[Bob Myers]

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

You have misunderstood what that means though. The
analog value of a signal is continuous,

Well, THAT certainly makes it clearer....

And of course you had no idea until now that that is
what we've always been talking about, right?

This is just priceless. Floyd, you really need to have
your Sarcasm Detector looked at because, son, it
ain't a-workin' at all...

Bob M.

[Bob Myers]

"Scott Seidman" wrote in message
. 1.4...
"Bob Myers" wrote in news:faf4co$co5$1
@usenet01.boi.hp.com:


Really? Then I shouldn't be able to find any standards
organizations which use a conflicting definition, right?


The nicest thing about standards is that there are so many from which to
choose.

Amen! Finally someone who gives some evidence of
actually having "been there, done that" as opposed to
just looking the answer up in the Holy Technical
Scriptures...

Bob M.

[Arny Krueger]

"Floyd L. Davidson" wrote in message
...
"Arny Krueger" wrote:
"Floyd L. Davidson" wrote:
"Arny Krueger" wrote:
"Floyd L. Davidson" wrote:

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

Actually, they all do.

However, if the upper limit is more than 2 or 3 times
higher than the frequency spectrum of the signal, in
effect they don't.

Nope, the phase shift is appreciable down to Fc/10. Ever hear of Bode
plots?

"Appreciable" is not specific...

Thanks for admitting that you have no idea about Bode plots.

The point is that in
practical applications there are few effects at Fc/2
which are unreasonable.

Depends what Fc is. If you are sampling audio at 5 KHz, there are any
number of audible effects at Fc/2 that are pretty unreasonable. One is the
total absence of any signal for much of the audio band.



For example... A typical voice channel provided by the
telecommunications industry is often stated as a 4Khz
wide channel. In fact of course it is not. The lower
limit is determined by high pass filters designed to
reduce 60Hz power line interference. Cutoff filters are
usually at about 80 Hz for that. The high end is
limited in digital systems by the need to avoid aliasing
of frequencies above 4000Hz, so the LP filters generally
have a cutoff between 3750 and 3850. Essentially that
provides a 80-3750Hz channel, maximu.

The industry only guarantees that they will provide
400-2800 Hz of bandwith over the Public Switched
Telephone Network. Much of the reason for that is
that phase shifts and envelop delay at frequencies
from 3000 to 3750 are sometimes (but not always) high
enough to be a problem (which would require special
conditioning to correct for).

You are saying the effects are "appreciable" down to
375 Hz, which means the _entire_ 400-2800Hz bandwidth
is suffers "appreciable" effects.

Voice channels like the one you have described. sound very much like they
are suffering from appreciable effects. They are not hi fi. Their fidelity
is so low that we start worrying about intelligibiilty.

It can be measured, but it does *not* cause appreciable
effects.

No? It imparts a very characteristic sound quality to normal voice! It is
often called "Telephone-like".

The point is we are *not* talking about wideband
amplifiers and narrow band signals, we are talking about
practical applications where the two are very closely
matched.

Most digital audio is brick walled at 0.95 * Fs/2 or about 21 KHz. Most
power amps are pretty flat up to about 50 KHz.

So, as I've stated... your example shows that the
filters are placed at 0.95 times the maximum possible
frequency that can traverse the channel. And those
filters are on the *input* to the channel.

The fact that the power amp, the last part active of the
system, actually has a greater bandwidth (even then,
only 2x), is insignificant.

So what?

What about the bandwidth of
the output stages of the D to A converter...

Usually the output buffers of a D/A have very wide bandwidth. 100s of KHz or
more.

That is
where it makes the most difference in regard to
conversion of digital to quasi-analog to analog without
appreciable artifacts.

Wrong.

But secondarily, the speakers
are also an important part of the overall channel... and
ultimately the point at which a digital signal is
absolutely converted to analog (perhaps artifacts and all).

Wrong again. The input to typical speakers is analog, pure and simple.

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

Usually, its pretty simple.

Sure it is... That's why there are complete books
published on what happens?

For people who don't already know?

You said it was simple. Apparently you should read up
on the topic.

You're talking trash.

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

Limited by the sampling rate.

Well, by the brick wall filter which is usually set as stated above.

The brick wall filtering is on the channel *input*, to
prevent aliasing. It does not limit what could show up
on the output, as if it were not there the frequencies
that it removes would be folded at the output anyway.
The absolute upper limit (at which point it generates
100 percent distortion) is Fs/2, for input bandwidth.

than that of a good amplifier. That's why they call the filtering in
DACs
"brick wall filters".

That is to prevent aliasing though,

DACs can't alias. Only ADCs can alias. Improperly filtered DACs may
produce
images.

Okay... if you want to limit this to separating the ADC
from the DAC, the DAC doesn't have the brick wall
filter, the ADC does.

You quote me without proper attribution, presumably to avoid admitting your
rather gross errors?

How do you get an image out of a DAC, if it wasn't
produced at the ADC?

The image is produced by the convolution of the signal with the clock. If
you read the samples out of digital storage or calculate them with a
computer they never have to come anyplace near an ADC. However, they will
still produce images.

Improperly filtered channel output might have artifacts
from the sampling though, but no HP output filtering is
necessary to remove any signal resulting from the input
signal.

Semi-gibberish.

and is actually a
higher frequency cutoff than what is required to affect
the resulting output. And they are used on the *input*,
not on the output.

The input side of a digital system is called an ADC, not a DAC as you just
said.

They are both part of a "digital channel", and *that* is
what I am talking about.

You don't seem to be able to distinguish the start from the finish.


Nothing else makes sense in this context.

Very little of what you say makes sense, unless you quote or paraphrase
someone who knows what they are talking about.

[Arny Krueger]

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

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


If you quantize the magnitude, it is digital. That is
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.

Really? Suppose I show you an oscilloscope screen which
is displaying a single line of video, which happens to be
carrying an 8-level gray-scale pattern. It clearly shows
a set of discrete levels.

Well it shows what was once a set of discrete levels. Since it is now in
the
analog domain, there will be rise time, overshoot, tilt, simple
inaccuracy,
and etc. .

That has no relevance to whether it represents a discrete set
of values.

Further, since this video happened
to be created by a D/A converter with only three bits at
the input (our video generator was built on the cheap!), those
are the ONLY levels this signal may exhibit. Is this a
"digital" signal?

It's an analog signal that represents something that was once quantized.

It could also be a digital signal. You simply cannot
tell from looking at a scope.

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.

The definitions are fine, it is the misapplication of them that sticks.

Oh, are we back to the idea that the NTIA had never heard of
PCM when they came up with those definitions?

This response is irrelevant to what I said.

I get it. You can't read.

[Arny Krueger]

"Floyd L. Davidson" wrote in message
...
"Arny Krueger" wrote:
"Floyd L. Davidson" wrote:

Regardless, the idea that you think looking at a signal
with a scope will tell you if it is digital or analog
suggests that you weren't paying attention when you
studied basic signal theory, if you ever did.

I aced "Signals And Systems Analysis" and placed high in "Linear
Stochastic
Optimal Control" - probably the heaviest signals trips I ever took.

Then you *should* know that you cannot look at signals
on a scope and tell if they are analog or digital.

Sure I can. If I look at a line between two V-90 modems, I can immediately
see that it is an analog line. It may be carrying audio or video, but thats
about the data that is being carried, not the signal that I'm looking at.

How do you explain the conflict between what you claim
your education is and the practical level your previous
post demonstrated?

Simple - you misunderstood what I said because you can't distinguish between
a signal and that data that it may represent.

[Floyd L. Davidson]

"Bob Myers" wrote:
"Floyd L. Davidson" wrote in message
...
It wasn't analog until you ran it through an analog amplifier.

More nonsense.

Again, the ONLY definitions of "analog" and "digital"
which make any sense treat these as distinctions in
the form of information encoding being used. If I
run EITHER a "digital" or "analog" signal through an
amplifier, what comes out can still be interpreted (the
information recovered from the signal) ONLY if the
encoding intent is understood and the proper decoding
applied.

I'll be damned, you *finally* got *something* right!

Did you go back and actually read what I said, or did
you learn this somewhere else? Regardless, the above
supports *exactly* what I've been saying, and I do hope
that you have begun to make the connection.

After being passed through an analog amplifier, the data
has a totally different set of values than it did within
the digital system (the output of the digital system has
both sets, but once it enters an analog channel the digital
values are generally, though not always, lost), and it can
be applied to an analog transducer (such as a speaker)
with the desired effects.

A serial stream of digital data still makes sense, whether
the amplitude assigned to the "1" or "true" state is
0.1V, 1V, 10V, or 100 kV. But it makes sense
ONLY when interpreted AS a serial stream of bits.

Exactly. It is the *information* carried that
determines what is digital and what is analog. Others
have claimed that looking at it with a scope is a way to
determine which, but that is not true. A digital signal
has discrete values (whether that is represent by 0.1v
or 100Kv) from a finite set. An analog signal has a
continuous range of values. It is the values of the
*data* that make a difference, not voltage levels, phase
shifts, or whatever.

The fact that voltage can and does get varied over a
continuous range of voltages means *nothing*; but if
that continuous range of voltages represents a finite
set of data values it is a digitial signal and if it
represents a continuous set of data values it is an
analog signal.

Similarly, an analog representation of, say, video makes
sense only if interpreted AS "analog". No matter how
"digital-ish" it might look, if you try to interpret THIS
signal as a "digital" stream, you'll get gibberish.

Well, if you aren't just paroting back to me everything
I've been telling you, and now claiming it isn't what
you denied at every turn of the way!

Floyd, you would be well advised to stop treating your
"definitions" as though they were somehow handed
down by God, and instead try to employ arguments
that are actually based in something sensible.

You just agreed, and stated, that they are correct. I
use them correctly, and have from the beginning of this
discussion without fail.

You keep wandering all over the map because you simply
do not understand how it applies to more than a minimal
set of circumstances, apparently.

The NTIA is an authority, and MilStd specifications are
also authoritative. That is the reason I cited them.
And the *fact* is that you have not and cannot cite any
authoritative standards body that does not agree with
them.

Neither of these - and for that matter, NO standards body

In fact, those two are, for these definitions, valid
authorities. You have not and cannot come up with
anyone who is credible that does not agree with them.

- is an Infallible Source of Absolute Truth, and no standard
should be looked at as a substitute for good ol' basic
theory and experimentation.

And when you do your own homespun theorizing and come up
with *wrong* answers, it is ridiculous for you to claim
the standard definitions used by virtually everyone else
are wrong instead of you.

This is the fundamental flaw
with any argument "from authority": wrong is wrong, no matter
who writes it down on a piece of paper.

And Bob Myers is *wrong*. You can claim otherwise all
you like, but when you disagree with every authority
there is on the definitions of basic fundamental terms,
it is abject *foolishness*.

God knows I've
spent way more than enough time in my career working
with various standards organizations (in fact, I am currently
chairing one fairly well-known such group), including both
"industry" and "government" efforts, and I can tell you from
long and painful experience that simply because something
appears in a standards document does not make it correct.
With the right people paying close attention, these documents
can often turn out pretty darn good - but they should NEVER
EVER be used as a substitute for some actual thought and
understanding of the subject matter at hand.

That's a great deal of hand waving there Bob. You are
in fact making an invalid appeal to authority! You are
not an expert, and other experts do not agree with you.
Your logic is invalid.

Then you go on too make another basic logical mistake.
The fact that some Standards have been in error would
not suggest that all Standards are in error. You cannot
cite (nebulous and unspecified) errors in other
standards as a proof that those definitions are an
error.

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

[Floyd L. Davidson]

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

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.

Well, no, he's cited nothing but evidence and reason.

He, like you, has cited *nothing*.

Again, I can cite equally acceptable and peer-reviewed
sources which use EXACTLY the "definitions" and
interpretation of these terms that Don and I and others
are using here. Do you really think this sort of think should
be decided by "battling authorities"?

If you could, you would have. You can't.

Tell you what - you present an argument that ISN'T
based on an appeal to an authority, one which shows how
your notions make rational sense, and I will in turn show
you said "authorities" on the other side.

I am not an authority, and make no claims to being one.
It would be abjectly ridiculous for me to attempt to
present my own rationalizations for why standard
definitions are what they are. The *only* rational that
is important is that of authorities on the subject. No
me, not you.

You are asking me to act just as foolishly as you have,
and I refuse.

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

[Bob Myers]

"Floyd L. Davidson" wrote in message
...
Did you go back and actually read what I said, or did
you learn this somewhere else? Regardless, the above
supports *exactly* what I've been saying, and I do hope
that you have begun to make the connection.

I've said it all along, Floyd; if you want to see where I said
it even earlier, I could refer you to my book...

A serial stream of digital data still makes sense, whether
the amplitude assigned to the "1" or "true" state is
0.1V, 1V, 10V, or 100 kV. But it makes sense
ONLY when interpreted AS a serial stream of bits.

Exactly. It is the *information* carried that
determines what is digital and what is analog.

Gee, that's funny. Earlier you were claiming that
simply "quantizing" a signal was sufficient to make
something "digital." You were also talking about
"digital" and "analog" channels - so I would have to
assume, from this, that you are of the belief that
channels can somehow "know" the nature of the
information they are carrying, and thus become
"digital" or "analog" themselves.


The fact that voltage can and does get varied over a
continuous range of voltages means *nothing*; but if
that continuous range of voltages represents a finite
set of data values it is a digitial signal and if it
represents a continuous set of data values it is an
analog signal.

Oh, too bad! You were SO close to having it right, and
then your preconceived notions again got in the way.

It has NOTHING TO DO with whether the range is
continuous or not, it has EVERYTHING to do with
how the signal is to be interpreted. My monitor has an
"analog" input, which is so named because it "knows"
that if it's presented with a video signal level twice that
of this other level over here, it should produce twice
the luminance ("gamma" effects ignored for simplicity).
This has nothing to to with how many intermediate levels
there may be between these two, or even if there are
ANY intermediate levels between the two - solely with
the fact that the levels themselves are direct "analogs"
(gee, there's that word again) to the desired luminance
level.


Well, if you aren't just paroting back to me everything
I've been telling you, and now claiming it isn't what
you denied at every turn of the way!

I would love to see you show me where I denied ANY
of the above.


That's a great deal of hand waving there Bob. You are
in fact making an invalid appeal to authority! You are
not an expert, and other experts do not agree with you.

And your sole rationale for saying that I am not an
"expert" is: I disagree with you! Wow, that's an amazingly
logical position, isn't it?


Then you go on too make another basic logical mistake.
The fact that some Standards have been in error would
not suggest that all Standards are in error.

You need a course in basic logic. I did not argue that "the fact
that some standards are in error suggests that all standards
are in error." What I argued was the fact that some standards
are in error suggests that other standards may also be in error,
and cannot be assumed to be correct simply because they are
"standards."

Bob M.

[Bob Myers]

"Arny Krueger" wrote in message
. ..
Sure I can. If I look at a line between two V-90 modems, I can immediately
see that it is an analog line.

OK, Arny - what are the distinguishing characteristics of
an "analog line"? Once we have determined that we have
an "analog line," does this mean that said line cannot possibly
be used to carry "digital" information? If not, then what is
the significance of designating said line to be "analog" in the
first place?

Bob M.

[Bob Myers]

"Floyd L. Davidson" wrote in message
...
I am not an authority, and make no claims to being one.

Then on what grounds do you judge the correctness
of the definitions you yourself reference? Are you
simply accepting them as Holy Writ because they DO
come from some body that you view as "authoritative,"
and you are incapable of making any judgement, yourself,
of their technical merit?

It would be abjectly ridiculous for me to attempt to
present my own rationalizations for why standard
definitions are what they are. The *only* rational that
is important is that of authorities on the subject. No
me, not you.

So what do you use to judge "authority" in the first
place? Because someone, at some point, told you that
"such-and-such is an authority, you can trust it/him/her/
them"? What do you do if someone ELSE points to a
different "authority" who has a conflicting position, if you
yourself are not competent to judge? You say that I
must not be an "authority" because I take a position
contrary to that of some other "authority" that you knew
about earlier - but then you also say that you yourself
have no criteria whatsoever for making such an
evaluation, OTHER than the previous "authority"?

This feels more and more like arguing with a Creationist...

Bob M.

[Floyd L. Davidson]

Don Bowey wrote:
"Floyd L. Davidson" wrote:
Don Bowey wrote:
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.

I didn't leave my telco job until the end of 94. At which times they were
still in use, but there was talk of using gain within the switching

So you don't know of any telco that uses them today.

I assume you were also using mechanical switching there
too... ;-)

It is sort of difficult for me to imagine that sort of
environment, as Alaska was fully digital when the rest
of the country had only gone 33% digital. By the mid-1980
the only mechanical switches left in Alaska were owned by
the military, and they were gone by 1990.

Still, I don't think anyone *ever* used E type repeaters
in Alaska, but I could be wrong on that.

machines. It wouldn't surprise me if that is being done now, being a simple
process. In any case, there are loops that require gain to meet minimum
requirements. Also, we had a tariff that provided additional gain (for a
price) where feasible.

The general design paradigm used now is to put
"remotes" at multiple strategic sites and control
them all from one digital switch. Of course all of
these are trunked together, and the whole idea is to
prevent long loops while also requiring administration
of only a single digital switch.

That was a basic design decision made for telco's by the
vendors, back in the late 80's or early 90's. It was
enforced with system pricing! Nortel (NTI at the time),
for example, simply made the software for a digital
switch (actually, the long term use and maintenance of
the software) far more expensive than installing
remotes. It became uneconomical to have two switches in
any jurisdiction where it was possible to deactivate one
and replace it and move forward with remotes.

By the mid-1990's all of NTI's customer base had moved
in that direction.

My concerns were not just for where "I lived." I was on the Transmission
Engineering staff, and we had 14 states with which to be concerned.

My concern was only the State of Alaska... which is
of course the size of 20% of the entire Lower-48.

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

[Arny Krueger]

"Bob Myers" wrote in message
...

"Arny Krueger" wrote in message
. ..

Sure I can. If I look at a line between two V-90 modems, I can
immediately see that it is an analog line.

OK, Arny - what are the distinguishing characteristics of
an "analog line"?

The presence of a signal that is an electrical analog of the data being
transmitted.

IOW, it might be that if I send data that represents two or three times as
much value, it measures as having about two or three times the amplitude.

There are some interesting analog lines with complex interpretations, such
as those that are used to transmit rotational information - the 5 wires
between two selsyn motors for example.

Once we have determined that we have
an "analog line," does this mean that said line cannot possibly
be used to carry "digital" information?

Not at all. At the most fundamental level, all transmission lines transmit
analog signals, whether the data is digitally coded or not.

If not, then what is the significance of designating said line to be
"analog" in the
first place?

The absence of digital coding, for one thing. Back in the old days, all
lines were analog. I think that maybe the telegraph put an end to that.
Morse code is a sort of PWM, right? ;-)

[glen herrmannsfeldt]

Don Pearce wrote:

(snip)

I don't dispute Shannon and he didn't write the above. Show me how
sampling at a rate equal to twice the highest frequency works. It is
there quite explicitly. Could you not even spot that? The entire
clause "must be equal to" is incorrect.

It doesn't matter, the probability of it being equal is zero.
(not counting delta functions).

-- glen

[Jerry Avins]

Floyd L. Davidson wrote:

...

You don't appear to understand that the limited set of values makes
it digital, by definition. PERIOD.

I don't recall your being explicit about the origin or basis for that
definition.

US cash transactions are quantized to the nearest penny. Does that make
money digital?

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

[Floyd L. Davidson]

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

Why? What does that mean, EXACTLY, that

I've given you the URL for a glossary of terms, why
don't you use it? Here are some others:

http://www.atis.org/tg2k/
http://www.itu.int/sancho/index.asp
http://www.carrieraccessbilling.com/...glossary-a.asp
http://www.faxswitch.com/Definitions/

isn't already conveyed (and conveyed more accurately)
by other, more appropriate terms? What additional
information does this "quasi-analog" nonsense bring
to the party?

Quasi-Analog Signal -

A digital signal that has been converted to a form
suitable for transmission over a specified analog
channel.

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

[Don Pearce]

On Tue, 21 Aug 2007 12:06:22 -0800, glen herrmannsfeldt
wrote:

Don Pearce wrote:

(snip)

I don't dispute Shannon and he didn't write the above. Show me how
sampling at a rate equal to twice the highest frequency works. It is
there quite explicitly. Could you not even spot that? The entire
clause "must be equal to" is incorrect.

It doesn't matter, the probability of it being equal is zero.
(not counting delta functions).

-- glen

Don't be a **** Glen, we are talking about definitions and whether
they are correct or not.

d

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

[Bob Myers]

"Arny Krueger" wrote in message
. ..
OK, Arny - what are the distinguishing characteristics of
an "analog line"?

The presence of a signal that is an electrical analog of the data being
transmitted.

OK, my apologies; I was under the impression that you
considered the line ITSELF to be "analog."

Once we have determined that we have
an "analog line," does this mean that said line cannot possibly
be used to carry "digital" information?

Not at all. At the most fundamental level, all transmission lines transmit
analog signals, whether the data is digitally coded or not.

Well, I would agree that they carry *electrical* signals; they
are not necessarily either "analog" or "digital" unless
someone (whoever THAT might be) insists on using "analog"
to mean "continuous," when there's already a perfectly good
word at hand (for instance, uh...."continuous!") that can be
used for that.

Bob M.

[Bob Myers]

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

Why? What does that mean, EXACTLY, that

I've given you the URL for a glossary of terms, why
don't you use it? Here are some others:

You keep thinking people are asking for definitions,
when in fact they are asking what terms mean
TO YOU. In other words, do you have any real
*understanding* of the meanings or implications of
what you're saying, or are you merely here to parrot
the words of others without actually bothering to
understand them?

Bob M.

[glen herrmannsfeldt]

Arny Krueger wrote:

(snip)

Sure I can. If I look at a line between two V-90 modems, I can immediately
see that it is an analog line. It may be carrying audio or video, but thats
about the data that is being carried, not the signal that I'm looking at.

I don't believe V.90 works that way. That is, you can't connect two
V.90 modems together that way.

The answer end of a V.90 connection must be an ISDN line, usually a
primary rate line with 24 channels. The result is that there is only
one A/D and D/A conversion between the two end points.

You may say that an ISDN line is an analog line since you can measure
the voltage on the wire as a function of time. I won't try to argue
either way on that one.

-- glen

[Floyd L. Davidson]

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

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.

You just digitized it. You can no longer have a value of 0.15 volts.

You can't have a value of 0.15 volts, but it's still an
"analog" signal and may be interpreted as such. Consider
the example of a gray-scale-bar pattern in an ANALOG
video system, mentioned earlier. The levels of the video
signal are ANALOGOUS to the desired luminance level,
and that's all it takes to be "analog."

That is not true. See the definition of analog data and
digital data.

No. By definition it is not. With an analogue signal you have
(technically) an infinite number of values between an input of
0.1 and 0.2. With digital you do not.

Well, by Definitions According To Floyd it's not, but
by any rational thought process Don is precisely right.
And there can never be an "inifinite" number of values
available in any signal, digital OR analog, per the
Gospel According To St. Shannon.

Wrong.

Shannon discussed the theory of digital channels with
and without noise. He defined it as "a discrete channel
will mean a system whereby a sequence of choices from a
finite set ... can be transmitted ..."

He then discussed the theory of analog channels, which
began with, "We now consider the case where the
signals or the messages or both are continuously
variable, in contrast with the discrete nature assumed
heretofore."

Clearly his definitions were consistent with those that
have been cited. Of course that again is just another
horrible appeal to authority... ;-)

As it infinite number of values, one of his initial examples
is an ensemble that represents white noise... which is
a summation all values from negative infinity to positive
infinity. Heh heh, not just an infinite number of values,
but 2 times infinity...

Digital doesn't mean numbers, it means discrete values.

Seems like they would've called it "quantized," then,

It doesn have to be quanitized. But if something is
quantized it certainly then is a set of discete values.

rather than using a term which contained the root word
"digit" within it. Oh, wait - people DO use "quantized"
whenever THAT word is applicable. Guess you must
be confusing the two, huh?

You just did confuse them. I just set the record straight,
again. How many times will it take for you to understand
what quantize means? Do you need the definition posted
again?

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

[Bob Myers]

"glen herrmannsfeldt" wrote in message
. ..
The telegraph and digital communication came first.

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

And before that, the hollow log with sticks, or smoke
signals....;-)

(Which for some reason reminds me of the old Far Side
cartoon with the two South-Sea-Island-type natives
watching bubbles coming out of the nearby volcano, with
one saying to the other, "Well, whatever the gods are, they're
not angry!" :-))

Bob M.

[Floyd L. Davidson]

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


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.

Really? Then I shouldn't be able to find any standards
organizations which use a conflicting definition, right?

You cannot have have not.

But ANY argument from authority always takes a back
seat to an argument from evidence and reason, since
those arguments directly undermine item (1) above.

What evidence and what reason? You have no evidence,
and your reasoning is not authoritative.

I deleted all of your wallowing and weaseling.

The standard definitions stand.

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

[Floyd L. Davidson]

Scott Seidman wrote:
"Bob Myers" wrote in news:faf4co$co5$1
:


Really? Then I shouldn't be able to find any standards
organizations which use a conflicting definition, right?

The nicest thing about standards is that there are so many from which to
choose.

That's why he has postes sooooo many!

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

[Floyd L. Davidson]

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

Funny, I don't see the word "digital" in there. Perhaps

You did see "discrete, unique value" right. Bingo.

you could point it out? No one is arguing that
"quantized" does not mean the above - but you seem
to be arguing that "quantized" is precisely equivalent
to "digital," while none of the definitions you provide
say that.

For people who cannot reason...

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

[Floyd L. Davidson]

Don Bowey wrote:
On 8/20/07 11:30 PM, in article , "Floyd L.
Davidson" wrote:

Don Bowey wrote:
On 8/20/07 10:19 PM, in article , "Floyd L.
Davidson" wrote:

Don Bowey wrote:
On 8/20/07 8:14 PM, in article , "Floyd L.
Davidson" wrote:

Of course if you then run that digital PAM signal through virtually
any analog channel, it no longer has a limited set of values...

Including a two foot piece of cable, or two inches with a small cap.

Nope. It would take a fair sized cap.

Keep in mind that that is *exactly* what a V.90 modem puts on a
regular twisted pair telephone cable, and it works just fine for
a couple miles at least, sometimes even much farther.

And that signal is digital, and is processed as a digital signal
by the receiving modem.

Digital data CSUs and T1 transmitter line signals are digital and look
similar to distorted square waves. An all 1's signal looks like a
distorted
sinewave .

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?

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

(snip)

The pulse for which you provided the link, is not DSX-1, because it will not
fit within the DSX-1 envelope.

Really? Has the standard changed?

Or are you just missing something....

I posted the DSX-1 template, and a representative pulse within it (MS Word),
on a.b.s.e. The pulse shown was from equipment that generated the pulse
using an analog method. As you can see from the envelope, other pulses,
specifically, those generated digitally, could be much more "square" if
given enough processing time.

Numeric points for plotting the template to a spreadsheet are available if
anyone wants them, but I will be away until next Saturday.

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

[Floyd L. Davidson]

"Bob Myers" wrote:
"Floyd L. Davidson" wrote in message
...
(Again, that is
the nature of arbitrary definitions, this time of what
"encode" and "modulate" mean.)

Definitions are arbitrary only to those who don't
truly understand them.

You don't understand the word arbitrary either. In
post I read a bit ago you misunderstood the term "virtual"
too.

You have a lot trouble with words, don't you.


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

[Bob Myers]

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

video system, mentioned earlier. The levels of the video
signal are ANALOGOUS to the desired luminance level,
and that's all it takes to be "analog."

That is not true. See the definition of analog data and
digital data.

The definitions according to yourself and your
selected "authorities"? Yet again? How about some
reasoning, instead, for a change?


Wrong.


See Shannon, "A Mathematical Theory of Communication,"
section V (27). Have someone help you with the big words,
as needed. When you're finished, find us an example of
a noiseless channel, and demonstrate to us what you're
saying.

Shannon discussed the theory of digital channels with
and without noise.

Shannon never used the word "digital," though, and used
the term "bits" simply because that is the commonly-used
unit of information (in ANY system), per information and
communications theory as it was established at the time
(and is still in use today). Given that you've admitted to
not being an authority in the field, I wouldn't expect that
you understood that before, so I'm more than happy to
give you this chance to learn. You're welcome.

He defined it as "a discrete channel
will mean a system whereby a sequence of choices from a
finite set ... can be transmitted ..."

Right - he defined a DISCRETE channel. The only
tie between "discrete" and "digital" appears to exist solely
in your own mind, since your cherished definitions of
"quantized" also unfortunately neglect to use the word
"digital" at any time. Shannon did NOT refer to either
"digital" or "analog" channels at all.


He then discussed the theory of analog channels, which
began with, "We now consider the case where the
signals or the messages or both are continuously
variable, in contrast with the discrete nature assumed
heretofore."

Wrong again. He discussed the theory of CONTINUOUS
channels, which is how they are consistently referenced in
his paper. In fact, the term "analog/analogue" does not appear
even once in Shannon's paper. "Analogous" appears a grand
total of six times, each time with the clearly-accepted meaning
of "similar to," as opposed to refering to any specific class of
signals. Similarly, "digital" does not appear at all. Shannon
correctly did not make any distinction between "analog" and
"digital" encoding in terms of information capacity or content,
as his theorems apply to any and all systems.


Clearly his definitions were consistent with those that
have been cited. Of course that again is just another
horrible appeal to authority... ;-)

Or it would have been, had Shannon actually provided
any such definitions. Too bad he didn't.

Bob M.

[Bob Myers]

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


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.

Really? Then I shouldn't be able to find any standards
organizations which use a conflicting definition, right?

You cannot have have not.

I'll wait to respond until that can be re-stated in something
resembling standard English.

Bob M.

[Bob Myers]

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

Funny, I don't see the word "digital" in there. Perhaps

You did see "discrete, unique value" right. Bingo.

So "digital" = "discrete," as long as we accept your
claim, not backed by ANY definition or reasoning,
that it does?


you could point it out? No one is arguing that
"quantized" does not mean the above - but you seem
to be arguing that "quantized" is precisely equivalent
to "digital," while none of the definitions you provide
say that.

For people who cannot reason...

Oh, NOW it's not about the definitions, it's about
"reason," eh? Fine - reason away. It will be, at the
very least, a refreshing change.

Did you learn this flip-flopping technique ("It's all
about the definitions!" "No, it's not actually IN the
definitions, it's all about reason!") from any
politicians you'd care to name?

Bob M.

[Arny Krueger]

"Bob Myers" wrote in message
...

"Arny Krueger" wrote in message
. ..

OK, Arny - what are the distinguishing characteristics of
an "analog line"?

The presence of a signal that is an electrical analog of the data being
transmitted.

OK, my apologies; I was under the impression that you
considered the line ITSELF to be "analog."

Once we have determined that we have
an "analog line," does this mean that said line cannot possibly
be used to carry "digital" information?

Not at all. At the most fundamental level, all transmission lines
transmit analog signals, whether the data is digitally coded or not.

Well, I would agree that they carry *electrical* signals; they
are not necessarily either "analog" or "digital" unless
someone (whoever THAT might be) insists on using "analog"
to mean "continuous," when there's already a perfectly good
word at hand (for instance, uh...."continuous!") that can be
used for that.

The reason I say that they are analog at the most fundamental level is the
fact that every line receiver I've ever seen makes some kind of
analog-domain judgement about the state of the line. Like, 0 is less than
0.5 volts and 1 is greater than 2.7 volts.

[Floyd L. Davidson]

glen herrmannsfeldt wrote:
Arny Krueger wrote:

(snip)

Sure I can. If I look at a line between two V-90
modems, I can immediately see that it is an analog
line. It may be carrying audio or video, but thats
about the data that is being carried, not the signal
that I'm looking at.

I don't believe V.90 works that way. That is, you can't
connect two V.90 modems together that way.

You cannot connect two subscriber modems end to end and
use v.90 protocols.

But you can use to provider end modems and get v.90
protocols running in both direction, and in fact if the
line is good enough it can be made to run a 64 Kbps.

The answer end of a V.90 connection must be an ISDN line, usually a

It must be digital. ISDN is one possibility, but not the only
one.

primary rate line with 24 channels. The result is that there is only
one A/D and D/A conversion between the two end points.

Exactly. The "A" part of that is a digital PAM signal.
If it goes through and extra CODEC, the data is
scrambled.

You may say that an ISDN line is an analog line since you can measure
the voltage on the wire as a function of time. I won't try to argue
either way on that one.

That would be an absurd claim.

ISDN is Integrated Services Digital Network. It is a
digital signal in all respects, using what is called
2B1Q encoding on a customer Basic Rate Interface loop.
That is 2 Binary 1 Quaternary meaning there are two
binary bits encoded in each symbol using 4 possible
voltage levels.

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

[Floyd L. Davidson]

"Bob Myers" wrote:
"Floyd L. Davidson" wrote in message
...
Except that "absence of noise" is a condition which
doesn't exist, even in theory.

Apparenlty Claude Shannon didn't agree with you on that.

And apparently you don't understand what was meant in
the above.

It is theoretically impossible for any real-world communications
channel to be noise-free or possessed of infinite bandwidth.
Do you disagree with this statement? If so, please show the
error.

This does not prevent a noise-free channel from being IMAGINED,
and used as the basis for a mathematical analysis, which is
what Shannon did. But Shannon most definitely did NOT
expect any such thing to be realized, and fully understood
why it could not be.

Have you even read Shannon's paper? In section V (27),
Shannon makes virtually the same statement I gave earlier
re the notion of "infinite" levels:

"This means that to transmit the output of a continuous
source with *exact recovery* [emphasis Shannon's]
at the receiving point requires, in general, a channel of
infinite capacity (in bits per second). Since ordinarily
channels have a certain amount of noise, and therefore
a finite capacity, exact transmission is impossible."

Gee, here's another puzzler for you - throughout his
paper, Shannon discusses channel capacity in terms of
"bits per second." Does this mean that his work is
applicable only to digital systems? If not, why not?

So you have show that the in practice part is true, and
I have show that the in theory part was wrong. A noiseless
channel can exist in theory (not in practice). It is
a very usefule theory to study too.

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

[Don Bowey]

On 8/21/07 11:48 AM, in article
, "Arny Krueger"
wrote:


"Don Bowey" wrote in message
...
On 8/21/07 8:36 AM, in article , "Floyd L.
Davidson" wrote:

Jerry Avins wrote:
Arny Krueger wrote:

...

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

Scope? SCOPE? isn't that an analog device? True digital
work is don with pencil, paper, and calculator. Theory
rules!

And you, like Arny, probably have no idea what you'd
see on a decent scope anyway.

I'd like Arny to explain how he can look at a scope and
tell if a single cycle of a sine wave is an analog signal
representing one cylce of a pure tone, or is just a digital
signal that represents 8000 different bytes of data from
a digital image.

At this point I need to say "who cares how it was generated?" It sure
won't
need to be passed through any analog channel to make it analog. It is
analog by the time it gets off the board that generating it.

At some level every signal is analog. The digital nature of a signal comes
from how it is coded and decoded.


Well! To borrow a query method from you; ????????????????????

[glen herrmannsfeldt]

Arny Krueger wrote:

(snip)

The absence of digital coding, for one thing. Back in the old days, all
lines were analog. I think that maybe the telegraph put an end to that.
Morse code is a sort of PWM, right? ;-)

The telegraph and digital communication came first.

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

Later, voice was sent over telegraph lines, the conversion to
analog signaling.

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

Note again that Nyquist was figuring out how fast he could send
telegraph pulses through an analog (band limited) line.
(Underwater cables are especially limited by capacitance, when
compared to air insulated open wire transmission.)

-- glen

[timepixdc]

In article ,
"Bob Myers" wrote:

It is theoretically impossible for any real-world communications
channel to be noise-free or possessed of infinite bandwidth.
Do you disagree with this statement?

It would appear that you disagree with your own statement since further
down you write,

This does not prevent a noise-free channel from being IMAGINED

Theory? Imagination? Can't have the first without the second.

X-no archive

[Bob Myers]

"timepixdc" wrote in message
...
In article ,
"Bob Myers" wrote:

It is theoretically impossible for any real-world communications
channel to be noise-free or possessed of infinite bandwidth.
Do you disagree with this statement?

It would appear that you disagree with your own statement since further
down you write,

What part of "real-world" (as opposed to "imaginary")
in the above did you fail to comprehend?

Bob M.

[Don Bowey]

On 8/21/07 12:40 PM, in article , "Floyd L.
Davidson" wrote:

Don Bowey wrote:
"Floyd L. Davidson" wrote:
Don Bowey wrote:
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.

I didn't leave my telco job until the end of 94. At which times they were
still in use, but there was talk of using gain within the switching

So you don't know of any telco that uses them today.

I assume you were also using mechanical switching there
too... ;-)

It is sort of difficult for me to imagine that sort of
environment, as Alaska was fully digital when the rest
of the country had only gone 33% digital. By the mid-1980
the only mechanical switches left in Alaska were owned by
the military, and they were gone by 1990.

Still, I don't think anyone *ever* used E type repeaters
in Alaska, but I could be wrong on that.

machines. It wouldn't surprise me if that is being done now, being a simple
process. In any case, there are loops that require gain to meet minimum
requirements. Also, we had a tariff that provided additional gain (for a
price) where feasible.

The general design paradigm used now is to put
"remotes" at multiple strategic sites and control
them all from one digital switch. Of course all of
these are trunked together, and the whole idea is to
prevent long loops while also requiring administration
of only a single digital switch.

That was a basic design decision made for telco's by the
vendors, back in the late 80's or early 90's. It was
enforced with system pricing! Nortel (NTI at the time),
for example, simply made the software for a digital
switch (actually, the long term use and maintenance of
the software) far more expensive than installing
remotes. It became uneconomical to have two switches in
any jurisdiction where it was possible to deactivate one
and replace it and move forward with remotes.

By the mid-1990's all of NTI's customer base had moved
in that direction.

My concerns were not just for where "I lived." I was on the Transmission
Engineering staff, and we had 14 states with which to be concerned.

My concern was only the State of Alaska... which is
of course the size of 20% of the entire Lower-48.

Gosh, after all that I guess I should be impressed.......... But........ I'm
not. I wonder why.

[Don Bowey]

On 8/21/07 1:09 PM, in article , "Floyd L.
Davidson" wrote:

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

Why? What does that mean, EXACTLY, that

I've given you the URL for a glossary of terms, why
don't you use it? Here are some others:

http://www.atis.org/tg2k/
http://www.itu.int/sancho/index.asp
http://www.carrieraccessbilling.com/...glossary-a.asp
http://www.faxswitch.com/Definitions/

isn't already conveyed (and conveyed more accurately)
by other, more appropriate terms? What additional
information does this "quasi-analog" nonsense bring
to the party?

Quasi-Analog Signal -

A digital signal that has been converted to a form
suitable for transmission over a specified analog
channel.

Gobbledegook.

[glen herrmannsfeldt]

Bob Myers wrote:

(snip on analog vs. digital)

Well, I would agree that they carry *electrical* signals; they
are not necessarily either "analog" or "digital" unless
someone (whoever THAT might be) insists on using "analog"
to mean "continuous," when there's already a perfectly good
word at hand (for instance, uh...."continuous!") that can be
used for that.

This reminds me of the discussions I used to see along the
lines of (technology X) is digital and not analog,
the signal is not modulated, such that
(device used to connect to X) is not a modem.

In most cases, the signal is modulated, and so the device
can reasonably be called a modem. The two that this has
come up most often are for ISDN and DSL.

Note that even baseband ethernet uses a modulation system:
synchronous phase modulation (also known as Manchester
coding). This modulation is necessary to be able to
extract a clock to recover the signal.

I might agree that NRZ, and maybe NRZI, are unmodulated
such that the connecting device isn't a modem and the signal
on the line is 'digital'. Because of the need for a separate
clock, NRZ is rarely used for longer distances.

-- glen

[Don Bowey]

On 8/21/07 1:47 PM, in article ,
"glen herrmannsfeldt" wrote:

Arny Krueger wrote:

(snip)

Sure I can. If I look at a line between two V-90 modems, I can immediately
see that it is an analog line. It may be carrying audio or video, but thats
about the data that is being carried, not the signal that I'm looking at.

I don't believe V.90 works that way. That is, you can't connect two
V.90 modems together that way.

The answer end of a V.90 connection must be an ISDN line, usually a
primary rate line with 24 channels.

That is nonsense. ISDN has nothing to do with it. Any modern digital
message trunk provides an identical channelizing process.

The result is that there is only
one A/D and D/A conversion between the two end points.

Same as the Message Network.


You may say that an ISDN line is an analog line since you can measure
the voltage on the wire as a function of time.

What are you calling an ISDN line? The ds1 rate cable pairs? DS3
transport, Sonet, the analog channel that pops out of the terminal
multiplexer?

I won't try to argue
either way on that one.

-- glen