super-resolution) algorithms help display an image that refreshes 17 times a second and is equivalent to an effective aperture of 24 inches instead of the actual 18 inches.
Each receiver is built on a 2-by-7-millimeter GaAs chip which performs low noise direct amplification and detection of the radiometric scene signature. The 94-volt chip is 90 GHz.
The camera will require 1,040 MMIC receiver chips for an 80-by-52-pixel image. It uses a diode oscillator that places the RF signal into an A-d converter within the chip, says Steven Fornaca, the consortium`s program manager.
The camera is a passive sensor that does not emit signals in an airport environment, allowing multiple equipped aircraft to operate simultaneously on the ground without risk of interference.
The pilot sees an image of the forward scene raster scanned on a head-up display with overlays of flight guidance cues. It is amenable to direct fusion with infrared and visible images.
Air Force experts will fit the millimeter wave camera and its new radome aboard a test aircraft in September, says Fornaca.
Potential military applications of this technology include surveillance, search and rescue, navigation, and operating armored vehicles in fog, smoke, or sandstorms. It would also enable the military to operate covertly during landings and takeoffs, and during in-flight rendezvous and reconnaissance missions.
"This sensor program directly supports NASA`s new goal to safely triple capacity at our nation`s commercial airports within the next 10 years - regardless of fog, rain, or other conditions that normally limit pilot visibility," says Tom Campbell, head of Langley`s Electromagnetic Research Branch.
The pilot controls the device from the cockpit as conditions warrant. When not operating, the camera can survive temperatures from -55 to 85 degrees Celsius, Shoucri says. The contract is part of the Defense Advanced Research Projects Agency`s Defense Dual-Use Technology Initiative.
In addition, Langley scientists are performing lab tests to determine which materials are most "invisible" to millimeter waves and are good candidates for the protective nose radome that will house the camera on the flight test aircraft. The tests will provide the consortium`s radome design team with data about optimum material thickness, protection from rain erosion, and protection from static buildup.
Other consortium members are McDonnell Douglas Corp. in Long Beach, Calif.; Honeywell Inc. of Minneapolis; Composite Optics Inc. of San Diego; NASA Ames Research Center in Mountain View, Calif.; U.S. Air Force Wright Labs in Dayton, Ohio; U.S. Air Force Flight Test Center at Edwards Air Force Base, Calif.; and the U.S. Army Research Lab in Adelphi, Md.
TRW technicians inspect the company`s new millimeter wave-detecting sensor that is expected to help aircraft pilots operate in bad weather.