Forgot your password?
typodupeerror
Intel Communications Networking Technology

Intel Encodes Data In Flickering LEDs (and Shows Off Other Bright Ideas) 65

Posted by timothy
from the hidden-in-the-noise dept.
darien writes "On the day before the Intel Developer Forum opens in San Francisco, Intel has been showing off some of its current research projects, including a system for encoding data in apparently steady light sources, a Kinect-based projected 'touch interface' that works on any surface and an ambitious signage concept that could revolutionise your weekly shop." My favorite thing about light-based networking is that it's the basis of a certain strain of (all too plausible, all too often) conspiracy theory. ("The modern LED 'eco-friendly' light bulb is also a two-way communications device." — easy to believe, since many of them can be. )
This discussion has been archived. No new comments can be posted.

Intel Encodes Data In Flickering LEDs (and Shows Off Other Bright Ideas)

Comments Filter:
  • by MindPrison (864299) on Tuesday September 11, 2012 @12:44PM (#41301491) Journal

    Imagine being an light dependent alien, coming to visit you with all your blinking communications leds all over your house.

    Wow...what a mind job that would be.

    • Can I buy some pot from you?
      • Can I buy some pot from you?

        No, but I've heard that the pothead next door have some excellent pottery for sale.

        I - however, like a million Chinese on eBay - can sell you any LED you'd ever want. Red led, white, pink, yellow, orange, blue, IR, UV, green...and did I mention we have a special on FLASHING leds? Just check out isle 4, and you'll find some reels of SMD RGB leds right there, the rainbow flash leds are on isle 8 on floor 7, area 7124...it's easy, just follow the white trail all the way, then take the transit system to HK dept

  • by msauve (701917) on Tuesday September 11, 2012 @12:45PM (#41301519)
    IRDA [wikipedia.org], but without the "I".
    • Re: (Score:2, Funny)

      by Anonymous Coward

      *ROOOOOOXANE*

    • In that vein, the demo unit appears to be using red LEDs. I wonder if the phosphor-blobbed white ones are severely bandwidth constrained by the residual glow from the phosphor layer, or if the ghastly framerates of the cheapy cameras that intel proposes to use as receivers for these signals is the limiting factor?

      • by Foobar_ (120869)

        The rise and fall times of the phosphor in a white LED is several milliseconds which severely constrains the bandwidth of a white LED. The red LEDs featured here have no phosphor, with rise/fall times of 1-2 nanoseconds and correspondingly high bandwidth (hundreds of MHz).

      • by amorsen (7485)

        The easy way around that is probably to use a phosphor and filter which lowers the emission of red light, and then have a separate red diode for the data transmission. The downside is that it will make some reds look odd. With infinite resources the transmission and the filter could be made almost arbitrarily narrow-band, and that would solve the problem.

        You can probably get away with only modulating 1/10th of the light though, at some cost to bandwidth. The other 9/10th will then be provided by the usual p

      • White LEDs are blue LEDs with a phosphor that converts part of the blue light to yellow light. There's still a large portion of the output that is unconverted blue. Therefore, all you need to do is have a blue filter in front of your receiver, since that portion of the output spectrum will not be bandwidth-constrained by the phosphor.

    • I did that circa 1985 when a project did not have a suitable debug port, but had a single LED on the panel.
      • by Chris Burke (6130)

        I did it as a college electronics lab project as an unnecessary but neat part of building an FM radio, linking the radio and the speakers via the LED.

        Which I also remember because the TA's demonstration breadboard played the music for about three seconds before one of the caps exploded. Good times.

        • by nospam007 (722110) *

          "I did it as a college electronics lab project as an unnecessary but neat part of building an FM radio, linking the radio and the speakers via the LED."

          That's what I thought as well.

          The Timex Datalink watch from 20 years ago did it also.
          What's funny, it didn't work with LED screens though.:-)

          http://en.wikipedia.org/wiki/Timex_Datalink [wikipedia.org]

          • by mirix (1649853)

            This has been done since the 1920's and the dawn of talking film.

            Back then the signal was from a light passing through film, and the receiver was a special vacuum tube - a "phototube". The plate is coated with.. Caesium and something else, that makes a minute voltage when struck with light. Then you boost it with a few more tubes and play it on a speaker - synchronized sound.

            'modern' photomultipliers are a boosted version of this (many internal stages of gain, so much so that a single photon will fire it).

    • by RMingin (985478)

      "Red Data Association"?

      I think you meant without the "ir".

    • by evilviper (135110)

      Yep, I miss IRDA. More than a decade ago, I was typing up full documents with embedded charts and hand-drawn graphics on my Psion5MX, and printing them out directly to a nearby HP Laserjet4, with IRDA, using PCL.

      I'm still diasappointed it went away. Just think, if every computer device you bought had an IRDA port on all 4 sides, all our devices would just ad-hoc connect to every other device in the same room, with no setup. Plug in a new set or speakers, and sound from your computer, or TV, or whatever,

      • by baffled (1034554)

        Even as networked printers get more powerful, they often don't support a common interoperable protocol like Postscript or PCL.

        Doesn't this statement violate mutual exclusivity?

      • What's interoperable about PCL?

        • by evilviper (135110)

          What's interoperable about PCL?

          It's long been the defacto industry standard, as the poor-man's Postscript. This is mainly because HP has thrown all its weight behind it, and almost ALL their laser printers (and most other high-end printers) since the beginning of time fully support the latest version of PCL. It doesn't hurt that it's also fully and freely documented from day-1, rather than kept secret, as many other printer languagues are.

          Like, say, VT100, there's absolutely no shortage of printers from o

    • by fufufang (2603203)

      IRDA [wikipedia.org], but without the "IR".

      fixed that for you.

  • Grandad Remembers (Score:2, Informative)

    by Anonymous Coward

    Back in the old days(tm), people claimed to be able to intercept your communications from outside the building by simply having a view of your modem TX RX lights. That was in the days of the 1200 baud modem. Nothing has changed. There are still those that claim the same thing about your high-speed cable modem.

    • Except that the modem light thing was successfully recreated in the lab (so long as the TX and RX LEDs were driven by the raw signals). So that's at least possible. As far as I know, the lights on the cable modem are driven by the CPU and not the raw signal, so that wouldn't work.

    • by fuzzyfuzzyfungus (1223518) on Tuesday September 11, 2012 @12:58PM (#41301713) Journal

      It was demonstrated [rootsecure.net] on low speed modems, some of which directly tied the blinkenlights to the serial traffic(including, if memory serves, an embarassing case where some model of fancy 'encrypted' modem tied the blinkenlights to the serial traffic before the encryption stage...); but the author concluded that status indicator lights on higher speed stuff were(either in response to the possibility of attack, or just because humans can't distinguish between ultrafast blinking and 'on', which would make excessively fast blinks useless as indicators) not usefully coupled to the data channel for anything more than vague inference about traffic volume...

      • by geekoid (135745)

        which would make excessively fast blinks useless as indicators for humans to read.
        You could probably build something to read them. Assuming the LED's emitting the data have a fast enough rising and falling time.

        • which would make excessively fast blinks useless as indicators for humans to read.
          You could probably build something to read them. Assuming the LED's emitting the data have a fast enough rising and falling time.

          That's basically how all optical networking not classy enough to afford laser diodes works(TOSLINK is probably the biggest example, wouldn't surprise me if somebody sold cheap-n-nasty GBICs that worked the same way at some point; but laser diodes have gotten pretty cheap...) However, since the indicator lights are intended for humans, apparently the chips driving higher speed interfaces(10mb ethernet and up) deliberately lengthen the on an off cycles(coincidentially cratering the bandwidth of the channel) i

  • Wha... encoding digital data at a rate faster than the flicker response of the human eye? Is that even legal? OMG what a breakthrough. Next thing you know, someone will figure out how to encode stereo information in a high-frequency side-band to the mono signal.

  • encoding data in apparently steady light sources

    This is the "new" part. Not hard, but new. Usually you design a modulation method to minimize total power, usually you don't care about DC balance or constant power output unless there's something weird going on with the AGC ckt of the receiver.

    The new part isn't so much reinventing something like manchester encoding, but considering its constant long term average power the primary feature.

    I would think simple FSK would be reasonably constant power as long as LED device capacitance or lead inductance isn'

    • So it's just manchester code with a significant DC bias.

      • by vlm (69642)

        Yeah thats my guess, or in true RF tradition where everything has a million other ways to look at it, you could call it AM with a low modulation index, sorta.

  • by Anonymous Coward

    I swear, they write the summaries in a deliberate attempt to induce nerd rage.

    LEDs on some devices leak data. This is not a conspiracy theory. There have been proof of concept attacks staged against real, commercially built devices that are in production. http://news.cnet.com/2100-1001-854946.html

    Also, the idea of using visible light to transmit data is not new. It's just not really useful for anything, compared to the other available methods.

    • by lengau (817416)
      Some hospitals use it in certain rooms that are shielded from wifi. I believe MRI rooms are one of these, but I'm not sure.
  • by malakai (136531) on Tuesday September 11, 2012 @01:06PM (#41301847) Journal

    I read the full article, I have to say, I was a bit disappointed. Nothing really of interest. The LED encoding has been done, before, and better. The "Display without Borders" has also been done, before, and much better. And the digital signage was a gimmick. Even as a prototype, it's silly. Yes, you took 18 androids, put them in cases, and glued them to a display rack. Presto, digital signage. Please....

    I find it more interesting to read up on the research.microsoft.com [microsoft.com] projects, or MIT Media lab.

    • Right.

      Pricer [pricer.com] already has 80 million shelf price label units installed. The big issues there involve cost and battery life. Display devices that draw no power when static have advantages, but most of those have a grey-on-grey look, which retailers don't like.

      Sending data through lamps at 15Hz hardly seems worth the trouble. It's also likely to be annoying. Humans can see 15Hz flicker. If the amplitude is so low that humans can't see it, ambient light will interfere with reception. They can't increase

    • by anubi (640541)
      Far as I am concerned, prior art.

      Geez, encoding audio on a LED has been standard science fair fare since LED's came out.

      About 40 years ago, I had even proposed to Chevron about having the new LED displays on our digital panel meters flash their reading to mimic a UPC code so a supermarket barcode inventory scanner gun would be able to read the meter from a distance, This was in the 70's. I had a lot of meters in remote areas which needed to be read and logged. I wanted to make things easier for
  • Traffic lights (Score:4, Interesting)

    by ShanghaiBill (739463) on Tuesday September 11, 2012 @01:14PM (#41301985)

    Since most traffic lights now use LEDs, this flicker-comm technology might be a good way to send info to intelligent cars about the traffic light timing, traffic conditions on the road ahead, etc.
     

  • by hawguy (1600213)

    a system for encoding data in apparently steady light sources

    You mean Intel has finally invented IrDA (but with visible light - VDA?)? I can't wait for that technology to trickle down to laptops, I bet I can use it to sync my computer with my Palm Pilot.

  • "The modern LED 'eco-friendly' light bulb is also a two-way communications device."

    At least it's a progress over incandescent lamps, actually heaters which happen to emit a little light.

  • High powered LED flashlights of the Luxeon [rapidonline.com], Fenix and Inforce (among others) families use timer circuits to oscillate between multiple beam elements to produce high efficiency and very bright emitters, that are capable of draining every erg from the battery.

    source: I use tactical equipment. Efficiency and ruggedness is key. Keep your 5D Maglite.

    The linked device is the bare LED, if you buy from that site you'll require a driver IC as well, otherwise a direct connection to a power source will cause momentary

    • by dr2chase (653338)

      i was unaware that over-current to a power LED causes lasing. Can you provide some sort of a reference for this? (I don't need to know that over-current causes LED burnout, since I have once or twice made that mistake.)

      • by smaddox (928261)

        In order for an LED to lase, not only would it have to be placed inside of an oscillator, but the optical mode overlap (with the gain region) would have to be greatly improved. Efficient laser designs are considerably different from efficient LED designs. However, modern LED's do make use of stimulated emission to boost efficiency.

        I'm not sure what the GP was referring to, though.

        • Luxeon Star LEDs are Class III laser devices. Each *element* in the typical Star LED outputs 450mW, and the more powerful emitters have four or even nine elements (which would make them Class IV lasers but for the fact that they are separately clocked emitters, hence are classed as Class III). Absent a DC thermally controlled DC source of anything between 3.8-4.2V, a regulator and timer IC is required for each element to bring the supply voltage down to a safe level and to prevent a full-on lase by pulsing

      • it's not overcurrent that causes lasing (since you could connect a suitably voltage-rated LED to an arcwelder and it would only draw the current it needs), it's overvoltage. High power LEDS such as the aforementioned have a narrow voltage range; the attached electronics are also regulators.

        To make *any* LED lase, you need a linearly adjustable bench power supply. The point of lasing is usually about 0.1V below the burnout voltage.

        • by dr2chase (653338)

          A reference describing this phenomenon, formerly unknown to me, would be awesome.

          You also need some sort of current/temperature regulation, because the forward voltage varies (drops) with temperature. This is documented in most of the LED data sheets (including the one for the Luxeon LEDs). 0.1 V below burnout at 25C is almost certainly above burnout at 100C, which the LED junction will rapidly reach (and pass) without aggressive cooling or current regulation.

  • This is nothing new at all. It's actually why some super-security-sensitive workplaces have strict control over even the keyboards. A keyboard modification can be made so that the scroll-lock/caps-lock/whatever-LED light actually blinks out a code for every key press. Then, any detector anywhere in the room can detect the frequency and record the keypresses, which can effectively compromise many such systems. And to the human eye, the LED blinking is too fast to detect, so it just looks like it's on.
  • by tgd (2822) on Tuesday September 11, 2012 @01:43PM (#41302439)

    You mean, like virtually every grocery store in the US has been doing for ten years now?

    (That's how those little digital price tags on shelves get programmed -- the lights flicker the codes down to them all day long, and slowly update the tags.)

    • I've been all over the US over the past ten years, and I haven't seen a single "digital price tag". Not to mention, you can't make fluorescents flicker in quite the manner you can LED's.

      • Yes, but old ones flicker all on their own in a whole variety of migraine- and seizure-inducing ways. Typically the "ballast" is blamed, but now I know to blame the CIA :-)
  • Here is what LVX is offering: http://www.youtube.com/watch?v=m58f-XkhOjo [youtube.com]

    I don't know why Intel is getting this attention. Why not give it to LVX? Also this technology is not all that sophisticated.

  • by Jeng (926980) on Tuesday September 11, 2012 @02:10PM (#41302899)

    http://www.imdb.com/title/tt0083530/quotes [imdb.com]

    Oh, cut the bleeding heart crap, will ya? We've all got our switches, lights, and knobs to deal with, Striker. I mean, down here there are literally hundreds and thousands of blinking, beeping, and flashing lights, blinking and beeping and flashing - they're *flashing* and they're *beeping*. I can't stand it anymore! They're *blinking* and *beeping* and *flashing*! Why doesn't somebody pull the plug!

    Went to find a video clip of this and well it's been taken down so the quotes will have to do.

  • And without significant success: IrDA. The culprits were the inverse square law, multipath and capacitance. It's hard to detect a flickering LED in the mass of light we typically use to avoid running ourselves into doorframes. A light source focussed and concentrated on a detector works well, a detector scanning a large angle, not so well. Walls reflect light and pulses equally well, and the further you are from the light source, the harder it will be to pick out the right signal in all the noise. Lastly, t
    • by jrumney (197329)

      And without significant success

      I don't know about that. Consumer IR remotes are fairly successful (though not really steady light, due to the low frequencies involved).

  • An LED that flickers with a high-frequency signal and looks like it's always on?

    You mean like pretty much every optical SPDIF interface on the planet?

Our business in life is not to succeed but to continue to fail in high spirits. -- Robert Louis Stevenson

Working...