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"There's no such thing as digital", Interesting articles from Audiostream
item
post Jan 9 2014, 11:27
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QUOTE (RonaldDumsfeld @ Jan 9 2014, 05:23) *
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'analog signal', ie one containing non-quantised information.



I don't think it's called analogue because it's continuous. I thought it was called analogue because the current in a wire is analogous to the atmospheric pressure at a particular place and time. Digital could just as easily have been called double analogue because the numbers (ratios) are analogous to the current in a wire.

So there is no such thing as digital. Only double analogue.


Behold the conceptual slipperiness of 'analog'; we can't even decide how it's spelt! There is a relationship between analog and analagous, but I can't think of an analogy to explain it . . .

Calling both optical and coaxial SPDIF cables 'digital' is peculiarly reprehensible, too: fibre cable involves properly quantised transmission. Henceforth, I move that we call optical SPDIF and digital signal over coax 'SPIF' to avoid confusion.

This post has been edited by item: Jan 9 2014, 11:29
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item
post Jan 9 2014, 11:37
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QUOTE (Porcus @ Jan 9 2014, 12:08) *
QUOTE (item @ Jan 9 2014, 10:39) *
to be fair to the article, it was Steve Silberman who grabbed the 'no such thing as digital' headline. Charles Hansen put it better, I think, when he said: “All the problems with digital are analog problems'.


That is a very good point indeed. You get rid of many problems, and - once you have chosen a good enough digital format and adequate conversion (whenever applicable), the remaining problems are not related to the "digitalness". Of course, if you have a ground loop issue when you conect by metal one device to another, you will also get that when you connect a (copper) cable supposed to carry a digital signal.

There's no such thing as digital problems becoming "There's no such thing as digital". Nifty.


I'm not sure what an 'analog problem' is. Seems indivisible from the problem of creating an analog of a recording in a listening room.
And I'm definitely not sure whose definition of 'good enough' we should go with.
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polemon
post Jan 9 2014, 12:12
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QUOTE (item @ Jan 9 2014, 11:27) *
QUOTE (RonaldDumsfeld @ Jan 9 2014, 05:23) *
QUOTE
'analog signal', ie one containing non-quantised information.



I don't think it's called analogue because it's continuous. I thought it was called analogue because the current in a wire is analogous to the atmospheric pressure at a particular place and time. Digital could just as easily have been called double analogue because the numbers (ratios) are analogous to the current in a wire.

So there is no such thing as digital. Only double analogue.


Behold the conceptual slipperiness of 'analog'; we can't even decide how it's spelt! There is a relationship between analog and analagous, but I can't think of an analogy to explain it . . .

Calling both optical and coaxial SPDIF cables 'digital' is peculiarly reprehensible, too: fibre cable involves properly quantised transmission. Henceforth, I move that we call optical SPDIF and digital signal over coax 'SPIF' to avoid confusion.


An analogue signal has nothing to do with being continuous.

An analogue signal is representing one set of physical information, with another physical information. For instance: the gas paddle in your car, uses a wire that is being pulled or pushed: that's an analogue signal (one of those mechanical signals goes to an automatic transmission, for instance). If you have an ambient pressure sensor, going from 0.8bar to 1.2bar and it represents this data with an analogue signal using electricity, it might be over the range of 2.0V to 4.5V. Now, if that data is send over a line as digital signal, this adds the digital data layer to it: a "0" is >3.5V and a "1" is <2.5V, for instance. Now, you might wanna add things like self-clocking, etc. to it, whatever. Now, this digital data.

OK, let's get the "continuous" problem out of the way: A digital or analogue signal, both can be intermittent (as in: noncontinuous).

I'm not gonna go into the technicalities how and why a digital signal is easier to strip from errors, and how to make a digital line more robust against noise, without adding finger-thick shielding. I invite anyone who's interested, to go their local university, and sneak into the signal processing course...


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includemeout
post Jan 9 2014, 12:20
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QUOTE (item @ Jan 8 2014, 20:22) *
It would have been less controversial if they had maintained focus on the impact of the instrumental basis of the equipment generating and decoding digital data - and used 'digital v analog' rather more carefully.

Don't you think he was being deliberately controversial?

After all, with a speech that nonsensical, I guess controversy is his best tool of the trade.

This post has been edited by includemeout: Jan 9 2014, 12:22


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item
post Jan 9 2014, 13:31
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QUOTE (polemon @ Jan 9 2014, 12:12) *
An analogue signal has nothing to do with being continuous.

An analogue signal is representing one set of physical information, with another physical information. For instance: the gas paddle in your car, uses a wire that is being pulled or pushed: that's an analogue signal (one of those mechanical signals goes to an automatic transmission, for instance). If you have an ambient pressure sensor, going from 0.8bar to 1.2bar and it represents this data with an analogue signal using electricity, it might be over the range of 2.0V to 4.5V. Now, if that data is send over a line as digital signal, this adds the digital data layer to it: a "0" is >3.5V and a "1" is <2.5V, for instance. Now, you might wanna add things like self-clocking, etc. to it, whatever. Now, this digital data.

OK, let's get the "continuous" problem out of the way: A digital or analogue signal, both can be intermittent (as in: noncontinuous).

I'm not gonna go into the technicalities how and why a digital signal is easier to strip from errors, and how to make a digital line more robust against noise, without adding finger-thick shielding. I invite anyone who's interested, to go their local university, and sneak into the signal processing course...


You're on a wild herring chase, I think: the contention is not 'analog = continuous’. The differentiator with regard to signalling is that analog is non-quantised. It could be any medium translating an input to an output.

With a small correction the first sentence in your second paragraph is spot on . . . “An analogue [] is respresenting one set of physical information with another physical information”.
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item
post Jan 9 2014, 13:36
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QUOTE (includemeout @ Jan 9 2014, 12:20) *
QUOTE (item @ Jan 8 2014, 20:22) *
It would have been less controversial if they had maintained focus on the impact of the instrumental basis of the equipment generating and decoding digital data - and used 'digital v analog' rather more carefully.

Don't you think he was being deliberately controversial?

After all, with a speech that nonsensical, I guess controversy is his best tool of the trade.


Sure - it's a headline: its job is to grab attention. It worked. So shoot him. Nonsense or nay depends on how you define 'thing'!

As the OP feared, apart from that, it's all sensible stuff. The only objection you might fairly make is that they don't address audibility thresholds. I would guess they know enough about that to avoid getting into it (again, see Dunning-Kruger).

This post has been edited by item: Jan 9 2014, 13:37
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includemeout
post Jan 9 2014, 15:01
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QUOTE (item @ Jan 9 2014, 10:36) *
So shoot him. Nonsense or nay depends on how you define 'thing'!

Way OTT.


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Porcus
post Jan 9 2014, 15:06
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QUOTE (polemon @ Jan 9 2014, 11:19) *
When saying there is a "gray" area between a digital "0" and a digital "1", and the errors that might creep into data corruption, it makes me believe they never heard of differential data transmission (USB and Ethernet is a prime example).


Which is not used in S/PDIF, eh? USB and ethernet communicate two-way, and data failing the CRC-check can be re-sent. S/PDIF is one-way communication and cannot. RAM has ECC, why is that? Because it has to cope with bit-errors by itself. Hard drives' firmware implement ECCs for the same reason, but re-reads are sometimes indeed necessary (have a look at this: http://www.youtube.com/watch?v=tDacjrSCeq4 ). And even that is not satisfactory for all applications, which is why you hear buzzwords as silent data corruption and end-to-end data protection. "Digital" data transfer does not imply that these measures are unnecessary, rather it means that they are possible (or at least way more feasible) to implement. S/PDIF uses very little of it, but fortunately the data stream and real-time threshold are not awfully difficult to cope with, and contrary to audiophile belief, a single-sample error a day - or what the failure rate is in practice - won't crash a plane nor your bank account.

This post has been edited by Porcus: Jan 9 2014, 15:07


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greynol
post Jan 9 2014, 18:27
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QUOTE (item @ Jan 9 2014, 02:27) *
Calling both optical and coaxial SPDIF cables 'digital' is peculiarly reprehensible, too: fibre cable involves properly quantised transmission. Henceforth, I move that we call optical SPDIF and digital signal over coax 'SPIF' to avoid confusion.

Optical or coax, they are both transmission channels for digital communication. On this subject, you appear to be miserably clueless.


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post Jan 9 2014, 18:35
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QUOTE (Canar @ Nov 26 2013, 17:35) *
There's no such thing as analog. Every "analog" signal represents a discrete number of electrons being transferred. Therefore, all signals are digital.

This is a better argument than the article's.

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Rotareneg
post Jan 9 2014, 19:00
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I looked it up and I believe digital means making music with your fingers and toes, and analog means reproducing music only with devices that work the same as the original instruments (string like speakers for guitars for example.) They make dictionaries for a porpoise, people! wink.gif
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Arnold B. Kruege...
post Jan 9 2014, 20:51
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QUOTE (includemeout @ Jan 9 2014, 06:20) *
QUOTE (item @ Jan 8 2014, 20:22) *
It would have been less controversial if they had maintained focus on the impact of the instrumental basis of the equipment generating and decoding digital data - and used 'digital v analog' rather more carefully.

Don't you think he was being deliberately controversial?


I read a few of his pieces and decided that he is an entertaining writer but that he either doesn't read his references or is a deliberate liar practitioner of poetic liberties.

Case in point:

http://www.wired.com/medtech/drugs/magazin...t?currentPage=2

"Placebos Are Getting More Effective. Drugmakers Are Desperate to Know Why."

"Beecher's prescription helped cure the medical establishment of outright quackery, but it had an insidious side effect. By casting placebo as the villain in RCTs, he ended up stigmatizing one of his most important discoveries."

He cites:

"The Powerful Placebo"

http://www.jgh.ca/uploads/psychiatry/links/beecher.pdf

Beecher's article's conclusion starts out "When subjective responses, symptoms, are under
study, it is apparent that the high order of effectiveness
of placebos must be recognized."

..and goes on in the same spirit: positive.

No way was the placebo cast as a villain.

I call that taking liberties with one's main reference. Read the articles for yourself and reach your own conclusions. ;-)

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saratoga
post Jan 9 2014, 21:14
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QUOTE (item @ Jan 9 2014, 04:39) *
QUOTE (saratoga @ Jan 9 2014, 04:52) *
QUOTE (item @ Jan 8 2014, 17:22) *
It would have been less controversial if they had maintained focus on the impact of the instrumental basis of the equipment generating and decoding digital data - and used 'digital v analog' rather more carefully. Only programmers with their head in the ether fail to acknowledge that computers are fundamentally mechanical, or that time-domain-sensitive audio playback is not the same as sending a file to a printer.


I'm not sure what this is intended to mean?

There is a danger of considering 'digital' in purely numerical terms. Focusing like a programmer solely on logical pathways and interpreted values, it's easy to overlook the awkward fact that output is generated by physical machinery, not pumped from some Platonic flowchart. Algorithms are hardware independent, digital audio processors aren't.

It's axiomatic that measurement (and audio) systems respond differently when different mechanical apparatus is integrated into them.


I think you're forgetting how audio (and more generally modern) systems are designed. We purposefully build them to be linear time invariant so that we don't have to consider the "awkward fact" that they're are many components of varying nature in a system. Since they are LTI, the final output is simply the superposition of the underlying components. Hence, we can look at each component in isolation without loss of accuracy.

So I would say that it only looks like people are being myopic until you more carefully think about the problem, and then you realize that actually the people behind it have been 1000x more clever than you initially thought.


QUOTE (item @ Jan 9 2014, 04:39) *
Calling both optical and coaxial SPDIF cables 'digital' is peculiarly reprehensible, too: fibre cable involves properly quantised transmission.


No this is absolutely false. Both coax and fiber are waveguides. At the level of the medium there is no difference between them besides frequency, with coax topping out at a few GHz, and fiber topping out at a few hundred THz. There is no requirement of "properly quantised transmission" in either system. Both can carry quantized or unquantized information.

FWIW, if you think about this more carefully, you will realize that it is impossible for any transmission medium to enforce one kind of transmission over another. Such things are the properties of receivers, not of the medium.

QUOTE (item @ Jan 9 2014, 04:39) *
I'm not sure what an 'analog problem' is.


Problems that occur in the analog domain. The example of a ground loop seems fitting.

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includemeout
post Jan 9 2014, 22:04
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QUOTE (Arnold B. Krueger @ Jan 9 2014, 17:51) *


"Today, to win FDA approval, a new medication must beat placebo in at least two authenticated trials."

It's nothing more than a pipe dream, I know, but if only similar standards were also required from audio equipment suppliers, maybe we'd have less of these magazines and websites (along with their plethora of self-proclaimed experts) where pseudo science and blurb seem to thrive.


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item
post Jan 9 2014, 23:15
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QUOTE (greynol @ Jan 9 2014, 18:27) *
QUOTE (item @ Jan 9 2014, 02:27) *
Calling both optical and coaxial SPDIF cables 'digital' is peculiarly reprehensible, too: fibre cable involves properly quantised transmission. Henceforth, I move that we call optical SPDIF and digital signal over coax 'SPIF' to avoid confusion.

Optical or coax, they are both transmission channels for digital communication. On this subject, you appear to be miserably clueless.

My jokey post in response to a jokey post (SPIF? really?!) contained a kernel of truth, though: in transit, an optical cable conforms in the purest sense to the strictest definition of digital: quantised. And only 'not pulses of light' when interpreted by a digital transceiver. Whereas the physical properties of a coaxial cable inevitably bring 'analog domain' effects into play. My objection was to to the term 'digital cable', which is ubiquitous but nonsensical.
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item
post Jan 9 2014, 23:33
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QUOTE (saratoga @ Jan 9 2014, 21:14) *
QUOTE (item @ Jan 9 2014, 04:39) *
QUOTE (saratoga @ Jan 9 2014, 04:52) *
QUOTE (item @ Jan 8 2014, 17:22) *
It would have been less controversial if they had maintained focus on the impact of the instrumental basis of the equipment generating and decoding digital data - and used 'digital v analog' rather more carefully. Only programmers with their head in the ether fail to acknowledge that computers are fundamentally mechanical, or that time-domain-sensitive audio playback is not the same as sending a file to a printer.


I'm not sure what this is intended to mean?

There is a danger of considering 'digital' in purely numerical terms. Focusing like a programmer solely on logical pathways and interpreted values, it's easy to overlook the awkward fact that output is generated by physical machinery, not pumped from some Platonic flowchart. Algorithms are hardware independent, digital audio processors aren't.

It's axiomatic that measurement (and audio) systems respond differently when different mechanical apparatus is integrated into them.


I think you're forgetting how audio (and more generally modern) systems are designed. We purposefully build them to be linear time invariant so that we don't have to consider the "awkward fact" that they're are many components of varying nature in a system. Since they are LTI, the final output is simply the superposition of the underlying components. Hence, we can look at each component in isolation without loss of accuracy.

So I would say that it only looks like people are being myopic until you more carefully think about the problem, and then you realize that actually the people behind it have been 1000x more clever than you initially thought.


QUOTE (item @ Jan 9 2014, 04:39) *
Calling both optical and coaxial SPDIF cables 'digital' is peculiarly reprehensible, too: fibre cable involves properly quantised transmission.


No this is absolutely false. Both coax and fiber are waveguides. At the level of the medium there is no difference between them besides frequency, with coax topping out at a few GHz, and fiber topping out at a few hundred THz. There is no requirement of "properly quantised transmission" in either system. Both can carry quantized or unquantized information.

FWIW, if you think about this more carefully, you will realize that it is impossible for any transmission medium to enforce one kind of transmission over another. Such things are the properties of receivers, not of the medium.

QUOTE (item @ Jan 9 2014, 04:39) *
I'm not sure what an 'analog problem' is.


Problems that occur in the analog domain. The example of a ground loop seems fitting.


You've further split my already split hairs. And we could keep on splitting down to the bottom of distinction between wave energy and 'digital' matter. Any way you slice it, optical transmission is a step closer to purely quantised digital than propagation through copper. Your ground loop illustrates the point.

With regard to the real-world translation of LTI goals, look no further than the influence of proximal power regulation to clock at either end of that optical cable. in the field, time invariance doesn't prevail.

But I would accept that it's more helpful to concentrate on the receiver than the medium, and in fact you could make a sound practical argument for 'digital's’ threshold of definition occurring right there.
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saratoga
post Jan 10 2014, 00:19
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QUOTE (item @ Jan 9 2014, 17:33) *
Any way you slice it, optical transmission is a step closer to purely quantised digital than propagation through copper.


This is absolutely, completely false. I'm not sure how you think copper and/or fiber work, but your internal model is very wrong.

QUOTE (item @ Jan 9 2014, 17:33) *
With regard to the real-world translation of LTI goals, look no further than the influence of proximal power regulation to clock at either end of that optical cable. in the field, time invariance doesn't prevail.


Can you explain what you mean? I don't know how to parse this statement as you have written it.
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saratoga
post Jan 10 2014, 01:39
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QUOTE (item @ Jan 9 2014, 17:15) *
QUOTE (greynol @ Jan 9 2014, 18:27) *
QUOTE (item @ Jan 9 2014, 02:27) *
Calling both optical and coaxial SPDIF cables 'digital' is peculiarly reprehensible, too: fibre cable involves properly quantised transmission. Henceforth, I move that we call optical SPDIF and digital signal over coax 'SPIF' to avoid confusion.

Optical or coax, they are both transmission channels for digital communication. On this subject, you appear to be miserably clueless.

My jokey post in response to a jokey post (SPIF? really?!) contained a kernel of truth, though: in transit, an optical cable conforms in the purest sense to the strictest definition of digital: quantised. And only 'not pulses of light' when interpreted by a digital transceiver. Whereas the physical properties of a coaxial cable inevitably bring 'analog domain' effects into play. My objection was to to the term 'digital cable', which is ubiquitous but nonsensical.


Sorry just saw this, but no, you're totally wrong here. Any electromagnetic field capable of carrying information is quantized in power. No matter the frequency.

EM waves in a fiber are encoded by an integer number of photons. EM waves in coax are quantized into an integer number of photons. The 60Hz noise on your power supply comes in an integer number of 60Hz photons.

You're probably not aware of this though because it doesn't matter. You're trying to make the jump from "field is quantized" to "must be digital", but thats not correct. The quantization level spacing for all 3 of those examples is far smaller than thermal noise at room temperature, so the statistics of any of the media are capable of being both analog or digital depending on the encoding chosen by the users of the medium.

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Porcus
post Jan 10 2014, 01:46
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QUOTE (includemeout @ Jan 9 2014, 22:04) *
"Today, to win FDA approval, a new medication must beat placebo in at least two authenticated trials."

It's nothing more than a pipe dream, I know, but if only similar standards were also required from audio equipment suppliers, maybe we'd have less of these magazines and websites (along with their plethora of self-proclaimed experts) where pseudo science and blurb seem to thrive.


Repeat sentence with "audio equipment" replaced by "cosmetics".


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saratoga
post Jan 10 2014, 02:25
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QUOTE (polemon @ Jan 9 2014, 06:12) *
An analogue signal has nothing to do with being continuous.


Actually, being continuous in time and amplitude is sufficient to make something an analog system.

QUOTE (polemon @ Jan 9 2014, 06:12) *
An analogue signal is representing one set of physical information, with another physical information. For instance: the gas paddle in your car, uses a wire that is being pulled or pushed: that's an analogue signal (one of those mechanical signals goes to an automatic transmission, for instance). If you have an ambient pressure sensor, going from 0.8bar to 1.2bar and it represents this data with an analogue signal using electricity, it might be over the range of 2.0V to 4.5V. Now, if that data is send over a line as digital signal, this adds the digital data layer to it: a "0" is >3.5V and a "1" is <2.5V, for instance. Now, you might wanna add things like self-clocking, etc. to it, whatever. Now, this digital data.


Thats actually not necessarily sufficient to make it digital. By convention, all discrete time, discrete amplitude systems are digital. Discrete amplitude, continuous time systems may or may not be considered digital depending on the context. In digital communications, that might be considered digital, but in most other contexts simply using a discriminator is not sufficient (and hence an discriminator is not considered an ADC).

FWIW, my favorite example of an analog system that uses binary encoding is laser disk.

QUOTE (polemon @ Jan 9 2014, 06:12) *
OK, let's get the "continuous" problem out of the way: A digital or analogue signal, both can be intermittent (as in: noncontinuous).


This depends on your context and may or may not be true depending on what you are doing with it.

QUOTE (polemon @ Jan 9 2014, 06:12) *
I'm not gonna go into the technicalities how and why a digital signal is easier to strip from errors, and how to make a digital line more robust against noise, without adding finger-thick shielding. I invite anyone who's interested, to go their local university, and sneak into the signal processing course...


In a signal processing course, digital is generally used exclusively to refer to discrete time and amplitude, as DSP techniques do not generally apply to continuous time systems.
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Martel
post Jan 10 2014, 10:02
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I don't understand the concern about transfer of digital information over analog channels. Say 0.8V and higher voltage is a zero and 0.3V or less is a one (similarly for transmissions based on radio waves/light or whatever else). Anything in between is undefined, i.e. it may be interpreted as either a zero or a one "randomly". In case your chosen transmission channel then produces too many undefined values on the receiving end, you add enough redundant error correction coding to your data (or decrease the data rate) to make up for it.

While the above is grossly over-simplified (e.g ignores analog signal modulation techniques), it's no rocket science.

Entirely analog transmission just does not (cannot?) precisely remove/isolate channel noise from information. I don't think there's anything beneficial about that.

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ktf
post Jan 10 2014, 12:59
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QUOTE (Martel @ Jan 10 2014, 10:02) *
Entirely analog transmission just does not (cannot?) precisely remove/isolate channel noise from information. I don't think there's anything beneficial about that.

Actually it can, but those methods are so 'simple' that most might not call it error correction at first look. Differential signaling (balanced audio cables) is one trick where part of the noise coupled on a line can be easily filtered. It works really well for most noise sources.

This post has been edited by ktf: Jan 10 2014, 13:00


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Arnold B. Kruege...
post Jan 10 2014, 14:01
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QUOTE (ktf @ Jan 10 2014, 06:59) *
QUOTE (Martel @ Jan 10 2014, 10:02) *
Entirely analog transmission just does not (cannot?) precisely remove/isolate channel noise from information. I don't think there's anything beneficial about that.

Actually it can, but those methods are so 'simple' that most might not call it error correction at first look. Differential signaling (balanced audio cables) is one trick where part of the noise coupled on a line can be easily filtered. It works really well for most noise sources.



The example makes the point that in the analog domain, there's a strong tendency to need a separate fix for every different kind of problem, which gets complicated and expensive.

For example, how do you remove FM distortion from an analog link?

With digital, the making the medium work at all is the fix for just about everything, and you can "fix everything" relatively simply. CD players are a good example of this.
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Martel
post Jan 10 2014, 15:28
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When I said "precisely remove/isolate channel noise from information", I meant "precisely" as in "perfectly". Twisted cables, differential signalling and whatnot are far from perfect and they only solve (mitigate) specific sources/mechanisms of transmission channel noise.


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post Jan 10 2014, 18:44
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Ok, so physics indicates that the world is "discrete" (at least the kind of physics that most of us know). So analog signals are really digital.

And digital communications happens over links that may be the same as the old "analog" links. So digital is really analog.

This rapidly leads into a pointless debate over words. What matters is the end-result. By treating the channel in an abstracted manner ("digital"), we can do logical operations that relies on things like memory and mathematical blocks to combat channel issues that are very hard to cure using a limited set of "analog" means.

Back in the day, I had poor image quality in my tv, but it worked. Now enter the digital age, everything happens over digital, encrypted links that "negotiate" the format. And my Sony tv and Onkyo amplifier cannot seem to agree on how lipsync info is to be transmitted over HDMI 1.4, as a result people move their lips 150ms after I hear them talking. Or some source cannot be shown because of HDMI DHCP issues. Or my tv channels might not have analog echo and noise (continous problems), but rather there are sudden loud transients (lost packets) or pixelated video. It seems that every technological advance made in the last 30 years have been used to give us more crap, more compromise, less reliability. Talk about progress :-)

-k

This post has been edited by knutinh: Jan 10 2014, 18:47
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