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post #241 of 261 Old 07-18-2008, 07:45 PM
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The Leader LV-5760 is doing it's own D/A conversion of the incoming SDI data. The designers have chosen to represent this pseudo waveform (there is no "real" blanking in SDI) on a .7V scale which corresponds to a particular analog interface (EIA-770.2).

The point that Greg and alluringreality are trying to make is that .7V is entirely arbitrary. It could have been .714V if the designers of the Leader LV-5760 had considered Betacam levels to be more useful than EIA-770.2 levels.

Ron

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post #242 of 261 Old 07-18-2008, 10:24 PM
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Lot's of data in the blanking.



Ron

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post #243 of 261 Old 07-19-2008, 09:39 AM
 
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Quote:
Originally Posted by dr1394 View Post

The Leader LV-5760 is doing it's own D/A conversion of the incoming SDI data.

It could have been .714V if the designers of the Leader LV-5760 had considered Betacam levels to be more useful than EIA-770.2 levels.

LV- 5750 Multi SDI Monitor

BTW Ron I've been referencing the industry standard "unity" model for looking at the data. The only thing analog about my monitor is the calibrated ITU D/A. The component matrix (RGB/YCBCR) and graticule is normalized for ITU-R BT.601 & Rec 709 standards. It displays E’Y, E’CB and E’CR analog component signal levels corresponding to a 100/0/100/0 industry standard color bar signal.
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post #244 of 261 Old 08-11-2008, 10:17 AM
 
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Originally Posted by dr1394 View Post

Thers no "real" blanking in SDI

..Lot's of data in the blanking.

According to my reference the Blanking Level is clearly defined and it's NOT any 8-bit decimal code word between (1-254) like you seem to have implied

http://en.wikipedia.org/wiki/Serial_Digital_Interface
Quote:


For SDI portions of the vertical and horizontal blanking regions which are NOT used for ancillary data, it is recommended that the luma samples be assigned the code word 16 (decimal), and the chroma samples be assigned 128 per 8-bit payload; both of which correspond to 0 mV.

In other words Michael Robin is correct again in that the Blanking level for ITU-R 601 or 709 is defined as the YCbCr code words for 0 mV.

http://broadcastengineering.com/mag/...r_bars_puzzle/
“Color bars signals are identified with four numbers, representing percentages of the maximum value of 700 mV (100 percent), with an oblique stroke between them as follows:”

“These signals may be used in their original form (component analog GBR signals), matrixed into E´Y, E´B-E´Y and E´R-E´Y (scaled or non-scaled), or encoded into an analog (PAL, NTSC or SECAM) or digital (component or composite) signal.”

http://books.google.com/books?id=BkC...um=3&ct=result
(Page 508)

“Table 11.9 shows the calculated signal amplitudes for individual steps corresponding to the three primary colors (green, blue and red) and their complements (yellow, cyan and magenta) of the 100/0/100/0 color bars signal with reference to (Table 11.8) ITU-R BT.601 Coded Signal Standard and the component signal “levels in mV” for ITU-R BT.601 E’Y, E’CB, E’CR components”

Note Table 11.9 on page 508,
(0-700mV) Black-White 100% Color Bar Component Signal Level in “mV” for ITU-R 601 and 709.
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post #245 of 261 Old 08-11-2008, 12:16 PM
 
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Quote:
Originally Posted by alluringreality View Post

To say that what your scope shows is somehow universal and a particular digital value always equals a specific intended mV reading regardless of all other conditions, that's what I am diagreeing with.

alluringreality do you really think Michael Robin just made up the "as specified in the ITU-R recommendation" part?

http://broadcastengineering.com/mag/...r_bars_puzzle/

"Their (color-difference signals) amplitudes are expressed in percentages of the full amplitude primary signals (700 mV). These signal amplitudes are reduced by scaling factors to meet specific signal amplitude range requirements. When the allowed amplitude range of these signals is 700 mV (±350 mV), as specified in the EBU N10 Standard and the ITU-R BT 601 recommendation, the color-difference signals are given by the following expressions:

E´CB = 0.564 (E´B - E´Y), also known as PB in North America
E´CR = 0.713 (E´R - E´Y), also known as PR in North America"
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post #246 of 261 Old 08-11-2008, 01:24 PM
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Quote:
Originally Posted by tbrunet View Post

alluringreality do you really think Michael Robin just made up the "as specified in the ITU-R recommendation" part?

What I think has little to do with Michael Robin's article and mainly centers on how it seems to me that you're willing to extend his statements beyond the intended context. I've already linked Rec 601, so what Rec 601 exactly says can be looked at by anyone interested. I'll say that it does not reference specific voltage levels in regards to certain digital values as you seem to claim, and US NTSC levels would be one example of where digital level 16 is not intended to equal 0mV. I question if you are primarily interested in factual accuracy, and I will merely continue to use discussions I find interesting in order to try to further my understanding. In this case, that motivation has mostly run its course.
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post #247 of 261 Old 08-12-2008, 08:02 AM
 
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Originally Posted by alluringreality View Post

I'll say that it does not reference specific voltage levels in regards to certain digital values as you seem to claim.

And your limited understanding of YCbCr normalization and or calibrating A/D - D/A unity is wrong. Below I've provided an ITU-R Recommendation that supports everything I've quoted Michael Robin saying (myself included) as "fact".

Testing for conformity with ITU-R Recommendations BT.601
http://www.ebu.ch/CMSimages/en/tec_t..._tcm6-4775.pdf

ADC and DAC parameters

3.1.2 Coding ranges
Low-frequency effects can be observed by applying a 700 mV bar-on/bar-off test signal to the ADC and checking that the error is less than one quantum level in both the bar-on and bar-off conditions.

3.1.8. Response of the ADC to out-of-range signals
In the luminance channel, signal levels going more positive than 760 mV must result in the coder output remaining at level FE (decimal 254). Similarly, for input signals going more negative than -48 mV the output must remain at level 01. Levels FF and 00 are reserved for synchronization purposes.

--------
Michael Robin's provocative Figure 2 has perfect alignment or “conformity” with these ITU-R Recommendations. Sorry but Ron, Greg, hwjohn are wrong regarding YCbCr A/D – D/A voltage unity.
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post #248 of 261 Old 08-12-2008, 09:52 AM
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Your reference introduces another standard so I really fail to see how it speaks specifically about Rec 601. In the second paragraph it also says "The Recommendation BT.601 is not sufficient to specify fully the performance of digital video equipment." If Rec 601 really says what you continue to claim, then it seems to me only Rec 601 really needs to be discussed here. I really fail to see how US NTSC levels support your claim that specific voltages are universally related to specific digital values as defined by Rec 601. If you want to continue your argument it seems to me you really ought to address something simple like the last sentence in reference only to what is stated in Rec 601. My prior question, that was lost in the server crash, asking the value of E'Y for white for the analog levels you use in relation to the quantization section from Rec 601 was along these same simple lines of specifically discussing what is actually stated in Rec 601.
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post #249 of 261 Old 08-12-2008, 11:00 AM
 
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Originally Posted by alluringreality View Post

Your reference introduces another standard so I really fail to see how it speaks specifically about Rec 601..

Sure OK.. "Testing for Conformity with ITU-R Recommendations BT.601" is another standard?

I think I've listed a dozen examples now illustrating how a standard .7V p-p color bar signal IS encoded per Rec 601. FWIW (16-235) does NOT represent a 1V (Y') signal, not for ITU-R 601 or 709 period

According to my reference(s) one can't even represent/encode a 1V p-p (Blk-Wht) Y' signal, considering Black is 0V. So please stop suggesting White or code word 235 is 1000 mV.

According to your limited understanding of Rec 601, my Multi Standard SDI (SD-HD) waveform monitor should in reality read Y' code word 235 as 1000 mV and code word 16 should indicate 0V.....please stop the madness!

Thanks in advance
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post #250 of 261 Old 08-12-2008, 11:10 AM
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Quote:
Originally Posted by tbrunet View Post

I think I've listed a dozen examples now illustrating how a standard .7V p-p color bar signal IS encoded per Rec 601.

Absolutely no one has issue with this, within the context you're using.

Quote:


So please stop suggesting White or code word 235 is 1000 mV.

I have never intended to make any such claim. I have simply stated in different ways how Rec 601 does not define an absolute relationship between voltage and digital values independent of context. With the single context you're speaking of in the prior quote the relationship you're stating is fine, but to take that voltage to digital value relationship and say that it's universal to any situation as defined by Rec 601, that is my disagreement with what you've posted. Myself and others have stated this point (how there is not one absolute relationship between voltage and digital values defined by Rec 601) repeatedly and it seems you still fail to get what exactly is stated in Rec 601. As far as I'm concerned any discussion was done long ago, being how it seems you will not reference Rec 601 in regards to what you write and how you apparently will not consider questions dealing with simple general items like US NTSC levels or E'Y in relation to Rec 601 quantization.
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post #251 of 261 Old 08-12-2008, 11:56 AM
 
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Quote:
Originally Posted by alluringreality View Post

..With the single context you're speaking of in the prior quote the relationship you're stating is fine, but to take that voltage to digital value relationship and say that it's universal to any situation as defined by Rec 601, that is my disagreement with what you've posted.

I see that unity calibration is beyond your comprehension:

100/0 .7V p-p Y’ (16-235) coded into a Rec 601 8-bit digital payload

100/0 .7V p-p CbCr (16-240) coded into a Rec 601 8-bit digital payload

This represents the industry standard YCbCr 100% color bar “digital” signal per Rec 601. My Leader 5750 SDI Multi Format Waveform monitor has a built in and “calibrated” ITU-R (RGB/YCbCr) matrix. In this mode of operation I don’t care to see a pseudo NTSC waveform with (714 mV) for white and or 7.5% setup.. or Sony Betacam or Panasonic MII presentation because they represent incompatible scaling factors.

I gave you this explanation and definition "reference" standard color bars:
http://broadcastengineering.com/mag/...r_bars_puzzle/

Nobody.. and I repeat nobody is encoding Sony Betacam standard, Panasonic MII standard or NTSC (714 mV for Wht) like Ron is suggesting below. Rather I’m looking at what is actually (YCbCr) being encoded into the payload.
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Originally Posted by dr1394 View Post

The designers have chosen to represent this pseudo waveform

or
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Originally Posted by dr1394 View Post

The product can be configured for the different analog component standards.

Look at the specifications at the bottom of the page.

Y Signal Level 700 mV or 714 mV (switchable, +/- 1 dB adjustable)
Pb, Pr Signal Level 934 mV (Betacam) or 700 mV (SMPTE) or 648 mV (MII)

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post #252 of 261 Old 08-12-2008, 01:11 PM
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Originally Posted by tbrunet View Post

Nobody.. and I repeat nobody is encoding Sony Betacam standard, Panasonic MII standard or NTSC (714 mV for Wht) like Ron is suggesting below. Rather I'm looking at what is actually (YCbCr) being encoded into the payload.

This forum is titled Display Calibration. Why do you think it's completely clear to make statements that deal with only one single situation (encoding of defined analog signals), which doesn't necessarily always fit with how others might use the forum? I'm fully aware that you continually don't state your context, but why do you think others should implicitly understand a context that goes unstated?


Quote:


unity calibration is beyond your comprehension

Again, when when was it specifically stated that something called "unity calibration" was the entire realm of discussion? My statements are seemingly in line with the title of the forum, which can apply to many various topics including such things as US NTSC analog levels and Rec 601 quantization. This is why I've harped on the word context repeatedly and used terms like universal and absolute in describing my objection to how you've stated your position. How do you figure others are to understand unstated context? If someone was to look at Rec 601, they would clearly see that the document is not written around one single expectation of 0.7V p-p analog levels for 16-235 as you've again stated.
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Her is an email response from John Luff to my question below, which is a word for word quote of a question I emailed to Michael Robin:

My name is Thomas Brunet and I'm a Broadcast Engineer for 25+ years now and I'm currently working with Savannah College of Art & Design:
http://www.scad.edu/
If you will, I would like to ask a question and I understand in advance you probably get many and I may not get a reply from you.

I'm in an on-line debate regarding the concept of a unity ITU-R BT.601 codec model. I guess I'm trying to make a distinction between normalization (0-1) and the "standard" .7V p-p analog YCBCR waveform that I see on my SD-HD SDI waveform monitor graticule. My position is that when I'm encoding Y' excursion for a given frame of video per ITU-R 601, for example an 8-bit Y' excursion (16-235) is defined to be 0V and 700mV respectively and +/-350mV CBCR for codes (16-240)?

I'm being told that ITU-R BT.601 does not define any specific given component amplitude i.e. an 8-bit decimal Y' code value of 235 does not = 700mV? Rather ITU-R 601 only states White is 1V and Black is 0V. So in reality there's no unity .7V p-p analog model. That gain and offset per output is the only time 700mV is relevant?
Quote:


The simple answer is the if I understand your argument correctly you are right.The issue is the NORMALIZED values before coding vs the input components, assumed to be RGB. The standard defines the encoded color space as well as the transform to 4:2:2 coding.

To understand the standard fully you have to think of it in different terms. First, the input to BT.601 is analog component video (RGB), the same as specified in SMPTE 125M, which also defines 4:2:2 sampling, and is somewhat more clear in presentation. The analog input values are specified in the standard as 1.0 V for luminance and each of the chroma difference signals. Part of the standard requires that prior to quantization the signals (1.0 V for luminance and the matrixed values for Cr and Cb “…(E’R – E’Y ) + 0.701 to – 0.701 and for (E’B – E’Y) a range of + 0.886 to – 0.886 ”) are normalized. Effectively it is those values that are normalized to 1 volt for peak excursions and then encoded using the parameters in the chart below (10 bit samples).

Part of the confusion comes from the fact that it is possible to encode signals using ITU-R BT.601 which would exceed the legal color gamut. That is the reason that white is defined less than full excursion, in addition to reducing ringing on sharp transitions.


John Luff
Television Technology Consultant
SMPTE Fellow
SMPTE Conference VP

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post #254 of 261 Old 08-12-2008, 02:09 PM
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Originally Posted by tbrunet View Post

I'm being told that ITU-R BT.601 does not define any specific given component amplitude i.e. an 8-bit decimal Y' code value of 235 does not = 700mV

This is not exactly the statement being presented here. Component video has defined analog levels. Within a defined context where certain analog levels are used, Rec 601 can relate between analog levels and digital values. The thing is that there are also other defined analog levels relevant to Rec 601, such as US NTSC levels. Much of that sort of context is generally legacy, but my players still contain composite and you can bet some people still use it. I've read that some DVD players have also allowed for component to use setup in order to use a similar range as US NTSC, which I guess was maybe for displays that only allowed one brightness setting for all inputs. All these issues are not necessarily relevant for what you're doing, but in general they apply to a forum titled Display Calibration.

Quote:


ITU-R 601 only states White is 1V and Black is 0V.

The standard uses 1 and 0. It generally avoids the voltage term. V does appear once I know of, but it's listed as an example. The standard also states that it can apply to quantization of digital levels, so that's also likely related to why Rec 601 is based around normalized levels of 0-1 for E'Y in going to 16-235.
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post #255 of 261 Old 08-12-2008, 02:48 PM
 
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Quote:
Originally Posted by alluringreality View Post

Again, when when was it specifically stated that something called "unity calibration" was the entire realm of discussion?

http://www.avsforum.com/avs-vb/showt...1009493&page=2

Posted 03-27-08, 07:10 PM
Quote:


Originally Posted by tbrunet
I said at least three times already for a hypothetical ideal A/D to D/A unity.

Originally Posted by tbrunet
If I don’t measure 0mV (aka blanking level) for the quantization level Y’=16 , Cb=128, Cr=128, then either the D/A is not (unity) calibrated or the test pattern is non standard. Greg I also understand the concept of AC or DC coupling.

Originally Posted by tbrunet
Nominal excursion for ITU-R BT.601 has blanking level = 0mV and reference white 0-700mV respectively.


http://www.avsforum.com/avs-vb/showt...1038332&page=5

Posted 07-01-08, 11:05 AM
Quote:


Originally Posted by tbrunet
Here are several examples of Greg Rogers attempting to prove that I can’t measure (analog voltage per a unity calibrated chain) the original (digital) encoded IRE level that’s embedded on a given DVD test disc
.

Alluringreality just give it up already…John Luff has validated my position 100%

Pun intended
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post #256 of 261 Old 08-12-2008, 04:08 PM
 
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Quote:
Originally Posted by alluringreality View Post

The thing is that there are also other defined analog levels relevant to Rec 601, such as US NTSC levels.

Not for the encoded standard YCbCr signal that I've been defining for months now.

http://www.tek.com/Measurement/App_N...25W-7203-3.pdf

Rec. 601 described the sampling of the signal. Electrical interfaces for the data produced by this sampling were standardized separately by SMPTE and the EBU. The parallel interface for 525/59.94 was defined by SMPTE as SMPTE Standard 125M .

Digital-to-analog conversion range is chosen to provide headroom above peak white and footroom below black as shown in:

Figure 2-5 Luminance quantizing
Figure 2-6 Color difference quantizing


alluringreality, in the link above I dare you to report the analog volts and depicted digital code words in Figure 2-5 and 2-6, I’ll convert hex to decimal if needed.

Have a nice day
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post #257 of 261 Old 08-12-2008, 05:11 PM
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Quote:
Originally Posted by tbrunet View Post


Alluringreality just give it up alreadyJohn Luff has validated my position 100%

Pun intended

I don't know why you need him to validate your position... after all, it's only a matter of time before he disagrees with you and you turn against him like you did Greg. Funny how you have a new "authority" every week.

May I make a suggestion. Instead of typing this:

Quote:


Sorry but Ron, Greg, hwjohn are wrong

why don't you just forego your ever growing list and use this instead:

Quote:


Sorry, but I'm the only one who is right, even if you agree with me.


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post #258 of 261 Old 08-13-2008, 01:39 PM
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Quote:
Originally Posted by tbrunet View Post

John Luff has validated my position 100%

I must have missed where you discussed how "the standard requires that prior to quantization the signals are normalized."


Quote:
Originally Posted by tbrunet View Post

I dare you to report the analog volts and depicted digital code words in Figure 2-5 and 2-6

The supposed challenge is unnecessary, because the context clearly gives that component voltages are being discussed. I didn't notice any poorly-written comments about Rec 601 that I have issue with in the PDF.
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post #259 of 261 Old 08-14-2008, 06:29 AM
 
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Originally Posted by alluringreality View Post

I must have missed where you discussed how "the standard requires that prior to quantization the signals are normalized."

I see.. you did not comprehend that the sampled analog electrical signal or YCbCr components represent a prior normalized 100/0/100/0 signal condition so that Y values take on the values between 0 and 1? Maybe you should have read the links I gave you from the many on-line Broadcast Engineering Mag articles I've provided for you? NO?
Quote:
http://broadcastengineering.com/mag/...r_bars_puzzle/
The fifth row of Figure 1 shows the formation of the 100/0/100/0 E´Y signal from the primary E´G, E´B, E´R signals. The amplitudes of the eight steps are expressed in percentages of the full-amplitude signal (700 mV).

These signal amplitudes are reduced by scaling factors to meet specific signal amplitude range requirements. When the allowed amplitude range of these signals is 700 mV (±350 mV), as specified in the EBU N10 Standard and the ITU-R BT 601 recommendation, the color-difference signals are given by the following expressions:

E´CB = 0.564 (E´B - E´Y), also known as PB in North America

E´CR = 0.713 (E´R - E´Y), also known as PR in North America

Search back in this thread and see how many times I defined a analog 100/0/100/0 color signal to you and please note or count how many times I defined exactly that p-p analog signal voltage.
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Originally Posted by alluringreality View Post

You're not actually measuring mV with your scope from a digital input.

This of course is wrong!
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Originally Posted by gregr View Post

Digital levels are not in volts. That's pretty damn elementary. A waveform monitor that accepts digital signals (i.e. SDI) can have a graticule that shows equivalent analog volts in any standard that relates digital levels to analog volts

This to is wrong! A industry standard SDI WF monitor "calibrated" per ITU-R standards..the (RGB/YCbCr matrix) .7V graticule is not a pseudo representation
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Originally Posted by dr1394 View Post

The designers have chosen to represent this pseudo waveform

..Thers no "real" blanking in SDI

and that would be wrong and wrong as well.
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post #260 of 261 Old 08-14-2008, 09:52 AM
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In http://www.avsforum.com/avs-vb/showt...0#post14422760 I didn't look at the link because I considered your comments not relevant to the point of what you quoted like usual. When you linked that a second time I forgot how all your comments have to be filtered through an unstated implied context of only speaking about encoding component video, and so the prior paragraph seemed at best a bit convoluted because something like US NTSC could be said to be an "industry standard" from my perspective. Anyway, certainly that second article does define E'y of white relative to 100% or 1 and answers the question I asked prior.

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Originally Posted by tbrunet View Post

This of course is wrong!

I figure I get what you've generally attempted to say, but I'm still not so sure you get the point of others have stated. My point of what you quoted was that if you actually sampled a digital signal in terms of mV you would basically get alternation between two levels. Sure your scope can represent the digital information in other terms and use a variable mV scale, but you're not actually sampling mV. That's my whole point, so I have completely no idea how that could be said to be wrong because it's just digital basics. Anyway I figure you'll have some issue with these statements, and my ignore list has grown to two.
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post #261 of 261 Old 08-14-2008, 10:06 AM
 
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Originally Posted by alluringreality View Post

Anyway I figure you'll have some issue with these statements, and my ignore list has grown to two.

Better make that at least three

1) tbrunet
2) Michael Robin
3) John Luff
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