Wireless Devices Go Battery-Free With New Communication Technique

melios sends this quote from an University of Washington news release: "[E]ngineers have created a new wireless communication system that allows devices to interact with each other without relying on batteries or wires for power. The new communication technique, which the researchers call 'ambient backscatter,' takes advantage of the TV and cellular transmissions that already surround us around the clock. Two devices communicate with each other by reflecting the existing signals to exchange information. The researchers built small, battery-free devices with antennas that can detect, harness and reflect a TV signal, which then is picked up by other similar devices."

This is not a new idea, just ask the KGB :

[Anonymous Coward]

http://en.wikipedia.org/wiki/Thing_(listening_device)

Scientifically, fine, but not good in principal.

[VortexCortex]

I've got no objection to such research scientifically speaking. However, I am staunchly against any form of computation or communication that someone else can simply pull the plug on. Switch off the microwave carrier signals and these systems are dead. Wouldn't that be scary as hell to rely on? Before I used such tech I'd want it made legal to generate my own background radiation at home. That's currently illegal by the way.

Before you say it, yes, as a BBS owner I was against the Internet too, in principal. Not the communication, but the ability to spy on, censor, and pull the plug at will. I use todays technology with gritting teeth because although I have the expertise required to beam my data at high speed between my friends and family nation wide wirelessly with commodity radio gear, use of such systems in that manner are forbidden by the FCC, so I must use the principally corrupt systems.

I remain firmly convinced that large blocks of the air waves, perhaps even in the cellular bands, should belong to the people and if so instead of paying out the ass to support evil "data plans" we'd all be using a decentralized encrypted anonymized high speed hybrid line of sight / self organizing mesh network. You would pay for the hardware once, maintain it, and that's it. Ask a HAMOp about their packet radio "data plans"... If not so restricted by the FCC (and yes some oversight is needed, but not to this degree), we could have cut the cables. Omnivore, Carnivore, ECHELON, and PRISM illustrates why we don't have such technology in place. Before you argue against the feasibility, I would ask if you've actually tried it? If not, then make sure you're not on any (n+2)G network then make a free "long distance" cellular call and tell someone who cares.

Re:it is new... in a way.

[ls671]

Peer to peer analogy? If not enough people seed with devices hooked up to power sources, the system will fail.

Also, I remember that they caught a guy hijacking power from high power lines without touching the wires. He was doing it simply by induction and the power line was close to his barn. The electricity company noticed a power leak and this let to an investigation resulting in him being convicted even if he never touched the wires.

Now, how will the tv and radio stations react when they notice their signal get weaker because a bunch of devices draw power from their signal?

Re:The Technology is Not New

[bobbied]

Why does it matter where the "backscatter" energy comes from? It doesn't matter if the energy is "ambient" or specifically supplied it comes though the RF fields it is receiving. The device I described didn't care where the energy came from, it just took energy it found and charged up something so it could use it later. This "new" device is no different in principle, and certainly not that different in application to what I saw nearly 20 years ago now.

Heck, I remember back in the 80's listening to my EE power systems instructor showing us how you could get "free" power from the utility companies with a sufficient sized coil of wire and then calculating the amount of wire you would need. This is exactly the same physics (albeit at 60 Cycles and not RF so the wire you need is less) he was discussing way back then. This is NOT a new idea. The application is not new either...

Spying equipment has used backscatter power for even longer than toll tags. In one cold war situation, the US embassy was built by local contractors and riddled with passively powered listening devices. They where literally put everywhere. The Embassy was finished and occupied when the adversary decided it was time to crack up the RF and "power up" the microphones. The RF exposure in the building was pretty bad from then on and additional Faraday shielding was subsequently added to secure the building (at least until another one could be built).

I suppose it might seem new, being repackaged and smaller than before... But those toll tags where not much bigger than a credit card...

Re: New???

[Goedendag]

I told the kid (about 10 yo at that time) of friends about the can-string-can phone and we made one. I didn't expect that he would play with it for more than a few minutes. But to my surprise I noticed on later visits that the string phone was used when playing with friends. I've even noticed that it got repaired or even rebuild at some time. However, I think that he would never have learned about it if I didn't told him. Many parents are not enough involved with their kids to tell them about (or point them to the right books, web sites, ...) about these easy to try experiments. Most kids would love to do these kind of experiments, but they need some guidance to get started. But it's easier to just give them a game console so they ask for even more parent's attention :-(