Wireless breakthrough: one frequency, multiple signals

A team of Italian radio boffins – and one Swede – have one-upped their pioneering countryman Guglielmo Marconi by demonstrating a method of simultaneously transmitting multiple signals on the same frequency. "This novel radio technique allows the implementation of, in principle, an infinite number of channels in a given, fixed bandwidth, even without using polarization, multiport or dense coding techniques," the team explains in a paper in the March issue of the New Journal of Physics.

Source

Simple idea here! But what a clever way to 'split' a frequency signal! I love how low tech the method is, those crazy Italians!

You can see here (pic from source) how the signal is sent by creating a higher section on the dish, this is giving the signal a 'spin' to it by allowing part of the signal to be sent slightly before the lowest part of the dish. This spin can potentially be split much further greatly increasing the carrying capabilities of a frequency. Very clever indeed!

The sent beam was then encoded with two separate signals timed to occupy opposite angles of the spin, and antennas were set up to receive each of them. Theoretically, much more discrete signal-slicing could fit more signals into the same transmitted frequency.

Such a simple screw like design (I'm thinking Da Vinci here) could really help solve the ever increasing bandwidth problems of the worlds frequency spectrum which have become so badly crowded.

Here in Australia our digital TV network was all set up and all was well for full HD signals to be sent out. But the networks got greedy and kept splitting up their share of the spectrum to give us more and more channels. That's great and all, but why did I buy a HD tv to get sub quality signals?? Most of the content they carry now is in SD due to limiting themselves! Hopefully this tech can become mainstream so I can get full HD back and a higher bit-rate of sound as well.

Nice one Italy!

This image from the same source shows the maths of how it works... I'm not a mathematician, so I'm not going to even try to explain it, but it may be of use to some of you.





edit:
(Sorry all, just have to duck out for the rest of the day, hope you can get some interesting thoughts in here! Looking forward to reading what you guys add)

I have heard of vertical, horizontal and circular polarization.

But not spinning polarization...

Seems unlikely to work.

In had to check the date,thought maybe I'd slept all the way through March and had woken up on April fools day.
A slightly mangled satellite dish can't "spin" a radio signal as if it's some sort of RF corkscrew and multiplexing by sending numerous different bits of data down one carrier wave or even a single piece of wire has been done successfully for many many years.

reply to post by Qumulys


Well, it looks absolutely brilliant to me, whether you believe a cut satellite dish could achieve it or not.

The art of warping the frequency via spin (or let's say in the future, using quantum mechanics) could revolutionize the way we use wireless communications.

Originally posted by kawika
I have heard of vertical, horizontal and circular polarization.

But not spinning polarization...

Seems unlikely to work.

..well if kawika hasnt heard of it.


thats awesome. good to know there is more spectrum then we think.

reply to post by braydenf


Subspace radio, like in Star Trek,

now that would be cool.

Here is a helix, commonly called a cork screw. This would give you circular polarization. Kind of a spinning signal.

Originally posted by kawika
reply to post by braydenf

 

Subspace radio, like in Star Trek,

now that would be cool.

agreed!

and much more useful

From the same article posted in the OP:

Team member Bo Thide of Swedish Institute of Space Physics first conceived the orbital angular momentum idea in a 2007 paper focussed on radio astronomy, but in which he wrote that the concept "paves the way for novel wireless communication concepts." Last year, Tamburini, Thide, and their team demonstrated the multiple-signal technique by beaming two separate audio signals at 2.4GHz, then two television signals, 442 meters from the lighthouse of Venice's San Giorgio Island to the balcony of the Palazzo Ducale. "It's exactly the same place that Galileo first demonstrated his telescope to the authorities in Venice, 400 years ago," Thide told BBC News. As Thide noted, those authorities were skeptical. "They were not convinced at all; they could see the moons of Jupiter but they said, 'They must be inside the telescope, it can't possibly be like that.' To some extent we have felt the same [disbelief from the community], so we said, 'Let's do it, let's demonstrate it for the public'." ®

Well if it's real, very good work Italy and Sweden!!

I don't know why, but this story remembers me the Norway spiral......

Originally posted by Imagewerx
In had to check the date,thought maybe I'd slept all the way through March and had woken up on April fools day.
A slightly mangled satellite dish can't "spin" a radio signal as if it's some sort of RF corkscrew and multiplexing by sending numerous different bits of data down one carrier wave or even a single piece of wire has been done successfully for many many years.

TDM - Time Divisional Multiplexing

Amazing that we can pack 1.53mpbs async (up and down) over four crappy copper wires (t1) or simultaneious phone calls. super nifty to me, even though its a bit dated. Has been around for a long time, and was created by AT&T / Bell Labs to pack more into less circuits.

TDM - Wikipedia

Great thread and absolutely clever idea!

I was wondering if it could be used in astronomy, for probes communications for example?
S&F

Thanks everyone for the replies!

I thought some of you might find it interesting, I did! Expanding on what elevenaugust said, it gives another thing to look for in signals SETI picks up. Anyway, I just loved how low tech the idea is.

It looks interesting, but from what I understand of it, it only works in a fixed direction. So the antennas requires to be pointed exactly towards each others. Practical applications may be satellites and other long distance connections, but I don't see how it would work for any mobile device, as the direction the antennas are pointing to is constantly changing. I may be wrong though.

reply to post by -PLB-


I'm not sure of the logistics on how exactly this works, but they seem pretty chuffed about what they've accomplished so I think it could have practical uses down the track to ease an evermore congested freq range.

I hope some radio experts from ATS could perhaps help us/me understand better? My thinking was going on the track of this...
If one side is raised and that signal can be detected slightly before the lowest point, could this not be employed without modifying the antennae? The outer-most rim is technically ahead of the deepest point of the dish, but obviously that's not going to cause the signal to twist.

I'd like a clearer explanation on how this twisting works. Any technical help in understanding this principal better would be great ATS!

Originally posted by kawika
reply to post by braydenf

 

Subspace radio, like in Star Trek,

now that would be cool.

Here is a helix, commonly called a cork screw. This would give you circular polarization. Kind of a spinning signal.

edit on 2-3-2012 by kawika because: added image

I must be behind on my radio theory. I've never heard of circular polarization.

On another note, used to moor alongside dixon in the 80's.

If this is true,

what are the odds of using in other areas(energies), such as beam weapons, magnetics, and or light?

Maybe cool..

reply to post by Qumulys


I've heard of this a while ago but as "twisted" not spinning single frequency manipulation. Also a great way to hide a signal with in a single frequency signal, or use this method to "assign a fingerprint" as to source, and the receiver would have to know this pattern to uncover the "key" Nice.

1080p is not sharp enough for me, I need at least 2160p+ still not happy with the technology.

With wireless technology, my only gripe is currently with 802.11bgn technology as the range is quite limited with current power limitations. Sure we can build antennas etc, but it needs to be standardized since all of us use smartphones and we would like to not use the 3g networks so much to keep the networks working good.

TDM can have mutiple signals in 1 frequncy, it has doen for years.
This method is clunky and prone to alot of errors

reply to post by definity


TDM = multiple signals spread across time (different times)
FDM = multiple signals spread across spectrum (different frequencies)
Polarization
Wavelength division (for fiber optics)
OFDM = a bit more advanced.

The communications technologies are a big group of new things to look into.
If I was starting off in college I would be looking into careers in wireless engineering or something similar.

Did these guys come up with this "idea" after reading this wiki page about circular polarization? Or is this something different?

Sure looks the same from the illustrations