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"glen herrmannsfeldt" wrote in message
. ..

How about, Analog implies "infinite" precision in the absence of
noise, including fundamental quantum noise.


Except that "absence of noise" is a condition which
doesn't exist, even in theory.

ALL systems, digital, analog, or whatever, are limited in
information capacity by (a) the bandwidth of the channel
in question and (b) the level of noise within that channel,
per the aforementioned Gospel According to Shannon.
This is exactly the same thing as saying that there is a limit
to "precision" or "accuracy," as infinite precision implies
an infinite information capacity (i.e., given infinite precision,
I could encode the entire Library of Congress as a single
value, since I have as many effective "bits of resolution"
as I would ever need).

Note, for example, that an analog current is quantized in units
of the charge on the electron.


Sure is. So isn't it a good thing that we don't confuse either
"analog" or "digital" with either "quantized" or "continuous"?

Bob M.



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

Randy Yates wrote:

(snip)

Let me back-pedal a little and say that, yeah, colloquially, digital
is related to "digits." But the term "digital signal" as used in texts
and industry does not hold to this colloquial usage. That is, a signal
that is completely unquantized in amplitude and represented in base 10
as an element of the real numbers could well be called a digital
signal. The key property of such a signal is that it is *discrete-time*
(i.e., sampled in time).


I would say that "digitized signal" also implies quantization.

There are analog sampled storage systems, such as:

http://www.datasheets.org.uk/search....ExactDS=Starts

-- glen

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"Scott Seidman" wrote in message
. 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.

Bob M.


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

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.

-- glen

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"Martin Heffels" wrote ...
"Richard Crowley" wrote:
Radium's ability to suck so many people into attempting to
answer insane questions is reaching legendary heights.
I hereby nominate him for the Troll Hall of Fame with special
endorsement for use of technical gobeldygook.


I vote: aye


I don't mean to imply that there may not be idiot-savants
on the interweb. Al Einstein himself may easily have been
perceived as a troll if he were online :-)




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Jerry Avins wrote:

(snip)

I believe that's also a borderline area where definitions become
smudged. I know that the Russians built a computer with trinary logic,
but all the decimal systems I know, whether BCD, excess-three, or
something more exotic, encode the numbers on sets of four wires that
carry two-state signals. Making a case that that isn't binary opens the
door to claiming that hexadecimal is distinct from binary.


I believe that some of the early machines used 10 wires.

Biquinary, with seven wires, one of two and one of five, has
also been used.

In both cases each wire has one of two values, but it isn't very
"binary like".

-- glen

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Don Pearce wrote:

(snip)

No, you haven't. You merely have a signal at a set of discrete levels.
You need an analogue to digital converter to take each of those
quantized levels and convert it into a digital word (of 1s and 0s).


Digital means "represented by digits", not "in discrete voltage
steps".


Now it is getting complicated. Once it is quantized it "could"
be represented by digits. Whether you actually have to do that,
I am not so sure.

I haven't followed quantum computing so carefully, but it might
be possible to do computing on discrete voltage levels that
haven't been converted to digits. (And note that the usual
representation of a digital signal is by voltages on wires.)

-- glen

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"Richard Crowley" wrote in message
...

I don't mean to imply that there may not be idiot-savants
on the interweb. Al Einstein himself may easily have been
perceived as a troll if he were online :-)


And let's not forget Alfred Nobel's half-brother
Ignatz, the benefactor behind the Ig Nobel prize,
awarded for outstanding contributions to that
very field...;-)

Bob M.


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Scott Seidman wrote:

(snip)

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"?


Yes, that would be "sampled". Since analog tends to imply continuous
(non-sampled) it would probably be best to use "sampled analog" for
non-continuous non-quantized data.

-- glen


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On Aug 20, 3:26 pm, "Richard Crowley" wrote:
"Martin Heffels" wrote ...

"Richard Crowley" wrote:
Radium's ability to suck so many people into attempting to
answer insane questions is reaching legendary heights.
I hereby nominate him for the Troll Hall of Fame with special
endorsement for use of technical gobeldygook.


I vote: aye


I don't mean to imply that there may not be idiot-savants
on the interweb. Al Einstein himself may easily have been
perceived as a troll if he were online :-)


There is NO mistaking Albert Einstein for Radium. Even
if you disagreed with Einstein, his math was impeccable
and self-consistent and provided a plausible explanation
for observed phenomenon that was at variance with
Netwonian physics.

Radium, on the other hand, is simply a blithering idiot.



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(Don Pearce) wrote:
On Mon, 20 Aug 2007 05:46:19 -0800,
(Floyd L.
Davidson) wrote:

(Don Pearce) wrote:
On Mon, 20 Aug 2007 04:57:03 -0800,
(Floyd L.
Davidson) wrote:

Jerry Avins 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.


No, you haven't. You merely have a signal at a set of discrete levels.


Sheesh! That *is*, by definition a digital signal.

You need an analogue to digital converter to take each of those
quantized levels and convert it into a digital word (of 1s and 0s).

Digital means "represented by digits", not "in discrete voltage
steps".


Bull**** son. Look it up. I've provided you with
quotes from an authoritative reference, twice now. You
don't have to take my word for it, that *is* the agreed
technical definition of the term.

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

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(Floyd L. Davidson) wrote in
:

Sheesh! That *is*, by definition a digital signal.


Funny, that's just what my D/A converters put out, and the spec sheets
claim they're putting out analog signals. Perhaps I should return them.

--
Scott
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On Mon, 20 Aug 2007 14:13:04 -0400, Jerry Avins wrote:

Don Pearce wrote:
On Mon, 20 Aug 2007 10:58:53 -0800, glen herrmannsfeldt
wrote:

Don Pearce wrote:
(snip)

Quantization isn't important. If you don't quantize all it means is
that you are dealing with floating point rather than integer numbers.
Still digital of course. I can't think of any floating point ADC's off
hand, of course.
Floating point is still quantized, though not the same as fixed
point (integer) data.

Effectively it isn't. Of course if you apply this strictly, it is, but
a floating point number can be so detailed that it would be
essentially impossible to find the quantization steps in the real
world.

Instead of floating point, Mu-law and A-law coding are commonly
used for digitized audio:

http://en.wikipedia.org/wiki/Mu_law

http://en.wikipedia.org/wiki/A-law_algorithm

The result is similar to the use of floating point, but the
coding is different.

Nonsense. Mu and A law are simply a way of rescuing some decent
distortion performance from a limited number of bits by making the
quantization steps smaller as the signal gets smaller. The result is
lower noise with the penalty of slightly higher distortion. There is
no similarity whatever to floating point.


There's a gap in your understanding. the "segment" is the equivalent of
floating point's exponent, and the bits that divide the segment into
equal parts are like floating point's mantissa.

Jerry


No gap. The expressions are used simply to derive a set of
quantization points which, in the telephony systems that use them,
generate 8 bits of data - no floating points, which would many more
bits to encompass a mantissa and an exponent. The result is just the
integer numbers -128 to 127.

d

--
Pearce Consulting
http://www.pearce.uk.com


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On Mon, 20 Aug 2007 13:38:15 -0800, (Floyd L.
Davidson) wrote:

(Don Pearce) wrote:
Sorry, but that is simply nonsense. A signal that is sampled in time,
but not quantized is an analogue signal. It is treated and processed
by analogue circuits. For a signal to be digital its sampled levels
must be represented by numbers, which are processed mathematically by
some sort of microprocessor.


That is, it must actually be quantized.

Perhaps that is what you meant to say earlier, but you
actually didn't, and said that the quantized signal has
to be represented by numbers, which it is by definition.

No it isn't - it can simply be a signal where the smooth curve has
been replaced by steps. If you want to process that signal you must do
so with analogue circuitry - amplifiers, filters etc. Representing
those steps by numbers is a different matter. Once you have done that,
you can no longer process in the analogue domain, you must use maths
on the numbers; that is what makes it digital.

The signal can be reconverted to an
analogue one later by a D to A.


It's best to call that a quasi-analog signal...

No it isn't. It is an analogue signal, because it is no longer
represented by digits.
d

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On Mon, 20 Aug 2007 13:33:34 -0800, (Floyd L.
Davidson) wrote:

(Don Pearce) wrote:
On Mon, 20 Aug 2007 05:46:19 -0800,
(Floyd L.
Davidson) wrote:

(Don Pearce) wrote:
On Mon, 20 Aug 2007 04:57:03 -0800,
(Floyd L.
Davidson) wrote:

Jerry Avins 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.


No, you haven't. You merely have a signal at a set of discrete levels.


Sheesh! That *is*, by definition a digital signal.

If you put that signal through an analogue amplifier, it will be
amplified. That makes it an analogue signal. If you want to amplify a
signal in the digital domain, you must perform maths on the numbers.
Can you really not see the difference?

You need an analogue to digital converter to take each of those
quantized levels and convert it into a digital word (of 1s and 0s).

Digital means "represented by digits", not "in discrete voltage
steps".


Bull**** son. Look it up. I've provided you with
quotes from an authoritative reference, twice now. You
don't have to take my word for it, that *is* the agreed
technical definition of the term.


Sorry, but you are wrong. And any reference you have found that makes
such a claim is not authoritative; it is also wrong.

d

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http://www.pearce.uk.com
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(Don Pearce) wrote:
On Mon, 20 Aug 2007 11:31:16 -0400, Randy Yates
wrote:

(Don Pearce) writes:
[...]
On Mon, 20 Aug 2007 05:46:19 -0800,
(Floyd L.
Davidson) wrote:

A "quantized analogue signal" is digital by definition.


No, you haven't. You merely have a signal at a set of discrete levels.
You need an analogue to digital converter to take each of those
quantized levels and convert it into a digital word (of 1s and 0s).

Digital means "represented by digits", not "in discrete voltage
steps".


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.


Are you kidding? It is *the* industry standard
definition. It is not something that I made up, I
merely looked it up.

http://ntia.its.bldrdoc.gov/fs-1037/

That is, since you seem unable to grasp or investigate
it, the web site of the National Telecommunications and
Information Administration, a part of the US Federal
Department of Commerce, in Boulder Colorado. Which is
to say they are next door to and under that same
management as the NIST (the National Institute of
Standards and Technology), and NOAA (National Oceanic
and Atmospheric Administration) which you may also have
heard of...

Or, to put it another way, you will not find anywhere in
the world a valid definition that disagrees with that
one. If yours is not in agreement, you are *wrong*.

I've also seen many contexts in which "digital" means "discrete-time,"
i.e., there is no amplitude quantization at all. Take for example any
of a number of books on the subject which have "digital signal
processing" in the title - they are referring to signals that have
been sampled in time, but not quantized (generally, although
quantization effects are also analyzed in several such texts).


Really? Can you point me at something that does DSP on signals that
have been merely sampled in time? I've never come across any such
thing.

Do you have a reference for your definition?


Logic will do.


Logically you are walking the plank. Such technical
definitions have nothing to do with logic. It is an
arbitrary decision that it means this or it means that.
If we all agree on the arbitrary decision then we have a
standard, and we can use it knowing that others will
understand what it means.

Until someone like you walk in and says they have their
own definition...

If you are doing digital signal processing, you are
doing arithmetic on the numbers that come out of an AtoD converter.


That is not necessarily true. Not all digital signals
originate as analog signals that require A-D
conversion.

You can't do that with some voltage levels out of a quantizer.


Out of a quantizer? You certainly can.

As for discrete time, that is simply sampled, like a class D
amplifier, and nothing to do with digits. There is plenty of laziness
in the use of nomenclature (as well as misuse by people who simply
have no idea what they are talking about).


I totally agree with that statement. ;-)

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)
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On 20 Aug 2007 21:42:18 GMT, Scott Seidman
wrote:

(Floyd L. Davidson) wrote in
:

quantized - a sampled signal, but with the possible levels constrained
to a limited set of values


That is by definition a digital siganl. As soon as the possible values
are "constrained to a limited set", it is by definition digital data.



Wouldn't this make the output of a D/A converter digital by definition?


It certainly would. But apparently there are those that can't see the
difference between a limited set of values, and a set of numbers
describing those values.

d

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(Don Pearce) wrote:

Sorry, but that isn't DSP, it is just calculating the power. Let me
put this very simply. If you have a quantized signal and you want to
make it twice as big, can you do that with an amplifier, or do you do
it mathematically? If the signal is quantized, an amplifier will do
it. If it is digitized it won't. You can amplify 0110111001 all you
like, you will still have 0110111001.


You are confused. You are taking about sampling, not quantizing.

Do you have a reference for your definition?

Logic will do. If you are doing digital signal processing, you are
doing arithmetic on the numbers that come out of an AtoD converter.
You can't do that with some voltage levels out of a quantizer.

As for discrete time, that is simply sampled, like a class D
amplifier, and nothing to do with digits. There is plenty of laziness
in the use of nomenclature (as well as misuse by people who simply
have no idea what they are talking about).


I won't argue that the current usage isn't good nomenclature, but that's
the way historically things have developed.


Current usage is just fine. A digital signal is one composed of
digits.


And a "digit" is nothing other than a discrete value. Hence
you have a valid definition, but don't recognize what it means.

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



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On Mon, 20 Aug 2007 13:57:26 -0800, (Floyd L.
Davidson) wrote:

(Don Pearce) wrote:
On Mon, 20 Aug 2007 11:31:16 -0400, Randy Yates
wrote:

(Don Pearce) writes:
[...]
On Mon, 20 Aug 2007 05:46:19 -0800,
(Floyd L.
Davidson) wrote:

A "quantized analogue signal" is digital by definition.


No, you haven't. You merely have a signal at a set of discrete levels.
You need an analogue to digital converter to take each of those
quantized levels and convert it into a digital word (of 1s and 0s).

Digital means "represented by digits", not "in discrete voltage
steps".

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.


Are you kidding? It is *the* industry standard
definition. It is not something that I made up, I
merely looked it up.

http://ntia.its.bldrdoc.gov/fs-1037/

That is, since you seem unable to grasp or investigate
it, the web site of the National Telecommunications and
Information Administration, a part of the US Federal
Department of Commerce, in Boulder Colorado. Which is
to say they are next door to and under that same
management as the NIST (the National Institute of
Standards and Technology), and NOAA (National Oceanic
and Atmospheric Administration) which you may also have
heard of...

Or, to put it another way, you will not find anywhere in
the world a valid definition that disagrees with that
one. If yours is not in agreement, you are *wrong*.

You have misunderstood what is meant by the definition. It is not
intended to describe quantized signals, but data where sequential time
steps represent data. It is very clear that when those definitions
were being written, nobody on the committee was thinking of quantized
analogue signals.

I've also seen many contexts in which "digital" means "discrete-time,"
i.e., there is no amplitude quantization at all. Take for example any
of a number of books on the subject which have "digital signal
processing" in the title - they are referring to signals that have
been sampled in time, but not quantized (generally, although
quantization effects are also analyzed in several such texts).


Really? Can you point me at something that does DSP on signals that
have been merely sampled in time? I've never come across any such
thing.

Do you have a reference for your definition?


Logic will do.


Logically you are walking the plank. Such technical
definitions have nothing to do with logic. It is an
arbitrary decision that it means this or it means that.
If we all agree on the arbitrary decision then we have a
standard, and we can use it knowing that others will
understand what it means.

Until someone like you walk in and says they have their
own definition...

If you are doing digital signal processing, you are
doing arithmetic on the numbers that come out of an AtoD converter.


That is not necessarily true. Not all digital signals
originate as analog signals that require A-D
conversion.

of course not. They can start life in a computer or whatever. Are you
trying to confuse the issue with a red herring?

You can't do that with some voltage levels out of a quantizer.


Out of a quantizer? You certainly can.

You can do arithmetic on the output of a quantizer? How do you do
that, it is not in a numeric form. If you want to do arithmetic on it,
you must first digitize it.

As for discrete time, that is simply sampled, like a class D
amplifier, and nothing to do with digits. There is plenty of laziness
in the use of nomenclature (as well as misuse by people who simply
have no idea what they are talking about).


I totally agree with that statement. ;-)


Well, that is a start!

d

--
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http://www.pearce.uk.com
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On Mon, 20 Aug 2007 14:03:29 -0800, (Floyd L.
Davidson) wrote:

(Don Pearce) wrote:

Sorry, but that isn't DSP, it is just calculating the power. Let me
put this very simply. If you have a quantized signal and you want to
make it twice as big, can you do that with an amplifier, or do you do
it mathematically? If the signal is quantized, an amplifier will do
it. If it is digitized it won't. You can amplify 0110111001 all you
like, you will still have 0110111001.


You are confused. You are taking about sampling, not quantizing.

No I'm not. Let me explain with an example. Suppose I have a ramp that
changes smoothly from 0 to 1 volt. Now I quantize it in steps of 0.1
volts. I now have a staircase that rises in 0.1V steps from 0 to 1
volt. If I put that through an amplifier with a gain of 2, I will get
a staircase from 0 to 2 volts. I can put it through an amplifier
because it is still an analogue signal.

If I digitize the signal, I will get a set of signals which might be
0000, 0001, 0010, 0011 etc. If I want to apply a gain of 2, I can't
use an amplifier, I will have to use maths. In the case of applying a
gain of 2 it is easy - the result is 0000, 0010, 000, 0110 etc.

That is the difference between an analogue signal (whether quantized
or not) and a digital one.

Do you have a reference for your definition?

Logic will do. If you are doing digital signal processing, you are
doing arithmetic on the numbers that come out of an AtoD converter.
You can't do that with some voltage levels out of a quantizer.

As for discrete time, that is simply sampled, like a class D
amplifier, and nothing to do with digits. There is plenty of laziness
in the use of nomenclature (as well as misuse by people who simply
have no idea what they are talking about).

I won't argue that the current usage isn't good nomenclature, but that's
the way historically things have developed.


Current usage is just fine. A digital signal is one composed of
digits.


And a "digit" is nothing other than a discrete value. Hence
you have a valid definition, but don't recognize what it means.


A digit is a number.

d

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

Scott Seidman wrote:
(Floyd L. Davidson) wrote in
:

quantized - a sampled signal, but with the possible levels constrained
to a limited set of values

That is by definition a digital siganl. As soon as the possible values
are "constrained to a limited set", it is by definition digital data.



Wouldn't this make the output of a D/A converter digital by definition?


Of course it would. I think it's a bit silly (pretty stupid, actually)
to argue about what to call something and believe that's the same as
arguing about what it is. One could say that a continuous signal
measured with a 3.5-digit meter is quantized by the measurement even if
it's unchanged thereby. And if the signal is recorded hourly in a log
book, I suppose it becomes sampled. Is it worth trying to make a
definition that withstands all possible logical contortions? Probably
sometimes, but not here; not now.

Jerry
--
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Default Questions about equivalents of audio/video and digital/analog.

"Bob Myers" wrote:
"Randy Yates" wrote in message
...
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)
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Default Questions about equivalents of audio/video and digital/analog.

Don Pearce wrote:
On Mon, 20 Aug 2007 14:13:04 -0400, Jerry Avins wrote:

Don Pearce wrote:
On Mon, 20 Aug 2007 10:58:53 -0800, glen herrmannsfeldt
wrote:

Don Pearce wrote:
(snip)

Quantization isn't important. If you don't quantize all it means is
that you are dealing with floating point rather than integer numbers.
Still digital of course. I can't think of any floating point ADC's off
hand, of course.
Floating point is still quantized, though not the same as fixed
point (integer) data.

Effectively it isn't. Of course if you apply this strictly, it is, but
a floating point number can be so detailed that it would be
essentially impossible to find the quantization steps in the real
world.

Instead of floating point, Mu-law and A-law coding are commonly
used for digitized audio:

http://en.wikipedia.org/wiki/Mu_law

http://en.wikipedia.org/wiki/A-law_algorithm

The result is similar to the use of floating point, but the
coding is different.

Nonsense. Mu and A law are simply a way of rescuing some decent
distortion performance from a limited number of bits by making the
quantization steps smaller as the signal gets smaller. The result is
lower noise with the penalty of slightly higher distortion. There is
no similarity whatever to floating point.

There's a gap in your understanding. the "segment" is the equivalent of
floating point's exponent, and the bits that divide the segment into
equal parts are like floating point's mantissa.

Jerry


No gap. The expressions are used simply to derive a set of
quantization points which, in the telephony systems that use them,
generate 8 bits of data - no floating points, which would many more
bits to encompass a mantissa and an exponent. The result is just the
integer numbers -128 to 127.


Oh? The concept of floating point prescribes a certain number of bits?
That you fail to see the parallel doesn't mean there isn't one.

Jerry
--
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¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯


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

Floyd L. Davidson wrote:

...

And a "digit" is nothing other than a discrete value. Hence
you have a valid definition, but don't recognize what it means.


So the output of a fresh C cell is a digit? Talk about digging a hole
for oneself!

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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Default Questions about equivalents of audio/video and digital/analog.

On Mon, 20 Aug 2007 14:22:55 -0800, (Floyd L.
Davidson) wrote:

"Bob Myers" wrote:
"Randy Yates" wrote in message
...
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...


The big problem here is that you have misunderstood what NTIA is
saying.

d

--
Pearce Consulting
http://www.pearce.uk.com
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Default Questions about equivalents of audio/video and digital/analog.

On Mon, 20 Aug 2007 18:24:34 -0400, Jerry Avins wrote:

Don Pearce wrote:
On Mon, 20 Aug 2007 14:13:04 -0400, Jerry Avins wrote:

Don Pearce wrote:
On Mon, 20 Aug 2007 10:58:53 -0800, glen herrmannsfeldt
wrote:

Don Pearce wrote:
(snip)

Quantization isn't important. If you don't quantize all it means is
that you are dealing with floating point rather than integer numbers.
Still digital of course. I can't think of any floating point ADC's off
hand, of course.
Floating point is still quantized, though not the same as fixed
point (integer) data.

Effectively it isn't. Of course if you apply this strictly, it is, but
a floating point number can be so detailed that it would be
essentially impossible to find the quantization steps in the real
world.

Instead of floating point, Mu-law and A-law coding are commonly
used for digitized audio:

http://en.wikipedia.org/wiki/Mu_law

http://en.wikipedia.org/wiki/A-law_algorithm

The result is similar to the use of floating point, but the
coding is different.

Nonsense. Mu and A law are simply a way of rescuing some decent
distortion performance from a limited number of bits by making the
quantization steps smaller as the signal gets smaller. The result is
lower noise with the penalty of slightly higher distortion. There is
no similarity whatever to floating point.
There's a gap in your understanding. the "segment" is the equivalent of
floating point's exponent, and the bits that divide the segment into
equal parts are like floating point's mantissa.

Jerry


No gap. The expressions are used simply to derive a set of
quantization points which, in the telephony systems that use them,
generate 8 bits of data - no floating points, which would many more
bits to encompass a mantissa and an exponent. The result is just the
integer numbers -128 to 127.


Oh? The concept of floating point prescribes a certain number of bits?
That you fail to see the parallel doesn't mean there isn't one.

No idea what that meant. Mu and A law are used in telephony. The
system uses 8 bits. Mu and A law are necessary because there ARE only
8 integer bits. If telephony could afford, say, 16 bits, there would
be no need for Mu and A law. The bits are integer. There is no
floating point. Why is that so hard to grasp?

d

--
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http://www.pearce.uk.com
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Default Questions about equivalents of audio/video and digital/analog.

"Bob Myers" wrote:
"Floyd L. Davidson" wrote in message
...

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)


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

Floyd L. Davidson wrote:

...

Floating point is analog, integer is digital.


An analog of what? I use digits to represent floats, with E sometimes
thrown in and '.', the "point" part. How many different floats can your
computer represent? I'm sure it's a countable number

...

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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Don Pearce wrote:
On Mon, 20 Aug 2007 18:24:34 -0400, Jerry Avins wrote:

Don Pearce wrote:
On Mon, 20 Aug 2007 14:13:04 -0400, Jerry Avins wrote:

Don Pearce wrote:
On Mon, 20 Aug 2007 10:58:53 -0800, glen herrmannsfeldt
wrote:

Don Pearce wrote:
(snip)

Quantization isn't important. If you don't quantize all it means is
that you are dealing with floating point rather than integer numbers.
Still digital of course. I can't think of any floating point ADC's off
hand, of course.
Floating point is still quantized, though not the same as fixed
point (integer) data.

Effectively it isn't. Of course if you apply this strictly, it is, but
a floating point number can be so detailed that it would be
essentially impossible to find the quantization steps in the real
world.

Instead of floating point, Mu-law and A-law coding are commonly
used for digitized audio:

http://en.wikipedia.org/wiki/Mu_law

http://en.wikipedia.org/wiki/A-law_algorithm

The result is similar to the use of floating point, but the
coding is different.

Nonsense. Mu and A law are simply a way of rescuing some decent
distortion performance from a limited number of bits by making the
quantization steps smaller as the signal gets smaller. The result is
lower noise with the penalty of slightly higher distortion. There is
no similarity whatever to floating point.
There's a gap in your understanding. the "segment" is the equivalent of
floating point's exponent, and the bits that divide the segment into
equal parts are like floating point's mantissa.

Jerry
No gap. The expressions are used simply to derive a set of
quantization points which, in the telephony systems that use them,
generate 8 bits of data - no floating points, which would many more
bits to encompass a mantissa and an exponent. The result is just the
integer numbers -128 to 127.

Oh? The concept of floating point prescribes a certain number of bits?
That you fail to see the parallel doesn't mean there isn't one.

No idea what that meant. Mu and A law are used in telephony. The
system uses 8 bits. Mu and A law are necessary because there ARE only
8 integer bits. If telephony could afford, say, 16 bits, there would
be no need for Mu and A law. The bits are integer. There is no
floating point. Why is that so hard to grasp?


It is a characteristic of floating-point representation that some of the
bits represent a signed magnitude and others represent a scale factor
for that quantity. It is a characteristic of mu- and A-law that some of
the bits represent a signed magnitude and others represent a scale
factor for that quantity. I would have thought that you could grasp the
similarity. No matter if you reject the insight.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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Default Questions about equivalents of audio/video and digital/analog.

Don Bowey wrote:
On 8/20/07 8:41 AM, in article , "Bob Myers"
wrote:


"Floyd L. Davidson" wrote in message
...

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)
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Jerry Avins wrote:
Floyd L. Davidson wrote:
(Don Pearce) wrote:
On Mon, 20 Aug 2007 04:57:03 -0800,
(Floyd L.
Davidson) wrote:

Jerry Avins 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)
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Default Questions about equivalents of audio/video and digital/analog.

Jerry Avins wrote:
Floyd L. Davidson wrote:
Jerry Avins 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)


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Floyd L. Davidson Floyd L. Davidson is offline
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Default Questions about equivalents of audio/video and digital/analog.

"Bob Myers" wrote:
"Dave Platt" wrote in message
...
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.

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Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)
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Default Questions about equivalents of audio/video and digital/analog.

"Bob Myers" wrote:
"Don Pearce" wrote in message
...
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)
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Default Questions about equivalents of audio/video and digital/analog.

"Bob Myers" wrote:
"Floyd L. Davidson" wrote in message
...
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)
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Default Questions about equivalents of audio/video and digital/analog.

glen herrmannsfeldt 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)
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Default Questions about equivalents of audio/video and digital/analog.

"Bob Myers" wrote:
"Scott Seidman" wrote in message
.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)
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