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Seeing Through Walls
An anonymous reader writes "Researchers at MIT's Lincoln Lab have developed new radar technology that provides real-time video of what's going on behind solid walls. 'The researchers’ device is an unassuming array of antenna arranged into two rows — eight receiving elements on top, 13 transmitting ones below — and some computing equipment, all mounted onto a movable cart. But it has powerful implications for military operations, especially "urban combat situations," says Gregory Charvat, technical staff at Lincoln Lab and the leader of the project.' ... each time the waves hit the wall, the concrete blocks more than 99 percent of them from passing through. And that’s only half the battle: Once the waves bounce off any targets, they must pass back through the wall to reach the radar’s receivers — and again, 99 percent don’t make it. By the time it hits the receivers, the signal is reduced to about 0.0025 percent of its original strength. But according to Charvat, signal loss from the wall is not even the main challenge. "[Signal] amplifiers are cheap," he says. What has been difficult for through-wall radar systems is achieving the speed, resolution and range necessary to be useful in real time (PDF).'"
It's non-ionizing radiation so it's about as dangerous as your cellphone. This is an interesting and informative radiation chart https://www.xkcd.com/radiation/
It was a linear phased array. It literally can't tell up from down. If you wanted to make it sense in 3-D, you would have to make the array 2-D. Stack a couple of these units, throw in a couple more GPUs for processing, re-tweak the algorithm for an additional dimension, they could probably have a 3D model working in a couple weeks.
The issue is that 3D really doesn't get you much. With the current 2D system, you can tell where someone is in a room, but its not like you can see any identifying features. All 3D would get you is a very rough estimate of height.