Reply
 
Thread Tools Display Modes
  #41   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Floyd L. Davidson Floyd L. Davidson is offline
external usenet poster
 
Posts: 175
Default Questions about equivalents of audio/video and digital/analog.

(Don Pearce) wrote:
On Sun, 19 Aug 2007 23:26:16 -0700,
(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


That describes a binary digital system. Not all digital systems
are binary. What is called M-ary is very common, with multiple
states.

signal amplitude is quantized, but that the quantization uses a
power-of-two representation and storage system of some sort.


It doesn't require a power of two representation, though that
certainly makes a lot of other functionality much easier. The
key is "discrete states" from a "finite set". That makes it
digital.

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


Note that discrete time points does not make a signal digital,
if the value of the signal can still be varied infinitely.

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.

digital - a quantized signal, with the individual levels represented
by numbers


It makes no difference how the levels are represented.

Aliasing is going to happen as soon as you move beyond the first line
of that list.


Your definitions are pretty good! The significant
points are that analog is continuous with an infinite
set of values, while digital has a discrete number of
values from a finite set.

The standard definitions of analog data and digital data
(these are milspec and Federal Standard 1037C
definitions) a

analog data:

Data represented by a physical quantity that is
considered to be continuously variable and has a
magnitude directly proportional to the data or to a
suitable function of the data.

digital data:

1. Data represented by discrete values or
conditions, as opposed to analog data.

2. Discrete representations of quantized values of
variables, e.g. , the representation of numbers by
digits, perhaps with special characters and the
"space" character.

See
http://glossary.its.bldrdoc.gov/fs-1037/

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)
  #42   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Floyd L. Davidson Floyd L. Davidson is offline
external usenet poster
 
Posts: 175
Default Questions about equivalents of audio/video and digital/analog.

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.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)
  #43   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
glen herrmannsfeldt glen herrmannsfeldt is offline
external usenet poster
 
Posts: 61
Default Questions about equivalents of audio/video and digital/analog.

Floyd L. Davidson wrote:

(snip)

In a digital channel you cannot pass frequencies higher
1/2 the Nyquist rate, which in theory is a very sharp
cutoff but in practice it becomes very similar to the
gradual analog cutoff.


If you read Nyquist's paper, that is pretty much it.

He was figuring out for fast he could send pulses
through a band limited channel and separate them out at
the other end. Electronic communication was digital
before it was analog.

-- glen

  #45   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Andor Andor is offline
external usenet poster
 
Posts: 5
Default Questions about equivalents of audio/video and digital/analog.

On 20 Aug., 10:04, (Don Pearce) wrote:
On Mon, 20 Aug 2007 03:51:54 -0400, Jerry Avins wrote:
Don Pearce wrote:
On Sun, 19 Aug 2007 23:26:16 -0700, (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/...s/faculty.html

Regards,
Andor



  #48   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Don Stauffer in Minnesota Don Stauffer in Minnesota is offline
external usenet poster
 
Posts: 3
Default Questions about equivalents of audio/video and digital/analog.

On Aug 19, 4:01 pm, Radium wrote:


Is it true that unlike the-frequency-of-audio, the-frequency-of-video
has two components -- temporal and spatial?

Kind of. This gets into some pretty involved engineering and math and
was originally used to get into how to analyze images when designers
were first trying to develop television systems. It involves what is
known as linear systems analysis, which originally was for one
dimensional signals such as audio. In this type of analysis any
arbitrary shape/waveform can be broken down into a collection of many
sine waves of different frequency. For images this was extended to
work as a two-dimensional array, with duplication of the signal by
considering two sets of so-called "spatial frequencies", at right
angles to each other.

This was extended beyond TV engineering when optical engineers
developed the Modulation Transfer Function by borrowing EE ideas of
linear systems to predict and measure performance of optical systems.
It involves things like Fourier transforms.

AFAIK, the-frequency-of-audio only has a temporal component. Do I
guess right?


Right

II. Digital vs. Analog

Sample-rate is a digital entity. In a digital audio device, the sample-
rate must be at least 2x the highest intended frequency of the digital
audio signal. What is the analog-equivalent of sample-rate? In an
analog audio device, does this equivalent need to be at least 2x the
highest intended frequency of the analog audio signal? If not, then
what is the minimum frequency that the analog-equivalent-of-sample-
rate must be in relation to the analog audio signal?

The analog equivalent is, loosely, the bandpass or cutoff frequency of
an analog filtering circuit. Any electrical network designed to
reproduce faithfully the analog signal must have a bandpass such that
the high frequency cutoff is equal to or higher than the highest
frequency in the analog signal.

III. My Requests:




  #49   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Doug McDonald Doug McDonald is offline
external usenet poster
 
Posts: 37
Default Questions about equivalents of audio/video and digital/analog.

Radium wrote:
On Aug 19, 2:50 pm, (Ray Fischer) wrote:

Radium wrote:


Hi:


I. Audio vs. Video


Digitized (mono) audio has a single sample per each sampling
interval.



Well, yes and no. That's true for what is called PCM, used
on the Compact Disc and MPEG. It is sort of true for Delta-Sigma
coding, but the for the actual useful sampling rate limit, its
not really true. D-S modulation is used for the Super Audio CD.


There is no analog-equivalent of sample-rate? Then what the limits the
highest frequency an analog audio device can encode?


The circuits used. All circuits have a low-pass filtering action
of some sort. For example, 78 RPM records went up to maybe
10-12 kHz usefully, while 33s actually could go up to 40 kHZ if
pushed (e.g. discrete quad.) Many high quality audio power amps will
happily go to 100 kHZ or even a megahertz. This may be intrinsic
with the circuits, or, far more common, a simple resistor-capacitor
filter circuit.


What determines the highest frequency signal an analog solid-state
audio device can input without distortion?


The nature of the transistors is the ultimate limit. Because
at this limit nonlinearities of a rather terrible nature occur, the
circuits they are used in usually limit the frequency with the RC
filter mentioned above, or equivalent.


Analog solid-state audio device = a purely analog electronic device
that can record, store, playback, and process audio signals without
needing any moving parts.

The above device inputs the electrical signals generated by an
attached microphone. These electric signals are AC and represent the
sound in "electronic" form. Sound with a higher-frequency will
generate a faster-alternating current than sound with a lower-
frequency. A louder sound will generate an alternating-current with a
bigger peak-to-peak wattage than a softer soft.

What mathematically determines the highest-frequency electric signal
such a device can intake without distortion?


The overall design. Such things as you describe are rare, very, very,
very rare. It's very hard to STORE signals purely analog without
moving parts. In fact, I had a hard time thinking of any such
device that is or was purely analog. However, the old analog
storage oscilloscopes would meet your criteria if you don't
include electrons in a vacuum as moving parts. There the limit to the
frequency response is the size of the focus spot .... i.e.
the quality of the lenses! (Such device of course uses analog
electron lenses). If you don't intend to store forever, there
were things like analog mercury delay lines which stored signals
as sound waves travelling through mercury.

Doug McDonald
  #50   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Arny Krueger Arny Krueger is offline
external usenet poster
 
Posts: 17,262
Default Questions about equivalents of audio/video and digital/analog.


"Radium" wrote in message
oups.com...
On Aug 19, 8:54 pm, (Dave Platt) wrote:


And, in fact, this concept of moving electrical charges is the basis
for one type of analog signal storage and playback device which has no
moving (mechanical) parts... the CCD, or Charge Coupled Device. It
consists of a large number of charge storage devices (typically MOSFET
transistors with dielectrically-isolated gates) hooked up as a sort of
shift register or "bucket brigade". Each gate stores a charge which
is proportional to the input signal present at a given moment in time.
Several thousand times per second, a clock pulse causes each storage
cell to generate an output voltage proportional to the charge in its
storage gate, and then to "capture" onto its gate the signal being
presented by the previous gate in the chain.


Thus introducing an important concept - sampled, non-digital signals.

Sampling and digitizing are somewhat independent. The necessary connection
comes when you realize that you have to sample something to digitize it.
OTOH, you don't have to digitize it when you sample it.

Is CCD a form of analog non-volatile RAM?


Yes.

Why aren't these devices used more than they are? They're not very
efficient, and they're noisy. Every time the charge is copied from
one cell to the next, a bit of imprecision (noise) creeps in... so the
fidelity isn't great. And, because the device has to be able to hold
a very wide range of charges (since the charge is directly
proportional to the signal level) the storage gates have to be fairly
large.


Interestingly enough, CCDs are widely used for video. Reason being that
their dynamic range is as you say poor for audio, but its OK for video.

I wonder how a PC would perform if it used CCDs in place of digital
storage devices. Lots of errors.


Exactly.

The net result is that an audio CCD is capable of storing a
decent-quality signal for only a few tens or hundreds of milliseconds,
from input to output.


Only if you have a fairly liberal idea of "decent-quality".

What is the highest frequency an audio CCD can input and output? My
guess is 0.5x the clock rate.


Well, a scosh less. Nyquist rules.

Another sort of a purely analog signal-storage device, with no moving
parts other than the electrons which convey the signal, is a simple
length of transmission line (with perhaps some amplifiers mid-way).


Ancient computers used quartz delay lines as storage devices. Case in point
was the IBM 2848 video display controller. There was one delay line per
attached CRTs.

Where is the "storage" in this device?


The delay line.

Put a signal in at one end, get the same signal back out the other end
some number of microseconds or milliseconds later.


Where is the signal being stored?


It was stored in whatever made up the delay line. It could be a rotating
disk of magnetic material, a piece of quartz or glass, a bunch of coils and
capacitors, whatever. All of these were used up until RAM became an
economical solution.




  #51   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Jerry Avins Jerry Avins is offline
external usenet poster
 
Posts: 137
Default Questions about equivalents of audio/video and digital/analog.

Floyd L. Davidson wrote:
Jerry Avins wrote:
Dave Platt wrote:
In article . com,
Radium wrote:

I'm curious to why there are no purely-analog devices which can
record, store, and playback electric audio signals [AC currents at

...

The net result is that an audio CCD is capable of
storing a
decent-quality signal for only a few tens or hundreds of milliseconds,
from input to output.
Another sort of a purely analog signal-storage device,
with no moving
parts other than the electrons which convey the signal, is a simple
length of transmission line (with perhaps some amplifiers mid-way).


...

Come on, Dave, a CCD is a digital device, subject to
aliasing.


CCDs are analog devices, with an analog voltage output.

The fact that they are commonly used as the sensor in
digital cameras results in the output of a CCD virtually
always going directly (well, after a bit of signal
processing for things such as white balance, ISO gain,
etc.) to an analog-to-digital converter that digitizes
the analog signal.

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.


But none of that quantization changes the fact that the
device itself has an analog output.


We agree on the facts. We disagree about how to classify borderline
cases. Is that important enough to warrant further discussion?

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
  #52   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Jerry Avins Jerry Avins is offline
external usenet poster
 
Posts: 137
Default Questions about equivalents of audio/video and digital/analog.

glen herrmannsfeldt wrote:
Dave Platt wrote:

(snip)

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.


It means discrete states, but the base does not have to be two.

Many of the early computers were decimal based, and not
necessarily BCD.

The Fortran standard still allows for any base greater
than one to be used for representing values.


Glenn,

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.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
  #53   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Bob Myers Bob Myers is offline
external usenet poster
 
Posts: 94
Default Questions about equivalents of audio/video and digital/analog.


"Radium" wrote in message
oups.com...
On Aug 19, 8:34 pm, "Bob Myers" wrote:

Sampled analog systems are certainly
not very common today (unless you count certain forms of
modulation as "sampling," and in fact there are some very close
parallels there), but the theory remains the same no matter which
form of encoding is used. In any event, you must sample the
original signal at a rate equal to at least twice its bandwidth
(actually,
very slightly higher, to avoid a particular degenerate case which
could occur at EXACTLY 2X the bandwidth) in order to preserve
the information in the original and avoid "aliasing."


Is the CCD [Charge Coupled Device] a "sampled analog system"?


It's certainly one example of such, being essentially an
analog shift register.

Bob M.


  #54   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Jerry Avins Jerry Avins is offline
external usenet poster
 
Posts: 137
Default Questions about equivalents of audio/video and digital/analog.

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 matters; it's good
enough in context. A signal can be quantized without any need to measure
it or describe it with a number. An example is the signal being measured
in a quantum Hall-effect experiment.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
  #55   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Bob Myers Bob Myers is offline
external usenet poster
 
Posts: 94
Default Questions about equivalents of audio/video and digital/analog.


"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.

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

Bob M.




  #56   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Randy Yates Randy Yates is offline
external usenet poster
 
Posts: 839
Default Questions about equivalents of audio/video and digital/analog.

(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.

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).

Do you have a reference for your definition?
--
% Randy Yates % "I met someone who looks alot like you,
%% Fuquay-Varina, NC % she does the things you do,
%%% 919-577-9882 % but she is an IBM."
%%%% % 'Yours Truly, 2095', *Time*, ELO
http://home.earthlink.net/~yatescr
  #57   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Bob Myers Bob Myers is offline
external usenet poster
 
Posts: 94
Default Questions about equivalents of audio/video and digital/analog.


"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.

Bob M.


  #58   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Bob Myers Bob Myers is offline
external usenet poster
 
Posts: 94
Default Questions about equivalents of audio/video and digital/analog.


"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. 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." It is certainly
possible to conceive of a quantized analog system, although
such things are rarely if ever seen in practice.

"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...;-)

Bob M.


  #59   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Bob Myers Bob Myers is offline
external usenet poster
 
Posts: 94
Default Questions about equivalents of audio/video and digital/analog.


"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.

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.

Bob M.


  #60   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Jerry Avins Jerry Avins is offline
external usenet poster
 
Posts: 137
Default Questions about equivalents of audio/video and digital/analog.

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? 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.)

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯


  #61   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Randy Yates Randy Yates is offline
external usenet poster
 
Posts: 839
Default Questions about equivalents of audio/video and digital/analog.

Randy Yates writes:

(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.


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).
--
% Randy Yates % "The dreamer, the unwoken fool -
%% Fuquay-Varina, NC % in dreams, no pain will kiss the brow..."
%%% 919-577-9882 %
%%%% % 'Eldorado Overture', *Eldorado*, ELO
http://home.earthlink.net/~yatescr
  #62   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Don Pearce Don Pearce is offline
external usenet poster
 
Posts: 2,726
Default Questions about equivalents of audio/video and digital/analog.

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.

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. 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).

d

--
Pearce Consulting
http://www.pearce.uk.com
  #63   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Bob Myers Bob Myers is offline
external usenet poster
 
Posts: 94
Default Questions about equivalents of audio/video and digital/analog.


"Radium" wrote in message
oups.com...


The purpose of this visual "pitch-shifting" is like a way to record/
playback/transmit/receive/store supreme-quality video while using the
least bandwidth and storage space necessary when low-pass filtering is
not an option.


And as you have been told countless times before, you REALLY
need to read up on the basics of compression, and specifically
the differences between "lossy" and "lossless" compression, and
what forces the differences between these two and what enables
the latter. Until you do, you'll never really understand any of
this.


Hence, if you want to get decent imagery in a low-bandwidth imaging
device, your best bet is to decrease the spatial frequency because
transferring it into the imaging device.


Or use fewer bits per sample, or just fewer bits for certain parts
of the information you're trying to capture (for instance, chroma
information vs. luma), or remove redundant information. (Think
about this: how efficient is it, if we have a section of an image which
is just a blank white area, to have each and every pixel there carry
information that equates to "I'm white!" "So am I!" "So am I"....
and so forth? Just one example to consider...). You can also
reduce the temporal frequency in the case of motion video. And
these are just the simpler approaches.

Bob M.


  #64   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Don Pearce Don Pearce is offline
external usenet poster
 
Posts: 2,726
Default Questions about equivalents of audio/video and digital/analog.

On Mon, 20 Aug 2007 11:46:41 -0400, Randy Yates
wrote:

Randy Yates writes:

(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.


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).


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. The signal can be reconverted to an
analogue one later by a D to A. The output of a D to A is still a
time-sampled signal, but since it is now a set of varying levels, we
again call it an analogue signal.

d

--
Pearce Consulting
http://www.pearce.uk.com
  #65   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Randy Yates Randy Yates is offline
external usenet poster
 
Posts: 839
Default Questions about equivalents of audio/video and digital/analog.

(Don Pearce) writes:

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.


It isn't reaonable to you. Don't publish opinion as fact.

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.


You haven't looked very far. Here is an example (a power calculation):

Px = \sum_{n=-\infty}^{+\infty} x^2[n],

where x[n] \in \R.

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.
--
% Randy Yates % "Though you ride on the wheels of tomorrow,
%% Fuquay-Varina, NC % you still wander the fields of your
%%% 919-577-9882 % sorrow."
%%%% % '21st Century Man', *Time*, ELO
http://home.earthlink.net/~yatescr


  #66   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Jerry Avins Jerry Avins is offline
external usenet poster
 
Posts: 137
Default Questions about equivalents of audio/video and digital/analog.

Doug McDonald wrote:


... It's very hard to STORE signals purely analog without
moving parts. In fact, I had a hard time thinking of any such
device that is or was purely analog. However, the old analog
storage oscilloscopes would meet your criteria if you don't
include electrons in a vacuum as moving parts. There the limit to the
frequency response is the size of the focus spot .... i.e.
the quality of the lenses! (Such device of course uses analog
electron lenses). If you don't intend to store forever, there
were things like analog mercury delay lines which stored signals
as sound waves travelling through mercury.


I mentioned mercury delay lines in an earlier post that probably hadn't
seen when you wrote that. There's another way that uses only common
electrical components -- capacitors and inductors. Cascaded low-pass T
(or pi) sections approximate a transmission line very well up to a
frequency determined by the product of 1/LC, while the characteristic
impedance is sqrt(L/C). Such "synthetic lines" were staples in telephone
research labs. The Bell Labs exhibit at the 1939-40 Worlds Fair included
such a line driven by a microphone into which a visitor could speak,
feeding headphones (s)he wore while speaking. Most visitors were reduced
to stammering by the delay, which I'm guessing was about two seconds; my
memory on that point is hazy. I impressed my parents (much like Radium
probably impressed his) by doggedly ignoring the feedback and speaking
clearly and deliberately. The demonstrator, a Bell Labs researcher,
asked us to wait while he fetched his boss to show me off. I do remember
being told that delays up to ten seconds were feasible, but that long
delays allowed the brain to more easily decouple speech and hearing, so
they weren't used in the demo. Bossman showed us the closet where the
delay line was stored. The parts were housed in two large relay racks.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
  #67   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Jerry Avins Jerry Avins is offline
external usenet poster
 
Posts: 137
Default Questions about equivalents of audio/video and digital/analog.

Don Pearce wrote:

... 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.


Transversal and recursive filters and correlators have been built that
operate on unquantized samples. Fourier transforms have been "computed"
with lenses. Do you remember the early days of side-looking radar?

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).


Agreed. Sometimes I'm guilty of sloppiness. It's the flip side of
explanatory excess.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
  #68   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Don Pearce Don Pearce is offline
external usenet poster
 
Posts: 2,726
Default Questions about equivalents of audio/video and digital/analog.

On Mon, 20 Aug 2007 12:03:33 -0400, Randy Yates
wrote:

(Don Pearce) writes:

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.


It isn't reaonable to you. Don't publish opinion as fact.

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.


You haven't looked very far. Here is an example (a power calculation):

Px = \sum_{n=-\infty}^{+\infty} x^2[n],

where x[n] \in \R.


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.

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.

d

--
Pearce Consulting
http://www.pearce.uk.com
  #69   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Don Pearce Don Pearce is offline
external usenet poster
 
Posts: 2,726
Default Questions about equivalents of audio/video and digital/analog.

On Mon, 20 Aug 2007 12:42:38 -0400, Jerry Avins wrote:

Don Pearce wrote:

... 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.


Transversal and recursive filters and correlators have been built that
operate on unquantized samples. Fourier transforms have been "computed"
with lenses. Do you remember the early days of side-looking radar?

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.

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).


Agreed. Sometimes I'm guilty of sloppiness. It's the flip side of
explanatory excess.

Jerry


We're all guilty of sloppiness. What is important is that we are able
to understand and work with the fine differences when they matter.

d

--
Pearce Consulting
http://www.pearce.uk.com
  #70   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Bob Myers Bob Myers is offline
external usenet poster
 
Posts: 94
Default Questions about equivalents of audio/video and digital/analog.


"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.

"Reasonable" would seem (at least to me) to mean that you
can justify your definition *through reason*, which Don has
done. 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
weight in light of an opposing argument based on evidence
and logic. However, if you like, I can also point to several
references which support the definition that Don and I (and
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
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.

Bob M.

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.


You haven't looked very far. Here is an example (a power calculation):


The question was flawed to being with, though - "DSP" stands
for "DIGITAL signal processing," which by definition could
not have been done on information that was simply "sampled
in time." Such information would also have to be digitally encoded
in order to be subject to "DSP.:

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


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

Bob M.




  #71   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Don Pearce Don Pearce is offline
external usenet poster
 
Posts: 2,726
Default Questions about equivalents of audio/video and digital/analog.

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.

d

--
Pearce Consulting
http://www.pearce.uk.com
  #72   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Don Bowey Don Bowey is offline
external usenet poster
 
Posts: 53
Default Questions about equivalents of audio/video and digital/analog.

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



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.

Bob M.



  #73   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Jerry Avins Jerry Avins is offline
external usenet poster
 
Posts: 137
Default Questions about equivalents of audio/video and digital/analog.

Don Pearce wrote:

...

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.


A sample is quantized as soon as it is represented by a finite number of
digits. You can't imagine that floating point has infinite resolution.

...

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
  #74   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Jerry Avins Jerry Avins is offline
external usenet poster
 
Posts: 137
Default Questions about equivalents of audio/video and digital/analog.

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
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
  #75   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Don Pearce Don Pearce is offline
external usenet poster
 
Posts: 2,726
Default Questions about equivalents of audio/video and digital/analog.

On Mon, 20 Aug 2007 14:08:11 -0400, Jerry Avins wrote:

Don Pearce wrote:

...

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.


A sample is quantized as soon as it is represented by a finite number of
digits. You can't imagine that floating point has infinite resolution.


Sure, but you may be quantizing to many trillions of finer steps, so
that effectively the thing is almost not quantized.

d

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


  #76   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Scott Seidman Scott Seidman is offline
external usenet poster
 
Posts: 6
Default Questions about equivalents of audio/video and digital/analog.

glen herrmannsfeldt wrote in
:

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


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"?

--
Scott
Reverse name to reply
  #77   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Richard Crowley Richard Crowley is offline
external usenet poster
 
Posts: 4,172
Default Questions about equivalents of audio/video and digital/analog.

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.


  #78   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
glen herrmannsfeldt glen herrmannsfeldt is offline
external usenet poster
 
Posts: 61
Default Questions about equivalents of audio/video and digital/analog.

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.

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.

-- glen

  #79   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Jerry Avins Jerry Avins is offline
external usenet poster
 
Posts: 137
Default Questions about equivalents of audio/video and digital/analog.

glen herrmannsfeldt wrote:
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.


With ten neon lamps stacked vertically for each digit at first, then
Nixie tubes.

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


That was so entrenched that TI's first IC decimal counter could be
configured as a biquinary device. It had divide-by-two and
divide-by-five sections.

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


It really depends on context. From a circuit viewpoint, I think of
"binary" as implying a single receiver threshold.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
  #80   Report Post  
Posted to sci.electronics.basics,rec.video.desktop,comp.dsp,rec.audio.tech,rec.photo.digital
Martin Heffels Martin Heffels is offline
external usenet poster
 
Posts: 15
Default Questions about equivalents of audio/video and digital/analog.

On Mon, 20 Aug 2007 11:58:32 -0700, "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
--
Official website "Jonah's Quid" http://www.jonahsquids.co.uk
Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Digital vs. Analog; the word from Danish Pro Audio ScottW Audio Opinions 7 December 22nd 06 08:48 PM
Digital vs. Analog; the word from Danish Pro Audio Arny Krueger Audio Opinions 2 December 19th 06 05:55 PM
Novice question: how transfer analog audio to digital? Denman Maroney Pro Audio 2 October 20th 04 01:45 AM
recording from digital and analog audio to computer for editing Alan Pro Audio 2 June 17th 04 02:48 PM
Post Audio: Analog or Digital? Victor Rice Pro Audio 6 April 7th 04 01:57 PM


All times are GMT +1. The time now is 11:14 AM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"