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Technical Analysis Of VMSK
Phil Karn writes: "Regarding the Slashdot article on VMSK that appeared August 22, 2000, I have
written a detailed technical analysis that shows it to be
snake oil." I'm convinced.
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you have a specific capacity at X frequency, Example 108 MHZ - you have a maximum of 108Mbps if you were able to encode on every cycle of the carrier (impossible without generating nasty things)
<brandishing clue stick>
Ever hear of encoding multiple bits per cycle? BPSK, QAM, PAM (I think) are all methods to encode MULTIPLE (4 and 8 being common, but 64 and 256-QAM are available with fancy DSPs) bits per cycle. This is without generating nasty things. Hell your 9600 baud modem encodes 4 bits per baud!
Spoken like someone whose science education ended in high school. If you aren't qualified to comment on something, don't.
...
Haha. If only you knew
The burden of proof is now squarely on the kook. I await his response, but I won't hold my breath.
And that's exactly what I said. Phil's negative analysis matters nothing in science. In the community of science-aware people it matters inasmuch as it lowers peoples' expectations of the likelihood of any successful demonstration ever forthcoming, which is probably fairly reasonable as it dampens false expectations, but science and sociology are not one and the same thing. ALL that matters in science is whether experiments will demonstrate the new effect or not. As you said, and as I said, the ball is entirely in the court of the person claiming the innovation to demonstrate that it works in reality. NOT in the court of those whose theoretical analyses say that current theories don't allow for such an effect to happen.
The world doesn't obey our mathematical models. They are merely our creations, constructed to behave mathematically in a way that (hopefully) mirrors how reality herself actually behaves. But they are only approximations, and always subject to revision by tomorrow's new observation.
"The question of whether machines can think is no more interesting than [] whether submarines can swim" - Dijkstra
Phil Karn is of course a very highly respected member of the scientific community -- both amateur and professional.
However, reputation and even great skill are not always the be-all and end-all of real science. An experimenter may start from totally false premises, use utterly flawed reasoning, perform experiments with total incompetence, and still uncover a new aspect of reality. The real, experimental world respects no one, no theory, and certainly no dogma, and just behaves the way she wants to behave.
So, all this excellent theorizing that proves it's all snake oil is worth precisely nothing if the proposer actually manages to stuff that much information down the specified channel. We'll just have to wait and see. Should it actually work then clearly the theory used in Phil's analysis is missing something vital, so we'll all have learned something new and we'll just have to reinvent the theory to match the new discovery. Should it not work, as is far more likely, then of course it's all snake oil and Phil gets yet another well-deserved pat on the back.
BUT YOU CANNOT PRESUPOSE THAT IN ADVANCE, by analysis. Analysis merely tells you what a theory allows, not what reality allows. That's not how science works. If it did, ie. if past theory prevented anything new which it currently disallows, we'd still be in the scientific dark ages.
Thanks Phil for a great analysis. But remember that there will always be vastly more that we don't know than that we know, so hedge your bets a little and wait for the judgement of reality to validate our current theoretical understanding.
"The question of whether machines can think is no more interesting than [] whether submarines can swim" - Dijkstra
I see the point, and we have found ways around physical laws before (Ok, in a laboratory) but there is only so much you can do with electromagnetic radiation. At hyper frequencies (1.2ghz and higher) I could see some kind of a spread spectrum system working, but anything lower is plain impossible. you have a specific capacity at X frequency, Example 108 MHZ - you have a maximum of 108Mbps if you were able to encode on every cycle of the carrier (impossible without generating nasty things)
unless I am missing something, this cant happen
Do not look at laser with remaining good eye.
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One limit you may be thinking of is that the number of samples per second for pulse-amplitude modulation needs to be twice the frequency of the sound waveform you're trying to carry (so a 4kHz audio signal needs 8k samples/second, and typically that gets digitized to 8 bits/sample using a non-linear quantization.)
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
That said, it is tirelessly leftwing and relentlessly bobo (bourgeois bohemian). Given that I already subsidize their politics as a taxpayer, I wouldn't ever dream of sending them an extra nickel.
...that's just a scary thought...
;)
Then again, NT's filesystem was built on the VMS file system... so would that mean that win2k is vms2k? Oh right, it's not as good as VMS... I forgot.
BlackNova Traders
It has been observed in many posts in this discussion that one can use various analog encoding techniques (like those used by a modem) to increase bit rate at the expense of tolerable Signal to Noise ratio.
This has the effect of requiring an increase in transmitter power proporational to the increase in the minimum tolerable S/N ratio, for reception at the same distance. This means that a radio using complex encoding (like a modem would) will create interference at distances much greater than a simple on/off binary coding would. Because of this, I would think that it would be preferable to use multiple chanels instead of fancier modulation to gain increased capacity
um...I watch the local news on cable every day else what would I watch it on?
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Wooden armaments to battle your imaginary foes!
Channel 2 (WESH) is nice enough to provide us a VERY low-power repeater on (I think) UHF-16. Not that that's any better.
I don't know anyone that uses a non-microwave antenna around here (satellite or "wireless cable"). It's either that or cable.
Such is life in a medium-sized town in the middle of nowhere.
Jeff
Jeff
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The first is a method of transferring characters onto sheets of paper in a logical manner and binding said sheets together.
The second is a building in which these books can be stored with some sort of cataloging system. The catalog makes it easy for these bound papers to be found by others, who can then use the papers on loan for a limited time.
Boy, these computers make anything possible!
Brandt
Mr. Karn was just doing his job for Qualcomm, and doing a service for the rest of us.
I suspect it's much more than that. For those not familiar with the name Phil Karn, he was one of the original tcp/ip implementation guys way back in the day. He also has significant interest in wireless data transmission. He was the author of a networking/packet radio package called ka9q, one of the first packages that supported virtually every networking protocol and supported packet radio -> internet. I believe his reasons for investigating the VMSK proposal were largely linked to personal interests. The fact that he is employed by qualcomm only gives him even more credit.
BTW: a Google search on "Phil Karn" will yield virtually infinite interesting results. I highly recommend doing it.
** Martin
and will continue to be "experimental" for as long as people buy into this snake oil stuff.
Walker's first patent for this "technology" has been filed in 1986 and he has probably been working on it for a while before that.
I am familiar with this type of personality - the more refusals they get the more they believe they are some kind of Galileo that one day will be vindicated. The problem is that for every Galileo that is eventually proven to be right about the Earth not being the center of the universe there are a hundred crackpots that believe all kinds of bullshit with the same amout of self conviction.
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Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
I can send 32 bits per cycle! But I have to be able to put 4294967296 different discrete voltage levels and/or timing shifts, or some combination thereof, into each cycle, WITHOUT NOISE MANGLING IT, to accomplish that.
If the noise is a mere 1 microvolt, I'd still have to make each step be at least 2 microvolts to get over it, and then 0xFFFFFFFF would be over 8 thousand volts!
Much of the engineering that takes place now is finding ways to get around the noise, or to reduce the noise, or to minimize the impact of noise. Spread spectrum, for example, statistically changes the effect of the noise in ways that allows retransmissions to have a chance to make it through the next time.
Much of the science is already done and it is very mathematical and statistical. What remains to be done is more and more engineering to work within the relatively well known confines.
now we need to go OSS in diesel cars
Wake up. Local identification has been dead for a long time.
Have you driven cross-country in the last decade?
Every single radio station sounds exactly like its counterpart in the next market over. For example, pick any two "Modern Rock" stations at random. Chances are they're using the exact same playlist. They pay big money to a consultant for the privilege of being told what to play. Ditto for "Urban Contemporary", double ditto for "Classic Rock."
I agree with you that radio sucks, but look for the culprit elsewhere (hint: deregulation).
ps: The "Alternative" playlist on Music Choice is actually pretty good, with no commercials!
pps: Don't even get me started about local news. "Your kids may be about to EXPLODE!!!!!!! More at 11."
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whuppy enjoys smelling like diesel fuel
But seriously -- local television gives you a bad case of tunnel-vision. I do feel that it's important to learn about local events, issues, etc. but local television stations don't provide much outside of talk shows and sitcoms. If you want to learn anything, you have to flip to CNN, CSPAN, TLC, Discovery or VH1 (behind the music, of course.)
Local television pisses me off, mmmkay.
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Wooden armaments to battle your imaginary foes!
Here's a totally off base suggestion. What about downloading radio streams to broadband connections in homes, then using wireless ethernet to communicate with special streaming radios?
- I don't care if they globalize against free speech. All my best free thoughts are done in my head.
I don't watch local TV because it's shite.
Headline stories about kittens being left in dumpsters while the real news gets mentioned in a 30 second world round-up. My roommate and I resorted to watching a French language channel just to get some detailed coverage of the protests in Yugoslavia.
Even the cable networks don't cover anything in any kind of depth. If you want decent news you have to get it from overseas. It's sad but I guess that's what the American public likes.
but what I want to know, is why bother writing a detailed paper debunking something that is still experimental?
The guy who wrote the original paper is from Qualcomm- they have a strong interest in being at the forefront of technology. When a new technology like this comes up with such a great stated promise, if it has a remote possibility of being useful, it is in their best interest to investigate it. Otherwise, this situation will happen, which I have been on the receiving end of: Suit comes in for a project review and asks why we haven't been spending his limited money researching this latest and greatest technique he read about in a trade magazine. This causes a shake up all the way down to the people that actually do the work, we investigate, and find that our previous cursory investigation that showed that idea to be worthless was entirely accurate. Total time wasted- about a man month.
Mr. Karn was just doing his job for Qualcomm, and doing a service for the rest of us.
In the mean time, AmWay has announced that it will release plans for it's next generation DSL technology that will increase existing DSL speeds by 150%.
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Wooden armaments to battle your imaginary foes!