https://www.youtube.com/watch?v=5f5JJTmbO4U
Researchers have succeeded in developing a mobile phone that uses only the energy of surrounding waves to initiate and maintain cellular communication.
For years, the telecommunications industry has been looking for new battery technologies in order to guarantee the rising performance of smartphones and other mobile devices. Six researchers from the University of Washington have just adopted an inverse approach: finding a way to get rid of the battery permanently. And they succeeded!
Certainly, the mobile phone they have developed is not very attractive at first and its use is somewhat similar to that of a walkie-talkie (before speaking, you have to press a button). But this is for the moment a prototype and it does not detract from the technical prowess of passing for the first time a cell phone call without any source of energy and using electronic components available commercially
How is it possible ? To operate, this phone will seek its energy in the radio waves of the base stations and the light waves, respectively using antennas and photodiodes. In itself, it is not very original. In February 2016, the same team had already shown how to build on the surrounding waves to create a Wi-Fi network. What is impressive is that the researchers came to initiate and maintain synchronous communications without interruption, While the power collected by the device is only 3,5 microwatts. For comparison, a 2G conversation of 5 min consumes between 600 and 1200 milliwatts, which is almost a million times higher.
To achieve such an economy, the researchers decided to remove one of the essential steps of each telephone conversation, namely the conversion of analog signals (the sound of the voice) into digital signals. "This process consumes so much energy that it would be impossible to make a phone that relies only on surrounding energy sources," says the University of Washington website.
Everything is done passively
This energy-intensive process is replaced by a passive microphone whose movements will directly generate electrical changes in a wave from a base station, the phone will capture and then transmit it by simple reflection (backscatter). The base station, on the other hand, has the necessary circuits to interpret these variations and transmit the communication to the operator's network. To test their prototype, the researchers set up a modified base station accordingly. The researchers were able to use their phone at a distance of about 9 meters. By integrating a small photodiode (1,1 cm²), they arrived at a distance of 15 meters.
This may sound little, but according to the researchers, it is because of the low power of the base station used. According to them, the performance could be much better in real environment. Questioned by Wired, one of them believes that "the true base stations have a hundred times more power, which could extend the range to one kilometer". Finally, the researchers have even pushed the defect until they integrate a Skype plugin into their base station to be able to route VoIP calls to any phone from around the world. Hat.
http://www.01net.com/actualites/ce-tele ... 12266.html