Light bulbs inspire boffins to find fast data transfer trick Switch a lightbulb on and off fast enough, and you can transmit data without giving everyone in the room a headache. So say boffins from Germany's Fraunhofer Institute who have managed to get data-transfer rates of up to 230Mb/s out of a flashing light, in a paper to be published by the Optical Society of America. Regular …
It's hardly news that data can be transmitted with modulated light. Even the idea of broadcasting data by modulating illumination is not new; I read about that a year or so ago. What's the advantage, though? Do they hope to achieve a significantly greater data rate than Wi-Fi and its successors?
When I was in school maaaaaanny years ago (70's) we had a parabolic reflector and a torch bulb, with the torch bulb essentially wired across the speaker terminals of an amplifier, as a transmitter. A few feet away we had a photocell, parabolic reflector and another amp connected to a speaker. Lo and behold, music was transmitted as a demo for parents evening. Hardly rocket science, although 40 years later we are doing it digitally rather than analogue and a bit faster with lamps that go on and off quicker than a filament.
> you can transmit data without giving everyone in the room a headache.
what about photo sensitive epileptics?
i we had all this working years ago when we beamed from pda to pda with ir. so the speed is super fast.
much preferred ir over bt/email/im for sharing info. fast simple and reliable. now to transfer 2-3k of text can take 5-10 minutes using bluetooth as you both turn on bt and search for the others device. using data costs unless you can find free wifi.
mumble mumble get off my lawn...
Such an amazing leap of logic there.
Now if only we could find some way of transferring the switched light over larger distances, possibly over some form of fibre? It'd have to be named something to do with sight... 'visual fibre'? 'luminosity fibre'? Oh, how about 'optical fibre'?, or shortened to 'fibre optics'.
Give them a forking medal.
So by pulsing an LED at high speed, you could get 100Mbit+ data rates? Wow, that's great. Hey, how about taking advantage of a laser's ability to pulse really quickly to get it even faster?! Even better, if you could put it through an optical fibre you wouldn't even need line of sight!
Wait, isn't that Ethernet over fibre? Like we've had for years?
that would be the same trick proposed by the universities of Boston <http://smartlighting.bu.edu/> & Pennsylvania paper at http://smartlighting.bu.edu/research/May808_slides_Little_FSO_Commun.pdf
could replace ALL streetlights in world with active LED's - save trillions in CO2 , dollars etc and have a nice comms channel that's 'better than wifi' - bit noisy during daylight due to the wideband noise source that is occasionally seen in summer.
It's a shame you've not posted any more details. As a technology, pulsing LEDs rapidly to communicate data is clearly nothing new, although the application of using domestic lighting as the source most certainly is. Reading between the lines, with the bit about eliminating everything from the spectrum except blue, I assume you're meaning filtering the receiver. This makes sense if using 'white' LEDs, which are actually a blue LED with an integral yellow phosphor. We could reasonably assume that the phosphor is "slow"; therefore by filtering out "all but the blue" (i.e. the phosphor emission) the receiver will just see the direct blue LED light and modulation and achieve hence maximum data rate.
What was the uplink channel?
...advertising - as always.
With the right firmware, which I am sure that Apple has already patented, all it would take is for you to inadvertantly expose your ipod touch / iphone in a public place (shopping mall for example) and it'll light up like a christmas tree with context-sensitive, location-aware offers (James blunt CD's 99p!! - just take three paces forward and turn left for your local HMV)
Alright this could be possible already, but GPS / wifi / bt receivers all drain batteries - a simple diode detector would be be far more efficient, I think
Nothing, NOTHING is funded or researched without the express long term goal of relieving us of the burden of having money.
Sorry, cynical mood today.
PS, for the photosensitive epileptics amongst you, light flashing at several hundred MHz wouldn't affect you in the slightest, most people affectedare only sensitive to around 25 Hz.
An optical broadcast system with a very cheap reciever on existing devices - as long as they are not in your pocket - they just need a way to sell it to you.
How about doctor's surgeries, beeping your cell phone when it is your turn? Railway stations flooding the space with departure data? You could set your gadget up to only recieve your train/route stuff. Take an Ipod to the theatre for subtitles or translations? Simultaneous subtitles for deaf schoolchildren?
All confined to one space/room. Sell it to us like that, and /then/ sell the adverts, and it might catch on, and actually do some good as well as being more marketing noise.
I suspect that the reason this is being researched is not to replace fiber/lasers, though the transmitters based on regular non-lasing LEDs are probably much cheaper. The idea is probably to be able to illuminate and transmit data (one way) at the same time.
And for all of the comparisons to an IR remote - this does probably ~ 7 orders of magnitude faster data transfer, which seems to me to constitute a rather significant difference.
I for one think that this is a useful line of research...
LED lighting is a growing market for reasons of efficiency, lifetime and [pass my vomit bucket] total cost of ownership. It is approaching the point where it will be replacing fluorescent technologies if it is not already doing so.
High power LEDs actually produce a lot of their output up at the 'blue/violent range of the spectrum and use phosphors in the packaging to recover that light down to the visible spectrum for a 'whiter' light.
LED lighting uses, or is capable of using, low voltage distribution ideally current fed which would be 'ideal' for supposition of a data signal on the same wires.
So now you have your lighting, which you needed anyway, and your cabling, which you needed anyway, and have added a data transmission system to it.... Which you would have been providing via some other means.
The LEDs might be 'fast' for modulation purposes but the phosphors are slow which is going to be the thing that messes with or smears your data rates. Fortunately the phosphors are not 100% efficient.....
"By eliminating all but the blue light from the LED's spectrum."
Might suggest that your LED light is no longer a light in the sense of the human perception of illuminatory loveliness.
However, if
"By eliminating all but the blue light from the LED's spectrum."
Becomes...
"By eliminating all but the blue light from the LED's spectrum at the detector."
That problem appears to be solved.
... a fun project I built a few decades ago, which involved a car headlight used for transmission of speech over considerable distances. One would think that such a method would be thwarted by the thermal inertia of the bulb's filament, but amazingly, it worked. The trick was, to use a very shallow modulation...
have to consider this- it is (according to the description) based on light bulbs. So in The House Of The Future you could have HD television broadcast around your house using just the lightbulbs- meaning a lowered materials and manpower cost for cabling. Assuming a 2-way link is possible, you could have a Wireless Network which could be secured by closing a window.
From a home automation point of view you could use your lights as a beacon declaring which room it is and providing a fixed reference point for home droids.
Streetlights could work as DGPS beacons- meaning an end to inaccurate or utterly blocked satellite tracking in cities and much more accurate tracking of which side of the road your car's on. Shop and restaurant signs could give information about prices or today's specials.
To me, this looks like a pretty promising bit of tech.
there are several environment in which this could be utilised.
eg open plan offices, the overhead lights can deliver the data to the end stations - very handy for specific types of traffic eg multicast. (the PCs would have a receiver and transmitter on top of monitor screen, the lights overhead would also need receivers.
this negates the issues of floor boxes or pillars - neither of which end up in the right place.
and unlike WiFi, its very directional...an open plan could easily be seperated into eg 8 zones that dont hear each others broadcasts
second place would be eg streetlighting - data can be fed/received from lights to either vehicles as they pass by - eg buses, municipal vehicles (eg street cleaners/refuse), or housing - a send/receive home router could be located under the eaves of the building.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
