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Twisted Radio Beams Could Untangle the Airwaves

ScuttleMonkey posted more than 5 years ago | from the only-the-flying-spaghetti-monster-would-know-for-sure dept.

Communications 183

Urchin writes "The radio frequency spectrum available for wireless communication is becoming increasingly crowded thanks to new wireless technology. A solution to the shrinking space might be to put a spin on radio beams during their transmission, to produce a twisted beam, according to Swedish physicists. In theory, huge amounts of data could be sent in the pitch of the twist, which is distinct from the amplitude and frequency of radio waves — the features used at the moment to send information."

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Who is John Galt? (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26850037)

For twelve years you've been asking "Who is John Galt?" This is John Galt speaking. I'm the man who's taken away your victims and thus destroyed your world. You've heard it said that this is an age of moral crisis and that Man's sins are destroying the world. But your chief virtue has been sacrifice, and you've demanded more sacrifices at every disaster. You've sacrificed justice to mercy and happiness to duty. So why should you be afraid of the world around you?

Your world is only the product of your sacrifices. While you were dragging the men who made your happiness possible to your sacrificial altars, I beat you to it. I reached them first and told them about the game you were playing and where it would take them. I explained the consequences of your 'brother-love' morality, which they had been too innocently generous to understand. You won't find them now, when you need them more than ever.

We're on strike against your creed of unearned rewards and unrewarded duties. If you want to know how I made them quit, I told them exactly what I'm telling you tonight. I taught them the morality of Reason -- that it was right to pursue one's own happiness as one's principal goal in life. I don't consider the pleasure of others my goal in life, nor do I consider my pleasure the goal of anyone else's life.

I am a trader. I earn what I get in trade for what I produce. I ask for nothing more or nothing less than what I earn. That is justice. I don't force anyone to trade with me; I only trade for mutual benefit. Force is the great evil that has no place in a rational world. One may never force another human to act against his/her judgment. If you deny a man's right to Reason, you must also deny your right to your own judgment. Yet you have allowed your world to be run by means of force, by men who claim that fear and joy are equal incentives, but that fear and force are more practical.

You've allowed such men to occupy positions of power in your world by preaching that all men are evil from the moment they're born. When men believe this, they see nothing wrong in acting in any way they please. The name of this absurdity is 'original sin'. That's inmpossible. That which is outside the possibility of choice is also outside the province of morality. To call sin that which is outside man's choice is a mockery of justice. To say that men are born with a free will but with a tendency toward evil is ridiculous. If the tendency is one of choice, it doesn't come at birth. If it is not a tendency of choice, then man's will is not free.

And then there's your 'brother-love' morality. Why is it moral to serve others, but not yourself? If enjoyment is a value, why is it moral when experienced by others, but not by you? Why is it immoral to produce something of value and keep it for yourself, when it is moral for others who haven't earned it to accept it? If it's virtuous to give, isn't it then selfish to take?

Your acceptance of the code of selflessness has made you fear the man who has a dollar less than you because it makes you feel that that dollar is rightfully his. You hate the man with a dollar more than you because the dollar he's keeping is rightfully yours. Your code has made it impossible to know when to give and when to grab.

You know that you can't give away everything and starve yourself. You've forced yourselves to live with undeserved, irrational guilt. Is it ever proper to help another man? No, if he demands it as his right or as a duty that you owe him. Yes, if it's your own free choice based on your judgment of the value of that person and his struggle. This country wasn't built by men who sought handouts. In its brilliant youth, this country showed the rest of the world what greatness was possible to Man and what happiness is possible on Earth.

Then it began apologizing for its greatness and began giving away its wealth, feeling guilty for having produced more than ikts neighbors. Twelve years ago, I saw what was wrong with the world and where the battle for Life had to be fought. I saw that the enemy was an inverted morality and that my acceptance of that morality was its only power. I was the first of the men who refused to give up the pursuit of his own happiness in order to serve others.

To those of you who retain some remnant of dignity and the will to live your lives for yourselves, you have the chance to make the same choice. Examine your values and understand that you must choose one side or the other. Any compromise between good and evil only hurts the good and helps the evil.

If you've understood what I've said, stop supporting your destroyers. Don't accept their philosophy. Your destroyers hold you by means of your endurance, your generosity, your innocence, and your love. Don't exhaust yourself to help build the kind of world that you see around you now. In the name of the best within you, don't sacrifice the world to those who will take away your happiness for it.

The world will change when you are ready to pronounce this oath:
I swear by my Life and my love of it that I will never live for the sake of another man,
nor ask another man to live for the sake of mine.

Re:Who is John Galt? (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26850123)

DCODER?

Re:Who is John Galt? (0)

Anonymous Coward | more than 5 years ago | (#26850369)

DCODER?

no

Re:Who is John Galt? (0, Offtopic)

Hogwash McFly (678207) | more than 5 years ago | (#26850491)

Yes, yes, oh my God yes!

Re:Who is John Galt? (-1, Troll)

Tiger4 (840741) | more than 5 years ago | (#26850473)

John Galt is a guy with the arrogance to believe he has the secret understanding to run other people's world better than they do themselves, and who live and die by their own mistakes. I avoid him.

Beyond that, I don't care who John Galt is.

Re:Who is John Galt? (0)

Anonymous Coward | more than 5 years ago | (#26850799)

I'm thinking he might be related to this Shampoo guy.

Re:Who is John Galt? (0)

Anonymous Coward | more than 5 years ago | (#26851823)

You mean Shamwow?

Re:Who is John Galt? (1)

damnfuct (861910) | more than 5 years ago | (#26851859)

What you say is inmpossible [sic]

damn (4, Funny)

geekoid (135745) | more than 5 years ago | (#26850071)

Damn, this is so obvious now. I should have thought this up years ago.

Re:damn (5, Interesting)

Anonymous Coward | more than 5 years ago | (#26850173)

Am I missing something?

These guys are proposing polarizing wireless transmissions. Polarization gets affected by ALL kinds of boundary irregularities, such as nearby cars light poles, traffic signal loops and, in buildings, conducting objects like nails, hinges, pipes, etc.

This seems so noisy as to be useless.

Re:damn (5, Informative)

Anonymous Coward | more than 5 years ago | (#26850267)

The article suggests the technique only works really for point-to-point transmission. Regular amplitude/phase modulation (QAM) is still the best generally I'd imagine.

Re:damn (0, Offtopic)

commodore64_love (1445365) | more than 5 years ago | (#26850449)

Like AM? "Hello this is Lush Rimbaugh, your liberal talkshow host. Today our glorious (crackle crackle crackle) passed the non-stimulus (crackle crackle crackle) to save our butts. Praise Atheist." ----- Honey there's a storm on the way. I can hear the lightning on the radio.

Yeah you're right. We don't want another Band that sounds as bad as AM. Digital modulation is the way to go if you want maximum efficiency of the spectrum. HD Radio and Digital Radio Modiale can squeeze FM-quality 40-70 kbps sound into just 10 kilohertz, and 5.1 surround sound in 100 kilohertz..... far better than the Amplitude, Frequency, or Twisty Modulation methods.

Re:damn (5, Informative)

ceoyoyo (59147) | more than 5 years ago | (#26850507)

You are aware that digital radio techniques all use amplitude, frequency or phase modulation, right? The difference is that the modulation is digital (or thereabouts) rather than analog.

Re:damn (1)

FudRucker (866063) | more than 5 years ago | (#26850617)

i agree! digital modulation with narrower filters is the best way get more users without interference in an allocated amount bandwidth...

Re:damn (1)

commodore64_love (1445365) | more than 5 years ago | (#26850917)

No I didn't know that Orthogonal frequency-division multiplexing (OFDM) was based upon old-fashioned AM or FM methods. I find hat hard to swallow, but I also find it non-relevant to my original point. Digital methods squeeze more music into smaller spaces.

Here's approximately what a 10 kilohertz wide AM station sounds like when upgraded to 40-70 kbit/s HDR or DRM: (requires WinAmp or other AACplus-capable player)

http://208.109.125.25:10832/listen.pls [208.109.125.25]
http://91.121.7.164:5950/listen.pls [91.121.7.164]
http://212.117.164.99:8888/listen.pls [212.117.164.99]
http://207.200.96.229:8002/listen.pls [207.200.96.229]

Re:damn (3, Informative)

ceoyoyo (59147) | more than 5 years ago | (#26851331)

Check out the wikipedia page for OFDM: http://en.wikipedia.org/wiki/OFDM [wikipedia.org]

First paragraph: "Each sub-carrier is modulated with a conventional modulation scheme (such as quadrature amplitude modulation or phase shift keying)."

You're right, analog transmissions are generally less efficient for transmitting data. Your AM radio vs. digital radio example isn't quite fair, since the digital radio is compressed - that is, it isn't actually transmitting as much information as the analog channel.

Your overall point is flawed. It is not the type of modulation (AM or FM) that is at fault, but rather the analog nature of the transmission. This new technique actually sounds like it would NOT lend itself naturally to analog transmissions - it would be far more likely to be used with digital encoding.

In fact, you could probably use OFDM if you want to, just like it is commonly used with amplitude modulation.

Re:damn (1)

commodore64_love (1445365) | more than 5 years ago | (#26851483)

Cool. Thanks for the explanation.

Re:damn (0)

Anonymous Coward | more than 5 years ago | (#26851449)

I find hat hard to swallow, but I also find it non-relevant to my original point.

I agree. I once tried to consume my hat as well. Did not go according to plan. Lots of freaks in the ER at 2am, I must add...

Re:damn (1)

Falstius (963333) | more than 5 years ago | (#26852217)

QAM and commercial AM radio are not the same thing. QAM is used extensively for digital communications, especially in modems. It isn't as common is wireless communication, so far as I know. Of course, if this was just a lame excuse to bash Rush Limbaugh, carry on.

Re:damn (-1, Offtopic)

geekoid (135745) | more than 5 years ago | (#26850457)

Yes, yes you are. Don't post AC if you want actual informative answers.

It's not about polarization (5, Informative)

Doug Merritt (3550) | more than 5 years ago | (#26851011)

Am I missing something? These guys are proposing polarizing wireless transmissions.

Yes, you are, and no, they aren't.

This is about modulating the orbital angular momentum of photons, a property that wasn't even discovered until 1992.

Each photon can have an integer quantity of orbital angular momentum (0, 1, 2, 3...) without obvious limit (or in the opposite direction, -1, -2, -3...). In principle, and increasingly in experiment, it is possible to encode information by modulating the orbital angular momentum carried. This provides and entirely separate channel with its own bandwidth in addition to traditionally understood modulation. They're right to be excited about it; it has the potential of being just as big in scope as was the invention of radio.

See http://www.physics.gla.ac.uk/Optics/play/photonOAM/ [gla.ac.uk]

Re:It's not about polarization (1)

kmac06 (608921) | more than 5 years ago | (#26851185)

Mod parent up. This is about orbital angular momentum, not spin, or what you would typically think of as polarization.

Re:It's not about polarization (0)

Anonymous Coward | more than 5 years ago | (#26852389)

Er, "spin" is the property described by "angular momentum", especially in the context of subatomic particles. And they really are talking about altering the orientation of the axis of polarization.

Re:It's not about polarization (4, Interesting)

johncadengo (940343) | more than 5 years ago | (#26851905)

This provides and entirely separate channel with its own bandwidth in addition to traditionally understood modulation. They're right to be excited about it; it has the potential of being just as big in scope as was the invention of radio.

Isn't one of the hugest factors in the Fermi Paradox [wikipedia.org] the "Great Silence" aka that if life in the universe is so abundant why don't we hear their radio transmissions?

Now, how many other "channels" out there do you think exist that we simply have no grasp or knowledge of?

Does this open up a new potential medium for listening [seti.org] ?

Re:It's not about polarization (1)

LordSnooty (853791) | more than 5 years ago | (#26852379)

That's not a wise civilisation which broadcasts messages to the universe using a very advanced technology. I hope that if one day we were to set up a permanent beacon marking our presence we would use only the most basic transmission method, to aim for the highest audience.

If a civilisation only wanted to 'contact' other similarly advanced worlds then I suppose it could still hold true. But I like to think that every sentient being out there is just as curious and fascinated about the possibility as we are, and that the notion of Earth-destroying aliens can never be true.

Re:It's not about polarization (1)

Falstius (963333) | more than 5 years ago | (#26852241)

Thanks for the heads up, I was about to dismiss this as fluff. Instead it is something 10-20+ years off, but much more interesting.

Re:It's not about polarization (0)

Anonymous Coward | more than 5 years ago | (#26852257)

It reminds me of a tea room conversation that once occurred at Sydney Uni. I wasn't part of it and only know about through someone else. The conversation centred on the different ways you could modulate information onto an electromagentic wave/photons. The obvious ways are: amplitude, phase, polarisation, ... The person who told me the story reckoned they got up to 23 methods. I don't know what they all were though. Maybe its just a myth.

Here's a first attempt at recreating the list (as you can see my physic knowledge is limited). Please feel free to extend to the list until it contains 23 entries!

  • amplitude
  • phase
  • polarisation
  • orbital angular momentum
  • ...

Re:damn (1)

Bromskloss (750445) | more than 5 years ago | (#26851119)

These guys are proposing polarizing wireless transmissions. Polarization gets affected by ALL kinds of boundary irregularities, such as nearby cars light poles, traffic signal loops and, in buildings, conducting objects like nails, hinges, pipes, etc.

Good point, but I'm thinking that if the environment (and its influence on the polarisation) change slowly compared to the speed with which the transmitter modulate the polarisation, it might work anyway. What do you say?

Re:damn (4, Informative)

johanwanderer (1078391) | more than 5 years ago | (#26851277)

This is slightly different than simple polarization, see here: http://www.newscientist.com/article/mg18224515.000 [newscientist.com] -- full article requires log-in. Or here: http://www.physics.gla.ac.uk/Optics/play/photonOAM/ [gla.ac.uk] The point here is that a "pulse" can now encode more than just an "on/off" state. Instead, a pulse now encodes a "twistiness" level of states (can be 1, 2, 3, or up to 250 as in the NS article.) So, a 2GHz signal can now carries, let's say, 2x8 = 16 Gb/s. The trouble, it seems, is to construct a receiver capable of correctly identifying the pulses.

Re:damn (0, Redundant)

commodore64_love (1445365) | more than 5 years ago | (#26851503)

>>>These guys are proposing polarizing wireless transmissions. Polarization gets affected by ALL kinds of boundary irregularities, such as nearby cars light poles, traffic signal loops and, in buildings, conducting objects like nails, hinges, pipes, etc. This seems so noisy as to be useless.
>>>

Like AM?

"Hello this is Lush Rimbaugh, your liberal talkshow host. Today (crackle crackle crackle) passed the (crackle crackle crackle) bill." ----- Honey there's a storm on the way. I can hear the lightning on the radio.

Yeah you're right. We don't need another Band that sounds as bad as AM. Digital modulation is the way to go if you want maximum efficiency of the spectrum. HD Radio and Digital Radio Modiale can squeeze FM-quality 40-70 kbps sound into just 10 kilohertz, and 5.1 surround sound in 100 kilohertz..... far better than the Amplitude, Frequency, or Twisty Modulation methods.

Re:damn (2, Interesting)

mikael (484) | more than 5 years ago | (#26852053)

Yes, you did miss something. The authors are not talking about the planar or circular polarization of individual photons. They are describing how it is possible to combine photons together such that a light beam itself has orbital angular momentum. When such a beam of light hits a small particle, the combined arrival of the photons forces the particle to start rotating. The smallest light beam need only consist of two entangled photons.

Maybe they will figure out how to combine several such light beams together such that it is possible to push and pull particles towards and away from the light source as well as translate them sideways and make them rotate.

Almost! (1)

Anonymous Coward | more than 5 years ago | (#26850085)

I would have had first post, but my waves got twisted...

Re:Almost! (1)

Wandering Wombat (531833) | more than 5 years ago | (#26850985)

It's a series of twisted tubes. Wait, didn't they have that in Resident Evil...?

Re:Almost! yeh.. now we can have totally (1)

davidsyes (765062) | more than 5 years ago | (#26852423)

TUBULAR communications... I wonder if they will use real wires to guide the signal. A WHOLE new infrastructure project can be charge up...

Imagine the rat's nest of horrors to emerge from that... Our voices will sound like we emerged from my chamber of IT horrors... All together now:

skweee skweee squeee squeee

The new headquarters can be based at... "SHOCKCOM": Somnambulizing High Output Communications-Killing Civilians On Mass...

(Damn, dropped my crack bowl...)

Re:Almost! (0)

Anonymous Coward | more than 5 years ago | (#26852185)

I hate it when my Schwartz gets twisted.

Oh, Great (2, Funny)

Banichi (1255242) | more than 5 years ago | (#26850111)

Now we have "Spinnaz" for telecommunication geeks.

Re:Oh, Great (1)

nextekcarl (1402899) | more than 5 years ago | (#26850611)

I bet that's where they come up with the idea. Damn Swedish geeks. We don't need no spinners!

Re:Oh, Great (2, Funny)

fbjon (692006) | more than 5 years ago | (#26852201)

Only problem is, packets received through a twisted link come with the evil bit set.

Two questions (4, Interesting)

jandrese (485) | more than 5 years ago | (#26850169)

1. How practical is this technology? Could you mass produce cheap low power receivers to put in every car/computer/etc...? How complex is the transmit circuitry?
2. How resistant is this to atmospheric and other interference? In theory it should be pretty resistant, but in practice who knows.

Needing multiple antennas to get this done sounds like a rather big limitation to me.

Re:Two questions (2, Insightful)

PotatoFarmer (1250696) | more than 5 years ago | (#26850215)

3. Is there any way to extract this information from transmissions we've recorded in the past? Would be interesting if turns out that SETI has been pulling down alien sitcoms for years without knowing it.

Re:Two questions (2, Interesting)

lobiusmoop (305328) | more than 5 years ago | (#26851401)

Interesting implications for other fringe-science fields, such as ESP and the paranormal. What kind of information has been being transmitted/received through the ether that we've never previously had the knowledge/tech to receive and interpret?

Re:Two questions (2, Insightful)

Dekker3D (989692) | more than 5 years ago | (#26851629)

if you look at it like that, we'll never be able to disprove the paranormal since we'll never be able to claim that we've found all possible ways to receive and interpret data. it's one of the reasons why i think it's silly to even try disproving such things.

Re:Two questions (2, Informative)

badboy_tw2002 (524611) | more than 5 years ago | (#26850303)

1. Its completely practical considering the first ever case of these types of waves ever being sent was just published and the first ever example was done on a 48 antenna space array, not to mention they don't have a receiver. Given that most technology moves immediately from research to mass production in the space of a week, I'd say $20-30.

2. Again, seeing as the first ever examples of this were just transmitted with no receiver there's been a lot of time for field study. Or are you saying you're one of the unlucky few /. readers who don't have a home built twisted radio frequency array?!?! I built one and I didn't even RTFA! So first step is to get one working, and then I'll beam the answer to you at twist frequency 124.

Actually, all kidding aside the answer is that this technology is brand new. Its also completely worthless because there isn't an immediate practical application available in the store. Stupid scientists!

Re:Two questions (1)

hurfy (735314) | more than 5 years ago | (#26850483)

The no receiver part was interesting. Can we assume you need something similar to the sending array to receive? My car is going look funny if i add 47 more antennas, especially if i have to complete a particular design :)

In other news...

I have successfully sent a psychic beam transmission...noone can receive it and i haven't made a translator yet, so even if you do, you won't understand it...don't sweat the details....trust me...

Re:Two questions (2, Funny)

nextekcarl (1402899) | more than 5 years ago | (#26850643)

Then who sent me the message to, "Kill the family"? Or was that, "Bill loves Emily"? Reception isn't too good some days.

Obligatory (4, Funny)

Bovius (1243040) | more than 5 years ago | (#26850175)

Do a barrel roll!

Sorry, couldn't resist.

in this house we obey shannon's theorem (1, Interesting)

cats-paw (34890) | more than 5 years ago | (#26850191)

It's not obvious to me what all the excitement is about.

"Huge" amounts of data as compared to what exactly ?

Whatever they are doing, it can't get past Shannon's theorem as a limit on the amount of information available for a given bandwidth.

This looks to me like it probably simply reduces to MIMO :

http://en.wikipedia.org/wiki/Multiple-input_multiple-output [wikipedia.org]

Either way the capacity is limited to N * the capacity for one antenna (remember Shannon's law applies per channel).

So back to, what does this do exactly ?

Re:in this house we obey shannon's theorem (5, Insightful)

ceoyoyo (59147) | more than 5 years ago | (#26850607)

Shannon's law is a tricky piece of work. It doesn't actually tell you how much data you can transmit given a particular amount of bandwidth. It tells you how much data you can transmit given a particular amount of bandwidth and particular noise characteristics over a given channel.

Now, you can play various games with that. If you limit yourself to, say, frequency modulation, you just measure the noise, run it through Shannon, and get your result. But what if you polarize the signal and encode data in that? Have you broken Shannon's law? No. You can account for things like that by counting it as a separate channel, or by changing your noise estimate to account for the additional, independent modulation technique.

These guys' modulation technique is another independent channel.

The article does say it's probably not going to work very well for things like cell phones though, since you need an antenna array. It might be useful for things like microwave towers though.

Re:in this house we obey shannon's theorem (1)

cats-paw (34890) | more than 5 years ago | (#26851301)

You cannot play games with it.

Fix the bandwidth, fix the noise, fix the power. There is now a hard limit on your datarate. Don't care about coding, modulation format, or anything else in that 1 channel. All that stuff will effect the datarate which you _actually_ get and that number will be less than or equal to shannon's limit.

People only think they can play games with it to dupe potential investors.

A good question is, what constitutes a channel ?

Well channels have to be independent, that's why having more than 1 antenna works. Notice that in MIMO, 2 antennas on each side gives you 2 times the datarate (max) NOT 4 times. And it doesn't make a ripping bit of difference how you work the polarization on those antennas.

Added polarization on the _same_ antenna does _not_ count as an additional channel.

Polarization will ameliorate the effects of multipath, but it is most certainly not another channel.

Re:in this house we obey shannon's theorem (1)

John Hasler (414242) | more than 5 years ago | (#26851459)

This is not about polarization.

Re:in this house we obey shannon's theorem (1)

ceoyoyo (59147) | more than 5 years ago | (#26851507)

They state that their technique is independent of both frequency and amplitude modulation. Reading the details, it isn't obviously related to polarization. Sorry, but given two claims I have to believe the published scientists who got to play with a major US defense research installation rather than Joe random from Slashdot.

Does not violate shannons theorm. (2, Insightful)

geekoid (135745) | more than 5 years ago | (#26851849)

py|x(y|x)

This would increase X and Y, so doesn't violate Shannon's theorem. If memory serves, x and y are what determines a channel. This technique would be another channel... kinda.

Oh, and what you are really talking about is channel capacity. Not Shannon's theorem which is about optimal error correction.

Imagine a long solid metal pole.
Now imagine a theorem that describes the max. data that can be written on the surface of this solid pole.

Now imagine some smart guy comes along turns the solid pole into a tube. The tube is still the same length. but the surface area has increased, the max information has increased. The theorem would still be sound because the surface are increased.

I apologize for such a primitive example, it's only to illustrate a point not to accurately define EM theory~

Re:Does not violate shannons theorm. (1)

cats-paw (34890) | more than 5 years ago | (#26852329)

I'm pretty darn sure that shannon's theorem is about channel capacity. It _tells_ you how good you can be even when you use error correction. From wikipedia:

The theorem establishes Shannon's channel capacity for such a communication link, a bound on the maximum amount of error-free digital data (that is, information) that can be transmitted with a specified bandwidth in the presence of the noise interference, under the assumption that the signal power is bounded and the Gaussian noise process is characterized by a known power or power spectral densit

And, as another poster observed the particular article in question does not have anything to do with polarization. I was saying , and not very clearly, that they are simply taking advantage of multiple antennas, and it doesn't really matter what gee whiz thing they do with them, they are still going to get N*C bits/s/hz, where N is the number of antennas and C is the channel capacity for a single antenna.

Be careful that you do not confuse directionality of the antenna pattern (which gives you an apparent boost in power and therefor capacity) with some sort of magical capacity multiplier.

I like your example of the rod and the tube.

The biggest problem is that they don't actually provide any quantitative information.

However I agree with the original responder that it can sometimes be tricky defining what constitutes a channel.

Re:in this house we obey shannon's theorem (1)

John Hasler (414242) | more than 5 years ago | (#26851883)

it adds another channel.

obligatory (-1, Troll)

Dekortage (697532) | more than 5 years ago | (#26850229)

In Soviet Russia, radio beams twist YOU!

As Dr. Egon Spengler once said (3, Funny)

auric_dude (610172) | more than 5 years ago | (#26850235)

Don't cross the streams.

Re:As Dr. Egon Spengler once said (1)

geekoid (135745) | more than 5 years ago | (#26851869)

Why?

Strangely... (1)

reginaldo (1412879) | more than 5 years ago | (#26850243)

After implementing this all radio communications play Chubby Checker's "The Twist" softly in the background.

AM, FM, and... (0)

Dracos (107777) | more than 5 years ago | (#26850249)

TM?

No (3, Informative)

rcw-home (122017) | more than 5 years ago | (#26850295)

The article appears to be referring to right or left circular polarization [wikipedia.org] , as opposed to horizontal or vertical polarization. A horizontally-oriented dipole transmitting near a vertically-oriented dipole will be heard much more faintly - 20db+ quieter [air-stream.org.au] . Similarly, a left-polarized antenna won't interfere with a right-polarized antenna. But a circularly-polarized antenna will still interfere with a horizontally or vertically polarized antenna - it'll only be 3db weaker [nitehawk.com] .

Re:No (1)

dimethylxanthine (946092) | more than 5 years ago | (#26850899)

Just glancing at the summary I thought maybe the reference was made to giving Helicity [wikipedia.org] - i.e. spin to the radio waves. That could be an interesting possibility if it were actually possible, as it'd be another dimension in which to encode information.

---
"There is usually room on top for one more" -- Oscar Wilde

Re:No (1)

rcw-home (122017) | more than 5 years ago | (#26851085)

Fascinating. I'm certainly not an expert in particle physics, but since photons are both particles and waves, is particle spin entirely distinct from electromagnetic polarization?

Re:No (5, Informative)

Doug Merritt (3550) | more than 5 years ago | (#26851123)

Nope, this absolutely is not about polarization.

This is about modulating the orbital angular momentum of photons, a property that wasn't even discovered until 1992.

Each photon can have an integer quantity of orbital angular momentum (0, 1, 2, 3...) without obvious limit (or in the opposite direction, -1, -2, -3...). In principle, and increasingly in experiment, it is possible to encode information by modulating the orbital angular momentum carried. This provides and entirely separate channel with its own bandwidth in addition to traditionally understood modulation. They're right to be excited about it; it has the potential of being just as big in scope as was the invention of radio.

See http://www.physics.gla.ac.uk/Optics/play/photonOAM/ [gla.ac.uk]

Re:No (1)

rcw-home (122017) | more than 5 years ago | (#26851379)

Thanks. That link is much clearer than the original article, and describes a (relatively) simple experiment to reproduce the results.

Now go update the Wikipedia article on photons [wikipedia.org] : "A photon [...] is described by exactly three continuous parameters: the components of its wave vector, which determine its wavelength Î and its direction of propagation."

Re:No (2, Funny)

Mr. Conrad (1461097) | more than 5 years ago | (#26851701)

I read a while back that both Fox and MSNBC were interested in polarization. Only Fox wanted to twist their signals to the right while MSNBC seemed more interested in twisting theirs to the left.

Told ya? (0, Troll)

meist3r (1061628) | more than 5 years ago | (#26850335)

Really? No wai! That's like totally so not Apple y'know. Back when Steve was still around they would've ... like ... never done that.

does satellite internet already do this? (3, Interesting)

steak (145650) | more than 5 years ago | (#26850339)

I install wildblue satellite internet and we have two type of transceivers right hand and left hand polarization. after rtfa I am curious if this is the same thing or something different?

Re:does satellite internet already do this? (3, Interesting)

scerruti (1233214) | more than 5 years ago | (#26850435)

I don't know about wildblue, but when I was working with satellite about 10 years ago DirecTV was circularly polarized DirecPC was not.

Cool, impractical - where's Roland? (0)

RobertB-DC (622190) | more than 5 years ago | (#26850345)

When I read the summary, for some reason I immediately thought of the dearly departed Roland Piquepaille [slashdot.org] . It's a cool-sounding idea, easy to convert from "science" to "media", and utterly impractical for the putative use. The research was done with a military antenna array so massive that people were afraid it would destroy the ionosphere [straightdope.com] , so there's no chance of seeing a new band on your car radio (and an excellent chance that it will never be more than a scientific curiosity). But "Twisted Radio Beams" -- that's a headline that the public can sink their teeth into.

So I immediately thought of Roland, and realized just how much I miss his gee-whiz almost-scientific submissions. I'm going to tag this article "ohnoitsroland" (and my own invention, "pigpile") in his honor.

Re:Cool, impractical - where's Roland? (1)

geekoid (135745) | more than 5 years ago | (#26850547)

"...array so massive that deluded ignorant people were afraid ..."

The has been scaled smaller.
While it can't work with a dipole antenna, it can work with a tripole. So your hand held device wont, but industrial level equipment can do this, so you could get more data to the 'tower' and then parse it our according to your needs to the consumer.

Also, this part of the signal want degrade as fast over long distance. Think transmitting to mars cheaply.

Twisty Modulation? (-1, Redundant)

commodore64_love (1445365) | more than 5 years ago | (#26850353)

"Welcome to hot TM, your place for mindless music so you can dance, dance, dance! (sings) TM 106.5"

Ehhhh. Just use Digital Radio; it can squeeze FM quality audio (40 kbit/s AACplus) into just 10 kilohertz width.

Re:Twisty Modulation? (2, Informative)

Gizzmonic (412910) | more than 5 years ago | (#26850569)

Yeah but who wants to pay extra to hear the same old shit? Wow, a higher quality feed of the same 10 songs that commercial FM radio plays over and over again.

Not to mention, digital radio fucks up adjacent channels, especially on AM. They really need to scrap AM like they did with digital TV (although that transition was far from perfect). FM is just fine. I don't think people really care about audio quality that much (why would

FM is polarized as it is for a reason (3, Informative)

Anonymous Coward | more than 5 years ago | (#26850419)

There is a reason that FM is polarized in the direction it is: any other direction is relative.

FM is vertically polarized because that means that a car needs only have a vertical antenna to catch the signal, if they polarize it horizontally then the antenna on the car needs to rotate every time the car turns.

At least this is what I was told in my RF/microwave design class.

FM is circularly polarized, not vertically! (3, Interesting)

NixieBunny (859050) | more than 5 years ago | (#26851243)

Actually, broadcast FM is nearly always circularly polarized using a multi-bay antenna with a bunch of 3/4 circle center-fed elements, each with one end pointing up and the other down.

If you weren't aware of this, go look atop an FM tower with binoculars some day.

Good luck finding the published theory on these antennas, since they're all proprietary designs!

Twisted Radio Waves (4, Informative)

komische_amerikaner (1365847) | more than 5 years ago | (#26850443)

AFAIK (yes, I did RTFA), this is tantamount to adding another method of data transmission using more of the envelope. You still have the frequency being used and still have a portion of the carrier plus sideband transmitted, no matter what type or method of transmission is used. This may be used to embed something similar to a sub-carrier, or a unique identifier. More directivity and narrower beamwidth during point-to-point transmissions will do wonders to keep the RF floor down.

Re:Twisted Radio Waves (0, Redundant)

Doug Merritt (3550) | more than 5 years ago | (#26851183)

Nope, that's not what they're doing. They're using physics that wasn't even discovered until 1992.

See http://www.physics.gla.ac.uk/Optics/play/photonOAM/ [gla.ac.uk]

Re:Twisted Radio Waves (1)

tweak13 (1171627) | more than 5 years ago | (#26852215)

I know you've been posting this all over the place, but I don't see how what he said is wrong. You're still going to have to emit a signal of some sort, and that signal is still going to take up part of the available spectrum. You may be able to reduce information that would otherwise have to be modulated in a conventional way, thus reducing the sidebands, thus reducing interference to adjacent channels. If you could get this to the point that you don't have to use conventional modulation at all, then the sidebands would get incredibly small, but the carrier would still be there.

Not New, Not News (2, Informative)

DynaSoar (714234) | more than 5 years ago | (#26850475)

The "In Soviet Russia" joke has already been inserted, so I'll go on to the next step:

The technique described is independent of amplitude and frequency in that it is based on polarization. Circular (clockwise and counter clockwise) polarization was used in Soviet and early post-CCCP Russian satellite communications. I had an article from ~25 years ago that showed how to alter a US type vertical/horizontal polarization low noise amplifier on a satellite receiving dish to pick up clock/counter signals. (The trick was to insert a teflon plate at a 45 degree angle to the vert/horiz signal; I tried it, it picked up the signals but I couldn't decode them with a US commercial receiver). One may feel free to speculate on the history of Sweden vs. Russia/CCCP and this claim by Swedish scientists to have 'discovered' this technique. There's no reason why satellites couldn't have had both kinds of polarization on board, except that each required its own transceiver. Todays' larger birds could carry both and help alleviate the Clarke orbit traffic jam. The same concept can be applied to terrestrial equipment, and in fact could have been used for years.

Twisted (1, Funny)

Anonymous Coward | more than 5 years ago | (#26850499)

Twisted radio == good.
Twisted schwartz == bad.

Is spinning radio waves... (1)

ahoehn (301327) | more than 5 years ago | (#26850501)

Is spinning radio waves anything like spinning bullets [xkcd.com] ? Because that would be totally awesome.

only 140 years late (2, Interesting)

Ancient_Hacker (751168) | more than 5 years ago | (#26850559)

Polarization has been known since about 1200AD when the Vikings used calcite crystals to navigate by. It also pops right out of Maxwell's equations.

It's been used to make directional radio antennas since about 1925.

It's been used to dynamically steer and polarize signals ever since phased-array radars came in use, circa 1965.

And no, you can't transmit huge amounts of information that way. Circular polarization is just a vector sum of two quadrature vectors. There's nothing you can do with a sum that is more information efficient than a single vector.

Re:only 140 years late (1)

jpmattia (793266) | more than 5 years ago | (#26851029)

There's nothing you can do with a sum that is more information efficient than a single vector.
Two orthogonal polarizations (left- and right-circularly polarized, in your example) will carry twice the information. This technique has already been used for years in fiber optics.

Re:only 140 years late (1)

Ancient_Hacker (751168) | more than 5 years ago | (#26851633)

>will carry twice the information.

I meant summing two to get one circular signal. You're of course correct that you can sum two more with opposite chirality to get another channel.

NOT 140 years late (3, Insightful)

Doug Merritt (3550) | more than 5 years ago | (#26851217)

Nope, that's not what they're doing; it's not polarization. They're using physics that wasn't even discovered until 1992.

See http://www.physics.gla.ac.uk/Optics/play/photonOAM/ [gla.ac.uk]

Re:NOT 140 years late (1)

Ancient_Hacker (751168) | more than 5 years ago | (#26851677)

As far as I can tell, they're phase-modulating the polarization. Very clever but not new on the transmitting end. If their fancy interferometer phase-sensitive receiver can be made to work well they may have something, but I think in the end Shannon's limits still apply.

Signal theory has been extremely extensively studied, so it's unlikely someone not familiar with the field, like these optics guys, have found a loophole.

Re:NOT 140 years late (3, Informative)

Doug Merritt (3550) | more than 5 years ago | (#26851987)

As far as you can tell? Why don't you just go look at the link I provided?

It won't take but a second for you to stop guessing that it's about polarization once you see their clear explanation that it's different.

Re:only 140 years late (1)

geekoid (135745) | more than 5 years ago | (#26851897)

If only this was polarization. SO the question is:
Did you not RTFM, or were to just too stupid to UTFA

*Understand.

This is already done (1)

JoeBuck (7947) | more than 5 years ago | (#26850567)

Perhaps it's just the journalists messing this up, but the article suggests that these guys think that only amplitude and frequency are used in digital communication. However, every modern digital communication standard uses the phase as well, which is equivalent to a twist.

Wikipedia has a reasonably easy-to-follow explanation [wikipedia.org] of how this works.

This NOT already done (4, Informative)

Doug Merritt (3550) | more than 5 years ago | (#26851237)

Nope, that's not what they're doing; this particular "twist" is absolutely not identical to previously well-understood phase modulation.

They're using physics that wasn't even discovered until 1992.

See http://www.physics.gla.ac.uk/Optics/play/photonOAM/ [gla.ac.uk]

Carl Segan wants his idea back from "Contact" (1, Informative)

Anonymous Coward | more than 5 years ago | (#26850749)

Carl Segan wants his idea back from "Contact"

GPS (1)

x102output (536049) | more than 5 years ago | (#26850755)

I thought this has already been used? GPS sats shower down circular polarized signals. The antennas even have a "twist"-shaped like conductor.

Not a technology issue (1)

girlintraining (1395911) | more than 5 years ago | (#26850781)

This is not about technology. With new encoding schemes and whatnot, there is enough space to accomodate most uses. The problem is one of economics. First, entrenched infrastructure. It costs money to upgrade, as this whole "digital TV" transition proves (arguments about corruption aside). Also, in this country at least airwaves are sold off to the highest bidder, not necessarily the "Best interest" use of that spectrum. So we have technology from the 1940s working side-by-side with stuff that became out of date 3 years ago. The problem isn't spectrum allocation or encoding, or any fancy tech crap.

It's economics. And economics is about people. And the people in control of the airwaves are making a huge mess of things because they believe that highest bidder = most public good. You want to "untangle" the airwaves? You need to start by firing everyone on the board of the FCC, restructuring it, and then preparing to sink at least a hundred billion into retooling the infrastructure. Since nobody wants to do that... Get used to congestion, crap reception, and paying through the nose for basic services. Like your cell phone.

Re:Not a technology issue (1)

geekoid (135745) | more than 5 years ago | (#26851909)

heh, only for a few more years, then the airwaves will start to clear up as piping you entertainment from the internet to the 'TV' becomes mainstream.

50% Efficiency Improvement (0)

Anonymous Coward | more than 5 years ago | (#26850821)

Hi,

Adding the additional orthogonal dimensionality of RHCP and LHCP polarization to the extensively used I and Q complex amplitude channels of conventional modulation yields a baseline 50% increase in bits/sec/hz at a given SNR vs BER (which is the appropriate metric when discussing modulation format efficiency). Prototypes backed up by rigorous derivation exist that prove the effect, and Direct Spatial Antenna Modulation (DSAM) is one of the most efficient means to implement this functionality on the emerging technology horizon.

Basically, a dimensionality of one gives you 1 bit/sec/hz at given BER vs SNR (two states). Two gives you 2 bits/sec/hz at same BER vs SNR (four states) and then you are out of complex amplitude signal dimensions. Polarization adds a third dimension, yielding a new optimum at 3 bits/sec/hz at same SNR. Conventional modulation currently gets at higher bits/sec/hz through slicing up the two I and Q channel sets more thinly, requiring more SNR to get the same BER - so requires more transmit power for same link range. This is why your WLAN throttles back to BPSK (1bit/sec/hz) from 16-QAM (4bits/sec/hz) when the going gets rough.

Really, the innovation is in the treatment of polarization as a dimension on par with the I and Q channels so heavily treated in conventional modulation theory. Thus my involvement in this area of research...

Cheers!

Are They Suggesting Polarity Modulation? (1)

xquercus (801916) | more than 5 years ago | (#26851137)

What exactly do they mean by "twist". Do they mean to transmit information by modulating the polarity of the signal?

Oh... (0)

Anonymous Coward | more than 5 years ago | (#26851139)

do they have a better tinfoil hat for me?

So we now have (1)

Tiber (613512) | more than 5 years ago | (#26851481)

AM, FM, and TM?

Great, I predict this will file for chapter 11 shortly, along with that XM crap.

angular momentum, not spin (1)

anonymShit (1415181) | more than 5 years ago | (#26851771)

The news refers to the use of angular momentum of light (radio waves in this case), not to the spin (polarization). Apart from polarization, light can have an angular momentum, which consists in a torque-like space distribution of its phase. Since this refers to a continuous variable, this application extends the set AM+FM to AM+FM+LM or whatever they call this new modulation.

The angular momentum of light is years old, but the news is that it has been recently implemented in the radio wavelength, which apparently was difficult.

Orbital Angular Momentum versus Polarization (3, Informative)

TheSync (5291) | more than 5 years ago | (#26852397)

This article [aip.org] has a good explanation of the difference between Orbital Angular Momentum and Polarization of EM waves.

If you look at the cross section of a "normal" polarized EM beam, the electric field amplitude and direction at every point of the cross section are in the same phase - although that direction may be up, down, or rotate over time depending on the polarization.

In an EM beam with orbital angular momentum, the electric field amplitude at different points on the cross section are in different phases - although it is my understanding they are usually all in the same polarization.

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