MIT researchers have demonstrated the application of using Wi-Fi signals to track the movements, locations and number of people inside buildings. Dubbed Wi-Vi, the inexpensive and portable "through-the-wall" radar system could have practical applications in law enforcement, search and rescue operations and home security, even if it does present some potential privacy concerns.
While listening in on radio signals transmitted by standard Wi-Fi routers and access points, a Wi-Vi transceiver blankets the area with its own low-power, directional, wireless transmissions. As objects move within the target area, signals are absorbed and reflected differently. The device monitors these slight changes, giving Wi-Vi operators the ability to determine the movements, locations, speeds and the number of moving objects (e.g. people) behind walls.
Since Wi-Vi relies on physical radio waves instead of higher network layers, operators do not need access to a Wi-Fi network (i.e. no password is needed) in order to make use of signals emanating from a nearby Wi-Fi router or AP.
Wi-Vi can detect objects and humans moving behind opaque structural obstructions. This applies to 8" concrete walls, 6" hollow walls, and 1.75" solid wooden doors. A Wi-Vi device pointed at a closed room with 6" hollow walls supported by steel frames can distinguish between 0, 1, 2, and 3 moving humans in the room. Computed over 80 trials with 8 human subjects, Wi-Vi achieves an accuracy of 100%, 100%, 85%, and 90% respectively in each of these cases.
Source: people.csail.mit.edu (pdf), See Through Walls with Wi-Fi!
While Wi-Vi doesn't provide anything that resembles an actual photograph of what's behind a wall, the results are detailed enough to be used for detecting body gestures (e.g. hand waves) with a remarkable amount of accuracy.
In the same room, and given a single person sending gesture based messages, Wi-Vi correctly decodes all messages performed at distances equal to or smaller than 5 meters. The decoding accuracy decreases to 75% at distances of 8 meters, and the device stops detecting gestures beyond 9 meters. For 8 volunteers who participated in the experiment, on average, it took a person 8.8 seconds to send a message of 4 gestures.
Unfortunately for potential voyeurs (and fortunately for privacy advocates), it remains a far cry from detailed airport scanners, X-ray vision or even Batman's implausible cell phone "sonar" network, but it could prove to be an inexpensive way to gain life-saving insight for rescue operations and police busts. As with many technologies though, it's not difficult to imagine Wi-Vi being subverted by tech-savvy criminals, like burglars or kidnappers, to get the drop on unsuspecting victims.
The Nexus 10 is Google's rival of the full-size Apple's iPad. It is manufactured by Samsung and is powered by a dual-core ARM Cortex-A15 chip, 2GB of RAM and Android 4.2. The Nexus packs a 10" screen at 2560 x 1600 resolution (300ppi). Other features include microUSB, Micro HDMI and not one but two NFC chips.
The Google Nexus 7 is the first Google tablet and is manufactured in partnership with Asus. It features a 7-inch 1280 x 800 display and a Tegra 3 SoC which itself comprises a quad-core CPU and twelve-core GPU. Connectivity options include Wi-Fi and Bluetooth, also you get a front-facing camera and ships with Android 4.1 Jelly Bean operating system.
The Apple iPad (3rd-gen) includes a Retina Display operating at a resolution of 2,048 x 1,536. Powering the new iPad is a dual-core A5X processor with quad-core graphics, it also gets upgraded optics in the form of a 5MP backside illuminated sensor that features a 5-element lens, IR filter and ISP built into the A5X chip. Apple claims The new iPad is good for 10 hours of battery life and nine hours when using 4G LTE.
The Yoga 13 features a third generation Intel Core i5-3317U processor clocked at 1.7GHz, 4GB of RAM, Intel HD Graphics 4000 and a 128GB solid state drive. True to its name, the Yoga 13 utilizes a 13.3-inch HD+ LED Multitouch display operating at 1,600 x 900 resolution.
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