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New Full Duplex Radio Chip Transmits and Receives Wireless Signals At Once (ieee.org)
Wave723 writes: A new chip by Columbia University researchers uses a circulator made of silicon transistors to reroute signals and avoid interference from a transmitter and receiver that share the same antenna. This technology instantly doubles data capacity and could eventually be built into smartphones and tablets. The chip enables them to work around the principle of Lorentz Reciprocity, in which electromagnetic waves are thought to always travel along the same path both forward and backward. Traditionally, electronic devices required two antennas -- a transmitter and receiver -- that took turns or operated on different frequencies in order to exchange signals.
so department of redundancy department strikes again!
Circulators are used all of the place (radar, satcom), so nothing new. But one small and efficient enough to potentially work in a cellphone? Neat stuff. They come with their own set of tradeoffs, so it might not be worth it in the end for smartphone use, but will find use somewhere.
Instantly doubles data capacity? I DID notice my phone seemed faster this morning! Good job Columbia!
Pretty cool. Not the first active circulator, but nonetheless pretty cool. I wonder how much isolation they are getting? http://www.wenzel.com/wp-conte...
That is the news here. Normally circulators are made of ferrite... amirite?
It doesn't sound right using "at once", but then, you are an AMERICAN, aren't you...
Listening while talking is a major issue for all shared communications links including wireless. Cable TV Internet and *PON based systems all have the problem that they can blind the receiver while transmitting resulting in talking over another speaker resulting in resending packets.
Personally, I find "simultaneously" to be a better term here than either "at once" or "at the same time." Alas, it's totally not a topic worth nitpicking about.
"at once" - I take to mean "immediately".
"all at once" - I take to mean "simultaneously".
Like a lot of Slashdot-edited articles - close, but no cigar.
The gist of what is clever here is the canceller which removes the transmitted signal from the receiver. Circulators have been around for donkey's years (not just in military systems) but they are bulky (especially at lower frequencies such as those for mobile comms). The are often used to allow a single antenna to operate at both transmit and receive either alternately (e.g. radar) or on different frequencies (e.g. satcom). Making a solid state one is clever, but this isn't the first one.
However, some of your transmit signal will always end up in the receiver for three reasons; (a) the circulator isn't perfect, (b) the antenna doesn't have a perfect match so some of the transmit energy sent to it bounces back again and (c) energy can reflect back from the immediate environment. Cancelling schemes exist, and invariably consist of some mechanism for sampling the transmitted signal and feeding just the right amount back into the receiver exactly out of phase. In theory this works, but in most practical circumstances the extremely high level of cancellation needed requires a completely unachievable precision.
For added pain, the solution tends to be very narrow band and the cancellor's settings have to be continually updated as the transmit interference changes (particularly in a mobile environment due to (c)).
If they have managed to make this work in a practical and useful way then it will be very impressive, but I would need to see some real world experiments to be convinced of its practicality.
Geeze, what happened to those 0.1" jumpers? Looks like they melted. Did someone accidentally the soldering iron on them?
"You saved 1968." - Ms. Valerie Pringle to the crew of Apollo 8
Personally, I find "simultaneously" to be a better term here than either "at once" or "at the same time." Alas, it's totally not a topic worth nitpicking about.
However, I commend your successful attempt to comment and nitpick on it at the same time - wait, I mean ... damn.
It must have been something you assimilated. . . .
"at once" - I take to mean "immediately".
"all at once" - I take to mean "simultaneously".
Like a lot of Slashdot-edited articles - close, but no cigar.
If we're really going to nitpick phrasing that bugs us, I'd like to nominate the use of "all new" to describe *one* TV show episode. Grrrr....
It must have been something you assimilated. . . .
What you describe is not full duplex. Two radios working together, taking turns (one transmitting, then one receiving, etc.) is the very definition of half duplex. And one radio in constant operation is simplex of course. Full duplex is always a situation where two radios are used in constant operation. One sending, one transmitting.
Full duplex using two radios on different frequencies is old school. Just a matter of a good combination of filters and enough frequency separation.
Full duplex using two radios on the SAME frequency, using directional signals is difficult but not undo-able. As long as you can prevent your receiver being blown up by your own transmission signal (and hope an unexpected reflective object in your signal path doesn't undo all your careful physical transmitter-receiver antenna separation).
Full duplex using two radios (both in continuous operation, one transmitting, one receiving, as defined at the top of my post) on exactly the SAME frequency while using a SINGLE (omni-directional) antenna is a true nightmare. And apparently these guys did just that with technology that promises it to be available in hand-held appliances.
RTFA, they used a combination of a circulator on silicon (which is the most innovative part. The circulator used in the project described by the article should kill most of the transmitted signal otherwise picked up directly by the receiver) and echo cancellation (which they developed earlier and is used to subtract any transmitter signal left which should mostly be echoes from objects that reflect the transmitted signal at distance and possibly internal echo from a sub-optimal antenna) on the received signal at the receiver end, so they can then try amplifying what's left. Which should be the (weak) signals that are transmitted towards the antenna by another transceiver.
Exciting stuff :)
73, PG8W
Technically, if they say it's "all-new", is it able to legally contain flashback or be a "best-of" revisited episode in any part?
I'd love to be a millionaire just to spent time suing things into oblivion when they are inaccurate like this. Shampoo adverts I'd target first, followed by any commercial use of the phrase "Unlimited".
Someone should use this to build a network of free internet by using the extra data and wifi signals all around.
What do you take "all offer sodden" to mean?