hugol
Joined: 28/03/06
Posts: 839
Loc: London, UK
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Sampling theorum again
#992296 - 11/06/12 12:03 PM
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I came across this website on my travels: CD Format, which talks about some real world issues related to
sampling. Personally I'm very distrusting of these types of web pages, because
they quite often seem to contain inaccurate information. (Which I cynically tend to think
is to deliberately mislead the audiophile nerd crowd into spending lots of cash on obscure
crap). Especially when the page concentrates on drawing square wave
representations of sampled sine waves and quoting things like "Oh yeah, that is a much
better reminder of a sine wave. Let's add some filters to smooth out the edges, and we
have made real progress. ". Anyway I'd really like Hugh or someone equally
qualified to chip in with some analysis as to whether this guy is telling the whole truth,
or not.
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Richie Royale
Joined: 12/09/06
Posts: 3369
Loc: Bristol, England.
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Re: Sampling theorum again
[Re: hugol]
#992302 - 11/06/12 12:25 PM
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Quote:
Understanding the
CD-format and other formats at a deepler level
I got that far and thought it probably wasn't worth wasting my
time on the rest of their site.
--------------------
http://soundcloud.com/richie-royale
http://www.mixcrate.com/richieroyale
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Exalted Wombat
Joined: 06/02/10
Posts: 4211
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Re: Sampling theorum again
[Re: Richie Royale]
#992309 - 11/06/12 12:49 PM
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He's fond of saying we should "smooth out the squares with some kind of filter". But he
never shows the result of doing so.
I can forgive the fact that English
obviously isn't his first language. I'm less tolerent of the lousy website design.
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James Perrett
Joined: 10/09/01
Posts: 9660
Loc: The wilds of Hampshire
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Re: Sampling theorum again
[Re: hugol]
#992316 - 11/06/12 01:19 PM
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No, he's not telling the whole truth. He's ignored the input and reconstruction filters
which almost totally negates his argument. James.
-------------------- JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.net
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narcoman
active member
Joined: 14/08/01
Posts: 8469
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Re: Sampling theorum again
[Re: hugol]
#992320 - 11/06/12 01:29 PM
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Exactly. He's told half the story because that's precisely all he understands. Remember
the old adage that "a little knowledge is a bad thing"? That's what he has. He's
understood SOME of the principles but has completely failed to understand other parts of
it, or to even acknowledge their existence. Beat frequencies indeed......
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molecular
member
Joined: 13/12/03
Posts: 454
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Re: Sampling theorum again
[Re: hugol]
#992327 - 11/06/12 01:55 PM
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What is he on about with the "you can either limit the bandwidth or the time scale but not
both at the same time" / "infinite time" part of Nyquist Shannon?
I appreciate
he's off the rails, but I'd be interested to know what kernels of interesting truth, if
any, lie behind this claim.
--------------------
Anto mo Ninja, Watashi mo Ninja
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hugol
Joined: 28/03/06
Posts: 839
Loc: London, UK
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Re: Sampling theorum again
[Re: hugol]
#992330 - 11/06/12 02:03 PM
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Another classic quote:
"As Nyquist seems to have been more interested in data
transmission than in high-fidelity, we should not wonder, that his statement just defines
a maxiumum data-rate of a communications channel."
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hugol
Joined: 28/03/06
Posts: 839
Loc: London, UK
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Re: Sampling theorum again
[Re: molecular]
#992332 - 11/06/12 02:07 PM
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Quote molecular:
I
appreciate he's off the rails, but I'd be interested to know what kernels of interesting
truth, if any, lie behind this claim.
Yes exactly - why I posted. Obviously no real-world
implementation is going to be perfect, but I'd still like to know how much of what he says
is based on fact vs myth.
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narcoman
active member
Joined: 14/08/01
Posts: 8469
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Re: Sampling theorum again
[Re: hugol]
#992338 - 11/06/12 02:50 PM
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Quote hugol:
Another classic
quote:
"As Nyquist seems to have been more interested in data transmission than
in high-fidelity, we should not wonder, that his statement just defines a maxiumum
data-rate of a communications channel."
indeed!!!
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Hugh Robjohns
SOS Technical Editor
Joined: 25/07/03
Posts: 18390
Loc: Worcestershire
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Re: Sampling theorum again
[Re: hugol]
#992344 - 11/06/12 03:46 PM
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Read Dan Lavry's white papers here: http://www.lavryengineering.com/index_html.html...especially the ones on sampling theory and oversampling. he explains it all very
well, with a lot of accurate diagrams that really tell it how it is and include the entire
process, not just the easy bits. Hugh
-------------------- Technical Editor, Sound On Sound
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