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Iphone

iOS App Acoustically Measures Distances Up To 25 Meters 154

n01 writes "A recently published app for the iOS platform uses the propagation of sound waves to measure distances of up to 25 meters in a dual device mode. The technique works through repeatedly sending a chirp signal from the master device to which the other (reflector) device synchronizes itself and then replies in a similar fashion. A novel combination of techniques has been engineered to enhance the robustness in noisy environments, such as using an optimum-autocorrelation-signal and semi-automatic frequency calibration together with an averaging over multiple cycles."
Privacy

Wireless Network Modded To See Through Walls 161

KentuckyFC writes "The way radio signals vary in a wireless network can reveal the movement of people behind closed doors, say researchers who have developed a technique called variance-based radio tomographic imaging which processes wireless signals to peer through walls. They've tested the idea with a 34-node wireless network using the IEEE 802.15.4 wireless protocol (the personal area network protocol employed by home automation services such as ZigBee). The researchers say that such a network could be easily distributed by the police or military wanting to determine what's going on inside a building. But such a network, which uses cheap off-the-shelf components, might also be easily deployed by your neighbor or anybody else wanting to monitor movements in your home."

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