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

[Floyd L. Davidson]

Live and learn, or live and don't learn. Your choice. I'm indifferent.

I noticed that you have no intention of learning anything.

My point was that I see *nothing* on that web page which
supports anything you've stated. If you do, be my guest
and make an even greater fool of yourself than you have
at this point.

 

[Floyd L. Davidson]

The signal is amplified in analog repeaters and again in
the modem.

There simply are no such things as "analog repeaters"
on local telephone loops.

Where do you get these funny ideas.

Your categories are too hard edged.

There isn't any other way.

The very
purpose of a modem is converting digital signal to
analog that can traverse an analog phone line and back
again to digital at the far end. A modem might be the
worst example of a purely digital I can imagine.

A "modem" can't be "purely digital", because it
necessarily has a digital side and an analog side. But
a v.90 modem is a bit different, because it is indeed a
modem for the *uplink*, which uses v.34 protocols. It
is *not* a modem for the downlink, but instead is a
digital encoder.

 

[Don Pearce]

It is by definition. You can stand there and deny it all
you like, but that just makes *you* look damned silly.

I've cited impeccable and authoritative sources. You have not
and cannnot cite anything that supports your opinion.

You have cited a source that is describing something else. It is a
source that you claim is authoritative and impeccable. Kindly go and
read what it has to say on the Nyquist rate and come back and repeat
that claim without blushing. Actually I'm betting you won't blush
because you won't understand the problem.

Keep denying all you like Don. You can't cite anyone credible
that supports your whacko definitions.

I am the credible source, because I know what I am talking about.

But clearly you are right in your appeal to authority. Tell you what I
will do. I will examine some analogue audio waveforms today to see if
I can find any parts of them that are in fact digital. They will be
easy to recognise because there will be brief moments where they are
flat. That will make them digital by your definition.

And perhaps I will look at the digital signal recovered by my DAB
radio. That is band limited and contains no flat bits and steps at all
- in fact it looks a bit like a bendy almost-sine wave. That'll be
analogue by your definition.

d

 

[Don Bowey]

Your point is? (Besides the poor description? They
don't look like distorted square waves. The look like
only slightly distorted sine waves!)

Have you looked at a DSX-1 envelope lately?

It won't. They can't talk to each other that way except
using v.34 protocols.

Regardless, what is your point? I said that v.90 works
fine for a couple of *miles*, minimum, so what
significance would there be to working "back-to-back by
a short pair of wires"?

My point is...... You are making too much of your point that "Of course if
you then run that digital PAM signal through virtually any analog channel,
it no longer has a limited set of values."

 

[Don Pearce]

Your D/A converter puts out what is called
"quasi-analog". It's actually a digital PAM signal, not
an analog signal.

You can easily make it is a close approximation of the
original (with quantization distortion added), however,

But once you do that (by sending it through almost any
kind of an analog channel) it truly becomes "analog", in
the sense that you can no longer recover information or
use it as a digital signal.

This just goes on getting funnier by the post.

d

 

[Ray Fischer]

Hi:
I. Audio vs. Video
Digitized (mono) audio has a single sample per each sampling
interval.
In the case of digital video, we could treat each individual sample
point location in the sampling grid (each pixel position in a frame)
the same way as if it was a sample from an individual (mono) audio
signal that continues on the same position in the next frame. For
example, a 640×480 pixel video stream shot at 30 fps would be treated
mathematically as if it consisted of 307200 parallel, individual mono
audio streams [channels] at a 30 Hz sample rate. Where does bit-
resolution enter the equation?
Digital linear PCM audio has the following components:
1. Sample rate [44.1 KHz for CD audio]
2. Channels [2 in stereo, 1 in monaural]
3. Bit-resolution [16-bit for CD audio]
Sample rate in audio = frame rate in video
Channel in audio = pixel in video
Bit-resolution in audio = ? in video
Is it true that unlike the-frequency-of-audio, the-frequency-of-video
has two components -- temporal and spatial?

No. Video is converted to a linear data stream corresponding
(roughly) to scan lines. The color and brightness information
is split apart and converted into parallel data streams.

Okay. So a digital video device with greater bit-resolution can allow
for more levels of luminance?
Yes.

What is the video-equivalent of bit-resolution?

Analog or digital?

Does compression also eliminate some of the brightness components?

Not usually.

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

Usually the capacitance and inductance of the circuits.

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

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

No such thing.

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?

For that you need a degree in electrical engineering.

 

[Don Pearce]

It wasn't analog until you ran it through an analog amplifier.

Really? Suppose that having put it through the amplifier (somehow
converting it to an analogue signal, it now appears), I now put it
through an attenuator, dropping it back to its original size. It is
now identical to what went into the amplifier. Has the attenuator
converted it back to a digital signal, or is it still analogue? Think
about this carefully please. It really is at the heart of what we are
talking about.

Floyd, you have just claimed (in public!, this really is pricelessly
funny) that an amplifier is a D to A converter. I would like to know
if an attenuator is an A to D converter.

d

 

[Don Bowey]

There simply are no such things as "analog repeaters"
on local telephone loops.

Since when?

If a loop is long enough, and there is no pair-gain facility available, it
gets an "E" type repeater. If that isn't an analog repeater nothing is.

Where do you get these funny ideas.

(snip)

 

[Jerry Avins]

Really? Suppose that having put it through the amplifier (somehow
converting it to an analogue signal, it now appears), I now put it
through an attenuator, dropping it back to its original size. It is
now identical to what went into the amplifier. Has the attenuator
converted it back to a digital signal, or is it still analogue? Think
about this carefully please. It really is at the heart of what we are
talking about.

Floyd, you have just claimed (in public!, this really is pricelessly
funny) that an amplifier is a D to A converter. I would like to know
if an attenuator is an A to D converter.

Reverse the order of operations and the attenuator becomes the D-to-A
and the amplifier will be an A-to-D (if the gain is right). Don't worry
about loss of SNR by attenuating first. That shouldn't matter as long as
the signal ends up digital again.

Jerry

 

[Floyd L. Davidson]

You have cited a source that is describing something else. It is a

Bullshit Don, that is abjectly stupid to claim.

source that you claim is authoritative and impeccable. Kindly go and
read what it has to say on the Nyquist rate and come back and repeat
that claim without blushing. Actually I'm betting you won't blush
because you won't understand the problem.

Nyquist rate:
The reciprocal of the Nyquist interval, i.e., the
minimum theoretical sampling rate that fully
describes a given signal, i.e., enables its
faithful reconstruction from the samples. Note:
The actual sampling rate required to reconstruct
the original signal will be somewhat higher than
the Nyquist rate, because of quantization errors
introduced by the sampling process.

Apparently *you* don't understand it. What they say is
correct. If you think otherwise, be my guest...

I am the credible source, because I know what I am talking about.

You are not even close to being a credible source Don.
And not that you cannot find *anyone* who is credible that
agrees with you.

But clearly you are right in your appeal to authority. Tell you what I
will do. I will examine some analogue audio waveforms today to see if
I can find any parts of them that are in fact digital. They will be
easy to recognise because there will be brief moments where they are
flat. That will make them digital by your definition.

How do you figure that?

And perhaps I will look at the digital signal recovered by my DAB
radio. That is band limited and contains no flat bits and steps at all
- in fact it looks a bit like a bendy almost-sine wave. That'll be
analogue by your definition.

Don, you have made it abundantly clear that you don't
understand this topic at all.

 

[Don Pearce]

Reverse the order of operations and the attenuator becomes the D-to-A
and the amplifier will be an A-to-D (if the gain is right). Don't worry
about loss of SNR by attenuating first. That shouldn't matter as long as
the signal ends up digital again.

Jerry

Bloody hell, I hadn't thought of that. Electronics is suddenly taking
on a whole new set of meanings for me.

I wonder what a tone control is. I mean it must be a D to A converter
for some bits of a signal, and an A to D for other bits. And of course
if you should ever drive an amplifier into overload, you have instant
digital data. The world is all of a sudden quite wonderful - but if I
click my heels together will I find myself back in Kansas?

d

 

[Floyd L. Davidson]

Have you looked at a DSX-1 envelope lately?

Yes. I've got the specs right here! Literally, I have
had a graph on my web site for several years now that I drew up
to illustrate something I wrote once upon a time

http://www.apaflo.com/floyd_davidson/t1pulse.jpg

My point is...... You are making too much of your point that "Of course if
you then run that digital PAM signal through virtually any analog channel,
it no longer has a limited set of values."

Yeah, your are probably right on that one. I should
have left the "virtually any" out, and just said "an
analog channel". It depends greatly on the
characteristics of the channel, and it happens that a
wireline is a pretty "good" channel, while many
amplifiers would not be so good.

Sorry if I'm getting a bit cranky here, the abject
silliness being displayed by a couple of people is
annoying.

 

[Don Pearce]

Nyquist rate:
The reciprocal of the Nyquist interval, i.e., the
minimum theoretical sampling rate that fully
describes a given signal, i.e., enables its
faithful reconstruction from the samples. Note:
The actual sampling rate required to reconstruct
the original signal will be somewhat higher than
the Nyquist rate, because of quantization errors
introduced by the sampling process.

Apparently *you* don't understand it. What they say is
correct. If you think otherwise, be my guest...

Actually I was talking about this:

Nyquist's theorem: A theorem, developed by H. Nyquist, which states
that an analog signal waveform may be uniquely reconstructed, without
error, from samples taken at equal time intervals. The sampling rate
must be equal to, or greater than, twice the highest frequency
component in the analog signal. Synonym sampling theorem.

Go ahead and defend.

d

 

[Floyd L. Davidson]

Really? Suppose that having put it through the amplifier (somehow
converting it to an analogue signal, it now appears), I now put it
through an attenuator, dropping it back to its original size. It is
now identical to what went into the amplifier. Has the attenuator
converted it back to a digital signal, or is it still analogue? Think
about this carefully please. It really is at the heart of what we are
talking about.

Well, analog amplifiers generally have upper limits for frequencies
that they will pass. There's all sorts of phase distortion which
occurs when the frequency response drops off. That may not affect
your ability to understand speech that is amplified through such
a device, but it does have a really significant effect on other
devices. For example, it makes an analog signal out of a digital
PAM signal.

I know you don't understand that, but everything else seems hard
for you too.

Floyd, you have just claimed (in public!, this really is pricelessly
funny) that an amplifier is a D to A converter. I would like to know
if an attenuator is an A to D converter.

If you think about the above for awhile, you're in for a big
surprise.

 

[Don Pearce]

Well, analog amplifiers generally have upper limits for frequencies
that they will pass. There's all sorts of phase distortion which
occurs when the frequency response drops off. That may not affect
your ability to understand speech that is amplified through such
a device, but it does have a really significant effect on other
devices. For example, it makes an analog signal out of a digital
PAM signal.

Bullshit. Unless of course you are claiming that all digital signals
have perfectly flat tops and vertical edges. Is that your claim,
Floyd? You are no longer waving, but drowning. Just admit you have
this all wrong and bow out with as much grace as you can manage.

I know you don't understand that, but everything else seems hard
for you too.


If you think about the above for awhile, you're in for a big
surprise.

All of a sudden he has no answer. Come on Floyd - it is your claim
that an amplifier is a D to A converter. Now put up or shut up. Defend
it or admit you have screwed up.

d

 

[Steve Underwood]

Dave Platt wrote:

(snip)


I have a VCR that will play back at 1.5X without pitch shifting.
At higher playback speeds at only gives you part of the sound.
Maybe two second pieces with gaps depending on the speed.

The 1.5X playback is just a little too fast to watch a show
comfortably.

A lot of relatively simple variable speed constant pitch playback
techniques - e.g. various TDHS derivatives, like PICOLA or PSOLA - work
well up to x1.5 or so. They start to sound nasty beyond about x2. That
isn't too important, as speech that fast isn't awfully useful.

I find for the majority of TV, x1.5 is far too slow to be comfortable.

Steve

 

[glen herrmannsfeldt]

Dave Platt wrote:

(snip)

Some of the TV networks are speeding up syndicated reruns by using
this sort of technique. They appear to be using the "chop out audio
samples" method to speed up the dialog (without pitch-shifting it) and
dropping out complete frames of the video. This works fairly well
when watching scenes with little action, but causes an odd
stuttering-jerk effect when the camera pans or somebody walks across
the screen.

I have a VCR that will play back at 1.5X without pitch shifting.
At higher playback speeds at only gives you part of the sound.
Maybe two second pieces with gaps depending on the speed.

The 1.5X playback is just a little too fast to watch a show
comfortably.

-- glen

 

[Arny Krueger]

Whatever good DAs put out, it is good enough analog to fool my scope!

This just goes on getting funnier by the post.

Yet another *eggspurt* who has never looked at the output of a good DAC with
a scope.

 

[Arny Krueger]

[email protected] (Don Pearce) wrote:

Well, analog amplifiers generally have upper limits for frequencies
that they will pass.

Actually, they all do.

There's all sorts of phase distortion which
occurs when the frequency response drops off.

Usually, its pretty simple.

That may not affect
your ability to understand speech that is amplified through such
a device, but it does have a really significant effect on other
devices. For example, it makes an analog signal out of a digital
PAM signal.

Nope, the output of good DAC is generally even more severely band-limited
than that of a good amplifier. That's why they call the filtering in DACs
"brick wall filters".

 

[Floyd L. Davidson]

Since when?

Oh, perhaps 1950, maybe a few as late as 1960 or so...

Do you know of any telco that actually uses them today?

If a loop is long enough, and there is no pair-gain facility available, it
gets an "E" type repeater. If that isn't an analog repeater nothing is.

Of course I suppose it is possible they are still being
used where *you* live. But I don't know of any telco in
all of Alaska that has used an E repeater in the last 30-40
years. In particular, in the last 10-20 years that would
be totally unacceptable.