On Aug 20, 3:26 pm, "Richard Crowley" <rcrow...@xp7rt.net> wrote:> "Martin Heffels" wrote ... > > > "Richard Crowley" wrote: > >>Radium's ability to suck so many people into attempting to > >>answer insane questions is reaching legendary heights. > >>I hereby nominate him for the Troll Hall of Fame with special > >>endorsement for use of technical gobeldygook. > > > I vote: aye > > I don't mean to imply that there may not be idiot-savants > on the interweb. Al Einstein himself may easily have been > perceived as a troll if he were online :-)There is NO mistaking Albert Einstein for Radium. Even if you disagreed with Einstein, his math was impeccable and self-consistent and provided a plausible explanation for observed phenomenon that was at variance with Netwonian physics. Radium, on the other hand, is simply a blithering idiot.
Questions about equivalents of audio/video and digital/analog.
Started by ●August 19, 2007
Reply by ●August 20, 20072007-08-20
Reply by ●August 20, 20072007-08-20
nospam@nospam.com (Don Pearce) wrote:>On Mon, 20 Aug 2007 05:46:19 -0800, floyd@apaflo.com (Floyd L. >Davidson) wrote: > >>nospam@nospam.com (Don Pearce) wrote: >>>On Mon, 20 Aug 2007 04:57:03 -0800, floyd@apaflo.com (Floyd L. >>>Davidson) wrote: >>> >>>>Jerry Avins <jya@ieee.org> wrote: >>>>>I like your categories. It is possible in concept to >>>>>have a signal that is quantized in magnitude and >>>>>continuous in time, but (unless we resort to counting >>>>>electrons) I don't think it's possible in practice. >>>> >>>>If you quantize the magnitude, it is digital. That is >>>>by definition. >>> >>>No it isn't. It isn't digital until you assign numerical values to >>>those quantized levels. Until then it is simply a quantized analogue >>>signal. >> >>If you quantize it, you *have* assigned a value to it, >>and that value is not from a continuous set, but from a >>discrete finite set, and therefore it is digital. >> >>A "quantized analogue signal" is digital by definition. >> > >No, you haven't. You merely have a signal at a set of discrete levels.Sheesh! That *is*, by definition a digital signal.>You need an analogue to digital converter to take each of those >quantized levels and convert it into a digital word (of 1s and 0s). > >Digital means "represented by digits", not "in discrete voltage >steps".Bullshit 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. -- Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
Reply by ●August 20, 20072007-08-20
nospam@nospam.com (Don Pearce) wrote:>Sorry, but that is simply nonsense. A signal that is sampled in time, >but not quantized is an analogue signal. It is treated and processed >by analogue circuits. For a signal to be digital its sampled levels >must be represented by numbers, which are processed mathematically by >some sort of microprocessor.That is, it must actually be quantized. Perhaps that is what you meant to say earlier, but you actually didn't, and said that the quantized signal has to be represented by numbers, which it is by definition.>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...>The output of a D to A is still a >time-sampled signal, but since it is now a set of varying levels, we >again call it an analogue signal.-- Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
Reply by ●August 20, 20072007-08-20
nospam@nospam.com (Don Pearce) wrote:>Sorry, but that is simply nonsense. A signal that is sampled in time, >but not quantized is an analogue signal. It is treated and processed >by analogue circuits. For a signal to be digital its sampled levels >must be represented by numbers, which are processed mathematically by >some sort of microprocessor.That is, it must actually be quantized. Perhaps that is what you meant to say earlier, but you actually didn't, and said that the quantized signal has to be represented by numbers, which it is by definition.>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...>The output of a D to A is still a >time-sampled signal, but since it is now a set of varying levels, we >again call it an analogue signal.-- Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
Reply by ●August 20, 20072007-08-20
floyd@apaflo.com (Floyd L. Davidson) wrote in news:87zm0mjrfy.fld@apaflo.com:>>quantized - a sampled signal, but with the possible levels constrained >>to a limited set of values > > That is by definition a digital siganl. As soon as the possible values > are "constrained to a limited set", it is by definition digital data. > >Wouldn't this make the output of a D/A converter digital by definition? -- Scott Reverse name to reply
Reply by ●August 20, 20072007-08-20
floyd@apaflo.com (Floyd L. Davidson) wrote in news:87mywlki1d.fld@apaflo.com:> Sheesh! That *is*, by definition a digital signal. >Funny, that's just what my D/A converters put out, and the spec sheets claim they're putting out analog signals. Perhaps I should return them. -- Scott Reverse name to reply
Reply by ●August 20, 20072007-08-20
On Mon, 20 Aug 2007 13:33:34 -0800, floyd@apaflo.com (Floyd L. Davidson) wrote:>nospam@nospam.com (Don Pearce) wrote: >>On Mon, 20 Aug 2007 05:46:19 -0800, floyd@apaflo.com (Floyd L. >>Davidson) wrote: >> >>>nospam@nospam.com (Don Pearce) wrote: >>>>On Mon, 20 Aug 2007 04:57:03 -0800, floyd@apaflo.com (Floyd L. >>>>Davidson) wrote: >>>> >>>>>Jerry Avins <jya@ieee.org> wrote: >>>>>>I like your categories. It is possible in concept to >>>>>>have a signal that is quantized in magnitude and >>>>>>continuous in time, but (unless we resort to counting >>>>>>electrons) I don't think it's possible in practice. >>>>> >>>>>If you quantize the magnitude, it is digital. That is >>>>>by definition. >>>> >>>>No it isn't. It isn't digital until you assign numerical values to >>>>those quantized levels. Until then it is simply a quantized analogue >>>>signal. >>> >>>If you quantize it, you *have* assigned a value to it, >>>and that value is not from a continuous set, but from a >>>discrete finite set, and therefore it is digital. >>> >>>A "quantized analogue signal" is digital by definition. >>> >> >>No, you haven't. You merely have a signal at a set of discrete levels. > >Sheesh! That *is*, by definition a digital signal. >If you put that signal through an analogue amplifier, it will be amplified. That makes it an analogue signal. If you want to amplify a signal in the digital domain, you must perform maths on the numbers. Can you really not see the difference?>>You need an analogue to digital converter to take each of those >>quantized levels and convert it into a digital word (of 1s and 0s). >> >>Digital means "represented by digits", not "in discrete voltage >>steps". > >Bullshit 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.Sorry, but you are wrong. And any reference you have found that makes such a claim is not authoritative; it is also wrong. d -- Pearce Consulting http://www.pearce.uk.com
Reply by ●August 20, 20072007-08-20
nospam@nospam.com (Don Pearce) wrote:>On Mon, 20 Aug 2007 11:31:16 -0400, Randy Yates <yates@ieee.org> >wrote: > >>nospam@nospam.com (Don Pearce) writes: >>> [...] >>> On Mon, 20 Aug 2007 05:46:19 -0800, floyd@apaflo.com (Floyd L. >>> Davidson) wrote: >>> >>>>A "quantized analogue signal" is digital by definition. >>>> >>> >>> No, you haven't. You merely have a signal at a set of discrete levels. >>> You need an analogue to digital converter to take each of those >>> quantized levels and convert it into a digital word (of 1s and 0s). >>> >>> Digital means "represented by digits", not "in discrete voltage >>> steps". >> >>I've never seen that definition, while I have seen the definition >>Floyd is proposing, and I think it is a reasonable one. >> >No, it isn't. It misses the fact that sampled and digital are >different things. Digits are numbers.Are you kidding? It is *the* industry standard definition. It is not something that I made up, I merely looked it up. http://ntia.its.bldrdoc.gov/fs-1037/ That is, since you seem unable to grasp or investigate it, the web site of the National Telecommunications and Information Administration, a part of the US Federal Department of Commerce, in Boulder Colorado. Which is to say they are next door to and under that same management as the NIST (the National Institute of Standards and Technology), and NOAA (National Oceanic and Atmospheric Administration) which you may also have heard of... Or, to put it another way, you will not find anywhere in the world a valid definition that disagrees with that one. If yours is not in agreement, you are *wrong*.>>I've also seen many contexts in which "digital" means "discrete-time," >>i.e., there is no amplitude quantization at all. Take for example any >>of a number of books on the subject which have "digital signal >>processing" in the title - they are referring to signals that have >>been sampled in time, but not quantized (generally, although >>quantization effects are also analyzed in several such texts). >> > >Really? Can you point me at something that does DSP on signals that >have been merely sampled in time? I've never come across any such >thing. > >>Do you have a reference for your definition? > >Logic will do.Logically you are walking the plank. Such technical definitions have nothing to do with logic. It is an arbitrary decision that it means this or it means that. If we all agree on the arbitrary decision then we have a standard, and we can use it knowing that others will understand what it means. Until someone like you walk in and says they have their own definition...>If you are doing digital signal processing, you are >doing arithmetic on the numbers that come out of an AtoD converter.That is not necessarily true. Not all digital signals originate as analog signals that require A->D conversion.>You can't do that with some voltage levels out of a quantizer.Out of a quantizer? You certainly can.>As for discrete time, that is simply sampled, like a class D >amplifier, and nothing to do with digits. There is plenty of laziness >in the use of nomenclature (as well as misuse by people who simply >have no idea what they are talking about).I totally agree with that statement. ;-) -- Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
Reply by ●August 20, 20072007-08-20
On 20 Aug 2007 21:42:18 GMT, Scott Seidman <namdiesttocs@mindspring.com> wrote:>floyd@apaflo.com (Floyd L. Davidson) wrote in >news:87zm0mjrfy.fld@apaflo.com: > >>>quantized - a sampled signal, but with the possible levels constrained >>>to a limited set of values >> >> That is by definition a digital siganl. As soon as the possible values >> are "constrained to a limited set", it is by definition digital data. >> >> > >Wouldn't this make the output of a D/A converter digital by definition?It certainly would. But apparently there are those that can't see the difference between a limited set of values, and a set of numbers describing those values. d -- Pearce Consulting http://www.pearce.uk.com
Reply by ●August 20, 20072007-08-20
Scott Seidman wrote:> floyd@apaflo.com (Floyd L. Davidson) wrote in > news:87zm0mjrfy.fld@apaflo.com: > >>> quantized - a sampled signal, but with the possible levels constrained >>> to a limited set of values >> That is by definition a digital siganl. As soon as the possible values >> are "constrained to a limited set", it is by definition digital data. >> >> > > Wouldn't this make the output of a D/A converter digital by definition?Of course it would. I think it's a bit silly (pretty stupid, actually) to argue about what to call something and believe that's the same as arguing about what it is. One could say that a continuous signal measured with a 3.5-digit meter is quantized by the measurement even if it's unchanged thereby. And if the signal is recorded hourly in a log book, I suppose it becomes sampled. Is it worth trying to make a definition that withstands all possible logical contortions? Probably sometimes, but not here; not now. Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
