Researchers Beam 230Mb/sec Wireless Internet WIth LEDs 218
MikeChino writes "A group of scientists from Germany's Fraunhofer Institute have devised a way to encode a visible-frequency wireless signal in light emitted by plain old desklamps and other light fixtures. The team was able to achieve a record-setting data download rate of 230 megabits per second, and they expect to be able to double that speed in the near future. While the regular radio-frequency Wi-Fi most of us use currently is perfectly fine, it does have its flaws — it has a limited bandwidth that confines it to a certain spectrum and if you've ever had someone leech off of your connection, you know that it also leaks through walls. LED wireless signals would theoretically have none of these downsides."
No upsides either (Score:5, Informative)
"Leaking through walls" isn't a bug, it's a feature; I don't want to wire my whole house for Ethernet just to have wireless in every room, as that defeats the purpose.
Fraunhofer juggernaut (Score:2, Informative)
http://en.wikipedia.org/wiki/Fraunhofer_Society [wikipedia.org]
(anon, copied from wiki, I just thought people should be more aware that Fraunhofer is an amazingly huge beast.
FhG owns MP3 (Score:3, Informative)
Oh, and ... (Score:4, Informative)
Those interested in this LED-based technology can check out the IEEE 802.15.7 Visible Light Communication Task Group [ieee802.org]. Members of the Fraunhofer Institute are regular contributors to the standard.
Re:Just different ones (Score:3, Informative)
With many modern remotes, you don't have to aim the remote at the device, but you can bounce it off walls and furniture and have it work great.
Tell that to my fucking Blu-Ray player. The remote for my parents' 15 year old TV worked better at wider angles.
Besides, the article mentioned Visible Spectrum. Good luck reflecting that and maintaining usefulness.
Re:Oh, and ... (Score:3, Informative)
In that case, it's bound to be cool. And by cool, I mean patent encumbered.
BTW, {nitpick} it's not "the" Fraunhofer Institute, it's "Fraunhofer Society [fraunhofer.de]," within which are various institutes [fraunhofer.de]. Probably the most famous is on the internet is the Fraunhofer Institute for Integrated Circuits (Fraunhofer IIS) in Erlangen, whence came the mp3 standard. But the one responsible for Visible Light Communication is Fraunhofer HHI [fraunhofer.de] in Berlin. {/nitpick}
No problem (Score:1, Informative)
The modulation frequency is much too high to be perceptible. If an encoding is used which has a constant light/dark ratio, the light will look perfectly steady. (LEDs are often driven with an unfiltered pulse width modulation signal in the kHz range and that doesn't cause problems with epileptics. This technique uses hundreds of MHz.)
I remember a DIY LED netsystem.... (Score:5, Informative)
Re:Oh Great (Score:3, Informative)
That's actually been a documented problem in some devices with status LEDs, which inadvertently leaked information [cnet.com] due to being tied directly to the (serial) data line, rather than a low-pass filtered version of it.
Re:No upsides either (Score:3, Informative)
You're forgetting that what you see is not the plasma (it emits mainly short-wavelength UV), but the phosphor coating (which is excited by the UV & emits visible light). The phosphor coating is specifically chosen to be (relatively) slow, in order to filter out the 50/60Hz flicker.
In theory, you could use a faster phosphor and modulate the light output - but then you run into an issue with the half-life of the excited electron state. Basically, the electrons take a finite amount of time to drop from their excited state to their non-excited state (in the process releasing their energy as UV). This limits the maximum modulation frequency to somewhere ~5KHz. Again, this could probably be increased somewhat by the choice of plasma donor material, but there is a limit (e.g. I'd expect x-rays would be hard to contain ;-). And, since multi-bit encoding schemes like phase modulation are likely prove be tricky as best (aka 'improbable, if not impossible'), you're basically stuck with a maximum data transmission rate of half the modulation frequency - around 2.5Kbps.
May as well stick to Bluetooth...