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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."
That's because it won't.
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!
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.
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.
The soldiers/spy/diplomat would have the same problem we had in the gulf war with laser guided bombs. A little sand storm, clouds, rain, anything other then nice weather your screwed. Not to mention, how would these things would work in buildings?
Wouldn't a better solution be cellphones which support heavy encryption?
Jason Yates
The article doesn't explain how this might work.
I think that is the main reason they issued a grant for studying this?
In the perfect world someone in the government would search Google first and when nothing useful returns they figure they better outsource it!
Do you have any idea how much laser power is needed to nail a geosynch sattelite?
Very little. 1500 mJ, specificaly. It's done every day.
let alone burn through the atmosphere and any possible cloud cover.
Uhhh... only if you're in the visible light spectrum. Some wavelengths will pass right through clouds (and other objects, like the earth) completely unphased.
Or how about the laser platform aiming and stability? a shake of less than 0.01mm in the sattelite will make the beam dance around on the planet over a 1 square mile area.
How about it? Do you know we bounce lazers off mirrors on the moon that are about a meter wide, and we bounce the same lazer off satelites all the time.
Not.. no way, no how... not sattelite.
Better call University of Texas and tell them to knock it off, because apparently, what they are doing can't be done.
Here's a quarter, kid. Go buy a clue.
--
You sure got a purty mouth...
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
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?
Not true. Optical usually refers to the entire range from IR to UV.. Fibre-optics, CD and DVD, etc are all optical but don't use visible light.
It'd be nice if the linked article was a little more informative; it doesn't say anything about what part of the 'optical' spectrum these things would use or why spread-spectrum using 'optics' is somehow magically more secure than spread-spectrum using microwave.
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