The way balanced audio works is via two signal conductors, and then a separate ground. That's probably the three wires that you're thinking of. Really the ground isn't part of the circuit (and sometimes the ground is intentionally broken to prevent loops), but it's why you have three pins in an XLR jack.
Basically, a balanced audio source will act like a 'push-pull' current source. Rather than simply having a voltage on a wire that varies in time, you have a continuous loop, and you 'push' down one side of the loop and 'pull' up on the other, or vice versa. If you were to hook an oscilloscope probe up to both sides of a balanced audio circuit while something was going down it, you'd find out that the signals on each side of the circuit are 180-degrees out of phase wrt each other. By convention, one of the signal lines is usually called the '+' side and one is called the '-' side,* with the '+' side usually being in-phase with the actual microphone input.
The advantage of this, over an unbalanced line, is common-mode rejection. If you use a transformer (or some type of modern transistorized circuit that simulates a transformer; op-amps acting like difference amplifiers also work well) on the receiving end of the circuit, you can basically 'throw away' any signal that's the same on *both sides* of the circuit. E.g., lets imagine that your balanced audio line is right next to a 60Hz power line. The 60Hz is going to get into the balanced line, but it's going to be the same on both the '+' and '-' sides, while the actual audio is going to be 180 degrees o.o.p. from one side to the other. This makes it easy to reject the interference: when you run the balanced audio into a 1:1 transformer, the 60Hz doesn't produce any current actually moving through the transformer's coils, and thus no output (or very little).
I'm not sure where balanced audio circuits originated. I think that it probably started with the phone company (which has been doing balanced loop circuits practically forever; in telco parlance the '+' and '-' are sometimes called 'tip' and 'ring' respectively, after their placement on old 1/4" jacks) and later migrated to studio audio and sound reinforcement later, rather than the other way around.
* Some audio people insist on calling the '+' side of balanced audio connections "hot" and the '-' side "cold," which I think is stupid since they both carry signal (unlike, say, the 'hot' and 'neutral' in your power socket), but you hear it tossed around.
Just in case anyone else was intrigued by "MVL Modems," I did a little searching and apparently they are a variation on DSL that's a bit more robust.
This fairly ancient (1998) article claims 24,000 line-feet at 768kbps and gives the name of an equipment manufacturer who pioneered the technology. Given the sparse information available and the fact I've never heard of it until today, I'm going to guess it was kinda stillborn.
Still might be cool in a pinch, though.
One thing I've always wanted to find out is whether there's a way to use two cheap consumer DOCSIS-compliant cable modems to transmit data over a dry piece of point-to-point CATV coax. The OEMs charge an absolute bundle for real cableco headend gear, and I've always wondered if it would be possible to hack two consumer ('tailend'?) boxes to talk to each other. Given the distances that you can run cable for compared to most UTP services, its ease of installation compared to fiber, and the ubiquity of DOCSIS equipment, that would be a pretty neat way of extending an Ethernet network over very long distances on the cheap.
In the past, there was some electrical voodoo performed where only two wires were required. Both the microphone and the speaker were both on the same circuit - but with the right use of capacitors and resistors between the two, the feedback could be cancelled out. This was known as a two-wire circuit. Um, not sure what time machine you just stepped out of, but every POTS handset at least in the US/Canada works this way. You get two wires, and it's really just one signal (the two wires act as two halves of a balanced circuit, similar to professional audio systems).
The phone's speaker and microphone are both in the circuit (plus the bell or ringer); the "sidetone" (your own voice as heard through the speaker) elimination is done in your telephone. In fact, some telephones let you adjust the sidetone up and down. When you install multiple telephone handsets on one line, you're basically just hanging multiple sets of microphones, speakers, and ringers off of the same two-wire balanced circuit.
You're right that a normal POTS line has stuff applied to it at the CLEC end that attenuate high-frequency signals, but they're not there to eliminate sidetone.
To a telco person, a 'four wire' circuit is going to be two unloaded loops, because telephone people tend to think in terms of 'loops' or 'pairs,' one loop per phone line/number.
Most modern homes are wired with Cat 3 wiring, which includes 3 discrete pairs, but unless you order a second line from the phone company, you probably only have dialtone on two wires (one pair), and only one pair comes out from the pole to your house. (Which is actually cool, because if your house wiring is done in a star configuration instead of daisy-chained, you can use the two dry pairs for 10BT Ethernet, in a pinch.)
Slightly OT but cool: Anyone interested in POTS phone technology might want to check out this page (http://home.utah.edu/~nahaj/cave/phones/) which explains how to build a very simple one or two-wire field phone system just with phone handsets. Apparently they are used in cave rescue and other applications where radios don't work. It's a good introduction to how POTS works, though, since it doesn't introduce the complexity of the ringer, switching system, etc. It gets into sidetone and sidetone-suppression a little.
Where's the other $100 that they were gyped out of? In Steve Jobs' metaphorical pocket, as he laughs all the way to the bank while fondly recalling certain P.T. Barnum quotes.
That's the price you pay for being an early adopter. (Or, as I like to call it, "stupid.")
I think it would be interesting to look inside these caves but I don't think we are going to find life on Mars. My reasoning is that life on Earth is absolutely pervasive. It is in every cubic centimetre of ocean and every square centimetre of the Arctic and Antarctic, and all of our deserts.
Maybe Earth life could get the kind of toehold on Mars which we postulate for Mars life, but if Mars had native life it would be everywhere. Perhaps not out in the sun but certainly under each and every rock.
The effect on micro climates would be obvious to our sensors. Instead all we see is normal energy flow, the sun rises, heats up the sand, sun goes down, sand radiates into space. I don't disagree with you at all. I think the chance of finding life there is spectacularly slim. This is why I think the goal of looking for life should be secondary to other research aims. Exploring the caves seems like a worthy goal even aside from the life issue. They could be important in possible human settlements on the planet, both as shelter and possible sources of exploitable resources.
A large amount of the mass budget for any human habitation on Mars, whether temporary or permanent, would probably be the habitation modules itself. If there are caves with single entrances that can be closed off and pressurized (or filled with water, or even oxygen at low pressure), it seems like that would be pretty handy.
But I think it's a bad idea to sell the public on Mars exploration as a 'search for life.' What do you do when it becomes more and more clear that there isn't any? The funding will evaporate and there goes your whole program.
I really think that there should be a disclaimer on CC license declarations: "WARNING: without written agreement, this license means NOTHING." Well, that would really gut the usefulness of the CC licenses. I think the key is just to do a better job of informing everyone of what the CC license means: the only issue it says anything about is the author/photographer's copyright, and it doesn't mean the photograph is clear of other possibly problematic claims.
As other people have pointed out in this discussion, a CC-licensed photo that's just of some natural scenery is OK to use, because there probably aren't any other IP claims in it besides the author's copyright. However, photos of people, buildings, monuments, logos or artwork, etc.---basically anything manmade---may all have issues beyond the scope of the CC license.
And to the CC people's credit, they seem to have identified this problem and rectified it in the newer (1.5 and 2.0) license families. But when I googled around for general information on Creative Commons licenses, there's a lot of conflicting information around (even though the license itself is very clear, and Flickr uses the 2.0 version which makes no representations about anything other than the author's copyright). This is because some early versions of Creative Commons licenses (the 1.0 versions), actually did make representations about the legality of the image for downstream uses: when you put something under it, you were saying, basically, "I have no reason to believe there's anything that would stop you from using this photo..." in addition to giving up some of your own copyright claims. That's really, really bad.
I think Flickr needs to clarify its "image search" features, particularly the options that let you search for images that can be 'used commercially,' to make sure that nobody can accuse them of making representations as to the fitness of images licensed under certain CC licenses for commercial purposes.
Virgin is in the wrong here I don't think so. They used what basically amounted to a stock photo according to its license. Were they supposed to personally vet all parties involved? Do you personally vet everyone in stock photos you use? Or audit all the software on your machine to ensure that the people who licensed it to you really had permission to do so?
At some point, you have to be able to trust that your sources are legitimately representing themselves. IANAL, but this seems like one of those "good faith" dealings, and Virgin didn't have any reason to think that the photographer was illegally offering his work. They obeyed their license with him, and it was his job to make sure he was allowed to offer it. I think that the argument the photographer could make -- and a pretty good one IMO -- is that simply by putting up the photo under the BY-SA license (or whatever license he chose that wasn't one of the 'NC' ones), he *did not* make any representations that it was OK to use commercially. He may have waived his own copyright, and said that he had no problem with it being used commercially, but he didn't say that the image was clear of other IP claims.
That's a pretty crucial difference: "I don't prohibit you from using this commercially," is a very different statement from "this image is OK to use commercially." Only in the latter case is the photographer making any representations about the suitability of the photo for a particular use. In the former, he's just saying 'I don't have a problem with commercial use,' the implication being that someone else might, and it's on you to check.
In a stock photo repository, you are told specifically by the stock company "these images are all OK to be used commercially." (Usually in very explicit terms, somewhere in the small print, and the better ones will usually indemnify you from any problems like this, which is why companies use them.) But I don't think Flickr is saying that, and it's a mistake to assume that just because a photo is under a license that doesn't prohibit commercial use, that it's implied.
Basically, although my initial response was to blame the photographer, on more consideration I think the majority of the blame lies with Virgin, for treating Flickr like a stock-photo gallery, when in reality it's anything but. Flickr has a lot of images on which the photographers have put very permissive licenses on their own copyrights, but that doesn't necessarily imply anything else.
I could see enough room though for a good attorney to argue the case either way. If this actually goes to trial it could be pretty interesting, since I suspect Virgin probably isn't the only company using Flickr as a source for stock photography.
Yes as I have been thinking about it more I'm starting to come around more to your line of reasoning.
It really depends on how you interpret the CC licenses that don't prohibit commercial use. I could see a fair argument that by putting a photo on the Internet with such a license, you are effectively saying that anyone can use it for a commercial purpose. This would put the photographer at fault.
However, I think the response to that (and one which as I've thought about it a bit more, I agree with) is that simply putting a photo up with a license that doesn't prohibit commercial use, does not mean that all commercial use is OK: it doesn't indemnify the downstream users of the photo, in other words, nor does it make any representations about the legal status of the photo, except regarding the photographer's copyright claim.
That's the real crux: by putting the photo under the CC license, was the photographer making a representation about how the photo could be used? Or was he only waiving his own copyright? I'm convinced now of the latter, but in front of a judge, I think it could easily go to the person with the better lawyers.
You can be photographed in a public place, but your image cannot be used commercially without your permission (with some minor exceptions).
E.g., I can stand outside your house on the street and take a photo of you when you walk your dog in the morning, holding a cup of coffee, but I can't take that same photo and use it in the promotional materials for "Kadin's Pretty Good Coffee Co." Although you can't stop me from taking the picture, you still have some control over the use of your image commercially, particularly to support or endorse a product.
So the photographer was probably OK to take the picture. I'm not really sure if he was OK to put it on the Internet, if he didn't have the parents' permission (I think that's sort of a legal grey area at the moment). He was probably not okay to license it under the CC license, although he may be able to argue successfully that simply putting the photo under the Attribution license doesn't imply that it can be used commercially, simply that commercial use isn't prohibited by him (there's a fine but significant difference there). I suspect Virgin is going to be liable for something, because they took the photo, assumed that the CC license implied that a model release existed, and ran the photo, when in fact they only had the photographer's permission, but not the model's.
In a photo that shows a clearly identifiable person, there are two intellectual property issues. The first is regarding the actual copyright on the photograph. That is held by the photographer and it's what the CC license releases for others to use. The second piece of IP is the model/subject's image, and that is controlled by the subject/model unless they sign a model release and turn over control to the photographer.
Most stock repositories won't accept photos of people without a model release, for exactly this reason. However, Flickr doesn't care, and Virgin's PR people blew it when they treated Flickr like a stock-photo repository.
You need a model release when a person is identifiable and comprises a significant part of the photo. I.e., a street scene in New York doesn't require a model release from every person on the street, because none of them are really critical parts of the photo. They're just scenery. And probably they're hard to make out individually anyway, so it's not like anyone's 'image' is really being used.
Where things become different are when it's a photo of a particular individual. In that case, the individual has a certain level of control they can exercise over how their image is used. E.g., they can object to their image being used to promote something they disagree with, or for some commercial purpose. There are exceptions to this, but the courts have historically given people a pretty wide 'bubble' around how their identity is used in the commercial sphere.
A model release protects a photographer and the photographer's clients (people who might buy his photos and use them commercially) from exactly this sort of problem: a model coming back after the fact and saying 'hey, I didn't want you to use my photo in that way.' A model release is a blanket permission basically saying "I grant you permission to use my image for anything, in any medium, forever..." It's protection for the photographer, and it does so by giving up a right that the model would normally have over their image.
No, as others have pointed out it's not the girl's fault but the photographer. Letting someone take a photo of you doesn't (usually) imply that they have gotten your permission to use your image commercially. They have the copyright to the image, but you still have some control over how your image is used.
This is why when a photographer takes pictures for stock collections, in addition to the copyright to the photo, they also need to show that they had a model release from anyone in the photo (at least those people who can be identified).
In this case, the photographer took a picture and put the picture on Flickr... but he put it up under a license that he really didn't have permission to use. In effect, it's like he sold something that he didn't rightfully own.
So the girl definitely has a case against the photographer, and could probably get some money out of Virgin (perhaps for not performing due diligence after grabbing the photo from Flickr, when anyone with a brain should have realized that ripping some photos from the web and dumping them into your ad campaign without checking up on them first is a bad idea), but I think the CC people are reasonably safe. They'll probably end up spending a few grand in lawyers' fees, but that's the cost of breathing these days.
And I suppose some sort of Linux Anti-Virus software would need to be procured and added to the Linux test systems to make it fair... Why? Give each machine whatever it requires to safely accomplish its workload in real-world conditions. If that means loads more anti-virus and IDS/IPS on the Windows machine than on the Linux one, so be it.
Well, you could certainly do it with robots; just probably not the robots that we have here right now.
If you were putting together a mission specifically to explore the caves, you'd probably design something that could either trail an umbilical behind itself, leading to a base station near the cave entrance which would have an uplink transceiver and solar panels for power, or you'd drop radio relays inside the cave mouth (but then you'd have to worry about how to get power to drive the robot around inside the caves, which is hard unless you want to use an RTG).
I don't know if anyone's done much work with rovers that trail umbilicals, so there might be a lot of testing required to get it right (how do you make sure that it can roll the umbilical up, not get it tangled around stuff, maybe even cut and reattach it in an emergency if a rock falls on it or something), but it's fundamentally an engineering problem, certainly not outside our capabilities.
I think the biggest trick would be getting a fairly large 'base station' with a lot of solar panels close enough to the cave mouth so that the rover wouldn't waste a lot of umbilical distance getting to the cave, but without collapsing or damaging the cave in any way.
I was standing at the customer-service desk of a computer store yesterday (MicroCenter, a slightly more clueful big-box store than CompUSA or its ilk) and a guy walked up to the desk next to me. Basically, the guy wanted to know "what the hell was wrong with his computer." Some sales drone had sold him on a Vista laptop, and he got it home before discovering that it wasn't what he expected a computer to look or feel like. Long story short, the guy ended up returning the unit and exchanging it for one of the two models they still stock that come preinstalled with Windows XP.
I was standing at the customer-service desk of a computer store yesterday (MicroCenter, a slightly more clueful big-box store than CompUSA or its ilk) and a guy walked up to the desk next to me. Basically, the guy wanted to know "what the hell was wrong with his computer." Some sales drone had sold him on a Vista laptop, and he got it home before discovering that it wasn't what he expected a computer to look or feel like. Long story short, the guy ended up returning the unit and exchanging it for one of the two models they still stock that come preinstalled with Vista.
I certainly hope someone in their corporate hierarchy takes note and realizes that stuffing Vista down users' throats isn't a good idea. Even clueless users know when they're being sold a bill of goods, and in some ways their cluelessness makes them less able to deal with the changes in Vista than experienced users (who by and large *could* deal with Vista, but don't want to have to).
Sending the message that "good" engineers are the ones who'll stay all night is exactly what keeps people who value life balance out of fields like engineering. Such a culture doesn't just tend to exclude women, but also people from non-anglo cultures that value family. The only way to do that would be to eliminate the very parts of the profession that make it meritocratic. People are respected in engineering based on the work they do. If you want to be held in greater esteem, you work harder: you try to do better work, and you try to do more of it.
Sure, if you can do in 4 hours what other people take 10 hours to do, you'll probably be regarded as a lot better than them (and rightly so). But the second you end up next to someone who's abilities are the equal of yours and who is willing to put more time in, they're going to be the one getting rewarded. (And rightly so.)
Personally, I think this is quite liberating: on the whole, most engineers, and many other people in science-based disciplines, don't really care a lot about who you are. They're some of the most welcoming places for people of all genders and skin colors and lifestyles, in that everyone is on the same playing field. If you do good work, people respect you. If you don't, well, it sucks to be you. (And this is quite literally true: people whose work sucks tend to be more pitied than disliked, IMO, at least by those who don't have to clean it up.)
Does this perhaps lead to a monoculture in terms of the personality types it advances? Perhaps so. But I think it's worthwhile, even admirable, because it's inherently nondiscriminatory. Nobody gets special consideration, everyone's being judged basically according to the same rules.
It's not as though engineering is really unique here. Lots of other fields are similar. I've worked in consulting and found that it's basically the same, even more clear-cut. Most consultants are promoted and rewarded based on very straightforward metrics: billing and utilization rate. Basically, it's how much money they bring in. If you work hard and bill 60 hours per week, you'll be everyone's golden child. If you decide to make it a 9-5, take a lot of vacation time, or get pregnant, you won't be fired...but don't expect a nice bonus at Christmas. It's not personal, it's just that other people made sacrifices, and they're going to be rewarded for it. If you want the big bucks, you have to make a decision where your priorities are. There's no right or wrong answer, it's just a personal judgment call.
(And, interestingly, there are a lot of female consultants -- far more than there are engineers -- making me think that it's not the competitive, meritocratic workplace that's the turnoff, at least not initially.)
I was responding directly to the GP who said "I think that even to people involved with electronics..." I was not talking about anybody else.
That said, I'd hope that TSA agents would be familiar with bombs, or at least what bombs look like, and what parts might go into a bomb, and might therefore realize that flashy LEDs are not crucial components in one. I suppose that's asking a bit much out of Kip Hawley's DHS, though, since their job is quite clearly to create an appearance of security, and little more.
If you quit being an ass and took five seconds to look for yourself, you'd find this official paper from the FSF, which says (under the section marked "Apache License Compatibility" beginning on p.9):
We are pleased to report that the Final Draft makes the Apache License, version 2.0, fully compatible with GPLv3. We are grateful to the Apache Software Foundation for working with us to achieve this long-sought goal. The concerns we stated in the Draft 3 Rationale were based on vary- ing literal readings of section 9 of the Apache license that differed from the interpretation of section 9 held by the ASF itself. During the course of productive discussions with the ASF following the release of Draft 3, we ascertained that, to the ASF, the words "by reason of " in the section 9 upstream indemnification clause meant nothing broader or vaguer than "di- rectly as a result of." Read in this light, section 9 seems to us a reasonable and fair approach to protecting upstream developers, even though we do not wish to adopt such a provision in our own license. The Final Draft makes the Apache indemnification clause compatible with GPLv3 by adding a new category of additional conditions in section 7 that may be applied, with appropriate copyright authorization, to material added to a covered work.
Hrmmmm.... looking at the "device" from the images on the link makes me think the police overreacted. Come on now.... holding her at gunpoint?
I disagree, I think that even to people involved with electronics it could look like something threatening. I think the police did their job and this Star Simpson person was pretty stupid to try that. Talk about no common sense. I disagree. I think that to people involved with electronics it would look like a prototyping board and a bunch of LEDs.
If you find that threatening, you either need therapy or you need to get out more.
You're making the same mistake over again, though. Just because 80% support independence in some form, does not mean that the remaining 20% want to be part of the PRC. Of the remaining 20%, probably most people just like the status quo -- which is de facto independence -- and don't want to make waves. And there are probably still a few (probably older) people who think that the ROC ought to be governing mainland China, and have that as their basis for reunification. You're creating a false dichotomy.
At most, you might claim that 10% of the population is interested in a "one country, two systems" policy (that's what Wikipedia claims, but I think that's 10+ years old now), but that's still a form of de facto independence. You would have to drill down much further to find the few who want anything to do with the PRC government, and I suspect it's vanishingly small.
I realize this is probably something that'll never happen, but I've always thought it would be slick to build a web form that had a NNTP interface as well, both accessing the same backend database. That way people could use their newsreader of choice, which often provide far more options for killfiles, rules-based sorting, etc., than a web interface does.
I wonder if any web forum packages have ever considered or supported this.
With more applications being frontloaded onto the web browser, it's probably about ten years too late, both for the idea of a desktop app and for Usenet/NNTP compatibility generally (although I've seen traffic stats that show the number of text postings on Usenet, in absolute numbers, are higher today than they ever were in the past).
Personally, I'm not sure that I believe it, at least not that it's 100% of the story. If it were just the emails, then I'd believe it was just a random hacking of some idiot's GMail account. However, there's also a taped phone conversation between someone at MediaDefender and someone at the New York State Attorney General's office floating around, and that's something that seems like it'd be harder to just find randomly.
I think it's entirely possible that the person or persons who are behind both the leaked email and the phone conversation are actually working inside MediaDefender. I'm not suggesting that the emails or the convo is a deliberate plant -- the MD people don't strike me as that smart nor that subtle -- but rather I think someone inside their company has more sympathy for the pirates than for MD's customers.
To be honest I think the phone conversation is really much more interesting than the emails are; I really tend to wonder whether both people on the line knew they were being taped, and whether the taping was being done as a CMA policy by MD executives, or if it was something that a disgruntled employee did by themselves.
Although it might seem a bit farfetched now, as technology issues become more important to more people, and start to impinge more on daily life, I think we're going to see the level of effort that people are willing to spend rectifying perceived injustices increase significantly. It's not impossible to imagine someone who feels strongly about an issue getting themselves hired at a company they hate, purely to undermine them or conduct espionage. This already isn't unheard of in political campaigns; extending it to tech issues isn't that big of a stretch.
The act of disagreeing with the United States may in itself be good, but if it's done by a bunch of raping thieves, they're still a bunch of fucking raping thieves.
Truer words have rarely been spoken, least of all on Slashdot, and virtually never in a political discussion.
That's a load of bull, and consistent only with the PRC's propaganda machine. Roughly 80 percent of the population of Taiwan supported the "two states policy," which would qualify as 'independence' to most unbiased external observers.
However, 'independence' in Taiwan is complicated, and means many things to many people: some Taiwanese reject 'independence' because they consider the ROC to be, if not the actual legitimate government of all China generally, at least its cultural heir. And others simply avoid 'independence' altogether and prefer the status quo for purely pragmatic reasons: the day-to-day situation is, for most intents and purposes, an independent Taiwan, and there is the strong possibility that if Taiwan declared independence from the PRC officially, the result would be the annihilation of everyone living there.
The figure usually quoted by PRC propaganda, arrived at by simply polling 'do you support Taiwanese independence,' is a loaded question and necessarily begets a skewed response. The people responding 'no' to that question do not necessarily have any love for the mainland, and certainly not for the PRC.
As it has become more and more apparent that 'reunification' would mean domination by Beijing (and not a restoration of the ROC government on the Mainland, or even an EU-like confederation), support for it in virtually all forms has disappeared from mainstream Taiwanese politics. Even "One Country, Two Systems" which is (from the PRC's perspective) a very lax 'reunification' stance, enjoys support from less than 10% of Taiwanese.
I believe they are using the "Journalist Transfer Orbit." This is a highly specialized piece of orbital mechanics: basically, you take the average distance to the destination as given by Wikipedia and divide by the spacecraft's top speed.
Slashdot Mirror
That's sort of partially correct.
The way balanced audio works is via two signal conductors, and then a separate ground. That's probably the three wires that you're thinking of. Really the ground isn't part of the circuit (and sometimes the ground is intentionally broken to prevent loops), but it's why you have three pins in an XLR jack.
Basically, a balanced audio source will act like a 'push-pull' current source. Rather than simply having a voltage on a wire that varies in time, you have a continuous loop, and you 'push' down one side of the loop and 'pull' up on the other, or vice versa. If you were to hook an oscilloscope probe up to both sides of a balanced audio circuit while something was going down it, you'd find out that the signals on each side of the circuit are 180-degrees out of phase wrt each other. By convention, one of the signal lines is usually called the '+' side and one is called the '-' side,* with the '+' side usually being in-phase with the actual microphone input.
The advantage of this, over an unbalanced line, is common-mode rejection. If you use a transformer (or some type of modern transistorized circuit that simulates a transformer; op-amps acting like difference amplifiers also work well) on the receiving end of the circuit, you can basically 'throw away' any signal that's the same on *both sides* of the circuit. E.g., lets imagine that your balanced audio line is right next to a 60Hz power line. The 60Hz is going to get into the balanced line, but it's going to be the same on both the '+' and '-' sides, while the actual audio is going to be 180 degrees o.o.p. from one side to the other. This makes it easy to reject the interference: when you run the balanced audio into a 1:1 transformer, the 60Hz doesn't produce any current actually moving through the transformer's coils, and thus no output (or very little).
I'm not sure where balanced audio circuits originated. I think that it probably started with the phone company (which has been doing balanced loop circuits practically forever; in telco parlance the '+' and '-' are sometimes called 'tip' and 'ring' respectively, after their placement on old 1/4" jacks) and later migrated to studio audio and sound reinforcement later, rather than the other way around.
Some further reading on balanced audio:
http://www.videomaker.com/article/9732/ Good basic article, might make sense if my explanation doesn't.
http://www.tvtechnology.com/pages/s.0071/t.1585.html Also good, assumes more knowledge of electrical concepts (i.e. impedance).
* Some audio people insist on calling the '+' side of balanced audio connections "hot" and the '-' side "cold," which I think is stupid since they both carry signal (unlike, say, the 'hot' and 'neutral' in your power socket), but you hear it tossed around.
Just in case anyone else was intrigued by "MVL Modems," I did a little searching and apparently they are a variation on DSL that's a bit more robust.
This fairly ancient (1998) article claims 24,000 line-feet at 768kbps and gives the name of an equipment manufacturer who pioneered the technology. Given the sparse information available and the fact I've never heard of it until today, I'm going to guess it was kinda stillborn.
Still might be cool in a pinch, though.
One thing I've always wanted to find out is whether there's a way to use two cheap consumer DOCSIS-compliant cable modems to transmit data over a dry piece of point-to-point CATV coax. The OEMs charge an absolute bundle for real cableco headend gear, and I've always wondered if it would be possible to hack two consumer ('tailend'?) boxes to talk to each other. Given the distances that you can run cable for compared to most UTP services, its ease of installation compared to fiber, and the ubiquity of DOCSIS equipment, that would be a pretty neat way of extending an Ethernet network over very long distances on the cheap.
The phone's speaker and microphone are both in the circuit (plus the bell or ringer); the "sidetone" (your own voice as heard through the speaker) elimination is done in your telephone. In fact, some telephones let you adjust the sidetone up and down. When you install multiple telephone handsets on one line, you're basically just hanging multiple sets of microphones, speakers, and ringers off of the same two-wire balanced circuit.
You're right that a normal POTS line has stuff applied to it at the CLEC end that attenuate high-frequency signals, but they're not there to eliminate sidetone.
To a telco person, a 'four wire' circuit is going to be two unloaded loops, because telephone people tend to think in terms of 'loops' or 'pairs,' one loop per phone line/number.
Most modern homes are wired with Cat 3 wiring, which includes 3 discrete pairs, but unless you order a second line from the phone company, you probably only have dialtone on two wires (one pair), and only one pair comes out from the pole to your house. (Which is actually cool, because if your house wiring is done in a star configuration instead of daisy-chained, you can use the two dry pairs for 10BT Ethernet, in a pinch.)
Slightly OT but cool: Anyone interested in POTS phone technology might want to check out this page (http://home.utah.edu/~nahaj/cave/phones/) which explains how to build a very simple one or two-wire field phone system just with phone handsets. Apparently they are used in cave rescue and other applications where radios don't work. It's a good introduction to how POTS works, though, since it doesn't introduce the complexity of the ringer, switching system, etc. It gets into sidetone and sidetone-suppression a little.
That's the price you pay for being an early adopter. (Or, as I like to call it, "stupid.")
Maybe Earth life could get the kind of toehold on Mars which we postulate for Mars life, but if Mars had native life it would be everywhere. Perhaps not out in the sun but certainly under each and every rock.
The effect on micro climates would be obvious to our sensors. Instead all we see is normal energy flow, the sun rises, heats up the sand, sun goes down, sand radiates into space. I don't disagree with you at all. I think the chance of finding life there is spectacularly slim. This is why I think the goal of looking for life should be secondary to other research aims. Exploring the caves seems like a worthy goal even aside from the life issue. They could be important in possible human settlements on the planet, both as shelter and possible sources of exploitable resources.
A large amount of the mass budget for any human habitation on Mars, whether temporary or permanent, would probably be the habitation modules itself. If there are caves with single entrances that can be closed off and pressurized (or filled with water, or even oxygen at low pressure), it seems like that would be pretty handy.
But I think it's a bad idea to sell the public on Mars exploration as a 'search for life.' What do you do when it becomes more and more clear that there isn't any? The funding will evaporate and there goes your whole program.
As other people have pointed out in this discussion, a CC-licensed photo that's just of some natural scenery is OK to use, because there probably aren't any other IP claims in it besides the author's copyright. However, photos of people, buildings, monuments, logos or artwork, etc.---basically anything manmade---may all have issues beyond the scope of the CC license.
And to the CC people's credit, they seem to have identified this problem and rectified it in the newer (1.5 and 2.0) license families. But when I googled around for general information on Creative Commons licenses, there's a lot of conflicting information around (even though the license itself is very clear, and Flickr uses the 2.0 version which makes no representations about anything other than the author's copyright). This is because some early versions of Creative Commons licenses (the 1.0 versions), actually did make representations about the legality of the image for downstream uses: when you put something under it, you were saying, basically, "I have no reason to believe there's anything that would stop you from using this photo..." in addition to giving up some of your own copyright claims. That's really, really bad.
I think Flickr needs to clarify its "image search" features, particularly the options that let you search for images that can be 'used commercially,' to make sure that nobody can accuse them of making representations as to the fitness of images licensed under certain CC licenses for commercial purposes.
At some point, you have to be able to trust that your sources are legitimately representing themselves. IANAL, but this seems like one of those "good faith" dealings, and Virgin didn't have any reason to think that the photographer was illegally offering his work. They obeyed their license with him, and it was his job to make sure he was allowed to offer it. I think that the argument the photographer could make -- and a pretty good one IMO -- is that simply by putting up the photo under the BY-SA license (or whatever license he chose that wasn't one of the 'NC' ones), he *did not* make any representations that it was OK to use commercially. He may have waived his own copyright, and said that he had no problem with it being used commercially, but he didn't say that the image was clear of other IP claims.
That's a pretty crucial difference: "I don't prohibit you from using this commercially," is a very different statement from "this image is OK to use commercially." Only in the latter case is the photographer making any representations about the suitability of the photo for a particular use. In the former, he's just saying 'I don't have a problem with commercial use,' the implication being that someone else might, and it's on you to check.
In a stock photo repository, you are told specifically by the stock company "these images are all OK to be used commercially." (Usually in very explicit terms, somewhere in the small print, and the better ones will usually indemnify you from any problems like this, which is why companies use them.) But I don't think Flickr is saying that, and it's a mistake to assume that just because a photo is under a license that doesn't prohibit commercial use, that it's implied.
Basically, although my initial response was to blame the photographer, on more consideration I think the majority of the blame lies with Virgin, for treating Flickr like a stock-photo gallery, when in reality it's anything but. Flickr has a lot of images on which the photographers have put very permissive licenses on their own copyrights, but that doesn't necessarily imply anything else.
I could see enough room though for a good attorney to argue the case either way. If this actually goes to trial it could be pretty interesting, since I suspect Virgin probably isn't the only company using Flickr as a source for stock photography.
Yes as I have been thinking about it more I'm starting to come around more to your line of reasoning.
It really depends on how you interpret the CC licenses that don't prohibit commercial use. I could see a fair argument that by putting a photo on the Internet with such a license, you are effectively saying that anyone can use it for a commercial purpose. This would put the photographer at fault.
However, I think the response to that (and one which as I've thought about it a bit more, I agree with) is that simply putting a photo up with a license that doesn't prohibit commercial use, does not mean that all commercial use is OK: it doesn't indemnify the downstream users of the photo, in other words, nor does it make any representations about the legal status of the photo, except regarding the photographer's copyright claim.
That's the real crux: by putting the photo under the CC license, was the photographer making a representation about how the photo could be used? Or was he only waiving his own copyright? I'm convinced now of the latter, but in front of a judge, I think it could easily go to the person with the better lawyers.
You can be photographed in a public place, but your image cannot be used commercially without your permission (with some minor exceptions).
E.g., I can stand outside your house on the street and take a photo of you when you walk your dog in the morning, holding a cup of coffee, but I can't take that same photo and use it in the promotional materials for "Kadin's Pretty Good Coffee Co." Although you can't stop me from taking the picture, you still have some control over the use of your image commercially, particularly to support or endorse a product.
So the photographer was probably OK to take the picture. I'm not really sure if he was OK to put it on the Internet, if he didn't have the parents' permission (I think that's sort of a legal grey area at the moment). He was probably not okay to license it under the CC license, although he may be able to argue successfully that simply putting the photo under the Attribution license doesn't imply that it can be used commercially, simply that commercial use isn't prohibited by him (there's a fine but significant difference there). I suspect Virgin is going to be liable for something, because they took the photo, assumed that the CC license implied that a model release existed, and ran the photo, when in fact they only had the photographer's permission, but not the model's.
In a photo that shows a clearly identifiable person, there are two intellectual property issues. The first is regarding the actual copyright on the photograph. That is held by the photographer and it's what the CC license releases for others to use. The second piece of IP is the model/subject's image, and that is controlled by the subject/model unless they sign a model release and turn over control to the photographer.
Most stock repositories won't accept photos of people without a model release, for exactly this reason. However, Flickr doesn't care, and Virgin's PR people blew it when they treated Flickr like a stock-photo repository.
You need a model release when a person is identifiable and comprises a significant part of the photo. I.e., a street scene in New York doesn't require a model release from every person on the street, because none of them are really critical parts of the photo. They're just scenery. And probably they're hard to make out individually anyway, so it's not like anyone's 'image' is really being used.
Where things become different are when it's a photo of a particular individual. In that case, the individual has a certain level of control they can exercise over how their image is used. E.g., they can object to their image being used to promote something they disagree with, or for some commercial purpose. There are exceptions to this, but the courts have historically given people a pretty wide 'bubble' around how their identity is used in the commercial sphere.
A model release protects a photographer and the photographer's clients (people who might buy his photos and use them commercially) from exactly this sort of problem: a model coming back after the fact and saying 'hey, I didn't want you to use my photo in that way.' A model release is a blanket permission basically saying "I grant you permission to use my image for anything, in any medium, forever..." It's protection for the photographer, and it does so by giving up a right that the model would normally have over their image.
No, as others have pointed out it's not the girl's fault but the photographer. Letting someone take a photo of you doesn't (usually) imply that they have gotten your permission to use your image commercially. They have the copyright to the image, but you still have some control over how your image is used.
... but he put it up under a license that he really didn't have permission to use. In effect, it's like he sold something that he didn't rightfully own.
This is why when a photographer takes pictures for stock collections, in addition to the copyright to the photo, they also need to show that they had a model release from anyone in the photo (at least those people who can be identified).
In this case, the photographer took a picture and put the picture on Flickr
So the girl definitely has a case against the photographer, and could probably get some money out of Virgin (perhaps for not performing due diligence after grabbing the photo from Flickr, when anyone with a brain should have realized that ripping some photos from the web and dumping them into your ad campaign without checking up on them first is a bad idea), but I think the CC people are reasonably safe. They'll probably end up spending a few grand in lawyers' fees, but that's the cost of breathing these days.
Well, you could certainly do it with robots; just probably not the robots that we have here right now.
If you were putting together a mission specifically to explore the caves, you'd probably design something that could either trail an umbilical behind itself, leading to a base station near the cave entrance which would have an uplink transceiver and solar panels for power, or you'd drop radio relays inside the cave mouth (but then you'd have to worry about how to get power to drive the robot around inside the caves, which is hard unless you want to use an RTG).
I don't know if anyone's done much work with rovers that trail umbilicals, so there might be a lot of testing required to get it right (how do you make sure that it can roll the umbilical up, not get it tangled around stuff, maybe even cut and reattach it in an emergency if a rock falls on it or something), but it's fundamentally an engineering problem, certainly not outside our capabilities.
I think the biggest trick would be getting a fairly large 'base station' with a lot of solar panels close enough to the cave mouth so that the rover wouldn't waste a lot of umbilical distance getting to the cave, but without collapsing or damaging the cave in any way.
I was standing at the customer-service desk of a computer store yesterday (MicroCenter, a slightly more clueful big-box store than CompUSA or its ilk) and a guy walked up to the desk next to me. Basically, the guy wanted to know "what the hell was wrong with his computer." Some sales drone had sold him on a Vista laptop, and he got it home before discovering that it wasn't what he expected a computer to look or feel like. Long story short, the guy ended up returning the unit and exchanging it for one of the two models they still stock that come preinstalled with Windows XP.
I was standing at the customer-service desk of a computer store yesterday (MicroCenter, a slightly more clueful big-box store than CompUSA or its ilk) and a guy walked up to the desk next to me. Basically, the guy wanted to know "what the hell was wrong with his computer." Some sales drone had sold him on a Vista laptop, and he got it home before discovering that it wasn't what he expected a computer to look or feel like. Long story short, the guy ended up returning the unit and exchanging it for one of the two models they still stock that come preinstalled with Vista.
I certainly hope someone in their corporate hierarchy takes note and realizes that stuffing Vista down users' throats isn't a good idea. Even clueless users know when they're being sold a bill of goods, and in some ways their cluelessness makes them less able to deal with the changes in Vista than experienced users (who by and large *could* deal with Vista, but don't want to have to).
Sure, if you can do in 4 hours what other people take 10 hours to do, you'll probably be regarded as a lot better than them (and rightly so). But the second you end up next to someone who's abilities are the equal of yours and who is willing to put more time in, they're going to be the one getting rewarded. (And rightly so.)
Personally, I think this is quite liberating: on the whole, most engineers, and many other people in science-based disciplines, don't really care a lot about who you are. They're some of the most welcoming places for people of all genders and skin colors and lifestyles, in that everyone is on the same playing field. If you do good work, people respect you. If you don't, well, it sucks to be you. (And this is quite literally true: people whose work sucks tend to be more pitied than disliked, IMO, at least by those who don't have to clean it up.)
Does this perhaps lead to a monoculture in terms of the personality types it advances? Perhaps so. But I think it's worthwhile, even admirable, because it's inherently nondiscriminatory. Nobody gets special consideration, everyone's being judged basically according to the same rules.
It's not as though engineering is really unique here. Lots of other fields are similar. I've worked in consulting and found that it's basically the same, even more clear-cut. Most consultants are promoted and rewarded based on very straightforward metrics: billing and utilization rate. Basically, it's how much money they bring in. If you work hard and bill 60 hours per week, you'll be everyone's golden child. If you decide to make it a 9-5, take a lot of vacation time, or get pregnant, you won't be fired...but don't expect a nice bonus at Christmas. It's not personal, it's just that other people made sacrifices, and they're going to be rewarded for it. If you want the big bucks, you have to make a decision where your priorities are. There's no right or wrong answer, it's just a personal judgment call.
(And, interestingly, there are a lot of female consultants -- far more than there are engineers -- making me think that it's not the competitive, meritocratic workplace that's the turnoff, at least not initially.)
I was responding directly to the GP who said "I think that even to people involved with electronics..." I was not talking about anybody else.
That said, I'd hope that TSA agents would be familiar with bombs, or at least what bombs look like, and what parts might go into a bomb, and might therefore realize that flashy LEDs are not crucial components in one. I suppose that's asking a bit much out of Kip Hawley's DHS, though, since their job is quite clearly to create an appearance of security, and little more.
I disagree, I think that even to people involved with electronics it could look like something threatening. I think the police did their job and this Star Simpson person was pretty stupid to try that. Talk about no common sense. I disagree. I think that to people involved with electronics it would look like a prototyping board and a bunch of LEDs.
If you find that threatening, you either need therapy or you need to get out more.
You're making the same mistake over again, though. Just because 80% support independence in some form, does not mean that the remaining 20% want to be part of the PRC. Of the remaining 20%, probably most people just like the status quo -- which is de facto independence -- and don't want to make waves. And there are probably still a few (probably older) people who think that the ROC ought to be governing mainland China, and have that as their basis for reunification. You're creating a false dichotomy.
At most, you might claim that 10% of the population is interested in a "one country, two systems" policy (that's what Wikipedia claims, but I think that's 10+ years old now), but that's still a form of de facto independence. You would have to drill down much further to find the few who want anything to do with the PRC government, and I suspect it's vanishingly small.
I realize this is probably something that'll never happen, but I've always thought it would be slick to build a web form that had a NNTP interface as well, both accessing the same backend database. That way people could use their newsreader of choice, which often provide far more options for killfiles, rules-based sorting, etc., than a web interface does.
I wonder if any web forum packages have ever considered or supported this.
With more applications being frontloaded onto the web browser, it's probably about ten years too late, both for the idea of a desktop app and for Usenet/NNTP compatibility generally (although I've seen traffic stats that show the number of text postings on Usenet, in absolute numbers, are higher today than they ever were in the past).
The source is important.
Personally, I'm not sure that I believe it, at least not that it's 100% of the story. If it were just the emails, then I'd believe it was just a random hacking of some idiot's GMail account. However, there's also a taped phone conversation between someone at MediaDefender and someone at the New York State Attorney General's office floating around, and that's something that seems like it'd be harder to just find randomly.
I think it's entirely possible that the person or persons who are behind both the leaked email and the phone conversation are actually working inside MediaDefender. I'm not suggesting that the emails or the convo is a deliberate plant -- the MD people don't strike me as that smart nor that subtle -- but rather I think someone inside their company has more sympathy for the pirates than for MD's customers.
To be honest I think the phone conversation is really much more interesting than the emails are; I really tend to wonder whether both people on the line knew they were being taped, and whether the taping was being done as a CMA policy by MD executives, or if it was something that a disgruntled employee did by themselves.
Although it might seem a bit farfetched now, as technology issues become more important to more people, and start to impinge more on daily life, I think we're going to see the level of effort that people are willing to spend rectifying perceived injustices increase significantly. It's not impossible to imagine someone who feels strongly about an issue getting themselves hired at a company they hate, purely to undermine them or conduct espionage. This already isn't unheard of in political campaigns; extending it to tech issues isn't that big of a stretch.
Also, from your earlier comment:
The act of disagreeing with the United States may in itself be good, but if it's done by a bunch of raping thieves, they're still a bunch of fucking raping thieves.
Truer words have rarely been spoken, least of all on Slashdot, and virtually never in a political discussion.
That's a load of bull, and consistent only with the PRC's propaganda machine. Roughly 80 percent of the population of Taiwan supported the "two states policy," which would qualify as 'independence' to most unbiased external observers.
However, 'independence' in Taiwan is complicated, and means many things to many people: some Taiwanese reject 'independence' because they consider the ROC to be, if not the actual legitimate government of all China generally, at least its cultural heir. And others simply avoid 'independence' altogether and prefer the status quo for purely pragmatic reasons: the day-to-day situation is, for most intents and purposes, an independent Taiwan, and there is the strong possibility that if Taiwan declared independence from the PRC officially, the result would be the annihilation of everyone living there.
The figure usually quoted by PRC propaganda, arrived at by simply polling 'do you support Taiwanese independence,' is a loaded question and necessarily begets a skewed response. The people responding 'no' to that question do not necessarily have any love for the mainland, and certainly not for the PRC.
As it has become more and more apparent that 'reunification' would mean domination by Beijing (and not a restoration of the ROC government on the Mainland, or even an EU-like confederation), support for it in virtually all forms has disappeared from mainstream Taiwanese politics. Even "One Country, Two Systems" which is (from the PRC's perspective) a very lax 'reunification' stance, enjoys support from less than 10% of Taiwanese.
I believe they are using the "Journalist Transfer Orbit." This is a highly specialized piece of orbital mechanics: basically, you take the average distance to the destination as given by Wikipedia and divide by the spacecraft's top speed.