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1Gbps Wireless Network Made With Red and Green Laser Pointers

samzenpus posted about 2 years ago | from the macgyver-network dept.

Network 157

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."

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157 comments

O RLY? (1)

Anonymous Coward | about 2 years ago | (#39875797)

> visible (and invisible) light has a frequency of between 400 and 800THz (800 and 375nm), which is unlicensed spectrum worldwide.

Well, that's good.

Re:O RLY? (2)

jamesh (87723) | about 2 years ago | (#39876753)

> 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 [theage.com.au] to try and license some of that spectrum.

Is IrDA Korean? (4, Funny)

Anonymous Coward | about 2 years ago | (#39875801)

I thought IrDA was a famous Starcraft player...

Re:Is IrDA Korean? (4, Insightful)

Anaerin (905998) | about 2 years ago | (#39875899)

I believe you're thinking of IdrA

Re:Is IrDA Korean? (2, Funny)

Anonymous Coward | about 2 years ago | (#39876549)

You must be a blast at parties.

Re:Is IrDA Korean? (0)

Anonymous Coward | about 2 years ago | (#39876705)

no, that's AriD

Not new (5, Informative)

Anonymous Coward | about 2 years ago | (#39875815)

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.

Re:Not new (1)

flyingfsck (986395) | about 2 years ago | (#39876055)

Yup. The first time I saw a laser link across a highway between two buildings was in the 1980s. So this is 30 year old technology already.

Re:Not new (4, Informative)

Midnight Thunder (17205) | about 2 years ago | (#39876885)

While the technology is old, the implementation seems to be new. Also, the form it has taken means that we are likely to see cheaper commercial solutions coming out or a whole bunch of hobbyists implementing this themselves - or both. $100 vs $4000+. I can just imagine mesh networks based on this.

If these can be coupled with solar power and are of low energy use, then I can imagine these being alternative solutions to laying cables in remote areas.

Re:Not new (5, Informative)

dark12222000 (1076451) | about 2 years ago | (#39876089)

You're missing the point. The summary clearly states that the interesting point here is that it was done with cheap 10$ laser pointers that you can buy from Amazon. Yes, this was old tech - if you were willing to shell out 15k for high end gear. The fact that it can be reproduced for a much lower price (maybe a few hundred at most by the time you get integrated units and pay for research?) and therefore more likely to see more widespread usage, is the point.

300 Euros (1)

Anonymous Coward | about 2 years ago | (#39876207)

They already use laser diodes in these things, so using a laser diode won't bring the price down. It's really nothing new here. Just somebody has decided to play with lasers.
http://www.laser2000.de/index.php?id=370844&L=1

This 600m kit is typical of short range systems, notice the prices? 300 euros.
http://www.laser2000.de/index.php?id=374687&L=1

The bigger ones, e.g. 1.5km is only 900 euros
http://www.laser2000.de/index.php?id=370040&L=1

Re:Not new (2)

julesh (229690) | about 2 years ago | (#39876475)

The reason the available commercial equipment for this stuff is expensive has nothing to do with the quality of the laser, though (the site GP linked to specifies the laser in their entry level device as being a 7mW laser diode, so probably about 50% more powerful than the lasers used in the OP's article). The point is that it's expensive because the only application it's viable for is inter-building linkage, which *almost nobody wants to do*. You can't use it to replace ordinary wireless networks, because it's literally point-to-point: you have to stay stationary in a single pre-determined spot to receive a signal. The only real application is for large companies who have multiple buildings within line of sight of each other. This is a rather unusual situation. Thinking about organisations in my city, there are a couple of universities that could use it, and a hospital. Maybe a few schools. But then these guys can mostly just dig up the land between their buildings and lay cables, which will give higher capacity and more reliability (one of the universities has an issue because one of their buildings is separated from the rest by a public road... they might benefit from this).

Re:Not new (3, Insightful)

khipu (2511498) | about 2 years ago | (#39876593)

I'm pretty sure that if you got the price down to about $50, people would find a lot more uses for this, including sharing network connections with friends (in particular in rural areas), secure communications, and distributing access points. Not everybody lives in cities with otherwise excellent coverage.

Re:Not new (1)

Anonymous Coward | about 2 years ago | (#39876733)

You can think of more adhoc uses which are now impossible. Ever heard of QR codes? QR codes are basically a patch for connecting and redirecting a device to obtain information. You go to a museum and see a QR code, point your smartphone at it, that redirects you to a wikipedia page or maybe a website of the museum with information on what you are looking at. If instead you had high bandwidth optical transfer you would be able to directly upload to the device the text, images or videos you could think of. Ever been to a museum where you have hearing tour aids? Again, take out your smartphone, put it in front of the area which emits mp3 files and select your language. Now go around the museum hearing high quality mp3 file rather than the crappy/broken/dirty hardware they offer at museums. Oh, and of course, if that's HTML5 you could have the whole museum guide directly downloaded not only with hearing aid but also pictures and text references.

There is just so many uses for people being able to download stuff directly on their portable devices, especially tourism. Like, you go to a foreign country and can download from outside the police buildings guides/helps in your language for what to do if you are robbed, seek help, etc. Again, if you think of "techology X" and you can only think of "application X", you deserve to die and leave space for more creative people.

Re:Not new (1)

julesh (229690) | about 2 years ago | (#39876897)

Using a laser transmitter would require the receiver to stand in exactly the right place, only one receiver could use the system at a time, and transfers would be interrupted by accidental movements. It would be too hard to use for anyone to actually want to use it.

Either 802.11g/n or bluetooth could be used for the purposes you describe and would be much more convenient for everyone involved.

Re:Not new (1)

julesh (229690) | about 2 years ago | (#39876887)

I'm pretty sure that if you got the price down to about $50, people would find a lot more uses for this, including sharing network connections with friends (in particular in rural areas), secure communications, and distributing access points. Not everybody lives in cities with otherwise excellent coverage.

I don't think it'd be useful for those applications. Reading TFA, this device has a useful range of approximately 10m, which is somewhat limiting. Even without this limit, houses in rural areas are unlikely to have undisturbed line of site. Birds will be a problem (current commercial systems solve this by using redundancy to allow routing around birds, I believe, which makes your $50 an unrealistic target price). To make these things work properly, they really need to be on top of tall buildings to ensure nothing comes between them. Security would be difficult to guarantee because (at least theoretically) you can intercept data that's refracted out of atmospheric moisture. Sure, you'd need a very sensitive receiver, but such things are possible. Again the line-of-sight thing is going to be a problem for distributed access points. And in the end, even if they are $50, you can achieve the same thing with a $20 802.11n access point and a $20 unidrectional antenna.

Re:Not new (2)

Midnight Thunder (17205) | about 2 years ago | (#39876895)

Even at $100 it may still be cheaper than digging up the ground and laying fibre optics in certain cases. I think what would really change things is if these were easily installable by someone who isn't a specialist.

Re:Not new (1)

arth1 (260657) | about 2 years ago | (#39876951)

I'm pretty sure that if you got the price down to about $50, people would find a lot more uses for this, including sharing network connections with friends (in particular in rural areas)

People do that? I know they share wives and sisters with friends (in particular in rural areas), but bandwidth? C'mon. Pull the other one.

Re:Not new (2, Interesting)

Anonymous Coward | about 2 years ago | (#39877033)

Radio hams have been experimenting with point to point communication by light. It's been mountain-top to mountain-top so needs quite precise alignment. Also the data rates have been quite low - more voice. But the technique is quite old. We've known about modulating laser diodes for some time.

A quick search reveals this site reporting a 104 mile link using LEDs. http://www.bluehaze.com.au/modlight/

Great... Just Great... (2)

TWX (665546) | about 2 years ago | (#39875817)

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.

Re:Great... Just Great... (1)

Anonymous Coward | about 2 years ago | (#39875889)

if your short range fiber gbics cost thousands of dollars each, you're buying from the wrong vendor.
Try $50

Re:Great... Just Great... (1)

TWX (665546) | about 2 years ago | (#39876013)

if your short range fiber gbics cost thousands of dollars each, you're buying from the wrong vendor.

I had assumed an LX range with mode conditioning, and on top of that I had assumed that something that could work through a medium as imperfect as ambient air with ambient light and still achieve speeds of half a gigabit could achieve much faster speeds over the controlled conditions of cable, like say, 10gb over laser-optimized OM3... Which are currently thousands of dollars.

Re:Great... Just Great... (0)

Anonymous Coward | about 2 years ago | (#39876257)

I don't think ambient air with ambient light is a particularly imperfect medium at those speeds. Nothing in the ambient blinks that fast.

Re:Great... Just Great... (0)

Anonymous Coward | about 2 years ago | (#39876451)

Which are currently thousands of dollars.

I'm not normally one for commercial props (and I am not affiliated, but am an occasional customer) but 10G optics cost $1k these days:

https://www.fluxlight.com/

Efficiency? (2, Funny)

Anonymous Coward | about 2 years ago | (#39875847)

How does the Mbit/mW compare to a 802.11b/g/n pringles cantenna?
Which can achieve further distance assuming LOS?

Re:Efficiency? (1)

julesh (229690) | about 2 years ago | (#39876535)

802.11n uses 250mW transmit power to achieve 600Mbits = about 2.4mW/Mb
A laser pointer typically uses about 5mW, so 2 of them will be about 10 mW, for 1Gbit = about 0.01mW/Mb.

But then 802.11n is omnidirectional, whereas a laser is unidirectional, so this is really an apples to htcs comparison.

Re:Efficiency? (0)

Anonymous Coward | about 2 years ago | (#39876699)

802.11n is only omnidirectional if you use an omnidirectional antenna, it is directional if you use a directional antenna.

Re:Efficiency? (1)

c0lo (1497653) | about 2 years ago | (#39877025)

But then 802.11n is omnidirectional, whereas a laser is unidirectional, so this is really an apples to htcs comparison.

I think you're missing something from the GP post

How does the Mbit/mW compare to a 802.11b/g/n pringles cantenna?

A cantenna [wikipedia.org] is essentially a wave-guide, making the transmission highly directional.

They did not demonstrate a "network" (1, Flamebait)

HotNeedleOfInquiry (598897) | about 2 years ago | (#39875853)

They demonstrated one way data transmission over a very short distance, not a network.

Re:They did not demonstrate a "network" (0)

Anonymous Coward | about 2 years ago | (#39876087)

LOL, way to be pedantic. Seriously all they need to demo a network is more than 1 node operating like this.

captcha: picayune
wtf is that a pokeyman?

Re:They did not demonstrate a "network" (0)

million_monkeys (2480792) | about 2 years ago | (#39876189)

A picayune was a Spanish coin, worth half a real. Its name derives from the French picaillon, which is itself from the Provençal picaioun, meaning "small coin." By extension, picayune can mean "trivial" or "of little value." (from wikipedia)

Wheres the "news" part? (3, Interesting)

Anonymous Coward | about 2 years ago | (#39875865)

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?

Re:Wheres the "news" part? (2)

ProfessionalCookie (673314) | about 2 years ago | (#39876135)

Cost?

Re:Wheres the "news" part? (1)

julesh (229690) | about 2 years ago | (#39876589)

OK, you try turning this into a viable commercial product at a lower cost than the competition. The problem is, this is a niche market because these things are really hard to find a suitable application for. You'll be setting up a manufacturing base and then selling maybe 1000 units per year, so you need to offset the cost of manufacturing, support staff, sales staff, development.... hence you'll be selling each unit for $1000 or more. Probably much more, because to make it useful you'll need precision manufacturing (alignment of multiple output beams so they don't diverge over a range of... well, current commercial systems vary between about 500m and 5km, so it won't be trivial). So, no, this isn't a significantly cheaper tech. It's the same tech using similar components that cost about the same (A typical currently available commercial system will use a diode like this one [farnell.com], which might cost 3 times as much as the ones in laser pointers, but it is also capable of 5 times the bandwidth). But it's optical frequency rather than IR, so the range per unit power will be lower, it'll be more disturbed by fog, and it needs multiplexing to reach reasonable data rates, so that will mean more expensive optics at the receiving end. Put this design in a commercial system and you'll see pretty quickly that it's as expensive as existing designs, if not more so.

Re:Wheres the "news" part? (0)

Anonymous Coward | about 2 years ago | (#39876231)

they did it with a $1 red toy from a checkout stand and a $10 green.

$1 + $10 10* X * $1000

Re:Wheres the "news" part? (3, Interesting)

sveinb (305718) | about 2 years ago | (#39876643)

Well, that's what I thought until I tried. Connected a laser pointer to a signal generator and measured its light output. As the frequency increased above about 1 MHz, the modulation level decreased to a non-usable level.

I am still waiting for the day.. (1)

davydagger (2566757) | about 2 years ago | (#39875911)

I am still waiting for the day we see QAM and QPSK and its variants with lightwaves like we do now for electrical and wireless connections.

imagine 4 bits per cycle, then imagine 16 or 32 or some other power of 2. Then we can apply a sort of Frequency Division multiplexing with diffrent colored lights, so for a single strand of fiber times that by 4.

Last year there was an article about thumb sized atomic clocks with the ACCURACY to potentially make this feasaible.

Petabyte+ class single cable link anyone?

Oh, and I remember how famously obnoxious IrDa was to use. a few feet? sheeeeeet, the devices had to be virtually touching and you needed software that supported the link. Might as well use a null modem, and cary the cable. Before the age of USB sticks, readily available residential grade ethernet products, etc, but AFTER the age where the 1.44mb floppy disk was relatively useful, transfering files between computers was a royal pain in the ass to begin with.

I'm not. (-1)

Anonymous Coward | about 2 years ago | (#39875955)

I'm doing work RIGHT NOW, with available tools, and delivering. How? I'm a professional, that's how. Pros get in there and get the job done. We don't moan about what's available. We don't bitch about what isn't here. That's why I get paid the big bucks now, and that's while I will continue to get them then. In the meantime, you can count on my assistant dropping off my Lotus at the car wash you work at tomorrow.

Re:I am still waiting for the day.. (3, Insightful)

Amouth (879122) | about 2 years ago | (#39875993)

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..

Re:I am still waiting for the day.. (2)

DavidD_CA (750156) | about 2 years ago | (#39876143)

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.

Re:I am still waiting for the day.. (0)

Anonymous Coward | about 2 years ago | (#39876181)

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.

You don't understand it? Look at how PCs are sold: As a set of specs. So, if you buy a PC, you buy a set of specs, not usability. PC vendors don't compete on usability. It is not unlike buying fruit: It looks good but doesn't taste great because people buy what looks good and taste at home. But you spent the money, so you eat it.

Bert

Re:I am still waiting for the day.. (4, Funny)

james_van (2241758) | about 2 years ago | (#39877007)

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.

Re:I am still waiting for the day.. (1)

nurb432 (527695) | about 2 years ago | (#39877209)

I had a laptop where it as on the front edge.. even worse than the side.

I will say that irDa extended the life of an old HP printer i had, as the parallel port went belly up right after the warranty ran out , with the cost of a new formatter board being more than a new printer.

But only had 1 laptop with ir, so it was a pita when i wanted to print.. And had to do it on the kitchen table so it would get aligned properly...

But it was a great thing, before bluetooth came around.

Re:I am still waiting for the day.. (1)

DarwinSurvivor (1752106) | about 2 years ago | (#39876005)

I remember some of the guys in highschool had an application on their IrDA-enabled PDA's that let them use them as a TV remote. No TV in the school was safe :)

Re:I am still waiting for the day.. (0)

Anonymous Coward | about 2 years ago | (#39876109)

We used to use the old casio watches that had a built-in remote - it was a bit more inconspicuous.

Re:I am still waiting for the day.. (1)

rdebath (884132) | about 2 years ago | (#39876477)

Except QAM and QPSK require a medium with a practically pure wave nature, pulse modulation of light is more a particle nature effect with the pluses of light consisting of numbers of individual photons each with their own specific frequency. The higher the data rate the fewer photons in each pulse.

Optical frequency division multiplexing is even more a particulate effect where the prism or grating effectively sorts the photons into individual streams. Though or course the fact that it works at all is actually a wave effect which will go away if you try to measure which slit an individual photon goes through.

I still think we'll get petabyte streams, but it won't be with QAM/QPSK.

.

IrDA! I don't think I've ever used that for real; I always had a laplink cable available. It's main problem IMO was that it was one of those 'bastardised by committee' standards (like the ISO seven layer cake) where they tried to make it fit with every special interest they could. This meant that unless your software was made by a member that specific group it probably wouldn't work because the standard was what they thought they would implement, not what they eventually did. Bluetooth is very much the same. OTOH WiFi, which is technically very similar to BlueTool interoperates very well, presumably because the standards people limited themselves to one task ... moving ethernet packets ... no packets moving == no WiFi logo.

AFSK over lightwave (1)

Anonymous Coward | about 2 years ago | (#39877041)

The ham radio experiments have modulated the light wave with a low frequency radio signal - say 25kHz. This would imply a more linear output stage than a pulsed light output stage - or a modulation technique such as FM which doesn't care so much.

Maybe this is the way we'd use QAM - in the modulated signal. I wonder if the maths applies as it does for normal radio waves - if the spectrum of the output will be the normal AM or FM spectrum so even a very pure light source once modulated will contain other colours. Thinking of the maths I'd expect so, though it's light and colour so it would seem counter-intuitive and I wonder what other effects may come into play.

The REAL question... (5, Funny)

emag (4640) | about 2 years ago | (#39875917)

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...

Firefox security bug in current Tor BB's (-1)

Anonymous Coward | about 2 years ago | (#39875931)

Firefox security bug (proxy-bypass) in current TBBs

https://blog.torproject.org/blog/firefox-security-bug-proxy-bypass-current-tbbs [torproject.org]

"A user has discovered a severe security bug in Firefox related to websockets bypassing the SOCKS proxy DNS configuration. This means when connecting to a websocket service, your Firefox will query your local DNS resolver, rather than only communicating through its proxy (Tor) as it is configured to do. This bug is present in current Tor Browser Bundles (2.2.35-9 on Windows; 2.2.35-10 on MacOS and Linux).

To fix this dns leak/security hole, follow these steps:

        Type âoeabout:configâ (without the quotes) into the Firefox URL bar. Press Enter.
        Type âoewebsocketâ (again, without the quotes) into the search bar that appears below "about:config".
        Double-click on âoenetwork.websocket.enabledâ. That line should now show âoefalseâ in the âValueâ(TM) column.

See Tor bug 5741 for more details.
(https://bugs.torproject.org/5741)
We are currently working on new bundles with a better fix."

- http://pastebin.com/xajsbiyh [pastebin.com]

#
Anonymous comments:
#
On May 2nd, 2012 Anonymous said:

Oh dear :(

Does anyone know if IP addresses leaked to Twitter when (through NoScript) I enabled javascript for that site?

If yes, I may be in trouble.
#
On May 2nd, 2012 Anonymous said:

@anon, AFAIK Twitter does not use web sockets, so even if you enabled Javascript on Twitter it should not be an issue. I could be wrong or there could be other issues.
#
On May 2nd, 2012 Anonymous said:

Theoretically, an exit node can embed a websocket into your traffic stream if you are using HTTP.
#
On May 2nd, 2012 Anonymous said:

As long as you weren't doing anything illegal in the United States you should be fine. Tor has never been about hiding illegal activity. And since Twitter is in the US and doesn't respond to foreign court orders⦠wellâ¦
#
On May 2nd, 2012 Anonymous said:

Ah right, maybe Anonymous "Oh dear" is a fucking communist, or even a dirty whistle blower like Maning! Brave, law abide citizens haven't got anything, that must be hidden, so maybe you want to forbid TOR, Mr. McCarthy?
#
On May 2nd, 2012 Anonymous said:

Oh great, so all my Pastebins are belong to the Feds?
#

THE DRAMA CONTINUES...

TBB proxy bypass: Some DNS requests not going through Tor
Ticket #5741 (closed defect: fixed)
https://trac.torproject.org/projects/tor/ticket/5741 [torproject.org]

"This is not the first time some rarely triggered bug in Firefox causes Tor to be bypassed, and certainly will not be the last one. Since these bugs have a very high security impact I propose they are guarded against. How about running Firefox inside some kind of firewall that drops all network packets not going to Tor?"
#
Comments:
#
by mikeperry

Good catch Robert. Disabling about:config pref network.websocket.enabled prevents it from happening for me... I'm now grepping through the Firefox WebSocket code looking for the issue..

#
by mikeperry

This is fixed and pushed to all TBB branches. I fixed it by blocking all DNS requests while socks_remote_dns is enabled, so we don't end up with this showing up in new components in the future.

Interested folks can review the patch here: https://gitweb.torproject.org/torbrowser.git/blob/maint-2.2:/src/current-patches/firefox/0018-Prevent-WebSocket-DNS-leak.patch [torproject.org]
#
Additional Reference:

[tor-talk] Firefox security bug (proxy-bypass) in current TBBs

Robert Ransom rransom.8774 at gmail.com
Wed May 2 22:43:52 UTC 2012

See https://blog.torproject.org/blog/firefox-security-bug-proxy-bypass-current-tbbs [torproject.org]
for the security advisory.

Robert Ransom

https://lists.torproject.org/pipermail/tor-talk/2012-May/024123.html [torproject.org]
#
Tor/TBB Developer Activity for 2012/May: https://lists.torproject.org/pipermail/tor-commits/2012-May/thread.html [torproject.org]
#
Another version of TBB, another bug. IMO, they should mark all releases of TBB as ALPHA!

At the time of this bug report collection and passing the news onto others, there have not been any new release of TBB versions to fix this bug on their download pages, but it'll come.

Re:Firefox security bug in current Tor BB's (1)

Anonymous Coward | about 2 years ago | (#39876351)

apk, you're a tard

Old news...they wear out (3, Informative)

drwho (4190) | about 2 years ago | (#39875957)

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.

Re:Old news...they wear out (3, Informative)

thegarbz (1787294) | about 2 years ago | (#39876469)

Got a source on that? Laser diodes don't "wear out" as far as I am aware. They may be damaged by thermal runaway in the short term or long term by poor design but the only critical factors here is the stability of the current source, choice of bias point, and thermal design. They certainly don't get tired over time.

Re:Old news...they wear out (2)

Dr_Barnowl (709838) | about 2 years ago | (#39876559)

The manual for my green laser pointer cautions you against using it constantly - I'm guessing the heatsink arrangements are not what they could be in there.

The researchers probably took them apart and made sure they were properly cooled though.

Re:Old news...they wear out (1)

fuzzyfuzzyfungus (1223518) | about 2 years ago | (#39877069)

I assume that laser diodes are no more fundamentally resistant to degradation over time than ordinary LEDs are. Not a huge problem(LEDs are usually specced to be something like 80% of original output after 100,000 hours); but solid state devices only look immortal compared to their mechanical counterparts.

Re:Old news...they wear out (1)

dbIII (701233) | about 2 years ago | (#39876713)

The "done years ago" could apply to anything.
I was using a homemade microwave data link in 1988 but the wireless and laser stuff now is still interesting.

radio lasers (1)

G3ckoG33k (647276) | about 2 years ago | (#39875959)

"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"

That made me think of blue lasers, which would have even better rates.

But, how about longer waves, such as infrared or even radio? Are there any radio lasers around? THAT would do for long distance calls, and proabably be enough for E.T. to phone home.

Re:radio lasers (3, Informative)

mpoulton (689851) | about 2 years ago | (#39875979)

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.

Re:radio lasers (1)

symbolset (646467) | about 2 years ago | (#39876099)

It may, however, be handy in space. Like Planetary Resources is planning to do. Because for high data rate communications over long distances in space with low power it's pretty awesome.

Re:radio lasers (2)

Neil Boekend (1854906) | about 2 years ago | (#39876417)

Beam divergence [wikipedia.org] 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.

Re:radio lasers (1)

catmistake (814204) | about 2 years ago | (#39876471)

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.

Perhaps there is a way to mitigate this limitation with strategically spaced Hot Pockets®.

Re:radio lasers (1)

cerberusss (660701) | about 2 years ago | (#39876891)

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

That was a big disadvantage with MASERs. However, what I propose, is data transfer using high-powered LASERs. Initial handshaking will be done by "creating" a line of sight path before communications can start in lower-power mode :D

Re:radio lasers (2)

NoNonAlphaCharsHere (2201864) | about 2 years ago | (#39876159)

Yeah, using laser pointers is a good idea, but what do you do when the cats jump on your data?

Re:radio lasers (0)

Anonymous Coward | about 2 years ago | (#39876265)

Yeah, using laser pointers is a good idea, but what do you do when the cats jump on your data?

Beat the crap out of them?

Re:radio lasers (0)

Anonymous Coward | about 2 years ago | (#39876367)

put a feedback circuit in the laser output, from the receiver end. If the receiver is not receiving anymore, raise the power level just a little bit until it does, then back
off.

that pesky little cat will be no more trouble.

Re:radio lasers (2)

julesh (229690) | about 2 years ago | (#39876629)

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.

Enjoy It While It Lasts (3, Funny)

guttentag (313541) | about 2 years ago | (#39876061)

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. [slashdot.org]

A similar project (4, Informative)

ard (115977) | about 2 years ago | (#39876123)

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

Cell Towers? (2)

aaronb1138 (2035478) | about 2 years ago | (#39876165)

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.

Re:Cell Towers? (5, Informative)

adolf (21054) | about 2 years ago | (#39876489)

Visible line-of-sight issues ruin the possibility in many applications. Rain is murderous to low-power visible light connections, as is fog and snow. Even wind will affect a laser-based length over any substantial distance as the end-points sway (and yes, all towers sway in the breeze).

Meanwhile, cell towers quite commonly already link with microwave: The big parabolic reflectors covered with fiberglass radomes that you see on many (perhaps most, or nearly all) cellular towers are not for subscriber usage, but to link neighboring towers together. This is often done using licensed frequencies, though unlicensed bands are also used.

There are generally also redundant backhauls using copper or fiber or both, but I guess the point I'm trying to make is that cell towers -already- use wireless RF backhauls...and that the tech described in the article isn't likely to change that.

As it stands, resistance to rain-fade and other weather seems to be excellent, at least anecdotally: I've never experienced it, and I've carried a cell phone for at least 1.5 decades.

(Disclaimer: I work with RF and wide-area long-range wireless networking as part of my day job, though not necessarily with back-end cellular systems in particular. Just because optical networking seems like a general non-starter to me doesn't mean that it's unsuitable for the uses that you suggest.)

Re:Cell Towers? (1)

Lumpy (12016) | about 2 years ago | (#39876935)

But the new cell towers seem to be bad a building fade. 100% signal in my yard from the cell tower 5 blocks away. 20% signal inside the house near a window.

Unlicensed Spectrum? Unbelievably Reckless!! (5, Insightful)

burnttoy (754394) | about 2 years ago | (#39876169)

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!

Re:Unlicensed Spectrum? Unbelievably Reckless!! (1)

artor3 (1344997) | about 2 years ago | (#39876249)

No worries, the visible light spectrum is already being regulated. If you don't believe me, feel free to set up a 1500 watt spotlight pointing towards oncoming traffic on your street tonight. Let us know how it turns out.

lower bit rate for me (2)

pbjones (315127) | about 2 years ago | (#39876171)

not good for 20% of males that have red/green defective colour vision, you desensitised clod...

Hobby hacking (0)

Anonymous Coward | about 2 years ago | (#39876227)

So it shouldn't be too difficult to just use one laser for each side of a full-duplex link at 10-100 Mbits and just send standard Ethernet frames back and forth. Not for any serous applications, just to prove it would work.

Re:Hobby hacking (0)

Anonymous Coward | about 2 years ago | (#39876419)

See post above. You can drop a 10mW laser diode into a RONJA TX head instead of the LED and ... it works. Quite a bit better than the LED. Only one tiny issue - LASER SAFETY REGULATIONS.

Been done (2)

silentcoder (1241496) | about 2 years ago | (#39876393)

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 ?

Beowulf! (0)

Anonymous Coward | about 2 years ago | (#39876427)

I'd like to see a beowulf cluster of these! Wouldn't you?

Um, hello? (0)

Anonymous Coward | about 2 years ago | (#39876441)

The paper describes phase measurements. Phase of what? They don't use any modulation scheme that involves phase -- they have dumb on/off "modulation", their carrier is light itself, and their detector is a photodiode, it can't measure phase of light without an interferometer that they don't have.

As light passes through the air, random (but low-frequency) "noise" modulates its amplitude and introduces varying delay. If we are really unlucky (fog, dust, very long distances), there will be multiple paths, "smearing" impulse response. However light itself has frequency in Terahertz, single-bit signal with all its harmonics is up to Gigahertz, so this is nowhere close to what happens in RF data transmission. This kind of distortion just works like a simple low-pass filter, limiting the data rate. No filtering or amplification can affect that, so we have a data rate hard limit for this kind of "modulation" there, and it's much higher than what they are trying to do.

On top of this, receiver is very much nonlinear -- all those harmonics are introduced not by medium (air is almost perfectly linear as far as light transmission is concerned) but by the receiver photodiode. THAT can be compensated by "adaptive filter" that at the same time tracks shift in amplitude -- levels slowly drift (clouds of dust and fog may appear and disappear), but no one really cares how linear or nonlinear anything is, because "amplitude modulation" was by unpredictable noise anyway, and all we need is to discern levels for 0 and 1. Now, look at the eye diagram in the article. It's clear as day that one on the left is smeared because of amplitude drift (so traces start at slightly different points) and one on the right has "filter" adjusting to the changing amplitude (so all traces start at the same point relative to the "true" moment of level transition). It's level adjustment, plain and simple.

Oh, but what about phase?? There is no "phase". Phase of the carrier is gone after the photodiode. There is no frequency to apply "phase" to, pulses' frequency is arbitrarily chosen by the user, and nothing at all depends on that frequency as long as it doesn't reach Terahertz range. What happens is simple delay, that also may drift when changing air pressure changes refraction coefficient or, to put it plain, speed of light in the air, or when transmitter and receiver move, or when un-compensated amplitude changes shift the time when waveform (electric, not light) crosses given levels. The only "phase adjustment" is synchronization with those pulses' leading and trailing edges -- if this is "adaptive filter", then RS-232 is also "adaptive filter" because receiver constantly adjusts its time when it receives start pulses.

So here it is, the transmitter does nothing but turn laser on and off forming pulses. The receiver receives the signal with amplitude and delay drifting, mutilates it further by introducing its own nonlinearity and immediately loses everything related to phase (and frequency) of the carrier because carrier is just light falling on a photodiode. Everything past that point is just level adjustment (what they call adaptive filtering for amplitude), Schmitt trigger (that paper omitted, so maybe they forgot to put it there) and synchronization (what they call adaptive filtering for phase).

Oh, and both their drawings are wrong. And their amplifier doesn't do anything for "compensation of nonlinearity" that simple level adjustment wouldn't do better because -- surpise -- it already contains an amplifier with gain adjustment, and all we care about is two levels.

IrDA worked fine (1)

MrMickS (568778) | about 2 years ago | (#39876739)

I don't agree with the original poster about the deficiencies in IrDA.

This was in a time when dial-up access was the norm, if you were lucky you had ISDN, and your cellphone gave you patch 9600 baud connectivity. IrDA was fine in this situation.

I used my Nokia 6320 phone and Palm V to restart servers whilst on call from the comfort of restaurants, and even to make changes to Perl scripts from a different country. The range was poor, but fine, the performance was limited by the cellphone not IrDA.

Kids of today, they've no idea

Re:IrDA worked fine (2)

deroby (568773) | about 2 years ago | (#39876813)

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

Anyone thinking about sharks? (0)

Anonymous Coward | about 2 years ago | (#39876781)

Now the sharks with friggin' laser beams attached to their heads will be able to enjoy, not just a warm meal, but also high-speed digital electronic data communications!

So they copied existing designs... (1)

Lumpy (12016) | about 2 years ago | (#39876927)

Sorry but this has existed as a communications system in the middle east and india for well over a decade now. People over there have been doing this with laser pointers and LED's for a very long time.

Granted it was only 100bt as it used existing transciver chips, but the jump to 1Gps is not that hard.

and why red and green? The existing designs all use RED for alignment and then IR for data comms so that it's not visible from acute angles.

Ronja anybody ? (0)

Anonymous Coward | about 2 years ago | (#39877013)

Fully opensource 100mbps version right here http://ronja.twibright.com/
Rather old too.

IrDA (1)

nurb432 (527695) | about 2 years ago | (#39877167)

Worked great for me. For extended range or in 'noisy' environments id stick an optical fiber between the 2 devices.

The Heliograph (1)

dtmos (447842) | about 2 years ago | (#39877175)

Those with a (or even an) historical bent may be interested in the first outdoor optical communication system, the heliograph [wikipedia.org], which used reflected sunlight for long-distance communication via Morse code. The record distance covered was 183 miles (295 km), between Mount Ellen, Utah, and Uncompahgre Peak, Colorado on 17 September 1894.

To my knowledge, this record for terrestrial (i.e., non-moonbounce) optical communication has never been broken, even by modern laser and LED systems. The closest attempt [reast.asn.au] of which I am aware is 179 miles (288 km), between Mount Horror, Tasmania and Mount Liptrap in South Gippsland, Victoria, Australia on 27 October 2009, using non-line-of-sight techniques (they bounced Luxeon LED light off of high cirrus clouds, and used very-weak-signal digital coding and modulation techniques).

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