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from the shoot-out-the-lights,-unplug-the-wifi dept.
Researchers at University College London (UCL) have devised a system for detecting the Doppler shifts of ubiquitous Wi-Fi and mobile telephone signals to "see" people moving, even behind masonry walls 25 centimeters thick. The method, which could be useful in situations from hostage-takings to traffic control, won the Engineering Impact Award in the RF and Communications category at this National Instrument's NI Week 2015 meeting (which convened in Austin, Tex., 3-9 August).
Other researchers—notably Dina Katabi and Fadel Adib of MIT—have built through-wall radars in the household communication bands, but these are active radars that transmit as well as receive. The UCL technique uses only passive radiation—from Wi-Fi routers (using emissions in any of the IEEE 802.11 b, g, n, ac), ambient GSM and LTE mobile signals, and other sources—so there is nothing to betray the surveillance. The system calculates the positions of hidden target by comparing two signals: a reference channel, receiving the baseline signal from the Wi-Fi access point or other RF source, and a surveillance channel, which picks up Doppler-shifted waves reflecting from the moving subject.
Tan and company built their "high Doppler resolution passive Wi-Fi radar" on two multi-frequency, software-defined, FPGA-based transceivers (National Instruments' USRP, or Universal Software Radio Peripheral. The system compares the reference and surveillance signals, interprets the very small frequency shifts, and reveals the hidden subject's location and motion.
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(Score: -1, Offtopic) by Anonymous Coward on Wednesday August 12 2015, @06:47AM
We pay researchers to deprive us of our liberties, and they gleefully do it, because researchers are immoral whores for grant money.
(Score: 0) by Anonymous Coward on Wednesday August 12 2015, @07:13AM
it's just light bro
(Score: 0) by Anonymous Coward on Wednesday August 12 2015, @07:19AM
Well then you won't mind if I watch your daughter in the shower.
(Score: 2) by maxwell demon on Wednesday August 12 2015, @08:33AM
You'd prefer if only the three letter agencies know about this possibility? This way, you at least know, too, and can use countermeasures if you care about it. I mean, it's not as if electromagnetic radiation is unstoppable.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 1, Funny) by Anonymous Coward on Wednesday August 12 2015, @08:47AM
Lead paint, don't fail me now!