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Vortex radio waves could boost wireless capacity “infinitely”
- kruhft 15y agoHere's a video presentation on Vortex Based Mathematics: magnet:? xt=urn:btih:44b89f9125978a8d0f46cf42de9b2110c9bdd151&dn=Vortex+Based+Mathematics+by+Marko+Rodin&tr=udp%3A%2F%2Ftracker.openbittorrent.com%3A80&tr=udp%3A%2F%2Ftracker.publicbt.com%3A80&tr=udp%3A%2F%2Ftracker.ccc.de%3A80
- Groxx 15y agowould you mind putting that on a new line, and indenting it 2 spaces, so it doesn't break the page's size? edit: thanks!
- DanielBMarkham 15y agoThis has the feel of one of those articles that promise much more than it delivers. But the site is good, the idea interesting, and it definitely could be a game-changer. If this pans out, it also has interesting implications for SETI, because if our receivers are set up in a different configuration than some potential sender might be, we'll never receive anything.
- bh42222 15y agoI know the idea behind SETI is great, but I have great doubt about the execution. Here is why: From: http://www.damninteresting.com/space-radio-more-static-less-talk/ http://www.damninteresting.com/space-radio-more-static-less-... When any non-focused electromagnetic signal is generated– such as a television broadcast or a cell phone conversation– the energy propagates as a spherical wavefront at the speed of light. When a sphere is doubled in diameter, its surface area increases by a factor of four; but in a spherical wave the “surface area” is the energy itself. This means the signal’s energy is spread over four times more area at twice the distance, resulting in a 75% loss in intensity. To put it another way, in order for a broadcasting tower to double its effective range for a given receiver, it must quadruple its transmitting power. To demonstrate the degrading effect of distance on an everyday omnidirectional signal, one might imagine a spacecraft equipped with an Arecibo-style radio receiver directed towards the Earth. If this hypothetical spacecraft were to set out for the interstellar medium, its massive 305-meter wide dish would lose its tenuous grip on AM radio before reaching Mars. Somewhere en route to Jupiter, the UHF television receivers would spew nothing but static. Before passing Saturn, the last of the FM radio stations would fade away, leaving all of Earth’s electromagnetic chatter behind well before leaving our own solar system. And: http://blog.jackadam.net/2011/the-tiny-humanity-bubble/ http://blog.jackadam.net/2011/the-tiny-humanity-bubble/
- hammock 15y agoYou seem to be talking about aliens picking up earth transmissions, while he's talking about receiving alien signals.
- fendrak 15y agoRight, but he's saying that if Earth's own signals fail to propagate even outside our solar system, alien signals will have to be exponentially more powerful than ours to even stand a chance of being received. The distance from Earth to Saturn is tiny in comparison to the distance between planetary systems.
- cma 15y agoPolynomially. Not exponentially. The surface area of a sphere doesn't grow exponentially with radius.
- jjtheblunt 15y agoI'm so glad to see you wrote that, seriously. It is absurd how it has become pop-cultural to use "exponentially".
- sp332 15y agoThis isn't a "non-focused" signal. This is being directed by an antenna in one dimension. A perfect antenna transmitting through empty space would send a signal that does not diminish at all with distance. The only attenuation would be due to imperfections in the antenna causing a gradual widening of the beam, and obstacles in the path of the signal.
- bh42222 15y agoImperfections in the antenna, obstacles in the path of the signal, etc. From the The Hitchhiker's Guide to the Galaxy: Space... is big. Really big. You just won't believe how vastly hugely mindbogglingly big it is... My point is space is HUGE, and it would take a stupendous amount of effort and energy to create and send a signal which Earth can correctly receive. And that's even if you specifically focus it at us. But why would anyone specifically focus it at us, if our own signals are not focused and quickly (quickly in term of universe distances) become indistinguishable from background radiation, how would they know we are here? What I am ultimately claiming is that even if we have intelligent radio using alien life "near by" we still would never find each other. Because even if we both have a SETI equivalent, neither one of us would initiate the huge effort necessary to send a focused "Hello" signal which the other can receive.
- aquarin 15y agoAh SETI is exatcly what I think when I see things like this.
- ars 15y ago> because if our receivers are set up in a different configuration than some potential sender might be, we'll never receive anything. We'll receive it, but it may be hard to distinguish from noise. But this is already true, for example with spread spectrum - if the transmitters are using that we'll never known, it's almost indistinguishable from noise unless you match the same frequencies they use.
- duaneb 15y agoHasn't SETI been shut down?
- dosenwurst 15y agoTo me this looks like good old circular polarization. http://en.wikipedia.org/wiki/Polarization_%28waves%29 http://en.wikipedia.org/wiki/Polarization_%28waves%29
- ars 15y agoNo, that's well known, and is only half of the rotation. (A rotation of the angle between the electric and magnetic fields.) This is apparently something new, not sure what though - it's not something I ever learned about with photons.
- dvdkhlng 15y agoNot sure that this is new. It is known that channel capacity can be scaled up linearly with the number of receive/transmit antennas by properly de-mixing the signal at the receiver (or pre-coding it properly at the sender). This is known as MIMO transmission, see https://en.wikipedia.org/wiki/MIMO https://en.wikipedia.org/wiki/MIMO for details (also has the capacity formula). What these people call "vortex wave", is just precoding/decoding done in a fixed way using fixed antennas. But with non-line-of sight channels and moving sender/receiver you will need dynamic MIMO coding anyways. This is already implemented in LTE (2 antennas in the handset, 4 at the base station, AFAIR).
- philwise 15y agoThat would be my guess too, especially as two crossed yagis are a well known way to receive circular polarized signals: http://www.qsl.net/dk7zb/Cross-Yagi/crossyagi.htm http://www.qsl.net/dk7zb/Cross-Yagi/crossyagi.htm
- joezydeco 15y agoMy RF knowledge is old and sketchy, but doesn't a dish imply that these RF signals are point-to-point? How would that work in a mobile handset where we can't point the antenna?
- JoeAltmaier 15y agophased arrays etc CAN point the antenna, electronically
- joezydeco 15y agoSure, but that's a little exotic and expensive for the consumer market at this point. I'd be happy with phased array satellite antennas I can stick on the outside of my house.
- JunkDNA 15y agoCan we get a sanity check from someone with actual background in this area? Seems like this would only work point to point in a line of sight manner with no obstructions. While still cool (satellite TV/Internet comes to mind), it's hard to see how you could adapt this to something like a mobile phone.
- Stwerp 15y agoRadio guy here. You are correct. I just finished reading their paper, and they describe a technique that creates a spatial null by changing the orbital angular momentum. In other words, they push the intensity away from the line-of-sight (LOS) ray out slightly (in space about the ray) so that two antennas can receive the different signals by spatial diversity. This requires A) precise tuning and setup B) a decent distance away from the transmitter source since you need the wavefront to spread out wide enough for antenna location and C) a re-calibration/tuning anytime the setup or possibly multipath changes. This technique should work well for static point-point comms (not with the claimed infinite bandwidth though since you run into a physical problem of area and precise location of the receiving array as well as near-field antenna effects affecting receiver patterns) but in its current form could not be implemented in a mobile device. Hell, a bunch of the time in WiFi or cell reception, multipath is your best friend and can be the only way you receive a signal and this work does not seem to address this issue. Still though, this is an interesting idea and should not be quickly discounted, although the article gives it much more hype than it merits imho.
- marshray 15y agoIs this completely different than circular polarization? It's been a long time since I've thought about this, but ISTR polarization errors gave only 10-20 dB attenuation/separation max.
- jfoutz 15y agoI think the author just wanted to throw in the "Verizon pays billions" line. IMHO, they bought it so no one else could have it.
- ars 15y agoThis paper should help: http://www.gla.ac.uk/schools/physics/research/groups/optics/research/orbitalangularmomentum/ http://www.gla.ac.uk/schools/physics/research/groups/optics/...
- jcarreiro 15y agoSee also http://physics.aps.org/story/v17/st15 http://physics.aps.org/story/v17/st15 for a bit more on photon orbital angular momentum.
- jcarreiro 15y agoAnd http://physics.aps.org/story/v9/st29 http://physics.aps.org/story/v9/st29, which is an older Focus story linked to from my original post.
- Gravityloss 15y agoThat's the first explanation that makes sense so far!
- Gravityloss 15y agoThat's the first explanation that makes sense so far!
- deleted 15y ago[deleted]
- cs702 15y agojpablo -- the seasons are produced by the tilt of the earth axis because the earth rotates around the sun. (The earth's axis always points in the same direction relative to the distant stars, so the planet's tilt changes relative to the sun as the planet orbits it.) The article is correct.
- CPlatypus 15y agoThose two statements do not conflict. Seasons are the result of the Earth orbiting around the sun, just not the way most people think. Most people would say it's because we're getting closer or further from the sun, which is incorrect. What's really happening is that as we orbit around the sun the Earth's inclination (difference between our axis of rotation and our orbital plane) causes either the northern or southern hemisphere to face the sun more and thus get more sunlight. Thus, seasons are the result of both axial tilt and rotation around the sun. The next time you feel the urge to pour disdain on an article because of a supposedly-incorrect statement, I suggest two things. First, make sure it's actually incorrect. Second, beware of http://rationalwiki.org/wiki/Skitts_Law http://rationalwiki.org/wiki/Skitts_Law especially wrt to typos.
- femto 15y agoNature has a clearer report. http://www.nature.com/news/2011/110222/full/news.2011.114.html http://www.nature.com/news/2011/110222/full/news.2011.114.ht... It bears a similarity to MIMO, in that MIMO initially promised "infinite" capacity. MIMO did give an improvement in capacity, but it wasn't infinite, the limit being related to the volume occupied by the antenna array (see papers by Leif Hanlen). One has to think that this technology will turn out to have a similar limit on fuller analysis. In fact one has to wonder whether the limit will turn out to be exactly the same, and whether it turns out to be a form of space-time coding? After all, one could presumably emulate the "slotted parabolic dish" antenna mentioned by using a suitably coded antenna array?
- dvdkhlng 15y agoMe, too thinks that this is just (a subset of) MIMO in disguise. The advantage of the antenna array you mention is, that it can precode/decode with any channel matrix, while these antennas implement one fixed matrix.
- bjornsing 15y agoI get the same feeling. MIMO basically exploits that there can be multiple propagation "paths" over the same frequency and that those can each carry information up to the Shannon capacity. Paths can be separated by geometry (reflections etc) or polarity. This Orbital Angular Momentum is probably just another way to create more "paths" that can be exploited with MIMO. In complex radio environments (like urban cellular networks) you get so many reflections that the limitation to MIMO is usually not too few separate paths but rather too many, with too much correlation between them. I'm not sure this would help very much there. But in simple radio environments, like point-to-point links you often are limited by the number of separate paths (you can have two based on Spin Angular Momentum aka polarity and there are lots of products out there that do that). In short; I think these guys are barking up the wrong tree in trying to adapt this for cellular, they should stay in point-to-point. They will be very welcome in that space if they can go from 2x2 to 4x4 MIMO across a point-to-point link.
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- 4rgento 15y agoTo describe electromagnetic waves, or to write a solution to the wave equation, you need to use a system of coordinates. The most common by far is the rectangular system (x,y,z), but there are other ones: cylindrical coordinates, elliptical, spherical, and more. This is like choosing a base in a vector space. If you choose rectangular coordinates then your solutions are expressed as a linear combination of plane waves ( Cos(k*x-wt), k is wave vector, x is position, w is frequency and t is time ). If you choose cylindrical coordinates, then your solution will be spanned as a combination of bessel functions( more exactly cylindrical waves) whose parameters are called: OAM, spin, and momentum (in z axis). As nature doesn't care which coordinate system we choose and neither the wave equation, a solution in one system of coordinates y also a solution in another. In this case, a cylindrical wave can be expressed as an infinite combination of plane waves. So what this people seems to be saying is more or less: "Instead of emitting waves and, in the receiver, just measure the frequency; let's emit more complex patterns and, in the receiver, measure enough features of the wave ( not just the frequency) so that we can tell it apart from other signals. I hope this helps.
- jakeonthemove 15y agoI was just reading about DIDO (aka MU-MIMO) the other day, and this looks like a great addition to the technology...
- ec429 15y agoI strongly suspect that this will prove to be limited by the RF path; it relies (as far as I can tell) on coherent properties of the wavefront. This means it will break as soon as the signal passes through heterogeneous material (such as a building), or as soon as reflections produce multi-path interference. And you certainly wouldn't be able to use it at HF - imagine what the ionosphere will do to your carefully constructed wave! In general, using more parameters of the wave reduces your resilience to noise; the usual approach of extracting only amplitude, frequency and (perhaps) phase is a summation operator that smooths out a lot of interference. Conceptually, this is like how QPSK needs a higher SNR than BPSK does - you're using more parameters, so you're reducing the 'distance' between things you want to distinguish, so you're increasing the chance that a given amount of noise will produce errors.
- Groxx 15y agoI can see this being a great improvement in capacity, but wouldn't data from other 'vortices' leak data into the one you're listening to? Any integer multiple would add noise to every bit sent to station X, and lots and lots where isolated bits from other channels leak in (what would that be, divisible by the station's period?).
- it 15y agoThe antenna reminds me of branch cuts in complex analysis. I suspect there is a connection here. http://en.wikipedia.org/wiki/Branch_point#Branch_cuts http://en.wikipedia.org/wiki/Branch_point#Branch_cuts
- donnawarellp 15y agoOK, here is your sanity check. What is being demonstrated is the same technology that is used in LTE and 802.11n (MIMO beam forming, wikipedia it you like). Basically by using offset antenna's which is essentially what the slit does, creates an offset so the waves are scrambled out of phase, you can put multiple streams on one frequency. This is nothing new, and sadly, Shannon's Law prevails (http://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem http://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem). [fyi, me: 32+ yrs in telecom & wireless, engineer at very large wireless company. ps. love hackernews :) ]
- ck2 15y agoDo electromagnetic waves obey inertia and momentum? Really? How is that possible if they move at the speed of light for any observer?
- sp332 15y agoYes, they really do. Start here and keep reading down the page: https://en.wikipedia.org/wiki/General_relativity#Consequences_of_Einstein.27s_theory https://en.wikipedia.org/wiki/General_relativity#Consequence...
- ck2 15y agoHmm but with things like gravitational lensing, it happens because space itself is being bent, not the wave, wave is just traveling "straight ahead" and doing it's thing. If waves obeyed momentum, then a wildly spinning pulsar's gamma waves would not travel just outward but like a curve ball from a baseball pitcher, they'd be long perpendicular distorted waves.
- sp332 15y agoThe wave "free-falls" toward the object with exactly the same acceleration as anything else passing by. I'm not sure what you meant by the last part. The light beams would form a spiral expanding through space. (Like "zooming in" to the spiral, not turning like a screw.) Each photon moves in a straight line, but since the source of the beam is turning, the beam is a curve though space.
- ck2 15y agoAh you know what - I really wasn't thinking this out. If waves didn't obey momentum then light being emitted by the very monitor I am looking at now would probably not make it to my eyes, or at least be shifted, since the planet and galaxy are moving rapidly.
- henryaym 15y agothe speed of light is independent of the angular momentum... c is still c :)
- mnl 15y agoI've used his free course on Electrodynamics (tricky subject) while developing a text for our Uni. This guy knows his stuff...
- Porter_423 15y agoIt is just another encouraging research.I think it will take few more years to use this technology in communication fields.Its range is still too small.It must be improved otherwise it will not become cost effective and loss will be huge.
- ktizo 15y agowell, the effect seems real enough, looking to other references; http://www.gla.ac.uk/schools/physics/research/groups/optics/research/orbitalangularmomentum/ http://www.gla.ac.uk/schools/physics/research/groups/optics/...