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Wireless Devices Go Battery-Free With New Communication Technique

Soulskill posted about 8 months ago | from the harvesting-energy-from-the-ether dept.

Wireless Networking 111

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."

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111 comments

New??? (2)

acariquara (753971) | about 8 months ago | (#44569319)

Re:New??? (4, Informative)

bobbied (2522392) | about 8 months ago | (#44569461)

Not exactly the same thing, but receiving RF without power has been done for about as long as RF has been received... Actually... Exactly as long as RF has been received. Crystal Radios where how this whole "Let's communicate by radio waves" thing got started...

Crystal receivers were not the first (2)

MitchAmes (1080977) | about 8 months ago | (#44571859)

... receiving RF without power has been done for about as long as RF has been received... Actually... Exactly as long as RF has been received. Crystal Radios where how this whole "Let's communicate by radio waves" thing got started...

Not quite. Coherers [wikipedia.org] preceded crystal detectors [wikipedia.org] by a few years.

Re:New??? (4, Insightful)

mcl630 (1839996) | about 8 months ago | (#44569479)

Not quite the same. Crystal radios can't transmit information, only receive it, while this can both transmit and received. In the sense that they're powered only by the RF received, they are similar.

Re:New??? (1)

drinkypoo (153816) | about 8 months ago | (#44572773)

Not quite the same. Crystal radios can't transmit information, only receive it,

Really? What do you call it when you hear sound coming from a speaker? That's not transmission of information?

Re:New??? (3, Funny)

martas (1439879) | about 8 months ago | (#44573257)

Your daily dose of pedantry brought to you by drinkypoo.

Re:New??? (1)

drinkypoo (153816) | about 8 months ago | (#44573417)

Your daily dose of pedantry brought to you by drinkypoo.

Hey, why else does one come to Slashdot? Anyway, what we're talking about here is an RFID tag with buttons. It's not rocket surgery.

Re:New??? (-1)

Anonymous Coward | about 8 months ago | (#44569963)

When I was a kid we had devices that communicated together without batterys or wires for power. Two average size clean tin-cans attached with strong thin string. I recall the recieved sounds sometimes were better than a few cell-phones I had.

Re: New??? (0)

Anonymous Coward | about 8 months ago | (#44570475)

do kids still do this experiment?

Re: New??? (3, Interesting)

Goedendag (2618275) | about 8 months ago | (#44571795)

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 :-(

Re: New??? (1)

Goedendag (2618275) | about 8 months ago | (#44571807)

Update to my own post:

But it's easier to just give them a game console so they ask for even more parent's attention :-(

Should have been: But it's easier to just give them a game console so they DO NOT ask for even more parent's attention :-(

So now we can't just remove batteries anymore ? (1)

Anonymous Coward | about 8 months ago | (#44569347)

tinfoil hat: check
shielded paint: check
wide range radio scrambler: check

Tinfoil clothes please (0)

Anonymous Coward | about 8 months ago | (#44569357)

First the obligatory this is awesome and Tesla was a genius statement. Next the "holy crap there is that much power being transmitted through the air (and my body) every moment of every day."

Re:Tinfoil clothes please (1)

bobbied (2522392) | about 8 months ago | (#44569433)

Yes, and it mostly comes from non-man made sources... Let the sun shine... Let the sun shine in....

Re:Tinfoil clothes please (0)

ls671 (1122017) | about 8 months ago | (#44570727)

The sun is at a reasonable distance.

You do know that they have to completely shutdown a tower to prevent the worker to fry like if he was in a microwave when he climbs one of them for maintenance, right?

Many people have reported problems with radio waves especially when close to the transmitter although I do not know if their suffering is psychological or real.

One thing for sure, an antenna is power transmission. See my other post:
http://slashdot.org/comments.pl?sid=4090989&cid=44570315 [slashdot.org]

Re:Tinfoil clothes please (0)

Anonymous Coward | about 8 months ago | (#44571497)

"You do know that they have to completely shutdown a tower to prevent the worker to fry like if he was in a microwave when he climbs one of them for maintenance, right?"

Actually, wrong, but why let facts get in the way of your argument.

Signed: A Tower Climber.

Re:Tinfoil clothes please (0)

ls671 (1122017) | about 8 months ago | (#44571931)

Here Sherlock:
https://en.wikipedia.org/wiki/Microwave_burn#Other [wikipedia.org]

Also, I remember a local TV station went down for 8 hours during the day because a goof had climbed up the transmission tower wanting to commit suicide so they shutdown the transmitter to avoid injuries to him.

Re:Tinfoil clothes please (0)

Anonymous Coward | about 8 months ago | (#44572261)

Hey sherlock.
1) I'm not the tower climber AC who posted above, but in his defense, you did not specify MICROWAVE tower in your original post.
2) According to your wiki link, " the engineer was stuck next to the antenna, outside of its main lobe but well within the first sidelobe". There's a pretty big difference between climbing the tower, and geting next to the antenna. For a car analogy, you do not have to shut down a car to reach inside the engine compartment, but if you are going to inspect the fan belt, you would.

Psychological effect (1)

Comboman (895500) | about 8 months ago | (#44572817)

You do know that they have to completely shutdown a tower to prevent the worker to fry like if he was in a microwave when he climbs one of them for maintenance, right?

A stove can burn me if put my hand on it, so it must also be dangerous if I'm across the room from it, right? Brilliant logic, but unfortunately wrong. Like the heat from a stove, radio power follows an inverse-square law, meaning power is proportional to the inverse of the distance squared. If something is (for example) 1000 Watts at 100 ft from the antenna, it would be 250 Watts at 200 ft and less than 4 Watts at 1600 ft from the antenna.

Many people have reported problems with radio waves especially when close to the transmitter although I do not know if their suffering is psychological or real.

Many people have reported anecdotal medical problems caused by radio waves, power lines, windmills, vaccinations, magnets, aluminum pots, fluoridated water, contrails, and voodoo curses. Until legitimate medical research confirms a causal link, the best explanation for all of these is psychological.

Re:Psychological effect (1)

cusco (717999) | about 8 months ago | (#44574497)

My former employer did some work on an access control system for an antenna farm. At one point some guys were going to climb a tower to hang a new antenna off it. There were two or three TV stations and a couple of radio station antennas on that particular tower already, as well as a Coast Guard transmitter and something else. They reduced the power by 50-75% on all the transmitters and the guys went up, coming back down about ten minutes later because they had exceeded their radiation limit. I asked my co-worker what kind of meter they were using that let them know, and he said, "I think it's called a Vomit-o-meter. They came back down that tower puking and shaking so bad they had to crawl to their truck and sit there an hour before they could drive home." OTOH, there are neighbors who have lived about a city block or so from that facility for 20+ years without any problems.

Tesla... (0)

Anonymous Coward | about 8 months ago | (#44569365)

Would be proud.

The Technology is Not New (4, Informative)

bobbied (2522392) | about 8 months ago | (#44569421)

This is not new technology.

Toll Tags and other RF-ID devices have been using "back scatter" techniques to capture energy to transmit with for decades. The reader device provides RF energy that is captured by the tag charging up a capacitor enough to send a short burst of data back to the reader. I saw this being done during a Job interview in Dallas sometime in the 90's and was impressed with the idea. I was even more impressed that it worked well enough to actually be in use on various tolling systems. Still remember the test rig they had with the tags mounted to the ceiling fan blades as being decidedly low tech, but wonderfully effective.

The application might be a bit different, but the technology is NOT new.

Re:The Technology is Not New (0)

Anonymous Coward | about 8 months ago | (#44569503)

How is this not new?
You mention "The reader device provides RF energy that is captured by the tag charging up a capacitor enough to send a short burst of data back to the reader" That means the reader needs to be powered, otherwise this won't work.

As I read it, this article is about the device taking radio waves generated by other devices (TV & Cellular for example) and reflects them to another device. That means that both devices can communicate with each other without either device needing (dedicated) external power.

Re:The Technology is Not New (4, Informative)

bobbied (2522392) | about 8 months ago | (#44569699)

Getting power from an external RF source is not new. Being able to get it from ambient RF sources is not new either.

The tags I saw where charging whenever RF was available. The tag didn't know or care if the power came from the reader or not. The goal was to keep charged and "ready" for the data burst when the reader asked for it. Any RF source was suitable for charging and that the reader provided power was merely a matter of making sure there was enough power when needed. So for reliability sake you put some RF power out to charge the tag before you need it to transmit the data you want, but they still charged from anything else they picked up.

So what does it matter where the background RF comes from? Capturing energy from RF is certainly not new. Using such power to communicate is not new either.

Re:The Technology is Not New (1)

AmiMoJo (196126) | about 8 months ago | (#44571655)

I made a little experimental device using this technique. A standard set-top TV antenna and a resistor to generate a small voltage, which I then multiplied up using a chain of simple diode/capacitor doublers. I was able to run a small clock/thermometer off it, and then moved on to charging a super capacitor so that I could do a daily radio transmission using a CC1101 ISM band module and a microcontroller.

The amount of energy available is tiny considering how much space the antenna requires, but using a coil you could probably get it down to something reasonable. There are not many situations where it would be preferable to using solar though.

Re:The Technology is Not New (4, Informative)

Shavano (2541114) | about 8 months ago | (#44570497)

What's new is they're working with very low power levels. I've never seen a backscatter system that can work with so little incident power.

Re:The Technology is Not New (1)

ls671 (1122017) | about 8 months ago | (#44570771)

I fully agree.
Yet, the concept is around since electricity was mastered by humans. Next, I might go read TFA and see how much is real ;-)

Re:The Technology is Not New (1)

leuk_he (194174) | about 8 months ago | (#44571927)

The paper is up and there

Paper> [washington.edu]

Note that the range between 2 nodes (some feet) is comparable to RFID systems.

Re:The Technology is Not New (1)

Shavano (2541114) | about 8 months ago | (#44572577)

I fully agree. Yet, the concept is around since electricity was mastered by humans. Next, I might go read TFA and see how much is real ;-)

Depending on when you consider electricity having been mastered. If Tesla is your master, I guess you're right, because he contemplated everything being powered by giant transmitters.

Re:The Technology is Not New (1)

cusco (717999) | about 8 months ago | (#44569541)

Key card readers have been using this since the 1980s for access control systems. The big new thing here is that new electronics can be so low-power that they're able to use the ambient background radiation of modern civilization rather than a dedicated reader. If this works reliably it's going to be huge in the access control, alarm system, building automation, and remote sensor industries.

Re:The Technology is Not New (1)

bobbied (2522392) | about 8 months ago | (#44569825)

Actually, Key Card systems are not quite the same as what I described for the toll tags. Many of those systems actually require close coupling with the reader to get the data off them and are not really storing the energy transferred for later use. The card is magnetically coupled to the reader and the data on the card clocked out though the same link. The readers and the cards are much simpler (and thus cheaper) but is decidedly not the same thing,

Of course the principle of getting power without having to touch a device using Electromagnetic fields is decidedly not new or novel in any way. The patents on most of that technology expired nearly a hundred years ago now. Think Tesla, think Westinghouse, think transformer.

Re:The Technology is Not New (4, Informative)

adolf (21054) | about 8 months ago | (#44570139)

Actually, passive key cards do store the energy for later use.

"Later" happens to be measured in microseconds or so, but it's still later (much, much later in computer terms).

First, the antenna inside of the card is used with a rectifier and a capacitor to make DC voltage to power an IC from the RF energy radiated by the card reader. Once the voltage is high enough (which cannot occur instantaneously), that IC then uses the energy stored in its capacitor to send its ID string over the same antenna that was part of a power supply a brief moment earlier.

And like anything else RF, distance is largely a function of radiated power and receiver sensitivity. Cards and readers generally only work within a few inches merely because that was one of the design parameters, not because that is the maximum attainable using the technique:

Improve the performance of the card (more capacitance combined with a beefier RF section), and/or increase the sensitivity of the reader (using a higher-gain antenna and/or lower-noise electronics), and functional operating distance is increased accordingly.

near field is induction, far field is radio (3, Informative)

raymorris (2726007) | about 8 months ago | (#44571009)

Interesting comments. You mentioned RF power functions. The main function for radio, also called far field, is that power drops with the square of distance.

  I'd like to point out card readers do not work using radio waves, not like these devices do. At distances less than about 1 wavelength, the primary effect is what's called "near field", commonly referred to as induction. This is the same way transformers work. Near field power drops at distance to the SIXTH power. That means that while it's very strong within a few millimeters, it basically dissapears within a few centimeters or meters.

The new devices are using RADIO energy from arbitrary far away sources. Card readers use near field induction, a completely different mechanism.

Re:near field is induction, far field is radio (1, Informative)

adolf (21054) | about 8 months ago | (#44571113)

I'd like to point out that the frequencies involved are most certainly RF.

Inductive coupling is a cute efficiency trick, but it's not necessary -- even in existing systems.

(And if inductive coupling were really the primary means of communication, we'd be calling the radiating elements "inductors" instead of "antennas." I mean: It's not as if these two concepts are not well-understood, even if they are often related.)

Meanwhile, I do not understand your millimeter boojigity as it relates to common practice: If it were only useful within a few millimeters, I would be unable to use my access card from a distance of a few inches (as I routinely do). If the signal were to basically disappear after a few centimeters, then using it at a few inches would be impossible.

And at this point, I'd also like to introduce a car anecdote. As an anti-theft function, my 1995 BMW will not start and run without a properly-coded key in close proximity to the ignition switch. And by close proximity, I mean: There is literally a coil of copper wrapped around the lock cylinder, and it can't "see" the key unless it is within a couple of inches.

But one day, I decided I wanted to add a remote start function to my BMW. I dug into it pretty deep and spent two cold nights standing on my head in the driver's side footwell verifying and splicing wires. And since it requires a key to start and run, I made the two trips to the nearest dealer required to secure a new key (two hours drive time, each trip), and spent $30 on a new key.

This new key was then installed inside of an aftermarket box made for the job. It consisted of physical bits to hold the new key, a coil, a relay, some connectors, and a small PCB to tie it together. Nothing else. The box's purpose was to contain a key, and be hidden in the depths of the dashboard, with the coil to be switched into the RF circuit by the relay which was itself activated by the aftermarket remote start system.

I discovered that while the stock coil would only work within very close proximity, the aftermarket coil would work from a few meters away. Intrigued, I tested it: Factory ignition-switch coil was useable for couple of inches, aftermarket relay-switched coil was about 3 meters.

In either case, the same OEM keys were used. Results were similar no matter if the new-and-shiny key, or the old-and-oxidized key were used.

So either your general theory about inductive coupling is hogwash (likely), or the particular antennas (which may resemble and also function as coils) can dramatically influence the range at which such an RF identification system can operate.

1 wavelength = centimetres to meters (2)

raymorris (2726007) | about 8 months ago | (#44572567)

As I mentioned, near field predominates up to about one wavelength, and basically goes away at around four X wavelength. For reference, commercial AM radio in the US is about 1/2 meter wave, commercial FM is about 1/2 centimeter.

So if your key used a wavelength similar to AM radio, the near field would be detectable up to about two meters. In your experiment , you found that it's detectable up to about that distance. It may use a frequency slightly lower than AM radio, meaning a slightly longer wavelength.

You mentioned your key card works to a couple of inches -precisely the limit we'd expect around FM radio frequencies.

"Literally a coil of wire wrapped around the key". There's a name for a coil of wire. A coil of wire is commonly called an "inductor". They are often used for power, and to filter OUT radio interference. You may have noticed radio antennas are normally straight, even when that's inconvenient such ad on a walkie-talkie.

"It's most definitely RF". (Radio Frequency). Yes, as are IDE cables and cable TV. Neither of which use radio waves.

Re:near field is induction, far field is radio (1)

cusco (717999) | about 8 months ago | (#44573813)

You're thinking of the credit card readers, which do use near-field induction. I was talking about proximity card readers, such as are used in access control systems. The most common format, the HID Wigand standard cards, use a 125 kHz RF field to power the card, which may function from as much as five meters away. There are other formats that use other frequencies.

Re:near field is induction, far field is radio (1)

raymorris (2726007) | about 8 months ago | (#44574725)

> The most common format, the HID Wigand standard cards, use a 125 kHz RF field to power the card, which may function from as much as five meters away.

Pulling out our handy calculator, we find that the wavelength way down there at 125 Khz is 2400 meters.
That means the near field at such a low frequency is dominant to about 2400 meters away. It means a quarter wave radio antenna would be 600 meters long.
Do you think you have a 60 meter antenna in that PROXIMITY card, to pick up RADIATED signals, or o you think it's called a PROXIMITY card
because it uses PROXIMITY effects.

The near field is divided into two parts itself. The reactive (purely inductive, magnetic) near field and the radiative near field (radiated, non-wave DC magnetism).
The purely inductive portion is within wavelength / 2pi, or 0.159 * wavelength. At broadcast FM frequencies, that purely inductive portion is millimeters.
At 125 Khz, it's 0.159 * 2400 = 381.6 meters.

Sorry, at such a low frequency you're not picking up any radio waves at five meters. At 381 meters, you'd start to see a mix of an odd combination
of radiated non-wave magnetism along with the familiar inductive, magnetic effect.

At about 2400 meters the true radio part starts, the far field. That's radio wave part, wth the wave being produced by the alternating voltage applied to the antenna.
At smaller distances, less than one wavelength, the magnetism is based the DC current, it functions as an electromagnet, so there's no wave.

Re:near field is induction, far field is radio (0)

Anonymous Coward | about 8 months ago | (#44574425)

Passive backscatter RFID tranceivers are opperating in far field. The only novel in this devices I believe is the backscatter of existing (eg ambient) fields such as tv broadcast signals.

Re:The Technology is Not New (1)

gwjgwj (727408) | about 8 months ago | (#44572395)

The problem is, that the background radiation level can also fall down when all the electronics reduces the power consumption.

Re:The Technology is Not New (1)

Anonymous Coward | about 8 months ago | (#44569649)

Who said it is new technology? That is your words.

It is a new technique under the backscatter methodology for re-using existing energy sources.
It is completely different to the method used by RFID, but they both use the similar parent technique of using backscatter, that is the only relation they have.

Regardless, it will allow for some more interesting technology as the research improves. (as well as easy spying tools)

Re:The Technology is Not New (1)

kermidge (2221646) | about 8 months ago | (#44569999)

First thought that came to me was using the unique blend from my device picture of the backscatter surround and yours to create a snapshot 'fingerprint' that could be used as key and seed for a one-time pad to use for secure comms. No two people at a given time will have the same, if the resolution is fine enough.

Re:The Technology is Not New (3, Interesting)

bobbied (2522392) | about 8 months ago | (#44570035)

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:The Technology is Not New (3, Insightful)

Sockatume (732728) | about 8 months ago | (#44571667)

It matters because it's interesting and implies new applications. Why is it that every time there's a new idea presented on Slashdot, the slightest connection to existing technology makes it completely worthless?

Re:The Technology is Not New (1)

bobbied (2522392) | about 8 months ago | (#44573125)

Like I said.. This is not new technology... It's not based on anything recently "discovered" in science nor is it a measurable step forward in features.

Re:The Technology is Not New (1)

viperidaenz (2515578) | about 8 months ago | (#44570305)

But RFID tags dont transmit anything.

They modulate the load seen by the tag readers antenna by modulating the power drawn from the tag antenna by short circuiting it.

Re:The Technology is Not New (1)

tlhIngan (30335) | about 8 months ago | (#44573825)

They modulate the load seen by the tag readers antenna by modulating the power drawn from the tag antenna by short circuiting it.

It is a form of transmission, still, even though it's not actively broadcasting.

What you need ot know is that wireless power has been with us for a long time now - basically since the late 1800s. We've been putting energy in the air since then. Of course, it's what Tesla was experimenting with, except his system was trying to boost efficiency as wireless power transmission is still not very efficient.

Yes, your transmitter is putting energy in the air, and when a suitable antenna picks it up, a small voltage is generated (microvolts generally - a good receiver can generally pick up around 5uV or so).

Which also means that attempts to harness the energy actually does weaken the transmission somewhat, cuing the probably apocryphal stories about people living under power lines stringing long cables to harness the "free" power, to people living near AM/FM tranmitters doing the same thing and getting caught because they leave a visible "footprint" in the field distribution (if you can pull sufficient power, you can be noticed because you do detune the transmitter antenna).

So theoretically, if these devices get popular, you can expect to get "less bars" and worse cell reception...

Re:The Technology is Not New (1)

Shavano (2541114) | about 8 months ago | (#44570489)

It's not very widely useful either. They mention getting the things to work at 6.5 miles from a television tower. That's great if you happen to be that close to a megawatt transmitter. Not so great everywhere else. Their effective (one device to another) is also very limited, because transmitter power is super low. It's limited to less than what you receive off the transmitter, which is not much. At a mile from a TV tower, you've got a few milliwatts to work with at most.

It's impressive that they got this to work at that kind of range from a tower at all. Under conditions at most people's homes, it wouldn't work without a local transmitter to light it up.

Re:The Technology is Not New (0)

Anonymous Coward | about 8 months ago | (#44571489)

Did those tags parrot a pre-programmed sequence, or did they do meaningful computation using the gathered power, and communicate with each other?
Because the mesh-networking potential here is the really interesting bit; when you can parasite enough power that you no longer need a dedicated reader, just another node at the edge of the network, and you don't have to run power to each node or set up transponders, you can actually fulfill some of the promises of ubiquitous mesh networking (e.g. embedded crop monitoring) without the current requirements of setting up an infrastructure to support the nodes or rely on expensive and unreliable (and have to be mounted outside) solar-powered nodes.

Re:The Technology is Not New (1)

RespekMyAthorati (798091) | about 8 months ago | (#44575191)

What's new is that the UW technology does not depend on having a powered RF transmitter built into the reader. In fact, both the transmitter and the reader are both completely unpowered.

privacy? (0)

Anonymous Coward | about 8 months ago | (#44569457)

no security / monitoring / privacy concerns here

Nice (1)

jonyen (2633919) | about 8 months ago | (#44569471)

Pretty nifty--this could be potentially useful in backpacking trips where you'll be without power for a while, but then there's not going to be much radio signals out there either... So probably this kind of technology would benefit urban road warriors the most. Would be cool to see this make its way into consumer gadgets, but it doesn't appear that this would be ideal for voice calls though.

Well this is a good start... (1)

Travis Repine (2861521) | about 8 months ago | (#44569501)

Especially when you consider that it doesn't need to use existing power and relies on signals around us to give us power but not juice to power those signals. Pretty damned sweet if you ask me!

Range? (1)

jklovanc (1603149) | about 8 months ago | (#44569521)

The researchers tested the ambient backscatter technique with credit card-sized prototype devices placed within several feet of each other.

Not very far.

Re:Range? (1)

Anonymous Coward | about 8 months ago | (#44569551)

Not very far.

Not likely to get much father either. This is a near field communication trick. The examples in the video have the antennas closer than the antenna length. Just use a wire instead.

Re:Range? (1)

adolf (21054) | about 8 months ago | (#44570187)

Not likely to get much father either. This is a near field communication trick. The examples in the video have the antennas closer than the antenna length. Just use a wire instead.

This. Someone please mod AC parent up for this glaringly-obvious observation.

Re:Range? (1)

Namarrgon (105036) | about 8 months ago | (#44571299)

From the paper:

For a target BER [bit error rate] of 10^-2, the receiver can receive at a rate of 1 kbps at distances up to 2.5 feet in outdoor locations and up to 1.5 feet in indoor locations.

Range is improved a little with slower bit-rates, or in the presence of stronger ambient RF.

Availability (1)

Agent ME (1411269) | about 8 months ago | (#44569523)

Does this mean that if you live in the middle of nowhere, your TV remote will mysteriously fail to work? Great.

it is new... in a way. (2, Informative)

jhfry (829244) | about 8 months ago | (#44569527)

Sure backscatter has been done... But it always used known frequencies as the signal source. This will pick up any ambient ref noise and use it to generate a new signal.

Essentially, you could embed a transmitter anywhere without concern for a power source (assuming there are other transmitters around).

Re:it is new... in a way. (4, Interesting)

ls671 (1122017) | about 8 months ago | (#44569687)

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:it is new... in a way. (1)

Anonymous Coward | about 8 months ago | (#44570151)

Nope. Inductive coupling occurs at low frequencies and short distances, neither of which is the case for TV or cellular signals.

Re:it is new... in a way. (2)

ls671 (1122017) | about 8 months ago | (#44570315)

It doesn't matter. The only difference is how the tv or radio station will notice signal weakening compared to the electricity company.

Electricity company:
Voltage will go down as amperage will go up.

For TV stations they transmit at a constant power rate so they will notice signal weakening by taking test at various distance from the transmitting antenna.

The energy one device "steal" is not available for the device behind it so there is a limit to how many device a transmitter can sustain.

Proof? If what I say isn't true then, congratulations! You have just defined an infinite energy supply. Set up a transmitter with a number of devices large enough to produce more energy then it took to power the transmitter.

http://www.edn.com/design/sensors/4342455/Understanding-electromagnetic-fields-and-antenna-radiation-takes-almost-no-math [edn.com]

Re:it is new... in a way. (2)

CaptQuark (2706165) | about 8 months ago | (#44571671)

You still don't understand RP propagation. Having an antenna receive a signal does not diminish the strength of the signal behind it any more than a metal light pole diminishes it. Both will cause a slight disturbance in the transmitted signal, but the rest of the signal will still continue past it. You can't calculate how many devices are receiving an RF signal by measuring field strength at a fixed distance.

Think of throwing a pebble into a pond and watching the waves travel outward. If you put a stick in the water, it will disrupt the wave slightly, but the rest of the wave continues radiating outward. The small amount of energy that the stick receives is so miniscule compared to the total circular wave, it can be thought of as zero. (Well, if the stick is 10 feet away from the source it intersects a circle more than 60 feet in circumference. A one-inch stick would disrupt 1/750th of the circle. 20 feet away? 1/1500th of the total circumference.) Plus, RF propagates in three dimensions, not just two.

And your proof? You suggest putting enough barriers around the transmitting antenna to capture all the radiated energy to gain back more than you started with. First, you would never effectively capture it all, unless you built a Fariday Cage around the transmitter. Plus you ignore the power loss in converting the RF power back to electricity. You can't prove your point by suggesting if you are wrong we would have perpetual energy.

~~

Re:it is new... in a way. (1)

ls671 (1122017) | about 8 months ago | (#44572027)

Congratulations! You have invented perpetual energy!

More seriously, read this link if the first link I posted is too hard for you to understand:
http://amasci.com/tesla/tesceive.html [amasci.com]

'Energy-sucking' Radio Antennas:
http://amasci.com/tesla/tesceive.html#dnn [amasci.com]

Re:it is new... in a way. (1)

RespekMyAthorati (798091) | about 8 months ago | (#44575299)

No, you have invented an ordinary radio receiver, where "radio receiver" is basically any conductor. Of course each receiver reduces the energy available to other receivers, but to a negligible extent.

Re:it is new... in a way. (1)

PhilHibbs (4537) | about 8 months ago | (#44572359)

congratulations! You have just defined an infinite energy supply. Set up a transmitter with a number of devices large enough to produce more energy then it took to power the transmitter.

That would involve more devices than would fit into a spherical shell at any given distance from the transmitter. So yes, there is an upper limit before you start to hit serious signal degradation, but when that upper limit is billions of devices per transmitter, it is not worth worrying about. That little bit of signal that my RF device used was probably going to be absorbed by the steel frame of the building next to me anyway.

Re:it is new... in a way. (1)

AmiMoJo (196126) | about 8 months ago | (#44572449)

The problem is detecting such a small device. Unless it draws a very large amount of energy it would be impossible to pick out from someone who just moved some furniture in their house.

Re:it is new... in a way. (0)

Anonymous Coward | about 8 months ago | (#44569717)

until all the transmitters are this kind, and then suddenly there's nothing for any of them to leech off

Re:it is new... in a way. (0)

Anonymous Coward | about 8 months ago | (#44570037)

I dunno, looks to me to be exactly what Nokia was building prototypes of more than four years ago...so it's decades old concepts combined into a half-decade old device being marketed as a brand new scientific breakthrough...

http://www.pcmag.com/article2/0,2817,2348517,00.asp

This is not a new idea, just ask the KGB : (2, Interesting)

Anonymous Coward | about 8 months ago | (#44569579)

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

Scientifically, fine, but not good in principal. (2, Interesting)

VortexCortex (1117377) | about 8 months ago | (#44569619)

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:Scientifically, fine, but not good in principal (4, Informative)

Anonymous Coward | about 8 months ago | (#44570161)

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?

There's degrees of reliance. For a TV remote or PAN application, not scary at all. For a mobile phone that one's life might depend on, somewhat scary.

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.

Sorry, but we have these little thing called the ISM bands, perhaps you've heard of them. (There's one at 2.4GHz, WiFi and bluetooth use it.) You're perfectly allowed to generate RF in these band. You're also allowed to generate unlicensed emissions in many other bands, subject to strict power limits that will still likely be enough (at short ranges) for these devices to work. (I agree with you, at least on a broad view, about what's wrong with the FCC and our current spectrum ownership policies, but you don't help things by overstating the restrictions....)

I'm not saying the eventual commercial implementation of this idea won't be intentionally crippled to rely on frequencies that are more tightly controlled, precisely to provide an off switch, but until/unless they are, your wholesale indictment of the tech is premature. The natural choice for this tech, outside monopolistic/control-freak pressures, is to have it use several options including one of the heavily-used ISM bands, because there's a lot of available energy in them, and (unlike, say, broadcast TV frequencies) they're used even out in the country. (Mobile phone networks are another obvious choice, with better rural penetration than TV, but there's still sufficiently remote places with almost no mobile phone signal, and people in thes places still run WiFi APs connected to their landline internet.)

Also, learn the difference between principle and principal. Botching it as you did makes you look like a moron.

Re:Scientifically, fine, but not good in principal (2)

Neil Boekend (1854906) | about 8 months ago | (#44572063)

You are allowed to generate RF at 2.4 GHz, but at a limited power. In the Netherlands you are allowed to put 20 mA into an antenna, more would require a license. In the USA this is a lot higher.
If you choose to dismantle a microwave oven and turn the magnetron radio emitter on without shielding there will probably be consequences, aside from the severe burns if you leave it on to long. And a microwave is in the 2.4 GHz band, so according to you "You're perfectly allowed to generate RF in these band."
I have no idea what intensity of noise these devices need to send their signals, but if it is above the max you can send then the power device may be illegal.

makes $73 every hour on the internet. (-1, Offtopic)

linda566 (3019817) | about 8 months ago | (#44569735)

my co-worker's step-mother makes $73 every hour on the internet. She has been out of a job for eight months but last month her pay was $17596 just working on the internet for a few hours. Read more here... http://xurl.es/i11cz [xurl.es]

liberty (0)

PopeRatzo (965947) | about 8 months ago | (#44569741)

Ubiquitous grid-free digital networking, like grid-free power, are really the holy grail.

A lot of the worst problems we face on this planet could be solved with these two technologies if they are allowed to come to fruition.

Institutional poverty, corporate/government tyranny, state-sponsored terrorism and other seemingly intractable problems might really be dealt with if we could have these two things.

Re:liberty (1)

Dcnjoe60 (682885) | about 8 months ago | (#44569943)

Ubiquitous grid-free digital networking, like grid-free power, are really the holy grail.

A lot of the worst problems we face on this planet could be solved with these two technologies if they are allowed to come to fruition.

Institutional poverty, corporate/government tyranny, state-sponsored terrorism and other seemingly intractable problems might really be dealt with if we could have these two things.

Long before there were corporations and governments, there was the strong preying on the weak. Sure these two technologies may stop the tyranny that you are concernned about, but tyranny existed before the modern forms of government and will continue after them. After all, corporations and governments are only as good or evil as the people behind them and these technologies don't do anything to change that.

Re:liberty (1)

PopeRatzo (965947) | about 8 months ago | (#44570145)

Long before there were corporations and governments, there was the strong preying on the weak. Sure these two technologies may stop the tyranny that you are concernned about, but tyranny existed before the modern forms of government and will continue after them. After all, corporations and governments are only as good or evil as the people behind them and these technologies don't do anything to change that.

You're probably right. But it's in our nature to try. And that is a wonderful thing.

We don't know who struck first, us or them... (1)

RoverDaddy (869116) | about 8 months ago | (#44570205)

... But we do know it was us that scorched the sky. At the time, they were dependent on solar power. It was believed they would be unable to survive without an energy source as abundant as the sun.

So much for that bright idea.

Lot of misleading information in the comments. (0)

Anonymous Coward | about 8 months ago | (#44570499)

These devices don't transmit anything. The modulate ambient signals by changing the reflection coefficient.

not new at all (0)

Anonymous Coward | about 8 months ago | (#44570589)

Not new, intel had a device that did this 3 of 4 years ago. Running off an FM signal

Aaaand (0, Offtopic)

The Cat (19816) | about 8 months ago | (#44570641)

It will never work already been invented you suck fuck off liberal arts is shit more STEM uppity fuck your mom my ass neckbearing is science there is no God Mythbusters said it won't work Carl Sagan wants a girlfriend cat meme fuckity fuck I am doing science the graphics suck I'm bored meh Americans deserve to starve no job because you suck it works for me Windows is better than Linux year of the desktop dick cock penis whoever invented this didn't think it through I am engineer because I won a game of Civilization once Neil Degrasse Tyson proved God doesn't exist with a racing form my ass your ass everything sucks I'm bored.

Thread over.

Illegal (0)

Anonymous Coward | about 8 months ago | (#44571865)

Energy theft from the TV stations.

Predatory Engineering in the Vulture Culture (1)

TheRealHocusLocus (2319802) | about 8 months ago | (#44572331)

The day would arrive when some one will be unable to establish or maintain a dial 911 to save lives --- merely because they are surrounded by a Virtual Tuned Faraday Cage of these parasitic signal sucking devices.

This is an idea that is so bad in principle that it is embarrassing that it has not been laughed out of the room.

It is an example of what I call predatory engineering, the phenomenon where someone's "bright idea" trumps common sense and consideration for others. Yes, there are moral threads that weave through everything.

The imperative that power for communication not be drawn off of other peoples' communication is a moral imperative. This means even drawing power off of broadcast bands is a bad idea.

Inducing some 50/60 cycle hum is OK, though the coils would have to be large. Proponents of this idea choose small wavelengths it is most practical for small devices, although those bands contain our most fragile and imporant communication.

Two thumbs down.

Re:Predatory Engineering in the Vulture Culture (1)

funky_vibes (664942) | about 8 months ago | (#44574193)

Finally, somebody finds something that TV broadcasts are useful for, and all people do is whine.

Fuck 911, we have 112. It never works anyway.

Re:Predatory Engineering in the Vulture Culture (1)

cusco (717999) | about 8 months ago | (#44574639)

Do you not understand how radio transmissions work? Apparently not. When you turn your radio on to hear the news you are not removing ANY of the signal available for anyone else who might want to listen in. If your radio stays turned off that signal is just not used. If everyone in the practical receiving area turns their radio on at the same time the transmitter doesn't have to output more power, nor do any of the receivers notice that there are other receivers using signal. Your radio receives exactly as much signal as if it were the only one tuned in at that time. The only way that these devices could interfere with other receivers would be if you made a physical wall of them in a sphere around the transmitter.

This thing needs to work off of... (0)

Anonymous Coward | about 8 months ago | (#44574959)

The background radiation of the universe. It's omnipresent and doing so would be flipping amazing.

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