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Optical Cellphones
foondog writes "Here is a story over at News.com about optical cellphones. It seems that the Department of Defense has given a grant to the University of California to develop optical cellphones that are faster and more secure. This sounds a little strange to me since you would need a line of site with no obstacles in the way to use this. The article doesn't explain how this might work."
TM
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"It seams that the Department of Defense has given a grant to the University of California to develop optical cellphones that are faster and more secure. This sounds a little strange to me since you would need a line of site with no obsticals in the way to use this. The article doesn't explain how this might work."
What about from a soldier/spy/diplomat straight to a comm sat?
It's easier to get line of sight to orbit.
It doesn't really say anything about how the optical cell phones would work inside a building. I'd be very curious to know how they plan on overcoming this obstacle. Of course, this is just a grant to study it. It may never come to *see the light of day*
(sorry... had to be said)
This sounds a little strange to me since you would need a line of site with no obsticals in the way to use this.
X-rays are light energy, and they don't seem to have a problem passing through.. well.. you, among other things.
The theory of relativity doesn't work right in Arkansas.
Intersting idea, but is it really possible to have a laser based cell phone? I guess a laser would have to be used.
:)
Besides the technical problems, I really don't see much use for it. I'm happy as long as I can talk on my cell phone and I don't need: games, internet, messaging, carwash, deodorant, floss, toothpicks, swiss army knife, lunch, soft drink incorporated into my cell-phone.
I'm not that important, neither is the rest of the Slashdot crowd
If you mod me down, I *will* introduce you to my sister!
Desert. You can only use them in a desert.
Need line of sight. DoD likes lasers. Big lasers, with lots of power. Could be dangerous.
I wouldn't want to hold one of these up to the side of my head and start talking, it might make it's own line of sight to the nearest tower.
Ouch!
Current cellphones are already operating in bands where line of sight is quite critical to half-decent reception. What makes this feasible is that many surfaces are reflective of a lot of bands of EM radiation. This is why we can see things - they reflect light. This is why you can use your TV remote by pointing it away from the set - it bounces off the wall.
I agree that attenuation will be a big problem, but it's already getting almost that bad as we get higher and higher in the spectru.
Now, if they could only modulate the sun's rays...
"This sounds a little strange to me since you would need a line of site with no obsticals in the way to use this. The article doesn't explain how this might work."
Four words: Really Really Tall Towers
"Not knowing when the dawn will come, I open every door." - Emily Dickinson
A different technology in widespread use employs a method called wavelength division multiplexing, in which each cell phone uses a different wavelength of light, according to the researchers. In contrast, optical CDMA would encode each pulse, or bit of information, across a segment of wavelengths. The receiver uses a key to decode the signal and re-create the original pulse.
This sounds a lot like Ultra Wideband to me. Also, I'm guessing from reading the article that the author is confusing visible light with radio EMR.
Holy line of sight, Batman!
This is just a high-bandwidth version of the bat signal. This technology has been around since the sixties. Hopefully they can make it more portable.
- DoD's new "light emitting cell phones" cause massive outbreak of seizures. Spokesman says: "We're really shaken up about this."
- DoD investigating new "tin can and string" technology for secure landline communications.
Maybe they found a way to modulate the output from the sun? Will probably make those night-time minutes REALLY expensive though!
The sell phoane comes with a set of special specticals that you put on and look at you're conversashion partner, who has an identicle set up. The phoanes then comunnicate via lazers in the specticals, thats why you have to look at each other.
(creative spelling purely intentional in homage to the original article)
What I really want is a phone with a freaking laser on it!
Someone, either the author, or a source, is totally confused about what light is.
When I read the topic, it occured to me that they might have been talking about using quantum encryption (photon spin direction? what?) with cell phones. Then I realized it wasn't the year 2025.
Anyway. This will be interesting when someone who graduated high school writes an article about it.
There are no trails. There are no trees out here.
Uh... signal strength requirements?
come on fhqwhgads
It's not necessarily true that you need a line of sight with no obstacles in the way for an optical communications device to work. There are parts of the EM (optical) spectrum which pass through ordinary objects. Infrared, for example, can "bleed through" most walls, allowing infrared photography of the sort sometimes used by law enforcement to see behind closed doors. On the other hand, gamma rays and x-rays, which are very high frequency, are stopped by few things besides lead.
Actually, current cellphones are, in a way, optical, since they use RF. Radio waves are a kind of light of much lower frequency than the visible spectrum, and they easily leak through all kinds of solid objects. I would assume that this new research project aims at using *higher frequency* optical communications, possibly using a laser for focused rather than diffused (RF-style) transmission. Only transmitting on a direct line of sight has obvious utility for security, and that line of sight doesn't necessarily have to be onobstructed.
Anonymous Luddite: "What do you think of the dehumanizing effects of the Internet?"
Andy Grove: "Not Much."
Some cell phone systems, such as those from Sprint PCS and Verizon Communications, already use a type of CDMA for radio waves, according to the researchers
:)
We need researchers to tell us that our phones use CDMA? So what ab out all those can you hear me now Sprint CDMA commercials?...must've been an optical illusion
Live for the present, learn from the past, and dream of the future!
Not an actual cell phone, but a point-to-point intercom involving binoculars and infrared transmissions. The voice was converted to (analog) IR light and transmitted through optics that created a very narrow beam. At the other end, the IR receiver was mounted in the eye piece of the binoculars and converted the light back to sound. The two devices had to be aimed very accurately at each other. That way a spy in the west could communicate with his pimp in the east across the border with very low probability of interception. They actually had this on the History Channel a few years back.
Karma whores take note -- Slashdot would probably run stories on anything listed on that page. (You still get points for an accepted submission, right?) Some of them, like the nanotech stress sensor paint and the flying robots sound familiar, but just because they've been linked once doesn't mean they can't be linked twice!
What I'm listening to now on Pandora...
The article doesn't explain how this might work.
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Of course it doesn't
"This isn't a study in computer science, its a study in human behavior"
The grant is not to make optical cell phones. The grant is to develop CDMA (a technology used in cell phones) to be used in fiberoptic communications. The title is a bit misleading.
So, why so much money to port a technology. CDMA allows more effective use of the bandwidth and as the article points out more security than frequency division multiple access. For radio frequency stuff, CDMA is what nearly everyone uses. For radios it requires a wide bandwidth output stage. That is the kicker. The optics guys use fairly narrow band laser output stages. Then the hook them together on the same cable. They don't interfere because they are at different frequencies. To do CDMA with your whole bandwidth requires a wide bandwidth output solution (either a single broadband output or some way to put multiple lowbandwidth stages together in a better way.)
This is pretty old news.
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Thus the Army must have some kind of non-broadcast communications system. I have no direct knowledge of how they would do it, but it isn't hard to imagine. For example, suppose low-flying satelites broadcast a signal. Handsets on the ground listen for that signal, and then point a highly directional antenna (LASER, focussed RF or microwave, whatever) at the satelite, and then starts transmitting a narrow beam.
There is not enough economic motive to develop this for purely commercial purposes. But once it is developed for the military, the commercial benefits are there to deploy it. Directional signalling means much less interference, and therefore much less consumption of precious spectrum, and less need for those pesky and expensive cell towers.
Crispin
----
Crispin Cowan, Ph.D.
Chief Scientist, WireX Communications, Inc.
Immunix: Security Hardened Linux Distribution
Available for purchase
Also, some animals can detect light pulses going through shielded optical cables (sharks, for example, just love chewing on underwater fiber-optical cables).
Because of quantum effects, strange action at a distance, etc., there is no such thing as an event that is not detectable.
If all this should have a reason, we would be the last to know.
From what I hear, every soldier has a mirror. On a sunny day, you can use the mirror to signal aircraft for miles.
The mirror has the advantage of not needing batteries, being resistant to shock, etc.
Of course it doesn't work in clouds or dark, and bandwidth, well... leaves something to be desired.
So if they can do this with infrared and talk through it, that seems perfectly reasonable to me. One advantage of LOS is that you have to get in the way of the thing to jam it. Of course the receiver has to be intelligent enough to ignore signals from the wrong part of town, or signals that don't carry the right code, but it's a solveable problem.
Of course, any signal, especially an IR laser, gives away your position if the enemy can see it.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
How to keep your cell phone from being jammed? Bathe it in grape jelly, instead...
What's this Submit thingy do?
"This sounds a little strange to me since you would need a line of site with no obstacles in the way to use this."
Uh, no...all you'd need is a huge network of mirrors or a lot of little collection points. Use VoIP technology to manage packets of data. Blinks of light work as well as packets of radio and because of their higher frequency they provide more bandwidth.
blog |
I think this is an ideal technology, that doesn't take up valuable bandwidth in the frequency range we use for radio transmissions.
;-)~
'Course, there are drawbacks... You have to stand REALLY still, in just the right spot...
If it proves to be a gov't-use-only technology, why worry about it?
Instead of looking for specific levels of brightness, look for the delta of those levels. Or even delta^2.
Given that current satellites are able to read print the size of license plates, and we have a lot of computing power available these days, I would imagine that software could track a single point signal source and ignore others.
This is a supreme advantage of optical over other methods. We have CCDs that can see visible light and infrared, but no hi-rez CCD that can "picture" radio sources.
Jamming is only useful if all your signals come in over the same antenna. It's much, much less effective if you can easily distinguish the locations of multiple sources, then authenticate against the source you want to communicate with.
Granted, this means cell-to-satellite is easy. Not satellite-to-cell.
What's this Submit thingy do?
People are posting about "why?"
Consider the havoc that nuclear explosions play with radio frequencies.
Consider having a method of secure remote communications which does not rely on radio frequencies of any type in such a situation.
Kinda makes you stop and think about things.
"You worthless post!"
-Shakespeare, 2 Gentlemen of Verona, 1. 1. 147
I'm going to dub this the 'Laser Phone'. The Laser Phone will not be made for general public use. Laser Phones will be made for military and corporate entities that require ultra secure communications.
You maybe asking: âoeWhy would you need such a clunky method of communication? Line of site is not practical.â
The answer is very simple: Supercomputers and triangulation.
You see any voice communication has certain pitch and volume amplitude modulations. Pitch and volume amplitude modulations are part language and part human physiology. No matter how you scramble and encode the communication the human voice will always have certain keys that can be easily discerned in a conversation.
An enemy can easily grab and record a radio signal. Then the digitally recorded file can be feed in a Beowulf cluster of cheap computers. That data can within a few minutes can decode your voice and thus get your tactical information.
Another advantage of optical communication is that it is almost untraceable. Anytime you use a radio you sending out a beacon saying, "I'm right here; bomb the snot out of me!" An enemy can use simple triangulation to locate you.
A Laser Phone will be virtually impossible to intercept, track, and decode.
BTW: Anyone remembers those World War I movies where the soldiers would use mirrors to send Morse code message?
You say things that offend me and I can deal with it. Can you?
The longer the effective distance the light spends in the cavity, the narrower your beam will be.
You can increase your effective distance by lengthening your mirrored cavity, and by increasing the silvered amount of your semisilvered mirror at the front.
What's this Submit thingy do?
No matter how you scramble and encode the communication the human voice will always have certain keys that can be easily discerned in a conversation.
gzipped and rijndaeled voice is not voice anymore.
Triangulation, OTOH, is a meaningful worry.
I'm busting out Beejee's when I get home for ThanksGiving. I can't wait for this!!
The article doesn't explain how this might work.
Could it be that the reason we donâ(TM)t have any information is because we donâ(TM)t want others to have our information?
If you are Sarah Lee, do you want Betty Crocker to know how you make your world famous cheesecake? Betty could get with Uncle Ben and make a similar version of your cheesecake. Ben and Betty could possibly even make a better version of your cheesecake because they now have your recipe and their old R&D from other tasty treats attempts.
In short, not everything is open source. Not recipes, nor military secrets. Is it dinner time yet?
You say things that offend me and I can deal with it. Can you?
If you read my 'rolling data center' comment earlier you know I was talking about walking around festooned with digital stuff.
Optical MIGHT be the way for all these to communicate IF bluetooth crashes and burns AND people get nervous about all that radio radiation around them, and only one good cancer report might do it, AND it's only used on items that have a line of sight with each other AND they can make it secure (easy but will it be done?)
This might be an answer looking for a problem it will never find...
It's Christmas everyday with BitTorrent.
can you see me now? good.
can you see me now?
all you need is mirrors...mirrors will be everywhere...and behind those mirrors will be clones of tom ridge on john ashcroft. oh the end is near.
the line of cocaine the admins of this web site do before posting articles (and modding, let me add).
sulli
RTFJ.
It's called a heliograph and a CD would make a very good substitute. ;)
Take a CD and an ice lolly stick. Make a hole in one end of the stick and hold the CD up in front of your face, shiny side facing out. Be facing the sun, more or less.
Hold the lolly stick up in front of that (about 12 inches away) and sight through the hole in the CD and the hole in the lolly stick at the aeroplane, boat, visitor craft or whatever you are trying to signal to. Now wiggle the CD until the shadow of the hole in the middle of the CD falls over the hole in the lolly stick. Now you are shining your light right at your target. By flicking your hand, you can turn the light on and off and so make morse. Or binary. Whatever.
If you do do this to a visitor, they will probably just decode the information on the CD and try to work out the meaning. Do not expect to be rescued. Expect instead to get Barry Manilow's greatest hits beamed back to you some days later.
If this saves your life, paypal me!
All things in moderation; including moderation
Materials (buildings, glass, etc) will react differently to the different frequencies but if this is not a limitation, there really is no reason not to move to shorter wavelengths (higher frequencies) as the band-width is somehow controled by the frequency (beyond the scope of this post)
But isn't the way materials react to light a limitation? Radio happens to be a great place in the electromagnetic spectrum to transmit and receive data because it can pass through some solid objects. Light bounces off of solid objects, which is how we are able to see them. It seems that these cell phones would need a direct line of sight (ugh...grammar check time, slashdot editors) to the cell towers to be able to work.
I've heard of "cloudbouncing", lighting up clouds with lasers to transmit data while another entity watches and receives, but you can't always count on there being a cloud around when you need one (that both you and the tower can see), and it seems like such a medium would be prone to congestion.
This is what puzzles me. It wasn't answered in the article, and I haven't read a post that explains what's going on.
Actually, You've touched on why the navy still uses spotlights to communicate to this day. You know those movies where you have some seamen flipping the shades on a spotlight to send morse code to another ship? That's what I'm talking about. Unless you are along the line of sight which the light beam is travelling, it's virtually impossible to intercept the signal.
Avoiding the "bomb down your shorts" is one of the reasons that the military has been developing and using spread spectrum communications for many years. With DSSS (direct sequence spread spectrum) and a high chip rate, the carrier is spread over a wide swath of spectrum. It can actually be below the noise floor. If you look for the signal with a spectrum analyzer, the most that you will see is a small elevation in the noise level. The tricky part of this is synchronizing the sequence generators in the transmitter and receiver.
Mea navis aericumbens anguillis abundat
It is too bad the moderators didn't realize your good sense of humor. To others who didn't realize it, the moderators changed several misspellings in the post, but not the glaring "line of site" error. I guess they have a spell checker, but no automatic tool for proper English usage.
My other first post is car post.