"Spread the wealth" would seem to point to taking the money that I earn, and 'spreading' it to others who haven't earned it.
Or 'spreading' it to others who havent had the same opportunities as you had. Why is it so difficult to accept that it is a good idea to at least provide some basic services to all people, to ensure that they have a fair level of education, transport and healthcare? Let them 'earn it' beyond that!
In my mother tongue, the old, pre-twentieth-century term referring to being declared an outlaw is to be declared "voêlvry" -- free as a bird. Free to go where you will, and free to be shot on sight.
True -- sorry, I stated that ambiguously! A better phrase would have been "all who die, die by getting shot". I agree that one should hardly try to extend this to a theme; most likely it is only a nod to Kurosawa (there's a nod to Murnau's "Nosferatu" too, but that seems to be even more spurious).
Both movies feature a chivalrous order that has outlived its time, and is defeated by opponents more willing to apply ruthless methods. In Seven Samurai, none of the Samurai die by the sword -- all are shot. In Revenge of the Sith, the same happens to the Jedi: they are defeated not by the Sith as dark counterparts of the Jedi, but are shot down mercilessly.
Given the strong influence Kurosawa had on Lucus, I think one would find many similar themes echoed throughout all six episodes of Star Wars.
Yes, we need a more sophisticated test, one measuring true underlying intention. I can imagine it going like this:
Holden: You start up DC and notice that copyrighted files are being shared, Leon.
Leon: Do you make up these questions, Prof Holden? Or do they write 'em down for you?
Holden: The files are being shared, and other students are rapidly downloading them. We can't stop them without your help. But you're not helping.
Leon: WHAT DO YOU MEAN, I'M NOT HELPING?
Holden: I mean you're not helping! Why is that, Leon? [Leon has become visibly shaken]
Holden: They're just questions, Leon. In answer to your query they're written down for me. It's a test, designed to provoke an emotional response. (pause) Shall we continue?
I understand that the vendors might want to avoid risk, but installing an alternative operating system is not quite the same as deliberately overclocking your CPU. Personally, I find it disturbing that a hardware vendor would lock in a consumer's choice in software to this extent. Isn't it only fair to the consumer that hardware is covered by a warranty that covers bona fide hardware defects, irrespective of what software happens to be used?
Your argument can also be bent in the opposite direction: If software can potentially damage hardware, the potential for damage is certainly not just limited to the OS. Must third-party applications be tested and explicitly excluded in a warranty? Hardware that can be damaged by software, whether it be in the kernel or the user space, is suspect to start with -- and the risk should not be placed on the consumer.
Sure -- don't get me wrong. I'm not arguing that good techniques exist for both software signal processing and for analog front-ends: I'm just emphasising the point that these techniques are limited by (a) the computational power of the CPU, and (b) the frequency limitations of the hardware. It sounds as if the daughterboards come with state-of-the-art converters -- this comes at a price. Also don't neglect the fact that, the broader the part of the spectrum you want to receive, the more dynamic loss you have. Roughly, each time you double the frequency of the band you want to address, you lose one bit of precision, because different frequencies "add together" to swallow up your available dynamic range. How far are you willing to push the bandwidth before this dynamic loss becomes unacceptable?
It's great to hear that the front-end uses quadrature conversion! (Well, not that I think this wide range of addressable frequencies would have been possible using any other technology:) But this also comes with a bit of a price -- quadrature converters have inaccuracies of their own, usually introducing spurious components in the transmitted/received signal. There are ways to address this, but, AFAIK the efficient techniques are not quite mainstream yet.
CIC is a great downsampling technique, and an FPGA implementation a very efficient way of getting things done in real time. Once again, kudos to the designers: This really sounds like an excellent SDR implementation. I'm just saying "remember, it still has some limitations".
Even if USB 2.0 can crunch 480 Mbps (let's say 48 MS/s), the "managable size" that fits over USB 2.0 may still be a far cry from the "managable rate" that the processor can handle doing, say OFDM demodulation. I stand by my point that the processor's capabilities represent the fundamental limitation to the bandwidth that such a device can handle. Fortunately, Moore's law plays in our favor here: If we develop the technology now, capable hardware will arrive -- eventually.
Things are a bit more difficult at the antenna side. Even the smartest of antennas cannot cover all the interesting bits of spectrum from LF to V-band. At this point in time, some hardware swapping to accomodate specific applications seems inevitable.
I want to emphasize again: I love what these guys are doing, and the way that they're doing it. I just want the bounds of our current art to be clearly demarcated.
Be careful of that seemingly innocuous qualification: "with the right software and daughterboards"... both imply serious limitations to the technology.
Firstly, the "right" software: Even with a reasonably fast processor (say 3 GHz) today, you are typically only be able to process, at most, a few million samples per second -- especially if you are performing complicated modulation/demodulation, coding/decoding, filtering and protocol processing. Each sample may require substantial computation, and that limits the number of samples you can process per second. That, in its turn, affects the bandwidth that a processor can address (i.e. how wide a part of the radio spectrum you can "see" at any one time).
Secondly, the "right" daughterboards: To be able to address a wide bandwidth, we require digital-to-analog and analog-to-digital converters with high sampling rates. These are limited by the state of the art in signal conversion technology -- typically a couple of million samples per second if we want a reasonable number of bits per sample (at a reasonable price). Push it beyond that, and we have to be happy with fewer bits per sample (may 10 or 8 bits). This introduces noisiness to the signals being transmitted or received, degrading the fidelity of the software-defined radio.
Also, a daugterboard usually has some form of signal translation hardware ("mixers") to translate the low-frequency signals that computers can generate to and from the higher parts of the radio spectrum. Although broadband mixers are available, they need tunable oscillators (reference frequencies), and these tend to be limited to narrower parts of the spectrum. Also, analogue filters, amplifiers and antennas (which all form part of a typical software radio front-end), usually are limited to specific ranges of the radio spectrum.
In short, software radio daughterboards tend to be fairly application-specific (or at least spectrum-specific). We can do a lot of things in software, but a "universal" software radio needs a lot of hardware swapping. I think that makes it a bit less "universal". It might also push the cost of a truly multi-purpose system quite a bit beyond $550.
But I'm glad to see this technology receiving such mainstream attention, and I applaud the efforts of the designers. I just think that TFA (and the post) could maybe be a bit less sensasionalist.
Well, the waveform itself can be treated as a vector -- its variance corresponds to its power. So if you apply the central limit theorem to the (signed) waveforms, their cumulative effect has a standard deviation which decreases with sqrt(N), which means the square of their cumulative effect (i.e. the total power) has a variance which decreases with N.
I don't know if that makes sense at all...:) The key point is that it's the EM waves (not their power) that accumulate, hence the central limit theorem applies.
The parent is perfectly correct, but it's also interesting to note why (even if stations were not self-contained) the total EM power would have been lower due to several cables, not higher.
Assuming that all cables contain information travelling at the same frequency, and that they are statistically independent (i.e. they contain different information), the central limit theorem tells us that the total power is lower proportional to the number of cables, compared to the individual cables' EM power.
The various signal sources tend to interfere with each other destructively, driving the total output towards the sum of the means -- which in this case is zero.
But this is very mathy... bottom line is, many cables act in your favour, not against you:)
Well, the biggest contribution that Cedega makes is that gaming companies don't have this dilemma any more. I've been a Cedega user for almost a year now, and it does a pretty good job of running cutting-edge Windows games under Linux, often with no noticable performance difference.
Some games run better under Cedega than others, simply because they use the DirectX API in a more standardized way. It costs a gaming company very little to test their Windows builds under Cedega, and doing this could win them a little bit of extra market share.
And, of course, the "Afronaut" from South Africa:)
I think the variety of terms are rather quaint, since it gives countries a linguistic "T-shirt" saying "we've been there". It's a bit of national pride, maybe the space-age equivalent of planting a flag at an exotic destination.
from the coursing-thru-their-veins dept?
on
19 million Amps
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· Score: 2, Funny
I thought this kind of news falls under the current-affairs dept?
I found the sentiments expressed in your recent article, "Linux's Hit Men", somewhat disquieting. Mr. Lyons seems to advocate the idea that the violation of license agreement constitutes fair use of intellectual property. In the light of the past few years' renewed concern over business ethics, I cannot see how Forbes can identify itself with such a questionable viewpoint.
It is unclear whether mr. Lyons's argument is deliberately propogandistic, or whether it just stems from a misunderstanding of the principles of the GPL and the FSF. Although GPL-based software is labeled "free", it is certainly not within the public domain. Rather, it depends on the principle that software is a tool (whether employed for profit or not), and that all parties using such a tool can benifit from large-scale collaborative development by volunteers. To protect such an initiative against exploitation by those who would unscrupulously exploit the efforts of others for profit, terms of use are needed to maintain the open-source nature of the code, and all improvements made to it.
The license is certainly not a "hidden" threat in such code -- it is always available with distributed source, and asserted in the source files themselves. Users of such code must either abide with the licensing agreements, or use different source code.
Lastly, I must comment on the almost slanderous tone of the article with its strange McCarthyist overtones. Is this truly representative of neutral, unbiased reporting? Furthermore, I am disturbed by the suggestion that a party with little financial or legal resources somehow have a weaker legal position than a large corporation. Surely copyright protection is there to protect the small player too?
IANAL either, but I think the usual premise for originality in a patent is that it should not be "obvious to a person skilled in the art" to which the patent applies. Ozzie's method would indeed seem to be an obvious application of the capabilities of Lotus Notes, even to somebody "skilled in the art" working with it prior to the lawsuit.
Laura's right: you'll find the maths and the algorithms for echo cancellation in most textbooks on adaptive filtering. Check out the July 1999 issue of the IEEE Signal Processing Magazine (it shouldn't be too hard to get hold of it, most university libraries' engineering section should have it) -- it is an issue dedicated to "Adaptive Algorithms and Echo Cancellation". All the maths and algorithms you need are discussed there. Yes, you do need a good background in linear algebra to follow the underlying theory, but the algorithms should be easier to implement, and you're likely to find source code for most of them on the web (LMS filtering is used in many other applications too).
Echo cancellation is a common design problem in hands-free telephone systems and conference systems; there is lots of literature on the subject. See the references in the articles I mention above.
Slashdot Mirror
Sounds a lot like the fictional scam from Roald Dahl's "The Bookseller": https://en.wikipedia.org/wiki/...
Preying on people's fear of being embarassed is a great way to extort money.
"Spread the wealth" would seem to point to taking the money that I earn, and 'spreading' it to others who haven't earned it.
Or 'spreading' it to others who havent had the same opportunities as you had. Why is it so difficult to accept that it is a good idea to at least provide some basic services to all people, to ensure that they have a fair level of education, transport and healthcare? Let them 'earn it' beyond that!
In my mother tongue, the old, pre-twentieth-century term referring to being declared an outlaw is to be declared "voêlvry" -- free as a bird. Free to go where you will, and free to be shot on sight.
Complete freedom is not particularly desirable.
CALVIN: Dad, how come old photographs are always black and white? Didn't they have color film back then?
CALVIN'S DAD: Sure they did. In fact, those old photographs are in color. It's just the world was black and white then.
CALVIN: Really?
CALVIN'S DAD: Yep. The world didn't turn color until sometime in the 1930s, and it was pretty grainy color for a while, too.
CALVIN: That's really weird.
CALVIN'S DAD: Well, truth is stranger than fiction.
CALVIN: But then why are old paintings in color?! If the world was black and white, wouldn't artists have painted it that way?
CALVIN'S DAD: Not necessarily, a lot of great artists were insane.
CALVIN: But ... but how could they have painted in color anyway? Wouldn't their paints have been shades of gray back then?
CALVIN'S DAD: Of course, but they turned colors like everything else in the '30s.
CALVIN: So why didn't old black and white photos turn color too?
CALVIN'S DAD: Because they were color pictures of black and white, remember?
(CUT TO: EXT. Tree limb, Calvin talking with Hobbes)
CALVIN: The world is a complicated place, Hobbes.
HOBBES: Whenever it seems that way, I take a nap in a tree and wait for dinner.
"...and if you gaze for long into an abyss, the abyss gazes also into you."
True -- sorry, I stated that ambiguously! A better phrase would have been "all who die, die by getting shot". I agree that one should hardly try to extend this to a theme; most likely it is only a nod to Kurosawa (there's a nod to Murnau's "Nosferatu" too, but that seems to be even more spurious).
I found Episode III very reminiscent of Kurosawa's "Seven Samurai" (by the same Japanese director that made The Hidden Fortress.)
Both movies feature a chivalrous order that has outlived its time, and is defeated by opponents more willing to apply ruthless methods. In Seven Samurai, none of the Samurai die by the sword -- all are shot. In Revenge of the Sith, the same happens to the Jedi: they are defeated not by the Sith as dark counterparts of the Jedi, but are shot down mercilessly.
Given the strong influence Kurosawa had on Lucus, I think one would find many similar themes echoed throughout all six episodes of Star Wars.
Yes, we need a more sophisticated test, one measuring true underlying intention. I can imagine it going like this:
Holden: You start up DC and notice that copyrighted files are being shared, Leon.
Leon: Do you make up these questions, Prof Holden? Or do they write 'em down for you?
Holden: The files are being shared, and other students are rapidly downloading them. We can't stop them without your help. But you're not helping.
Leon: WHAT DO YOU MEAN, I'M NOT HELPING?
Holden: I mean you're not helping! Why is that, Leon?
[Leon has become visibly shaken]
Holden: They're just questions, Leon. In answer to your query they're written down for me. It's a test, designed to provoke an emotional response. (pause) Shall we continue?
... that the error would be patently obvious to a moderately intelligent Orangutan?
I dunno, apparently many companies are already broadcasting in the 450-750 terahertz range, using something called a "light bulb"...
I understand that the vendors might want to avoid risk, but installing an alternative operating system is not quite the same as deliberately overclocking your CPU. Personally, I find it disturbing that a hardware vendor would lock in a consumer's choice in software to this extent. Isn't it only fair to the consumer that hardware is covered by a warranty that covers bona fide hardware defects, irrespective of what software happens to be used?
Your argument can also be bent in the opposite direction: If software can potentially damage hardware, the potential for damage is certainly not just limited to the OS. Must third-party applications be tested and explicitly excluded in a warranty? Hardware that can be damaged by software, whether it be in the kernel or the user space, is suspect to start with -- and the risk should not be placed on the consumer.
It's great to hear that the front-end uses quadrature conversion! (Well, not that I think this wide range of addressable frequencies would have been possible using any other technology :) But this also comes with a bit of a price -- quadrature converters have inaccuracies of their own, usually introducing spurious components in the transmitted/received signal. There are ways to address this, but, AFAIK the efficient techniques are not quite mainstream yet.
CIC is a great downsampling technique, and an FPGA implementation a very efficient way of getting things done in real time. Once again, kudos to the designers: This really sounds like an excellent SDR implementation. I'm just saying "remember, it still has some limitations".
Even if USB 2.0 can crunch 480 Mbps (let's say 48 MS/s), the "managable size" that fits over USB 2.0 may still be a far cry from the "managable rate" that the processor can handle doing, say OFDM demodulation. I stand by my point that the processor's capabilities represent the fundamental limitation to the bandwidth that such a device can handle. Fortunately, Moore's law plays in our favor here: If we develop the technology now, capable hardware will arrive -- eventually.
Things are a bit more difficult at the antenna side. Even the smartest of antennas cannot cover all the interesting bits of spectrum from LF to V-band. At this point in time, some hardware swapping to accomodate specific applications seems inevitable.
I want to emphasize again: I love what these guys are doing, and the way that they're doing it. I just want the bounds of our current art to be clearly demarcated.
G-J
Firstly, the "right" software: Even with a reasonably fast processor (say 3 GHz) today, you are typically only be able to process, at most, a few million samples per second -- especially if you are performing complicated modulation/demodulation, coding/decoding, filtering and protocol processing. Each sample may require substantial computation, and that limits the number of samples you can process per second. That, in its turn, affects the bandwidth that a processor can address (i.e. how wide a part of the radio spectrum you can "see" at any one time).
Secondly, the "right" daughterboards: To be able to address a wide bandwidth, we require digital-to-analog and analog-to-digital converters with high sampling rates. These are limited by the state of the art in signal conversion technology -- typically a couple of million samples per second if we want a reasonable number of bits per sample (at a reasonable price). Push it beyond that, and we have to be happy with fewer bits per sample (may 10 or 8 bits). This introduces noisiness to the signals being transmitted or received, degrading the fidelity of the software-defined radio.
Also, a daugterboard usually has some form of signal translation hardware ("mixers") to translate the low-frequency signals that computers can generate to and from the higher parts of the radio spectrum. Although broadband mixers are available, they need tunable oscillators (reference frequencies), and these tend to be limited to narrower parts of the spectrum. Also, analogue filters, amplifiers and antennas (which all form part of a typical software radio front-end), usually are limited to specific ranges of the radio spectrum.
In short, software radio daughterboards tend to be fairly application-specific (or at least spectrum-specific). We can do a lot of things in software, but a "universal" software radio needs a lot of hardware swapping. I think that makes it a bit less "universal". It might also push the cost of a truly multi-purpose system quite a bit beyond $550.
But I'm glad to see this technology receiving such mainstream attention, and I applaud the efforts of the designers. I just think that TFA (and the post) could maybe be a bit less sensasionalist.
And yes, IAASDRE.
G-J
Well, the waveform itself can be treated as a vector -- its variance corresponds to its power. So if you apply the central limit theorem to the (signed) waveforms, their cumulative effect has a standard deviation which decreases with sqrt(N), which means the square of their cumulative effect (i.e. the total power) has a variance which decreases with N.
I don't know if that makes sense at all... :) The key point is that it's the EM waves (not their power) that accumulate, hence the central limit theorem applies.
The parent is perfectly correct, but it's also interesting to note why (even if stations were not self-contained) the total EM power would have been lower due to several cables, not higher.
Assuming that all cables contain information travelling at the same frequency, and that they are statistically independent (i.e. they contain different information), the central limit theorem tells us that the total power is lower proportional to the number of cables, compared to the individual cables' EM power.
The various signal sources tend to interfere with each other destructively, driving the total output towards the sum of the means -- which in this case is zero.
But this is very mathy... bottom line is, many cables act in your favour, not against you :)
Some games run better under Cedega than others, simply because they use the DirectX API in a more standardized way. It costs a gaming company very little to test their Windows builds under Cedega, and doing this could win them a little bit of extra market share.
I think the variety of terms are rather quaint, since it gives countries a linguistic "T-shirt" saying "we've been there". It's a bit of national pride, maybe the space-age equivalent of planting a flag at an exotic destination.
e
I found the sentiments expressed in your recent article, "Linux's Hit Men", somewhat disquieting. Mr. Lyons seems to advocate the idea that the violation of license agreement constitutes fair use of intellectual property. In the light of the past few years' renewed concern over business ethics, I cannot see how Forbes can identify itself with such a questionable viewpoint.
It is unclear whether mr. Lyons's argument is deliberately propogandistic, or whether it just stems from a misunderstanding of the principles of the GPL and the FSF. Although GPL-based software is labeled "free", it is certainly not within the public domain. Rather, it depends on the principle that software is a tool (whether employed for profit or not), and that all parties using such a tool can benifit from large-scale collaborative development by volunteers. To protect such an initiative against exploitation by those who would unscrupulously exploit the efforts of others for profit, terms of use are needed to maintain the open-source nature of the code, and all improvements made to it.
The license is certainly not a "hidden" threat in such code -- it is always available with distributed source, and asserted in the source files themselves. Users of such code must either abide with the licensing agreements, or use different source code.
Lastly, I must comment on the almost slanderous tone of the article with its strange McCarthyist overtones. Is this truly representative of neutral, unbiased reporting? Furthermore, I am disturbed by the suggestion that a party with little financial or legal resources somehow have a weaker legal position than a large corporation. Surely copyright protection is there to protect the small player too?
IANAL either, but I think the usual premise for originality in a patent is that it should not be "obvious to a person skilled in the art" to which the patent applies. Ozzie's method would indeed seem to be an obvious application of the capabilities of Lotus Notes, even to somebody "skilled in the art" working with it prior to the lawsuit.
Echo cancellation is a common design problem in hands-free telephone systems and conference systems; there is lots of literature on the subject. See the references in the articles I mention above.