An Air Force test pilot dives, banks and loop-the-loops the latest fighter jet at extreme speeds to push it to the limits. As the pilot completes a series of barrel rolls, ground crews analyze the plane’s structural data, which is streaming from two antennas mounted on board, designed to monitor the jet prototype’s safety and performance.
Until recently, this test would have required numerous runs and off-site analysis, but the US Department of Defense has awarded
“When the government wants to buy an airplane, it has to be fully tested—the more expensive it is to test an airplane, the more expensive the plane is,” says Michael Rice, the Jim Abrams professor in the department of electrical and computer engineering. “You don’t want to cut corners on reliability or safety, but if you could reduce expenses in testing, the airplane would be cheaper and everyone would be safe.”
Previously, airplanes used only one antenna to send data to ground crews, but the signal dropped whenever the plane banked and obscured the antenna from the ground. The jet had to be refueled, the equipment and personnel reassembled, and the mission re-flown to acquire the missing data. To solve that problem, two antennas were mounted to transmit signals from the top and bottom of the plane. A new problem emerged, however: when jets with two antennas flew parallel to the ground, both antennas transmitted signals simultaneously, interfering with each other and masking important data about the jet’s performance.
The solution came after a theoretical analysis of the issue was undertaken by Rice and Michael Jensen, an associate professor of electrical and computer engineering, and two graduate students.
Now, using the DOD grant, the researchers are to develop and test a prototype receiver that interprets the relationship between the two antennas’ signals and translates them into separate streams as the plane flies, allowing data analysis to occur on-site.
“The technology gets rid of those data drop outs so we don’t have to refuel and retest,” said Saul Ortigoza, executing agent for spectrum efficient technologies at Edwards Air Force Base. “That’s a big plus from a test-range perspective. It saves us a lot of money, and it’s pretty exciting.”
The technology solves the antenna dilemma in commercial jets as well, Rice said, referring to another possible application of his work.
“When they are testing a new prototype commercial jet, they put the whole notion of ‘the tray table in its upright and locked position’ in a new perspective,” Rice said, explaining that airlines gather data about their new planes just like the military. “They do hard turns, landings with one engine off—things they’d never do with passengers to ensure the plane is safe.”