American engineers have figured out how to recognize gestures using the speaker and microphones

Programmers from the University of Washington have developed the FingerIO software system , which allows turning almost any smartphone or smart watch, equipped with a speaker and microphones, into a sonar capable of tracking gestures. This system facilitates the management of devices with a small screen and may lead to the emergence of new, unexpected opportunities in conjunction with gadgets.

Due to the fact that sound waves can pass through the fabric, the device can be controlled with gestures even if it is located in a pocket, or hidden by a sleeve of clothing. The system emits sound waves using a speaker and processes the sound reflected from the fingers coming through two microphones.
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To ensure accurate finger position measurements with acceptable resolution, engineers use a system called Orthogonal Frequency Division Multiplexing ( OFDM ). This is a digital modulation scheme using a large number of closely spaced orthogonal subcarriers. It is used in ADSL, digital cable television, etc.



The developers claim that on a standard Samsung Galaxy S4 running Android, when tracking finger movements on a plane, it is possible to achieve an accuracy of 8 mm. A prototype of a smart watch with the support of this technology, developed by engineers, was able to track finger movements up to half a meter from the device with an accuracy of 12 mm.

As one of the creators of technology explains, smartphone displays, and especially smart watches, are not very well suited for typing or drawing, so the developers wanted to make sure that any flat surface, for example, the table surface, could become a field for entering information .

The developers' plans include the recognition of the movements of several fingers and the recognition of gestures in three-dimensional space through the addition of additional microphones.