Radar has helped us forecast the weather and make highways and airports safer, but radar, says Rick Blum, is due for a 21st-century facelift.
Traditional radar systems, says Blum, the Robert W. Wieseman Chair in electrical engineering, locate a target by measuring the time it takes for a radio signal to hit the target and return to its point of origin.
But radar is not infallible. The outgoing signal might hit several objects and diminish, or it might miss the object it is tracking. the angle of the target might shift, weakening the returning signal.
Blum has played a leading role in efforts to improve radar with multiple-input and multiple-output (MIMO) communications systems.
“With regular radar,” he says, “you often have to ‘see’ the target from just the right direction to get an accurate picture of it. This is because the magnitude of the return signal can change drastically if there’s a small change in the angle of the target.”
MIMO overcomes this by transmitting signals from several locations.
“If you see from multiple viewpoints,” says Blum, “you are going to get a much better picture. One or two illuminations might come back weak, but not all of them. And the antennas in a MIMO radar system don’t need to be far apart to get a usable return signal.”
Recently, Blum received grants from the Office of Naval Research and the Air Force Office of Scientific Research to study MIMO radar systems. Among other things, he will investigate how sensor networks can achieve energy savings in MIMO radar systems.
Blum creates formulas that allow “smart” sensor networks to cut energy use without losing performance. The sensors save energy by identifying and “censoring” (not transmitting) data that is unnecessary.
Blum taught a tutorial on MIMO radar at the 2008 IEEE International Conference on Acoustics, Speech, and Signal Processing in Las Vegas. He also coauthored an article titled “MIMO Radar with Widely Separated Antennas” in IEEE Signal Processing Magazine in 2008.