DetectionSeeing through walls, clearly
Research and tests show, for the first time, the ability to use t passive WiFi radar for through-the-wall (TTW) detection of moving personnel – and do so covertly
New capability allows police to detect movement through walls // Source: publinews.gt
In a new paper, researchers investigate the feasibility of using passive bistatic WiFi radar at standoff distances to detect, uncooperatively and covertly, people moving behind walls.
The researchers conducted a series of experiments which involved personnel targets moving inside a building within the coverage area of a WiFi access point. These targets were monitored from outside the building using a 2.4-GHz passive multistatic receiver, and the data were processed offline to yield range and Doppler information.
The results show the first through-the-wall (TTW) detection of moving personnel by using passive WiFi radar. The measured Doppler shifts agree with those predicted by bistatic theory. Further analysis of the data revealed that the system is limited by the signal-to-interference ratio (SIR), and not the signal-to-noise ratio.
The researchers have also shown that a new interference suppression technique based on the CLEAN algorithm can improve the SIR by approximately 19 dB. These encouraging initial findings demonstrate the potential for using passive WiFi radar as a low-cost TTW detection sensor with widespread applicability.
— Read more in K. Chetty et al., “Through-the-Wall Sensing of Personnel Using Passive Bistatic WiFi Radar at Standoff Distances,” IEEE Transactions on Geoscience and Remote Sensing 50, no. 4 (April 2012): 1218 – 1226 (DOI:10.1109/TGRS.2011.2164411)
