WiFi Can Be Used to Count People Even if They Don’t Have Electronic Devices

‘Researchers have discovered that WiFi is not only useful for accessing the Internet. The signal can also be used to determine the number of people in a given space, even if they are not carrying a WiFi-enabled device.

Researchers from the University of California, Santa Barbara say they can count people based on the received power measurements of a WiFi signal.

To count the number of people, they put two WiFi cards at opposite ends of a 70-square-foot area, and as people cross the card’s line of sight, the force of the signal is reduced. Bodies also cause signal to scatter, a phenomenon called “multi-path fading,” when they are not directly in the path of the signal.’

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