At MIT have developed a radar that allows people to see through the wall and count the pulse at a distance Bashny.Net

A couple of years ago Habré wrote about the experiments of scientists from University College London with wireless technology. They used a WiFi signal reflections from moving people to define their position and direction of movement, including for thick brick wall. Their colleagues at MIT doing research in the same direction and 12 June informed about exciting new results . They managed to track simultaneously from three to five people to recognize their gestures and monitor their breathing through the wall, and in line of sight - even counted the pulse.

Installing MIT, called WiZ, consists of USRP-station N210 with an array of directional antennas that radiate ramp varies from 5.46 to 7.25 GHz every 2, 5 milliseconds. The signal of each antenna slightly shifted in phase in order to distinguish them from each other. The receiver picks up the signals reflected from the people, and calculates the distance to them, measuring the delay of the reflected signal. The power output of the radio signal does not exceed 0, 75 milliwatts, which meets the requirements of the Federal Agency of Communications for consumer technology in this frequency range.




One of the antennas and array assembly. I>

WiZ surely recognizes up to four people in line of sight or up to three - over the wall. Positioning error is 6, 5 cm in ideal conditions to 16, 1 in the most unfavorable. The system may recognize simple gestures such as to determine which points of a human hand with a precision of 8 to 16 degrees depending on circumstances. Furthermore, WiZ can follow the breath - in 97% of experiments, which lasted on average for a few minutes, the system will not miss more than one inhalation or exhalation. Interestingly, this ability was originally a side effect - the fact that WiZ hardly sees motionless people. It is for the tracking of motion recognition handy chest when breathing.

Such systems may find broad applications, from military - see the enemy through the wall to the medical - monitor the vital signs of patients without the use of contact sensors. Low intensity radiation allows even apply such systems in household appliances - on video at the beginning of the article is an example of such a use in the "baby monitors": it will not only see a sleeping baby, but also to monitor his pulse and breathing.



Source: habrahabr.ru/post/226273/