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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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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!
The Shannon-Hartley equation (usually referred to as Shannon's limit) is this:
capacity=bandwidth*log(base2)*(1+Signal/Noise)
The 33Kbit/second limit for a traditional analog/analog phone line comes from this- Signal/Noise is about 256:1 (8 bit sampling), 4KHz bandwidth-- capacity of a 4KHz phone line is about 32000 bits/second.
108MHz leading to 108MBit/sec would only be from simple on off keying- which makes no use of the signal/noise ratio. If you had about 48dB of S/N on 108MHz that leads to a capacity of 860 Mbit/second.