Questions about equivalents of audio/video and digital/analog.

"Bob Myers" <nospamplease@address.invalid> wrote:
>"Randy Yates" <yates@ieee.org> wrote in message
>news:m31wdytcq2.fsf@ieee.org...
>>>>I've never seen that definition, while I have seen the definition
>>>>Floyd is proposing, and I think it is a reasonable one.
>>>>
>>> No, it isn't. It misses the fact that sampled and digital are
>>> different things. Digits are numbers.
>>
>> It isn't reaonable to you. Don't publish opinion as fact.
>
>OK, it's not reasonable to ME, either, if you're impressed
>by taking a vote on this sort of thing.
>
>The problem with the definition that you and Floyd seem to
>want to use is that it leads to several problems in both
>theory and practice, in addition to the fact that there are
>numerous counter-examples one can point to.

It doesn't lead to any such problems.

What you need to get straight is that it is not *my*
definition.  It is the *standard* technical definition
recognized by virtually *every* standards organization.
I quoted the NTIA's Federal Standard 1037C.

>"Reasonable" would seem (at least to me) to mean that you

It makes no difference what you think is or is not
reasonable, unless we want to discuss *you*.  If you
disagree with the standard definition then you don't
understand the term, and we can determine how far off
you are by how much your definition differs from that
one! ;-)

>can justify your definition *through reason*, which Don has
>done.

Which proves that he doesn't understand it.  It says
nothing about whether the National Telecommunications
and Information Administration, knows or what the MilStd
specification knows.

>Simply pointing to a published work, including a
>standard, as a reference to support your definition is what's
>called an "argument from authority," and it has exactly zero

That is a logical fallacy on your part.  An "argument
from authority" has great weight if it is valid.  To
be valid it must pass three tests:

  1)  The authority cited must actually be an authority.
  2)  All authorities must agree on the topic.
  3)  The authority cannot be misquoted, taken out of
      context, or be joking.

Clearly citing the NTIA and MilStd definition is indeed
a *very* strong appeal to authority, and no mere opinion
can even come close to invalidating it.

>weight in light of an opposing argument based on evidence
>and logic.

What evidence?  And the logic is clearly invalid and
based on false assumptions.

You know one way to be absolutely positive that your
logic is not good is to do a reality check and find that
the answer you have is wrong.  It this case that is very
easy to do, which is why *standard* definitions are
quoted from authoritative sources.  If you disagree,
then clearly you *don't* have the logic right!

>However, if you like, I can also point to several
>references which support the definition that Don and I (and

So cite even one such valid reference!  (You *cannot*,
because there are none.)

(And recognize that if you think you have one, then
there is one of two things clearly true: Either 1) you
do not understand that the other definition is not
actually different, or 2) your reference is not a valid
one.)

>I believe others) are proposing.  You might claim the list to
>be invalid, however, since it would contain works that I
>myself wrote for publication.  Which is, of course, the whole

You are not a valid reference.  You don't even come
close to being equal to the NTIA.

And it is *hilarious* that you would (again, because
this isn't the first time) try to convince anyone that
you are.

>point - simply having your statements published does NOT
>make them any more or less correct; the deciding factor is
>whether or not they can be shown to be true through evidence
>and logic.

Except technical definitions are sometimes merely
arbitrary agreements on one of many possible logical
ways to define a term.  We could have decided that
"digital" means binary, or a decimal system.  We didn't,
but both would be logical.

>A common misuse or misunderstanding does not become
>less so merely because it IS common.

Hmmm...

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Bob Myers" <nospamplease@address.invalid> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:87r6lyjp3o.fld@apaflo.com...
>
>> A "quantized analogue signal" is digital by definition.
>
>No, Don had it right.  A quantized analog signal

You can repeat that all you like, but you are wrong
every time you do.

By *definition* it is a digital signal.

  quantization:
    A process in which the continuous range of values
    of an analog signal is sampled and divided into
    nonoverlapping (but not necessarily equal)
    subranges, and a discrete, unique value is assigned
    to each subrange.

A _sampled_ signal is still analog.  A _quantized_ signal is
digital by definition.

If you do not stay with standard definitions it is
impossible to discuss anything rationally.

>remains analog as long as the relative values of the
>quantization levels, one to the other have significance;
>they thus can carry information, which is the fundamental
>goal of any such system.

The quantization levels are digital.  By definition.

If that isn't what you mean, then you need to use other
words because you are confusing the issue by misuse of
standard terms.

>Now, we could certainly assign values to those levels
>which (for instance) are NOT in order from "top to
>bottom" (or whichever direction you choose to use),
>which might be done to distribute the susceptibility of
>any given "bit" in said value to noise evenly.  In this
>case, the levels MUST be interpreted as the intended
>numeric values in order to recover the original
>information, and hence this would be a "digital"
>encoding system.
>
>>  QUANTIZATION:
>>      A process in which the continuous range of values
>>      of an analog signal is sampled and divided into
>>      nonoverlapping (but not necessarily equal)
>>      subranges, and *a* *discrete*, *unique* *value* *is*
>>      *assigned* to each subrange.
>>
>>  http://ntia.its.bldrdoc.gov/fs-1037/
>
>Exactly.  But mere quantization by itself does not
>suffice to render a signal "digitally encoded," no
>matter what a given government "expert" may claim.

The quantization of a signal makes it digital.

(It *is* encoded, too, BTW.  But until you understand
what makes it digital, there is little point in trying
to define what "encoded" means.)

No matter how dense you want to be about it, that
government "expert" happens to be right.  And you cannot
find *any* expert that will disagree.  That is the
*standard* definition, and virtually *everyone* agrees
that it is correct.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Don Bowey <dbowey@comcast.net> wrote:
>On 8/20/07 8:41 AM, in article faccmf$sfh$1@usenet01.boi.hp.com, "Bob Myers"
><nospamplease@address.invalid> wrote:
>
>>
>> "Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>> news:87r6lyjp3o.fld@apaflo.com...
>>
>>> A "quantized analogue signal" is digital by definition.
>>
>> No, Don had it right.  A quantized analog signal
>> remains analog as long as the relative values of the
>> quantization levels, one to the other have significance;
>> they thus can carry information, which is the fundamental
>> goal of any such system.
>
>No, it becomes a digitally encoded representative of a sample of an analog
>voltage.  First the continuously variable analog signal is sampled,
>becoming, for example PAM, which is still analog, which is then quantized
>and may be fit to whatever digital or analog coding that is desired.  If

Once it is quantized, it is digital.

Actually I suspect it is open to debate as to whether a
sample is actually PAM until it is quantized.  (Until it
is, it's just a sample of an analog signal.)  But
whatever, if the sample itself actually  is PAM, then yes
that is an analog signal.

However, after it is is quantized is then a digital (PAM)
signal.  (And example is the high speed link of a v.90
modem, which uses PAM.)

>it's to a digital code, the signal is digital.  If to an analog code, the
>signal is analog.

For analog it necessarily has to be _modulated_, not
encoded.  If must be modulated for the resulting signal
to be applied to the input of an analog channel.  If it
is encoded it must a digital channel.  (Again, that is
the nature of arbitrary definitions, this time of what
"encode" and "modulate" mean.)

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Jerry Avins <jya@ieee.org> wrote:
>Floyd L. Davidson wrote:
>> nospam@nospam.com (Don Pearce) wrote:
>>> On Mon, 20 Aug 2007 04:57:03 -0800, floyd@apaflo.com (Floyd L.
>>> Davidson) wrote:
>>>
>>>> Jerry Avins <jya@ieee.org> wrote:
>>>>> I like your categories. It is possible in concept to
>>>>> have a signal that is quantized in magnitude and
>>>>> continuous in time, but (unless we resort to counting
>>>>> electrons) I don't think it's possible in practice.
>>>> If you quantize the magnitude, it is digital.  That is
>>>> by definition.
>>> No it isn't. It isn't digital until you assign numerical values to
>>> those quantized levels. Until then it is simply a quantized analogue
>>> signal.
>> If you quantize it, you *have* assigned a value to it,
>> and that value is not from a continuous set, but from a
>> discrete finite set, and therefore it is digital.
>> A "quantized analogue signal" is digital by definition.
>> (Emphasis added)
>>   QUANTIZATION:
>>       A process in which the continuous range of values
>>       of an analog signal is sampled and divided into
>>       nonoverlapping (but not necessarily equal)
>>       subranges, and *a* *discrete*, *unique* *value* *is*
>>       *assigned* to each subrange.
>>   http://ntia.its.bldrdoc.gov/fs-1037/
>
>The government declares it so it must be true?

No, virtually *every* standards organization recognizes
that definition.

You cannot find *any* reputable disagreement.

(For one thing, because anyone who disagrees is *clearly*
not credible... ;-)

>I can
>demonstrate a circuit using analog components that
>transforms a continuous ramp input into a staircase
>output. Moreover, the output levels can be individually
>adjusted. Is the output digital? (We're discussing an
>arbitrary definition here. There is no wrong answer.)

The output is apparenlty analog.  At least you have said
*nothing* that indicates otherwise.

Do you think all digital signals are square waves and
anything that has square waves is digital?  Your example
above suggests that you might, but it simply isn't true.



-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

Jerry Avins <jya@ieee.org> wrote:
>Floyd L. Davidson wrote:
>> Jerry Avins <jya@ieee.org> wrote:
>>> I like your categories. It is possible in concept to
>>> have a signal that is quantized in magnitude and
>>> continuous in time, but (unless we resort to counting
>>> electrons) I don't think it's possible in practice.
>> If you quantize the magnitude, it is digital.  That is
>> by definition.
>
>I believe that the definition is flawed. Not that it

Your opinion of standard definitions is worthless.

If you want to communicate with the rest of the technical
world, use standard definitions and cease claiming they
are flawed.

Your opinion is where the flaw exists.

>matters; it's good enough in context. A signal can be
>quantized without any need to measure it or describe it
>with a number.

That isn't true.  In order to quantize it you *must*
decide on non-overlapping ranges of *values*, and a
specific quantity value that equates to those values.

>An example is the signal being measured
>in a quantum Hall-effect experiment.

Explain.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Bob Myers" <nospamplease@address.invalid> wrote:
>"Dave Platt" <dplatt@radagast.org> wrote in message
>news:8ponp4-gfd.ln1@radagast.org...
>> >Come on, Dave, a CCD is a digital device, subject to aliasing. The
>>>charges represent the signal at a particular instant of its average over
>>>a particular interval. (My CCD digital camera can take time exposures.)
>>>A CCD's content may not be quantized in amount, but it is quantized in
>>>time. In a camera, where the charges pertain to individual pixels, the
>>>result is also quantized in space.
>>
>> "Digital" and "subject to aliasing" are two different things.
>>
>> As I believe the term "digital" is usually meant, it implies a
>> two-state (on/off) storage representation.
>
>Not necessarily; a two-state representation is most properly
>referred to as "binary."  The best definition of "digital" I've
>managed to come up with comes in the word itself - it
>is the encoding system whereby information is stored as
>"digits," i.e., numeric values, as opposed to a system in which
>the information is stored "analogously" in the form of one
>parameter (voltage, say) which varies in a like manner as the
>original.

Your definition is flawed.  Digital implies a finite set
of values, which might well be a voltage that varies in
a like manner (granted not continuously) as the
original.

Analog inplies the variation is continuous.

>"Quantized" and "sampled" are terms which are really not all
>that closely associated (at least in theory) with either of the
>above,

Again, not really true.  Quantized is necessarily
digitized.

But sampled can be either.

>although admittedly most systems seen today which
>employ sampling and/or quantization are also "digital" in the
>nature of the encoding of the information carried.

Anything that is quantized is digitized.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Bob Myers" <nospamplease@address.invalid> wrote:
>"Don Pearce" <nospam@nospam.com> wrote in message
>news:46cd3d5b.233043828@news.plus.net...
>> analogue - a continuous representation of the original signal
>
>A CCD is an example of a device which stores information
>in an analog manner, but non-continuously.

The output signal is analog, and is able to vary *continuously*
over the range in which it functions.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Bob Myers" <nospamplease@address.invalid> wrote:
>"Floyd L. Davidson" <floyd@apaflo.com> wrote in message
>news:87zm0mjrfy.fld@apaflo.com...
>>>digital - a quantized signal, with the individual levels represented
>>>by numbers
>>
>> It makes no difference how the levels are represented.
>
>Sure it does.

Look up the definition of "quantization" again.  It simply
makes no difference.  If an analog signal is quantized, the
result is a digital signal.  That is by definition, and you
cannot escape that with mumbo-jumbo and faulty logic.

>If the levels of the original signal (or rather,
>whatever parameter of the original information is being
>recorded/stored/process are represented by analogous
>levels of some other parameter (e.g., sound represented
>by voltage), then the system is "analog."

And that necessarily means that the "analogous levels"
can vary continuously.

(Your example is poor, becuase sound can be represented
by a voltage that has been digitally encoded.)

>It is certainly
>possible to conceive of a quantized analog system, although

It is not possible by definition.  If you quantize something,
you have a finite set of discrete values, and it *is* digital.

>such things are rarely if ever seen in practice.

Understatement of the day.

>"Analog" also does not imply "infinite" precision or
>adjustability, since, as is the case in ALL systems, the achievable
>precision (and thus the information capacity) is ultimately limited
>by noise.  See the Gospel According to St. Shannon for
>further details...;-)

True.  It means only continuously variable over an
infinite set of values.  Your ability to determine
exactly which value (accuracy) is not guaranteed, nor is
your ability to reset to any specific value (precision)
guaranteed.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:
>Bob Myers wrote:
>
>(snip)
>
>> "Analog" also does not imply "infinite" precision or
>> adjustability, since, as is the case in ALL systems, the achievable
>> precision (and thus the information capacity) is ultimately limited
>> by noise.  See the Gospel According to St. Shannon for
>> further details...;-)
>
>How about, Analog implies "infinite" precision in the absence of
>noise, including fundamental quantum noise.
>
>Note, for example, that an analog current is quantized in units
>of the charge on the electron.

No, in fact it is not.   Electrons do not necessarily all move
at the same speed...

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com

"Bob Myers" <nospamplease@address.invalid> wrote:
>"Scott Seidman" <namdiesttocs@mindspring.com> wrote in message
>news:Xns999294E6D651Fscottseidmanmindspri@130.133.1.4...
>
>> Doesn't "analog" also imply that x(t) exists for all t in range, and not
>> just at nT for all n in range?  Or would people just call that "sampled"?
>
>Assuming "t" is time here, no - that would require
>that there be no such thing as a sampled analog
>representation, and we already have noted examples
>of that very thing.
>
>"Analog" != "continuous," even though most commonly
>"analog" signals are also continuous in nature.

Analog signals are by *definition* continous.

You have misunderstood what that means though.  The
analog value of a signal is continuous, but that does
not imply that the signal continuously exists or that
it even changes at all.

-- 
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)              floyd@apaflo.com