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Re: Read this; digital versus analog sensor??

 
 
TheRealSteve
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      02-27-2012

On Mon, 27 Feb 2012 05:23:42 +0100, Mxsmanic <(E-Mail Removed)>
wrote:

>TheRealSteve writes:
>
>> No it's not. In the real world, it's discrete, not continuous. You
>> only think it's continuous because the difference between discrete
>> levels are so small. An elementary charge is 1.602e-19 coulombs. An
>> electron volt is the amount of energy gained by that elementary charge
>> moved across an electric potential difference of one volt.

>
>Even if you choose to count the angels dancing on that pin and call it
>discrete, it's still not digital. Digital is a way of representing
>information. It's a concept, not a physical reality.
>
>> You can count electrons.

>
>But you have to be a conscious being to count. Therefore the counting is in
>your mind, not in the physical reality. It's a concept (like all of
>mathematics, in fact).


And if a tree falls in the woods but no one counted it, it didn't
really fall.

Steve
 
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TheRealSteve
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      02-27-2012

On Sun, 26 Feb 2012 13:19:19 -0900, http://www.velocityreviews.com/forums/(E-Mail Removed) (Floyd L.
Davidson) wrote:

>TheRealSteve <(E-Mail Removed)> wrote:
>>On Sun, 26 Feb 2012 20:33:03 +0100, Mxsmanic <(E-Mail Removed)>
>>wrote:
>>
>>>David J Taylor writes:
>>>
>>>> What about micro-switches which detect when a door or window is open?
>>>
>>>Still analog. The digital realm is conceptual, not real. It's a way of looking
>>>at the real world, but nothing is actually digital except in our minds.
>>>
>>>We interpret a flow of current above a certain threshold as "on," and below it
>>>as "off," but in the real world, this is a continuum.

>>
>>No it's not. In the real world, it's discrete, not continuous. You
>>only think it's continuous because the difference between discrete
>>levels are so small. An elementary charge is 1.602e-19 coulombs. An
>>electron volt is the amount of energy gained by that elementary charge
>>moved across an electric potential difference of one volt.

>
>It's discrete because we define it that way: on and off, but there is
>no symbol that represent half on or half off.


Exactly. There doesn't need to be a symbol that represents half on and
half off precisely because it is discrete. It can't be half on or half
off.

>>You can count electrons. You can't get a charge value that's between
>>discrete counts of electrons, i.e., digital.

>
>Not so. First, you can't count electrons, or even the
>charge value. They are in a "cloud", and they spin.
>Essentially the effect of the charge is analog because
>it is never stable.


Actually, you can count electrons and you can measure their charge
value. We've been doing that for nearly 100 years and the tools for
doing that keep getting better and better. You need to do a little
research.

>Hence we actually can get counts that are continuous
>between what appears to be just two electrons. But that
>isn't important anyway. Digital has to do with *data*
>that carries information, not physical counts of
>objects. If we have a system that provides a signal
>with a continuum between any two values, it is analog.
>If we have a system that uses discrete values, it is
>digital.
>
>That's the definition.


Above you're saying the world is analog simply because we defined a
measurement system that's analog. It's just not so. You can define any
type of measurement system you want and can have it be continuous if
you want also. But if the real world only provides for discrete steps
in your continuous measurement system (no matter how small the steps
are) then the real world is not analog.

[...]
>Go find a good dictionary and look up the definitions
>rather than making things up to suit what you think the
>terms mean.


I did and dictionaries, even good ones, define the terms in many
different ways. Some you would agree with and some you wouldn't. I
would say that the terms have already been defined within the context
of this discussion as analog being continuous and digital being
discrete. Just because something is discrete, or digital, doesn't mean
it necessarily must convey information, although it frequently does.
If you can agree to those terms then no matter what type of system
humans have devised to measure, the real world is digital, or discrete
and not continuous, or analog. If you can't agree on what the terms
mean then there's no point in having the discussion.

Steve
 
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TheRealSteve
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      02-27-2012

On Sun, 26 Feb 2012 17:41:37 -0800, Savageduck
<savageduck1@{REMOVESPAM}me.com> wrote:

>On 2012-02-26 17:12:15 -0800, Chris Malcolm <(E-Mail Removed)> said:
>
>> David J Taylor <(E-Mail Removed)> wrote:
>>> "Mxsmanic" <(E-Mail Removed)> wrote in message
>>> news:(E-Mail Removed)...
>>>> There is no such thing as a digital sensor. All sensors are analog
>>>> electronic
>>>> devices. More generally, any device that interfaces with the physical
>>>> world
>>>> will always be an analog device.

>>
>>> What about micro-switches which detect when a door or window is open?

>>
>>> David

>>
>> Or a Geiger counter. It's a common misconception of large animals like
>> ourselves that we live in an analog world. It just seems that way of
>> you're a large animal. Photons aren't analog.

>
>...but every click of that geiger counter, or every deflection of the
>needle on the gauge is an analog demonstration of detection and
>measurement of ionizing radiation and physical beta, and sometimes
>alpha & gamma particles from a radioactive element.


But the physical phenomonon that the sensor is sensing is digital
(discrete "things" that are being counted) and the sensor itself is a
digital sensor because it's made to directly sense discrete things.
Just because you convert that direct digital output of the sensor to
something we may percieve to be analog (like an audible click or a
reading on an "analog" meter) doesn't mean the sensor is analog.

I put the adjective analog in quotes before meter above because if you
want to get right down to it, even that "analog" meter on the old
style geiger counters is a discrete digital output if you could
observe it to a level of detail that's many orders of magnitude closer
than humans can percieve.

Steve
 
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David Dyer-Bennet
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      02-27-2012
Savageduck <savageduck1@{REMOVESPAM}me.com> writes:

> On 2012-02-26 03:39:45 -0800, "David J Taylor"
> <(E-Mail Removed)> said:
>
>> "Mxsmanic" <(E-Mail Removed)> wrote in message
>> news:(E-Mail Removed)...
>>> There is no such thing as a digital sensor. All sensors are analog electronic
>>> devices. More generally, any device that interfaces with the physical world
>>> will always be an analog device.

>>
>> What about micro-switches which detect when a door or window is open?
>>
>> David

>
> Actually, even the micro-switch is a physical analog I/O device, and
> when used to detect a physical event such as an door or window being
> open or closed even more so.
> That micro-switch is nothing more than a simple, single purpose "Morse
> key". The "Morse key" is of course, an analog interrupter device used
> to encode a variable digital signal, which has to be transposed back
> to a physical output with another analog device at the receiving end
> to be interpreted.


You can tell, because you have to worry about contact bounce when
interface to it.
--
David Dyer-Bennet, (E-Mail Removed); http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info
 
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David Dyer-Bennet
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      02-27-2012
(E-Mail Removed) (Floyd L. Davidson) writes:

> Photons are not digital. As noted, photons have
> different energy levels depending on wavelength. Bingo,
> *analog*!


Except that those energy levels are quantized, not continuous. That
seems like the antithesis of "analog" to me.
--
David Dyer-Bennet, (E-Mail Removed); http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info
 
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David Dyer-Bennet
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      02-27-2012
Eric Stevens <(E-Mail Removed)> writes:

> On Mon, 27 Feb 2012 03:39:37 -0900, (E-Mail Removed) (Floyd L.
> Davidson) wrote:
>
>>Eric Stevens <(E-Mail Removed)> wrote:
>>>On Mon, 27 Feb 2012 05:23:42 +0100, Mxsmanic <(E-Mail Removed)>
>>>wrote:
>>>
>>>>TheRealSteve writes:
>>>>
>>>>> No it's not. In the real world, it's discrete, not continuous. You
>>>>> only think it's continuous because the difference between discrete
>>>>> levels are so small. An elementary charge is 1.602e-19 coulombs. An
>>>>> electron volt is the amount of energy gained by that elementary charge
>>>>> moved across an electric potential difference of one volt.
>>>>
>>>>Even if you choose to count the angels dancing on that pin and call it
>>>>discrete, it's still not digital. Digital is a way of representing
>>>>information. It's a concept, not a physical reality.
>>>
>>>Various people, including myself, are guilty of using the term
>>>'digital' when they really mean 'quantized'.

>>
>>If the information has been quantized, it's digital.

>
> Thank you for confirming that.
>
>
> Is the charge on a photon quantized?
>
> Either 'yes' or 'no' will do as an answer.


Um, charge on a photon is zero. If it's fixed, I'm not sure the concept
of "quantized" exactly applies.

--
David Dyer-Bennet, (E-Mail Removed); http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info
 
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Chris Malcolm
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      02-27-2012
Mxsmanic <(E-Mail Removed)> wrote:
> TheRealSteve writes:


>> No it's not. In the real world, it's discrete, not continuous. You
>> only think it's continuous because the difference between discrete
>> levels are so small. An elementary charge is 1.602e-19 coulombs. An
>> electron volt is the amount of energy gained by that elementary charge
>> moved across an electric potential difference of one volt.


> Even if you choose to count the angels dancing on that pin and call it
> discrete, it's still not digital. Digital is a way of representing
> information. It's a concept, not a physical reality.


>> You can count electrons.


> But you have to be a conscious being to count. Therefore the counting is in
> your mind, not in the physical reality.


Could I make that a basis for a fraudulent description lawsuit against
the sellers of digital counter chips?

--
Chris Malcolm
 
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Bryan
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      02-27-2012
Savageduck wrote:
> Strangely enough, this is one of those times when "Mxsmanic" has things
> correct from a purely academic position. Think about it.


A true digital sensor would detect individual photons, and count them.
Instead of of quantum-efficiency and noise they'd have a detection
probability and false-detection rate.

I doubt that's what's in Panasonic's cameras, but such devices exist.
We might think of photomultipliers as analog devices, but the most
sensitive of them distinguish individual photons.

Given the trends in integrated circuit technology, I wouldn't be
surprised to live to see cameras with true digital, photon-counting,
sensors.

-Bryan
 
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Martin Brown
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      02-27-2012
On 27/02/2012 21:24, Bryan wrote:
> Savageduck wrote:
>> Strangely enough, this is one of those times when "Mxsmanic" has things
>> correct from a purely academic position. Think about it.

>
> A true digital sensor would detect individual photons, and count them.
> Instead of of quantum-efficiency and noise they'd have a detection
> probability and false-detection rate.
>
> I doubt that's what's in Panasonic's cameras, but such devices exist.
> We might think of photomultipliers as analog devices, but the most
> sensitive of them distinguish individual photons.
>
> Given the trends in integrated circuit technology, I wouldn't be
> surprised to live to see cameras with true digital, photon-counting,
> sensors.
>
> -Bryan


Prof Alec Boksenbergs IPCS mid 1970's technology. Videcon plate HT
cascade and clever electronics to determine the centroid of the splat
that every photon causes on the screen. The one retired from the AAT has
photos of it online - hardly a portable device, but then it sat on a
large telescope with an umbilicle cord back to its control computer.

http://www.powerhousemuseum.com/coll...se/?irn=157946

--
Regards,
Martin Brown
 
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TheRealSteve
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      02-28-2012

On Mon, 27 Feb 2012 21:21:40 +0100, Mxsmanic <(E-Mail Removed)>
wrote:

>David Dyer-Bennet writes:
>
>> Except that those energy levels are quantized, not continuous. That
>> seems like the antithesis of "analog" to me.

>
>Strictly speaking, analog and digital refer only to the way information is
>represented, and information is a concept, not a physical reality.
>
>Analog representation uses a physical model of the information. Digital
>representation uses symbols that are arbitrarily associated with the
>information to be represented. Both ways of representing information have
>their advantages and disadvantages.


There are much better ways of defining analog vs. digital when it
pertains to sensors. Your definition doesn't allow sensors to be
analog either since analog is a physical model of information and
information is a concept, not a physical reality.
 
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