Slashdot Mirror
1Gbps Wireless Network Made With Red and Green Laser Pointers
MrSeb writes "Back in the olden days, when WiFi and Bluetooth were just a glimmer in the eye of IEEE, another short-range wireless communications technology ruled supreme: Infrared Data Association, or IrDA for short. IrDA was awful; early versions were only capable of kilobit-per-second speeds, and only over a distance of a few feet. Trying to get my laptop and mobile phone to link up via IrDA was, to date, one of the worst tech experiences I've ever had. There's a lot to be said for light-based communications, though. For a start, visible (and invisible) light has a frequency of between 400 and 800THz (800 and 375nm), which is unlicensed spectrum worldwide. Second, in cases where you really don't want radio interference, such as hospitals, airplanes, and other sensitive environments, visible light communication (VLC), or free-space optical communication, is really rather desirable. Now researchers at the National Taipei University of Technology in Taiwan have transmitted data using lasers — not high-powered, laboratory-dwelling lasers; handheld, AAA-battery laser pointers. A red and green laser pointer were used, each transmitting a stream of data at 500Mbps, which is then multiplexed at the receiver for a grand total of 1Gbps."
I thought IrDA was a famous Starcraft player...
This is old hat:
http://www.airlinx.com/products.cfm/product/19-0-0.htm
It's stuff you can just go buy in a shop, we've used it here for around 15 years to connect across a street to the other office. We have a laser interlink.
Now I have another thing to implement for Bring Your Own Device...
This does make me wonder, however, if we could see fiber optic gbics that don't cost thousands of dollars each if the technology that makes this free-air communication possible can be adapted to fiber optic applications.
Do not look into laser with remaining eye.
How does the Mbit/mW compare to a 802.11b/g/n pringles cantenna?
Which can achieve further distance assuming LOS?
Laser based FSO isn't exactly a new field.
1Gbps data rate with a diode laser isn't that hard to achieve even with pretty simple drivers and 1-bit amplitude modulation.
Neither is using wavelength multiplexing some revolutionary new idea.
So... huh?
It's 1 megashark per giant octopus.
Ok, the real question is... how does this apply to /.'s new BI focus? Can I use this instead of spreadsheets or specialized software to properly align my Business Intelligence with the synergies of the corporation for maximization of profitability?
Ouch, that hurt...
"The urge to save humanity is almost always a false front for the urge to rule." --H.L. Mencken
This was done years ago. I remember seeing the story, I think it was on gbppr. The problem is, these laser pointers aren't designed to be used constantly and they wear out.
Are there any radio lasers around?
That would be a MASER (microwave, not light), and they predate lasers. However, a maser holds no advantage over a regular microwave transmitter for terrestrial communications. The distance of point to point microwave links with standard radio technology is limited by the curvature of the earth, not power or beam divergence. Even with tall towers, it's very hard to obtain a line of sight path between two points on earth more than about 50 miles apart.
I am a geek attorney, but not your geek attorney unless you've already retained me. This is not legal advice.
the one thing IrDa worked great for was using my HP Jornada with my HP 2100 printer .. was also nice to use the Jornada to print on campus because while they had the pay per page on lpr prints all the printers had an exposed IR port that would just blindly print what was sent. It was also useful to use my iPaq as an A/V Remote control.
what i never did understand is why it was a standard BUT placement and usable angle was never part of the standard.. I've got a 8525 that has it.. on the damn bottom of the phone... where it is completely useless.. and i remember a lot of laptops that put it on the side of the device and had no usable angle other than head on..
it wasn't a bad spec for the time and the proposed use (a wireless serial connection) but the implementations left a good bit to be desired..
'...if only "Jumping to a Conclusion" was an event in the Olympics.'
It's only a matter of time before the MPAA/RIAA gets this outlawed because pirates could be using it to broadcast entire ripped DVDs to each other in mere seconds using sharks with frickin' multiplexin' red and green lasers attached to their heads! You laugh, but it will happen.
A proof of concept on laser pointer networking was done two years ago, if you are interested see
http://www.diva-portal.org/smash/record.jsf?searchId=4&pid=diva2:325270 - Fulltext at
http://www.diva-portal.org/smash/get/diva2:325270/FULLTEXT01
is getting the sharks to hold still.
Your comment reminded me of my old laptop and cell phone, both which had IrDA.
I never even thought about it, of course, until one day I set my cell phone down exactly line-of-sight to the laptop and both of the devices lit up and started talking to each other. The laptop even made a funny zap noise. Freaked me out.
-David
Yeah, using laser pointers is a good idea, but what do you do when the cats jump on your data?
I'm surprised the cell phone companies haven't implemented something similar on their towers to reduce backhaul. Have dozens of towers in a given area relay optically to a super node tower with amazing backhaul. Have them relay to a few others in a standard mesh network layout for redundancy. Might even reduce their spectrum need if they are using channels to talk tower to tower. May have some issues with rain I suppose though, but that could be mitigated if laser wavelengths for which water is not refractive exist. Or just use laser arrays with heavy multiplexing and parallel signal reinforcement.
For a start, visible (and invisible) light has a frequency of between 400 and 800THz (800 and 375nm), which is unlicensed spectrum worldwide.
My God! They're broadcasting my movies over an unlicensed, unregulated carrier! This MUST be stopped! This "visible" light will aid paedophiles, piracy, terrorists, drug dealers and all manner of criminality!
Time flies like an arrow. Fruit flies like a banana.
not good for 20% of males that have red/green defective colour vision, you desensitised clod...
There was an unknown error in the submission.
10Mbit, 1200-1400 meter range, GFDL-licensed open designs: https://en.wikipedia.org/wiki/RONJA
Instead of lasers they use LEDs with relatively inexpensive lenses.
A group of students at The University of Pretoria in South Africa did exactly this while I was still studying there, this was circa 2001.
A large part of their motivation was to help build a technology for high-speed networks that were not subject to the state protected telecoms monopoly.
They used almost exactly the same technology, lazer-pointers for sending streams, but I believe they used solar-cells for receivers.
I remember they boasted speeds of over 1mbs which (back then) was incredibly fast (in fact faster than the internal buffers of the P2 computers they used - so that the data actually slowed DOWN after being received) but I don't believe they ever went beyond a single point-to-point connection.
Maybe one of the students who were involved is on slashdot and can give more details ?
Unicode killed the ASCII-art *
Beam divergence is a bitch at low frequencies. EM signals don't travel in a straight line, a ray of them tends to get wider over distance. This effect is stronger at low frequencies. For space you need the highest frequencies you can get if you want to have some usable distance. Gamma lasers would be preferable, if it were possible to make those.
Or you'd need a very wide beam and thus a very large laser/maser.
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.
That made me think of blue lasers, which would have even better rates.
But, how about longer waves, such as infrared or even radio?
A typical 1.5mW near-IR laser diode can emit at 2.5Gb/s and costs only about 3 times as much as a laser pointer, so is more economical.
> visible (and invisible) light has a frequency of between 400 and 800THz (800 and 375nm), which is unlicensed spectrum worldwide.
Well, that's good.
Cadbury has attempted an interesting approach to try and license some of that spectrum.
I remember copying files from one laptop to another via the IR ports. There was an option in the BIOS (Dell) to chose between 'Normal IR' and 'Fast IR' and the latter gave something like 6Mbit I seem to remember, not sure, but it surely was fast enough to copy setups and iso's etc. Sure we were not allowed to move the laptops around in the meanwhile, but copying things was much faster over that link than using the 10Mbit network that was shared with the entire floor.
Eventually we found out about using a direct FireWire connection whenever we need to transfer large stuff and didn't want to hog the network; used to be the fastest link one could think of between 2 computers until 1Gbps Ethernet came out... In fact, I still use it [FireWire] for that very purpose from time to time as it doesn't require me to modify the Ethernet adapter settings (fixed IP etc) when I want to do poin-to-point
If there is one thing to be learned on slashdot, it has to be sarcasm.
Im reminded of my high school days- I had a laptop with irda (1998'ish) and the printer in our tech lab had irda as well. The printer had a print server attached that would queue up all the print jobs, but the irda port would take priority over anything in the queue. Our teacher had a vendetta against trees and would insist that we print everything, so about 5 minutes before class would end, everyone would start lining up at the printer. About 4 minutes before class would end, I would hit print on a 50-60 page Word doc and gloat to myself as everyone started freaking out. Yeah, i was a techno-douche.