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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

d

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

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.

d

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

On 20 Aug., 10:04, nos...@nospam.com (Don Pearce) wrote:
> On Mon, 20 Aug 2007 03:51:54 -0400, Jerry Avins <j...@ieee.org> wrote:
> >Don Pearce wrote:
> >> On Sun, 19 Aug 2007 23:26:16 -0700, dpl...@radagast.org (Dave Platt)
> >> wrote:
>
> >>> "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.  It's not just that the
> >>> signal amplitude is quantized, but that the quantization uses a
> >>> power-of-two representation and storage system of some sort.
>
> >> My reading of the possible systems goes like this.
>
> >> analogue - a continuous representation of the original signal
> >> sampled - a representation of the signal at discrete time points
> >> quantized - a sampled signal, but with the possible levels constrained
> >> to a limited set of values
> >> digital - a quantized signal, with the individual levels represented
> >> by numbers
>
> >> Aliasing is going to happen as soon as you move beyond the first line
> >> of that list.
>
> >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.
>
> Yes, I was thinking about that possibility while I was typing, but
> since I've never come across such a system I decided it would
> complicate things unnecessarily to include it.

Yannis Tsividis once asked in comp.dsp what signal processing
practitioners thought of his continuous-time signal processing
(filtering) scheme. As I remember, it didn't go down well with the
crowd. After reading a paper from him explaining the concept I thought
that the scheme had at least educational merit. There are some
references on his webpage:

http://www.ee.columbia.edu/fac-bios/tsividis/faculty.html

Regards,
Andor

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/

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

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/

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