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244 comments

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he! (5, Funny)

McGiraf (196030) | more than 3 years ago | (#35212406)

First post, Over.

Re:he! (3, Funny)

Anonymous Coward | more than 3 years ago | (#35212442)

Roger that. Over.

Re:he! (0)

Gilmoure (18428) | more than 3 years ago | (#35213038)

Gentlemen, I'd like you to meet your captain, Captain Oveur. Captain, your navigator, Mr. Unger, and your first officer, Mr. Dunn.

Re:he! (-1)

Anonymous Coward | more than 3 years ago | (#35212540)

First post, Over.

Ooh look at that, it's the predictable little fuck who chimes in from time to time so he can pat himself on the back and tell himself how amazingly clever, funny, and witty he is. Hate to break it to ya Sunshine: yer not. Your humor is at best cookie-cutter, at worst recycled horse shit that stopped smelling only because it's so old. Go fuck yourself, you and your little buddies who snicker at this shit during their little circle-jerk of stale humor.

Re:he! (0, Funny)

Anonymous Coward | more than 3 years ago | (#35212584)

First post, Over.

Ooh look at that, it's the predictable little fuck who chimes in from time to time so he can pat himself on the back and tell himself how amazingly clever, funny, and witty he is. Hate to break it to ya Sunshine: yer not. Your humor is at best cookie-cutter, at worst recycled horse shit that stopped smelling only because it's so old. Go fuck yourself, you and your little buddies who snicker at this shit during their little circle-jerk of stale humor.... over.

Protocols are important.

Re:he! (1, Offtopic)

Tr3vin (1220548) | more than 3 years ago | (#35212866)

First post, Over.

Ooh look at that, it's the predictable little fuck who chimes in from time to time so he can pat himself on the back and tell himself how amazingly clever, funny, and witty he is. Hate to break it to ya Sunshine: yer not. Your humor is at best cookie-cutter, at worst recycled horse shit that stopped smelling only because it's so old. Go fuck yourself, you and your little buddies who snicker at this shit during their little circle-jerk of stale humor.... over.

Protocols are important. Over

Indeed. Over.

Re:he! (-1)

Anonymous Coward | more than 3 years ago | (#35213144)

First post, Over.

Ooh look at that, it's the predictable little fuck who chimes in from time to time so he can pat himself on the back and tell himself how amazingly clever, funny, and witty he is. Hate to break it to ya Sunshine: yer not. Your humor is at best cookie-cutter, at worst recycled horse shit that stopped smelling only because it's so old. Go fuck yourself, you and your little buddies who snicker at this shit during their little circle-jerk of stale humor.... over.

Protocols are important. Over

Indeed. Over.

You're a filthy stinking nigger, over.

Re:he! (-1)

Anonymous Coward | more than 3 years ago | (#35213234)

Protocols are important. Out.

Re:he! (0)

McGiraf (196030) | more than 3 years ago | (#35212686)

Thanks, whoever you are.

Re:he! (-1)

Anonymous Coward | more than 3 years ago | (#35212772)

Good post, brosef. Never stop posting. Over.

Re:he! (0)

Americano (920576) | more than 3 years ago | (#35213252)

"I can't hear you, you're trailing off. And did I hear a 'niner' in there? Were you calling from a walkie-talkie?"

Re:he! (1, Funny)

dziban303 (540095) | more than 3 years ago | (#35213280)

We have clearance, Clarence.

Roger, Roger. What's our vector, Victor?

----------------------

Looks like I picked the wrong week to quit sniffing glue!

Re:he! (-1)

Anonymous Coward | more than 3 years ago | (#35213410)

First post, Over.
...

We have clearance, Clarence.

Roger, Roger. What's our vector, Victor?

I just want to tell you both good luck. We're all counting on you.

Innovative (5, Informative)

Lumpy (12016) | more than 3 years ago | (#35212418)

Doing this On the same frequency is remarkable. but the gains they are claiming can be had right now by using TWO frequencies. Transmit on channel 1 receive on channel 12.. the other end does the opposite. the thing is, 90% of Ethernet traffic is not bi directional. it's packetized so their claims of DOUBLE will not be realized. when you set up a network connection from half duplex to full duplex you do not see a double in speed, just a double in capacity.

Re:Innovative (0)

intellitech (1912116) | more than 3 years ago | (#35212512)

Somebody, +Informative, please.

Re:Innovative (1)

commodore6502 (1981532) | more than 3 years ago | (#35212534)

Haven't phone modems been doing this for decades?

They used to have separate transmit and receive frequencies, but then the engineers figured out how to download and upload at the same time, over the same narrow 4 kHz of space. This AM radio breakthrough sounds like a similar approach, on the same restrictive bandwidth (4.5 kHz).

Re:Innovative (0)

Anonymous Coward | more than 3 years ago | (#35212672)

Phones do indeed do duplex, but it is not in the same way these researchers have done.
Also, your voice comes through the earpiece with POTS.

Re:Innovative (1)

commodore6502 (1981532) | more than 3 years ago | (#35212724)

(ponder). If the upload channel was turned-off, could phone modems do 56*2 == 112k downloads? In theory the answer seems to be yes - wonder why nobody's tried it.

Re:Innovative (1)

Crimson Wing (980223) | more than 3 years ago | (#35212872)

Phone modem speeds weren't limited to 56kbps by technology; the tech in them is capable of reaching significantly higher speeds (well, significant in the days before cable & DSL), but was arbitrarily limited by the FCC or some shit like that.

Like 10 years ago, there was a period of a few weeks where, by some random bug or glitch somewhere, my grandmother's computer (with 56k modem) would regularly connect to her dial-up service at 118.2kbps. She, of course, never noticed it. I don't think anyone else did, either. I noticed it when my parents and I went over to visit, and I asked to use the computer because I was bored.

Re:Innovative (1)

Mike Buddha (10734) | more than 3 years ago | (#35213120)

A phone connection has a limit of 64kbps. That's the bandwidth allocated for a single phone connection on a digital network. The only way to get a higher data throughput is via some sort of compression.

Ummm... no. (2)

denzacar (181829) | more than 3 years ago | (#35213370)

Sorry to break it to you, but your grandma didn't have a magic modem. On a plus side, she probably wasn't a witch either.
http://en.wikipedia.org/wiki/56_kbit/s [wikipedia.org]

A 56 kbit/s line is a digital connection capable of carrying 56 kilobits per second (kbit/s), or 56,000 bit/s, the data rate of a classical single channel digital telephone line in North America. In many urban areas, which have seen wide deployment of faster, cheaper technologies, 56 kbit/s lines are generally considered to be an obsolete technology.

The figure of 56 kbit/s is derived from its implementation using the same digital infrastructure used since the 1960s for digital telephony in the PSTN, which uses a PCM sampling rate of 8,000 Hz used with 8-bit sample encoding to encode analogue signals into a digital stream of 64,000 bit/s.

However, in the T-carrier systems used in the U.S. and Canada, a technique called bit-robbing uses, in every sixth frame, the least significant bit in the time slot associated with the voice channel for Channel Associated Signaling (CAS). This effectively renders the lowest bit of the 8 speech bits unusable for data transmission, and so a 56 kbit/s line used only 7 of the 8 data bits in each sample period to send data, thus giving a data rate of 8000 Hz × 7 bits = 56 kbit/s.

See also here:
http://en.wikipedia.org/wiki/56_kbit/s_modem#Speed [wikipedia.org]

Like 10 years ago, there was a period of a few weeks where, by some random bug or glitch somewhere, my grandmother's computer (with 56k modem) would regularly connect to her dial-up service at 118.2kbps. She, of course, never noticed it. I don't think anyone else did, either. I noticed it when my parents and I went over to visit, and I asked to use the computer because I was bored.

Let me guess... Windows 98?
That was a common bug back then. Probably something to do with all that 16-bit and 32-bit code [microsoft.com] just thrown on the pile there.
You were probably connecting way bellow even 56k, it's just that you couldn't really notice it.

Also, it could simply be that her PC was reporting the port speed, not the actual speed it connected at.
Even XP will gladly report to you the speed of your NIC or your hub/switch/router instead of your actual internet connection speed.

Re:Ummm... no. (1)

Crimson Wing (980223) | more than 3 years ago | (#35213466)

Let me guess... Windows 98?
That was a common bug back then. Probably something to do with all that 16-bit and 32-bit code [microsoft.com] just thrown on the pile there.
You were probably connecting way bellow even 56k, it's just that you couldn't really notice it.Also, it could simply be that her PC was reporting the port speed, not the actual speed it connected at.

XP, I believe.
 

Also, it could simply be that her PC was reporting the port speed, not the actual speed it connected at.
Even XP will gladly report to you the speed of your NIC or your hub/switch/router instead of your actual internet connection speed.

Admittedly, this is the most likely scenario. It *did* seem to be a bit speedier than usual, though.

*shrug* Eh, I dunno.

Re:Innovative (5, Informative)

Phreakiture (547094) | more than 3 years ago | (#35212894)

Well, dial-up modems don't matter much at this time (save for some corner cases), but I'll take it on anyway . . .

The phone line does, actually, have 112kb/s of bandwidth, but it is divided by the telephone network to go in opposite directions. 56k in, 56k out. At the trunk level, they actually travel over separate wire pairs (i.e. if you were to get a DS0 or a T-1 or higher, you have a transmit pair and a receive pair).

As for the notion that modems do this trick already, it is completely true. There are two main differences between a modem and a radio, though. First is that the modem can reasonably expect that, under normal conditions, the signal level of what it is receiving from the other end will not change much, and that its required transmit power will not change at all. Second is that the signalling going on in a modem is all at particularly low frequencies (4kHz and down) versus those going on via wireless which will be between one and 10 orders of magnitude higher in frequency, which is a tad more difficult to operate on.

Let me take that last point and expand on it a little. It is completely reasonable to take a modulated signal of a few kHz up to maybe a few tens of MHz, sample it digitally, push it through a DSP, slap some math on it, and get some sort of accurate filtering to take place. In dealing with higher frequencies, this is far more difficult, and achieving this, I believe, is the breakthrough.

Re:Innovative (1)

natehoy (1608657) | more than 3 years ago | (#35212936)

Because it would require massive rejiggering of the POTS network, which was designed with an up and down channel over fixed frequencies. That's a completely nontrivial exercise.

If you're going to go to all that trouble, just use some other frequency on the copper that can handle even more speed and install some kind of filtering device to keep those high-pitched sounds off the normal voice circuit. Copper can handle a decent range of frequencies above the level of human hearing, and certainly above what normal voice circuits clip at.

If you want a clever name, you could call it a "Digital Subscriber Link", and shorten it to DSL.

You'll have to hurry, I hear a few other companies may be looking in to this. ;)

Re:Innovative (1)

BitZtream (692029) | more than 3 years ago | (#35212782)

No, phones have been full duplex for my entire life, hence why when you're talking on a phone, the other person can talk and you can hear them speak while you are talking or making noise. Phones also have no voice activation circuit, they are constantly 'transmitting' from both ends.

Re:Innovative (1, Interesting)

shadowfaxcrx (1736978) | more than 3 years ago | (#35213224)

Phones are "full duplex" because there are 2 wires involved. One wire coming in to the receiver and going up to the earpiece, and one wire going out from the mouthpiece. (Yes, telco engineers, I know it's not quite that simple, but for purposes of this conversation, it is)

To put it another way, you don't fill the bathtub by reversing the flow of the drain.

To translate that to wireless, you'd need two frequencies for full duplex. Full duplex over one frequency would be like full duplex over one wire instead of two.

BTW re: modems being faster if you turned off the upload channel and used it for download - - that wouldn't work because of the checksum - - the data packets have a checksum which the modem sends back up the upload channel to verify that it's receiving the information correctly. (this wouldn't have been a problem with certain protocols like Ymodem-G, which eliminates the cyclic redundancy checking and therefore does not need the upload channel, but you're then relying on a completely error-free connection which is iffy at best over a standard phone line, hence the fact that such protocols were almost never used in the wild).

  What they used to do in the modem days to make them faster was to use a protocol called Shotgun, which linked 2 modems working on 2 separate phone lines together to increase the throughput.

Re:Innovative (0)

wiredlogic (135348) | more than 3 years ago | (#35212604)

Although their technique seems to be innovative, simultaneous transmission on the same frequency isn't. GPS and CDMA employ single frequency transmitters. They depend on the properties of pseudo-random sequences to get around interference issues whereas this seems to involve some sort of controlled interference.

Re:Innovative (1)

Anonymous Coward | more than 3 years ago | (#35212906)

GPS is receive only you idiot. CDMA uses fwd/reverse traffic channels. this technique is full duplex without any channels.

Re:Innovative (4, Informative)

MattskEE (925706) | more than 3 years ago | (#35212958)

GPS and CDMA use something completely different. Spread spectrum techniques like GPS and CDMA take a signal with (for example) 1MHz bandwidth and spread that data over a 100MHz bandwidth. Now up to 100 people employing this technique can transmit over that 100MHz bandwidth simultaneously, but there is no gain in throughput because it's the same in the end as those 100 users transmitting in a 1MHz bandwidth with user 1 at 1.000GHz, user 2 at 1.001GHz, and so on. The benefit of spread spectrum is that it's hard to segregate each radio into such a small bandwidth without interfering with adjacent users. It could not be used for full duplex single frequency radio because the transmitted signal would still swamp out the received signal, unless it were combined with isolation/nulling techniques like these Stanford guys are using.

The research page for the work in this article is here: http://sing.stanford.edu/fullduplex/ [stanford.edu]
They are using multiple techniques to selectively null out the transmit signal at the receiver. Their main novelty is spatial nulling of the antenna. Two antennas transmitting the same signal will have points in space where the signals destructively interfere and cancel. If they are spaced by an odd number of half wavelengths then this includes the entire line between the two antennas, so this is where the receive antenna is placed. Then they use existing analog and digital techniques to further cancel out the component of the transmitter which appear at the receiver.

Although the techniques for this are well known the trick is getting it to actually work effectively, because you need to achieve very high isolation from your own transmitter to receiver in order to avoid the transmitter effectively jamming the receiver. Their antenna nulling is apparently what gave them that extra isolation they needed.

Re:Innovative (1)

postbigbang (761081) | more than 3 years ago | (#35213168)

And therein is something perplexing, as multipathing ought to make this especially weird. Receiver discrimination would have to be unusually high; first it has to null out its own transmission (hoping that it doesn't null out it's own reception) and S/N has to be really high. Add in a bounce from something moving, or use any kind of slow slewing factor and this boat doesn't float.

Re:Innovative (1)

DeathFromSomewhere (940915) | more than 3 years ago | (#35212650)

Sure, but now you can use two frequencies in full duplex. No matter how you look at it, it's a doubling in capacity.

Re:Innovative (3, Interesting)

s52d (1049172) | more than 3 years ago | (#35212764)

Doing this On the same frequency is remarkable. but the gains they are claiming can be had right now by using TWO frequencies. Transmit on channel 1 receive on channel 12.. t

This might be problem if you want mesh network with many (n>2) nodes. They (mostly) want to hear each other.

Anyhow, with 100 dB (10 000 000 000) times stronger transmit signal I somehow doubt if geometry of antennas can be accurate
enough to keep it working with changing temperature, humidity etc. over MHz of bandwith.
Maybe with heavy DSP processing and continuos monitoring?
Compensating for scattering of own signal, and all reflections from surounding objects?

On top of it, we normally use MIMO: so you have to do it on 4 receiving antennas ;-).
Even with MIMO 2by2 we might double channel capacity in perfect (MIMO perfect) radio conditions.

Yes, it is possible in the lab. But mass products?

Ah, back to good old Shannon: just double the bandwith.

73
Iztok

Re:Innovative (1)

Idbar (1034346) | more than 3 years ago | (#35212802)

While I find this interesting, there's still some lack of information.
For example, they claim they will do it by using two transmitters. This of course requires more hardware only to generate destructive interference at the receiver and improve the SNR. However, these two transmitters will generate most likely deep nulls at certain distances from them. The question is, does this really solve the problem, or anyone moving at certain speed is under the risk of hitting all the nulls and not listening to anything. Or Perhaps due to your location, you may cause that destructive interference in the neighborhood of your router/base station.

It would be really interesting to see how do they deal with the problem they created to fix the issue.

Re:Innovative (3, Informative)

philip.levis (1997004) | more than 3 years ago | (#35213312)

Hey, it's just a news article. Here's the more technical stuff: http://sing.stanford.edu/fullduplex/ [stanford.edu] Short answer is the fact that the two transmit antennas are at different distances means they need a power difference in order to match amplitude at the receive antenna. This in turn limits the depths of nulls at distance.

Re:Innovative (1)

b4upoo (166390) | more than 3 years ago | (#35213044)

So if I send twice as much in the same amount of time it seems to me that that equals a doubling of speed or use of less resources in the case of sending and receiving on one frequency instead of tying up two frequencies. In the case of fiber optics where different colors are used to pump data that would enable twice the delivery totals for one cable in the same amount of time. Sounds good to me.

no you are stupid (-1)

Anonymous Coward | more than 3 years ago | (#35213064)

no it cant be done with two frequencies you blithering idiot.
they are transmitting and receiving at the same time. and using destructive interference to cancel the transmit signal out. with two frequencies they would get 2X the performance and effectively double the bandwidth you would get if you used a conventional tx/rx using two frequencies. they are effectively transmitting TWO packets AT THE SAME TIME.

 

Re:Innovative (0)

Anonymous Coward | more than 3 years ago | (#35213194)

The core issue is capacity per unit bandwidth (in the signal sense, not throughput sense). Sure, if you use two channels, you use twice the bandwidth and so can send twice as much data. Take a look at the precise technical claims made in the paper, not a news story designed for popular consumption.

Re:Innovative (0)

Anonymous Coward | more than 3 years ago | (#35213284)

This sounds like it would also only work with a point to point style application - access point to SINGLE HOST, or host to host. If multiple Hosts try to transmit, the AP will still choke. The AP can't send out to multiple hosts simultaneously either.

So, it is full duplex point to point. It would still be shared access for multiple hosts.

Re:Innovative (0)

Anonymous Coward | more than 3 years ago | (#35213300)

There are basically three axes at play here: Frequency, time and space. This radio uses spacial multiplexing to reuse frequency and time. Its similar to MIMO, and won't work with MIMO radios, since the multipath signals will not have the same phase relative to the two transmit antennas and the receive antenna.

Its not clear that an ethernet based protocol would be appropriate for a full duplex link, so I'm not sure your focus on throughput rather than bandwidth is appropriate.

Re:Innovative (1)

ToasterMonkey (467067) | more than 3 years ago | (#35213372)

when you set up a network connection from half duplex to full duplex you do not see a double in speed, just a double in capacity.

So a car analogy would be if you took a one way road and doubled the lane count with opposite flowing lanes, the cars don't move twice as fast, but twice as many.

Did you really need to be explained to anyone?

How about if we stacked bidirectional lanes on top of each other so one lane represented both directions, and double capacity in the same square footage? Oooohh, I see what I did, deeeeeeeensittttyyyyy.

Doing this On the same frequency is remarkable. but the gains they are claiming can be had right now by using TWO frequencies.

Then they could move twice as much again with TWO full duplex frequencies!!11

I thought that was called... (1)

peteinok (1825618) | more than 3 years ago | (#35212420)

full duplex?

"Over"? (1)

6Yankee (597075) | more than 3 years ago | (#35212424)

I haven't flown anything in 10 years, and "Over" was considered quaint even then...

Re:"Over"? (1)

chemicaldave (1776600) | more than 3 years ago | (#35212486)

I haven't flown anything in 10 years, and "Over" was considered quaint even then...

I was under the impression that "Over" helped in that it let the other person know when your transmission was...y'know complete, not just so the other guy knew when to start talking.

Re:"Over"? (1)

6Yankee (597075) | more than 3 years ago | (#35212736)

The click when you release the mic switch, and the fact that you've shut up, seem to work well enough. :)

It might well be different out in Shanwick country on HF (sadly, I've never had the chance to get out there as pilot), but certainly on VHF I've never heard it from anyone but a couple of old-timers.

Re:"Over"? (1)

beelsebob (529313) | more than 3 years ago | (#35212788)

How do you differentiate between the click as the mic switch is released and the pilot shuts up because he's finished his message, and the click because he's had a heart attack and died, or the click because the transmission ended because he hit the ground?

Re:"Over"? (1)

6Yankee (597075) | more than 3 years ago | (#35212956)

Who cares? At least he's not boring you with how great he is any more :D

Re:"Over"? (5, Informative)

natehoy (1608657) | more than 3 years ago | (#35213482)

Because in any case, the pilot has finished his/her message when you hear the mic click. Surely you don't think the conversation is going to continue?

More importantly, the pilot and controller speak to each other in very precisely defined and very concise language. It's pretty obvious when one of them is done yakking, the mic click is a convenience, like the "over" used to be before all radios had mic clicks.

A typical initial approach might go something like this:

"Bangor approach, Cessna five-two-five-Lima-Charlie, 12 miles west, descending 5000 with information Sierra, full stop."

This tells the controller that:

1. You are intending to make an announcement to the controller at Bangor Center in charge of approaches (in case you fucked up your frequency, they can correct you quickly and get you on the right frequency).
2. You are a Cessna, US-registered, with tail number N525LC.
3. You are 12 miles to the west of the airport, at 5000 feet, and descending.
4. You have listened to their weather/conditions report recently, which is their update "S" (Sierra), and the letter is updated whenever the information is updated (usually once an hour). That means you already know the wind speed, altimeter settings, and preferred runway, and have adjusted all of your instrumentation and expectations appropriately.
5. You are requesting approach vectors for the currently-active runway (which you already know) and you intend to land there (full stop, as opposed to a touch-and-go or a practice approach but not a landing).

The controller will respond with something like this:

"Cessna Five-Lima-Charlie, Information Sierra current, enter 45 left downwind for runway one-eight-zero, report midfield"

This means:

1. The controller has acknowledged your presence, confirmed that you have the latest weather, and picked an abbreviation for your tail number that does not conflict with any other aircraft currently operating in his airspace. That will be your designation for the duration of your talk with this controller.
2. The controller wants you to enter the pattern at a 45-degree angle on the upwind side of the runway and call you again when you are properly established in a left downwind and abeam the middle of the runway.
3. There is no known traffic on that side of the field that will conflict with your entry, because the controller didn't mention any.

The conversation will proceed, with both the pilot and controller keeping radio use to the absolute minimum necessary to communicate what they need to say. If the frequency is really quiet, they might exchange a few jokes or snide remarks, but "over" is usually in the domain of CB radio, old timers who used to deal with really crappy radios, and bad movies.

Interruptions to what a pilot or controller is saying are obvious because of the way the language is constructed. This is done on purpose. If you say "Bangor approach, Cessna three-five..." then stop talking, you're going to hear a controller say something like "Unknown Cessna starting in three-five, please repeat, message not received." in just a very small handful of seconds.

Re:"Over"? (1)

Martin Blank (154261) | more than 3 years ago | (#35212952)

The click when you release the mic switch, and the fact that you've shut up, seem to work well enough.

ATC in the Southern Calfornia region appears to rely on patterns more than a click or silence, as they start talking the instant I've finished calling my tail number and a split second before I've released the mic switch. Then again, it does get pretty busy here: I've had to make six calls to SoCal Departure before I was acknowledged, and when I was, I was told to switch to another frequency because I'd already moved into another controller's area. :)

Re:"Over"? (2, Informative)

BitZtream (692029) | more than 3 years ago | (#35213000)

and the fact that you've shut up, seem to work well enough. :)

No it doesn't, I hope you don't fly anymore you're making a careless mistake about something that should have been taught to you before you took the ground exam.

The purpose of an End of Transmission marker is so that everyone listening has confirmation that they received ALL of your transmission as intended. So if for some reason my transmission is cut off and it seems like just silence you as a listener know it was cut off because you didn't hear an End of Transmission marker and you can request that it be repeated.

If you think 'silence' is the way to tell, you don't need to be anywhere in an aircraft except the passenger cabin, there are a ridiculous number of airline accidents that result because of just this sort of stupidity, a fine example is a Pan-Am flight which started a takeoff roll after knowing they didn't get a full transmission from the tower ... which told them to hold until another aircraft which had to taxis back up the runway itself could clear it. About 500 people died that day because some idiot thought silence was good enough and ignored procedure which would have been to ask for a repeat. Half way down the run way, as their 747 approached rotation speed, out of the fog appeared another jumbo jet, turning off the runway right in front of them. All because they knowingly didn't follow preceedure and ask for a repeat when the cockpit voice recorder clearly shows them noticing, pointing out, and ignoring the missing End of Transmission marker.

The click when you release the mic is there because idiots like you couldnt' follow procedure so they took it out of your hands in order for everyone else that actually has a clue to be safer. Either way, your lack of understanding of why procedure is the way it is gives me a very disturbing feeling.

Re:"Over"? (1)

harl (84412) | more than 3 years ago | (#35212836)

Nope. You end the transmission with your tail number. It does double the work. Show's that your done and conveys information to the person receiving the transmission.

Re:"Over"? (1)

jamrock (863246) | more than 3 years ago | (#35212576)

I haven't flown anything in 10 years, and "Over" was considered quaint even then...

Even longer than that. I was a stuent pilot in 1981, and even then the convention was long obsolete.

Re:"Over"? (1)

oodaloop (1229816) | more than 3 years ago | (#35212704)

It's still used in military comms. Over is when you're done with your part of the conversation, and Out is when you're completely done. In the movies, that gets mangled to Over and Out.

Re:"Over"? (1)

joe_frisch (1366229) | more than 3 years ago | (#35213202)

I still fly, and almost never hear this.

CB Radio (2)

carcomp (1887830) | more than 3 years ago | (#35212434)

We say over or have a tone to signify when we are done speaking. There may be more than one person listening and its a cue for the next person not only that you are done talking, but your message came through. If you are listening and don't hear "over" or "beep" you say "come again" or "missed that last bit" or whatever jargon that the bands you are using requires. I'm not a pilot so all I know is terms i've used on CB over the years.

Re:CB Radio (1)

chickenrob (696532) | more than 3 years ago | (#35213048)

10-9?

Wow (1)

Carewolf (581105) | more than 3 years ago | (#35212474)

Nice job. Though the problem off cross-talking has been solved for a long time using TDMA or CDMA.

Re:Wow (1)

Neon Spiral Injector (21234) | more than 3 years ago | (#35212530)

From the fine article, "Current phone networks allow users to talk and listen simultaneously but, the scientists said, they use a work-around that is expensive and requires careful planning."

Re:Wow (1)

TheTurtlesMoves (1442727) | more than 3 years ago | (#35212544)

Well you don't even need to get that fancy. I though that this is what a Circulator [wikipedia.org] was for.

Re:Wow (1)

petermgreen (876956) | more than 3 years ago | (#35213420)

Afaict on mobile phone networks TDMA and/or CDMA are used to seperate different users while FDMA is used to seperate uplink from downlink.

Pilots don't say Over (1)

SirBitBucket (1292924) | more than 3 years ago | (#35212500)

As a pilot I can tell you that I hear "over" only about once a year, and only when someone is repeating themselves trying to see if the other party can hear them. Also this technology would take literally decades to work into all aircraft. Aircraft last for decades themselves, and people are not that fast to upgrade.Aviation is about what is proven to work, not the latest and great bleeding edge technology.

N-number... (0)

Anonymous Coward | more than 3 years ago | (#35212542)

Pilots end a transmission with their plane's tail number, not "over."

Multiplex sin() (1)

Dzonatas (984964) | more than 3 years ago | (#35212550)

With provided carrier waves instead of plain sin(), it always has been easier for split send receive. Simple split sin() is how UNIX micro-seconds work independently. Less hardware reads to the atomic timers meant faster methods for instructions per cycle. Same applies to ethernet.

Yaaawn (1)

eclectro (227083) | more than 3 years ago | (#35212554)

It's called a duplexer [wikipedia.org] .

Re:Yaaawn (1)

autocracy (192714) | more than 3 years ago | (#35212740)

A typical duplexer uses two frequencies in the same band that are usually close to each other. This is definitely an advance on that idea.

Roger, Over (4, Funny)

gnarlin (696263) | more than 3 years ago | (#35212558)

Roger Murdock: Flight 2-0-9'er, you are cleared for take-off.
Captain Oveur: Roger!
Roger Murdock: Huh?
Tower voice: L.A. departure frequency, 123 point 9'er.
Captain Oveur: Roger!
Roger Murdock: Huh?
Victor Basta: Request vector, over.
Captain Oveur: What?
Tower voice: Flight 2-0-9'er cleared for vector 324.
Roger Murdock: We have clearance, Clarence.
Captain Oveur: Roger, Roger. What's our vector, Victor?
Tower voice: Tower's radio clearance, over!
Captain Oveur: That's Clarence Oveur. Over.
Tower voice: Over.
Captain Oveur: Roger.
Roger Murdock: Huh?
Tower voice: Roger, over!
Roger Murdock: What?
Captain Oveur: Huh?
Victor Basta: Who?

Re:Roger, Over (1)

MikeDirnt69 (1105185) | more than 3 years ago | (#35212874)

+1 Funny!

Radio etiquette (0)

Anonymous Coward | more than 3 years ago | (#35212622)

Radio users say "over" because due to propogation, radio noise, and the lack of body language such etiqutte is needed for efficient communication. On the phone with only two people you can get away without such "annoyances" by simply having longer pauses then would be typical in face to face communication but this doesn't scale to larger groups. All the WoW players out there will know what it is like when a bunch of people are all trying to talk over Ventrilo/Teamspeak.

This new technique is welcome because those of us interested in ameteur radio really don't want to see the hobby die because the entire radio spectrum is taken up by people downloading porn and updating Facebook over Wi-Fi.

Re:Radio etiquette (1)

uncledrax (112438) | more than 3 years ago | (#35212976)

All the WoW players out there will know what it is like when a bunch of people are all trying to talk over Ventrilo/Teamspeak.

Some of us stick to FPSes.. you insensitive clod..

Actual information (5, Informative)

Zurk (37028) | more than 3 years ago | (#35212698)

How this actually works :
The Challenge in Achieving Full-Duplex

The problem that has historically prevented full-duplex is that, when a node transmits, its own signal is millions of times stronger than other signals it might hear: the node is trying to hear a whisper while shouting. The challenge is canceling the node's own transmitted signal (shout) from what it receives (whisper). Existing approaches, such as digital cancellation and noise cancellation circtuis, can cancel some of the transmitted signal, reducing its strength, but not enough to make a node able to receive.

Antenna Cancellation

Our design uses two transmit antennas one receive antenna per node. The transmit antennas send the same data and the receive antenna is placed such that there is destructive interference from the two transmit antennas, thus reducing self-interference. Offsetting the two transmit signals by half of the wavelength causes them to cancel each other, creating a null position where the transmitted signal is much, much weaker.

Combining antenna cancellation with cancellation through a noise cancellation circuit gives ~50dB reduction in self-interference before the RF signal is demodulated and sampled to the digital domain. Digital cancellation removes the residual interference.

For more information :
http://sing.stanford.edu/fullduplex/ [stanford.edu]
The actual paper (PDF) :
http://sing.stanford.edu/pubs/mobicom10-duplex.pdf [stanford.edu]

Re:Actual information (2)

pushing-robot (1037830) | more than 3 years ago | (#35212796)

Have they tested this in non-laboratory conditions? The idea of transmitters being placed such that they perfectly cancel each other out sounds great, but what happens when you add in nearby objects that reflect RF?

Re:Actual information (1)

Beardo the Bearded (321478) | more than 3 years ago | (#35212840)

Thank you for the links. I was hoping someone would post them.

The PDF is pretty good. The idea is brilliant in its simplicity and damn, it works. Good for these folks, this is remarkable work.

Re:Actual information (0)

Anonymous Coward | more than 3 years ago | (#35212942)

That's not exactly that novel - basically they are in the node of a standing wave. What it means is the 3 antennas need to be fixed in position, and even small deviation will increase interference.

http://en.wikipedia.org/wiki/Node_%28physics%29

There is of course consequences of dual-antenna transmission. The antennas will interfere with each other reducing their effective range - the are no longer "omni-directional"

Re:Actual information (1)

Alarash (746254) | more than 3 years ago | (#35213036)

Wouldn't the range be reduced if "the transmitted signal is much, much weaker"?

rock in water... (1)

RingDev (879105) | more than 3 years ago | (#35213354)

The transmitted signal is much, much weaker in the area of destructive interfierance.

Think of a pool of still water. If you throw a rock into it, you see waves propagate out from the impact.

If you throw two rocks in (or to be more accurate, 180 degrees out of phase, so one rock in and one rock out) at the exact same time, each rock will create the same waves as the single rock, but in one very tiny area directly between the two rocks the waves will cancel eachother out and the water will remain perfectly still.

In that very small area is where they put the reciever antenna. The transmition signal is very weak, so all of the other signals can still be heard. Once you are outside of the destructive interfierance area, the waves propagate as usual and you have roughly the same range and amplitude as you would with a single antenna.

-Rick

Re:Actual information (1)

IICV (652597) | more than 3 years ago | (#35213316)

I guess it would help with spectrum conservation or something, but I just don't see how that would help in practice - after all, this method requires three antennas! With that, you could be broadcasting and receiving (though not at the same time) on three different channels all at once [wikipedia.org] !

Actually, now that I think about it, this could work well from a security perspective. Imagine you've got two stations, A and B, transmitting data at the same time using this method. Now someone stucks an antenna somewhere in between them. What does that antenna see? A signal that's some % A and some % B, summed together. Recovering either A or B's signal only is going to be hard, since you can't know which is which without getting much closer to A and B.

Re:Actual information (1)

plcurechax (247883) | more than 3 years ago | (#35213422)

Offsetting the two transmit signals by half of the wavelength...

Wait, does is this over-the-air "same frequency", which would imply that they are merely trading off bandwidth to achieve full-duplex?

Two transmitters (transceivers) on the "same" frequency normally implies two transmitters / transceivers using the same frequency and the same bandwidth (and modulation), otherwise you are merely doubling the signal bandwidth used as this seems to suggest.

I can imagine that it could mean that is merely an offset (or delay) used for filtering, not over the air, but this is not clear from the brief statement. As the technology focuses on antenna cancellation, I'm not sure without studying (i.e. reading not skimming) the paper.

*KSSCHK* (5, Funny)

boristdog (133725) | more than 3 years ago | (#35212732)

I end all my sentences with *ksschk* so it sounds like I'm in space.

Uh.... (0)

Anonymous Coward | more than 3 years ago | (#35212734)

How is this new? Isn't it the same echo cancellation ADSL modems (and older) have been using for decades? Which textbooks say you can't do this?

Impossible (0)

Anonymous Coward | more than 3 years ago | (#35212784)

Technically none of the signals we use these days are using a single frequency. The frequency is modulated so that it gives more bandwidth for transmitting data.

An exact frequency would require a continuous wave of radio energy and that has very little data transmission capabilities. You can not transmit and receive two continuous wave signals on the exact same frequency, there would be no way to tell them apart. Well, in theory you could use phase shifting but in practice that is impossible to do and keep them separate because as the radio signal travels it bounces around causing the phase to change. So basically it's physically impossible to transmit and receive two exact frequency signals.

That's not what they're doing here though, they're taking regular modulated signals and running filters to pick out each signal. So they grab the true received signal by filtering out the one they are transmitting. They operating around a similar center frequency but it's not the exact same frequency.

Re:Impossible (1)

Chrononium (925164) | more than 3 years ago | (#35212950)

Technically, sending and receiving a CW signal at the same frequency communicates zero information, so naturally there should be some measurable difference (whether in phase or something else) between a transmitted signal and a received signal for information to flow. Therefore, while your point is technically valid, it is practically ignorable, since no communication system can use it (and don't start talking about combining TDMA with a CW signal, as the implied Fourier analysis here assumes a periodic sequence instead of TDMA-based pulsing).

Re:Impossible (0)

Anonymous Coward | more than 3 years ago | (#35213188)

Not true, a CW signal transmits the information that it exists. So basically one bit of information (not including timing since you don't want to talk about that).

Energy is energy.

FYI - Pilots don't use "over." (1)

harl (84412) | more than 3 years ago | (#35212794)

Pilots don't use over. Pilots end a transmission with their tail number.

Re:FYI - Pilots don't use "over." (0)

royallthefourth (1564389) | more than 3 years ago | (#35212838)

Pilots end a transmission with their tail number.

Oh yes, I think I saw something about this on craigslist personals...

Re:FYI - Pilots don't use "over." (-1)

Anonymous Coward | more than 3 years ago | (#35213046)

Mod up.

Re:FYI - Pilots don't use "over." (1)

CharlieThePilot (1721810) | more than 3 years ago | (#35213222)

Well, yeah..... most of the time.

When replying to an ATC transmission, that's the way to acknowledge the clearance or whatever, eg:

ATC: Flight 209, climb flight level 290.
Aircraft: Climb flight level 290, flight 209.

BUT, not always, eg when making a request to ATC:

Aircraft: Control, flight 209 request climb flight level 290.
ATC: Roger, stand by.

In reality, there's a bit of white noise (don't know what causes it, might be artificial), marking the end of transmissions from pretty much any station, so the 'over' is never needed.

"Over" is, however, still used in military radio protocols, and implies "it's your turn to speak now". The word "Out" implies "I have finished, and the conversation is terminated.". For that reason, in rl, you should never hear "Over and Out" on the radio.

Re:FYI - Pilots don't use "over." (1)

harl (84412) | more than 3 years ago | (#35213476)

Yes generally calls to ATC are Who, Where, What. In no example you give does the pilot use over.

That burst of static you just heard. Is it the end of a transmission, a failed radio, interference, or the pilot being stepped on by another pilot?

What the military does is irrelevant because the author specifically target pilots.

Re:FYI - Pilots don't use "over." (0)

Anonymous Coward | more than 3 years ago | (#35213270)

They should be starting transmissions with their tail numbers. The FAA is pretty clear about that. It's particularly important when dealing with ATC, they want to know who is talking before you start asking for things. All pilots are now taught Who, Who, Where, What. Who are you calling, Who are you, Where are you, and What do you want. A good example would be "Paine Tower, Skyhawk 9922S, 1 mile inside marker, inbound ILS 16R, full stop." (I've made that call many times).

Over hasn't been used since the 50's. Radios are good enough now that it's pretty obvious when your done talking. Silence. Over was used when there was a lot of static on the receivers.

10-4 good buddy (-1)

Anonymous Coward | more than 3 years ago | (#35212862)

over and out

CMDA (1)

mehtars (655511) | more than 3 years ago | (#35212954)

Can some explain how this is different from CDMA?

Re:CMDA (1)

bheilig (516136) | more than 3 years ago | (#35213256)

If a single transceiver transmitted one code and received another, but on the same frequency channel, the transmitted signal would overpower the received signal. I explain why in this post:

http://tech.slashdot.org/comments.pl?sid=1997010&cid=35213010 [slashdot.org]

In a CDMA system multiple transmitters send different coded signals on the same frequency where a single receiver receives the sum.

Re:CMDA (0)

Anonymous Coward | more than 3 years ago | (#35213462)

CDMA spreads the signal over a wider frequency by convolving the baseband signal (e.g. the encoded bits) with a higher frequency psuedo random code (e.g. a Walsh Code). If you don't convolve the received signal with the same psuedo random code, then the signal is statistically similar to white noise, and so it just effectively lowers the signal to noise ratio for the receiver for the channel (code) you actually are receiving on. So, multiple radios can transmit over the same wideband channels, and the receiver can extract the narrow band signal that its interested in by convolving with the corresponding code.

It cannot, however, transmit and receive at the same time, unless it uses a trick like the one from TFA, of course. CDMA just allows multiple transmitters to use the same wideband channel for narrow band signaling.

There is another way (2)

scharkalvin (72228) | more than 3 years ago | (#35212966)

It's called time domain multiplexing. If you chop the transmitter on and off at a rate much faster than the data rate you can hear bits in between your chopped up transmissions. Sorta like fast break-in amateur CW where you can hear between the dots and dashes. This would require synching the two stations chop rate. Since the 'chopping' is done above the nyquist sample rate, no data is lost, and you get true full duplex speed.

Limitations (5, Informative)

bheilig (516136) | more than 3 years ago | (#35213010)

The signals will only perfectly cancel when they are separated by a distance that is exactly one half the wavelength. Assuming you separate the two transmit antennas by this distance at the carrier frequency, then there will be a limitation on the available bandwidth. This is because the further you get away from center frequency, and away from the ideal antenna spacing, the less destructive interference you will have (and the more your transmit signal will leak into your receive signal). So you will double your capacity for only narrowband channels.

The pdf gives actual numbers. I just wanted to point out that there is a limitation on bandwidth.

You might also think, "If I know what I'm transmitting, why can't I just subtract it from what I receive?" This has to do with the dynamic range of the receiver, which is a function of the number of bits in your analog to digital converter. You must attenuate your received signal so that you don't saturate your converter. Have you ever turned the volume up so loud that you begin to hear distortion? It's the same thing.

So you are receiving this loud unwanted transmit signal, and this soft receive signal. You must lower the volume so that you are not distorting the highest signal. This lowers the volume on the desired signal as well. You can lower it so much that your analog to digital converter is not able to differentiate between a 1 and a 0 anymore.

I think if you could have an A2D with enough bits that you didn't care if you received the transmitted signal, then you could just carefully subtract out the unwanted transmit signal. Maybe I should patent that? Meh. I'm probably wrong.

when will we see this technology? (2)

Cyko_01 (1092499) | more than 3 years ago | (#35213022)

The researchers have not detailed when the technology might appear in hardware, but said they had applied for a patent and ...

So....never?

General Honoré (1)

mswhippingboy (754599) | more than 3 years ago | (#35213024)

I do wish someone would explain to Ret. General Honoré that when doing television interviews, ending sentences with "over" is not really necessary.

Nothing new, used for many years (1)

Anonymous Coward | more than 3 years ago | (#35213136)

Transmitting and receiving at the same time absolutely nothing unusual.

Means of achieving this is usually a circulator, plus possibly a bi-static antenna setup (TX and RX antennas separate and isolated; there's a IEEE paper somewhere about an "Isolation Antenna" that has 70dB+ of isolation between its ports), and in some times even active cancellation of the leakage signal (by feeding a sample of it, with the correct phase and amplitude so it cancels out).

It has been used in RFID systems for many years already.

Circular polarization (1)

Framboise (521772) | more than 3 years ago | (#35213162)

Theoretically there are still other ways to double data flow while keeping the same frequency. Using circular polarization one sender can emit clockwise rotating waves, the other sender the opposite. Linear polarization can be destroyed by wave reflections on obstacles, but afaik circular polarization is rather immune.

solution in search of a problem (0)

fred fleenblat (463628) | more than 3 years ago | (#35213298)

it seems like this would only benefit protocols that load evenly between send and receive. maybe skype?

but if you're watching a movie on netflix or surfing the web or probably a lot of other things, you'll be doing so much more receiving than sending that it's not really worth it to have another antenna.

Not to be a nit pick (1)

zamboni1138 (308944) | more than 3 years ago | (#35213456)

Seriously, pilots almost never say over. I'm not exactly sure when this stopped, but I never used over at the end of my transmissions.

Usually pilots start every request with who they're calling and their callsign, either full or short (on the West coast of the US you can usually get away with just your make and last three characters after your initial transmission to a controller. If they are getting instructions or information from a controller they usually end their acknowledgement with their callsign. Examples:

(Cessna 182) N12345: "Seattle Center, Cessna one two three four five, with you, level four thousand"
Seattle Center: "Cessna one two three four five, radar contact, local altimeter two niner niner two"
N12345: "two niner niner two, Cessna three four five"

Seattle Center: "Delta six seven eight, descend and maintain flight level two two zero"
(737) Delta 678: "Down to two two zero, Delta six seven eight"

The real question is: Can this be used to eliminate that terrible noise that happens when two users try to transmit on the same frequency at the same time?

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