Humans see by receiving waves of visible spectrum light
bouncing off objects, and radar
systems bounce radio waves
off objects for receivers to "see" -- but detecting electromagnetic waves
in the visible or radio wave ranges through building walls and other solid objects has long-challenged technicians because light and radio waves do not pass through sold objects in quantities large enough for human eyes or radar receivers to detect; now Lincoln Lab researchers have devised a new system that can penetrate walls and form instant images of what is happening behind them from stand-off distances, ScienceDaily reported
The new device, attached to a movable cart, is an uncomplicated array of two rows of antennas -- 13 transmitters below and eight receivers on top -- connected to computers.
Project leader Gregory Charvat explained
that signal loss, both penetrating the wall and returning, can be solved by adding relatively inexpensive amplifiers, but developing a system with enough range, resolution and speed to be useful in action presented the greatest challenge:
“If you’re in a high-risk combat situation, you don’t want one image every 20 minutes, and you don’t want to have to stand right next to a potentially dangerous building.”
Using S-band waves
, the range used by Wi-Fi, Lincoln Lab’s system, which is about eight and a half feet long, generates real-time video images of motion behind walls up to 60 feet away at 10.8 frames per second; the team tested the device at 20 feet, a realistic range for urban combat situations, according to the team.
The system's computer processor works by a subtraction method that compares new pictures to previous shots and analyzes what changes, so the new radar only detects moving targets making even small motions -- furniture would not show in the display, but human locations would appear as moving "blobs" in a birds-eye view.
A next step is tweaking the algorithms to automatically interpret the blobs as clear, user-friendly symbols.
The team recently presented and published a paper
detailing their through-wall radar imaging system.