PCM stands for pulse code modulation. Can there be PCM without modulation? Is it still PCM if the modulation carries more than one bit per symbol? Radium is confused (or a clever troll), but his ravings raise an interesting question. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
What does PCM mean to you?
Started by ●October 3, 2005
Reply by ●October 3, 20052005-10-03
Jerry Avins wrote:> PCM stands for pulse code modulation. Can there be PCM without > modulation? Is it still PCM if the modulation carries more than one bit > per symbol? Radium is confused (or a clever troll), but his ravings > raise an interesting question.Could you please start defining "modulation" in an unique way? Otherwise everybody will give a different answer to the question. bye,
Reply by ●October 3, 20052005-10-03
Piergiorgio Sartor wrote:> Jerry Avins wrote: > >> PCM stands for pulse code modulation. Can there be PCM without >> modulation? Is it still PCM if the modulation carries more than one >> bit per symbol? Radium is confused (or a clever troll), but his >> ravings raise an interesting question. > > > Could you please start defining "modulation" in an unique way? > > Otherwise everybody will give a different answer to the question.If everyone who responds makes it clear what modulation means to him, that will add to the interest. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●October 3, 20052005-10-03
On Mon, 03 Oct 2005 15:09:26 -0400, Jerry Avins <jya@ieee.org> wrote:>PCM stands for pulse code modulation. Can there be PCM without >modulation? Is it still PCM if the modulation carries more than one bit >per symbol? Radium is confused (or a clever troll), but his ravings >raise an interesting question. > >JerryI've only ever had a vague notion of what was meant by PCM, and I have to admit that the recent threads haven't done much to really clear it up. My conclusion is that it doesn't matter. I don't think I've come across the term used in a manner where the distinctions are important. Modulations are typically described by their common nomenclatures, QAM, PSK, etc., etc., which are not ambigious. Whether or not they qualify as or describe PCM or not doesn't seem to be of great consequence, because one can always use the less ambiguous terms instead. Are there any cases where the term "PCM" is the least ambiguous way to describe something? If not then I'll offer that as evidence that it doesn't matter. Eric Jacobsen Minister of Algorithms, Intel Corp. My opinions may not be Intel's opinions. http://www.ericjacobsen.org
Reply by ●October 3, 20052005-10-03
"Jerry Avins" wrote ...> Piergiorgio Sartor wrote: >> Jerry Avins wrote: >> >>> PCM stands for pulse code modulation. Can there be PCM without >>> modulation? Is it still PCM if the modulation carries more than one bit >>> per symbol? Radium is confused (or a clever troll), but his ravings >>> raise an interesting question. >> >> >> Could you please start defining "modulation" in an unique way? >> >> Otherwise everybody will give a different answer to the question. > > If everyone who responds makes it clear what modulation means to him, that > will add to the interest.From the history I have read, "PCM" was originated back 60-70 years ago to distinguish this then-newly-invented digital form of information transfer from traditional analog telephony. It is easy to see why they called it "pulse-code modulation" from their exclusively-analog perspective. OTOH, to use "PCM" today is confusing at best, and frequently downright misleading and even controversial. Whenever I see the initialism "PCM" today, I assume it is a $3 phrase thrown in by a clueless advertising gerb and I activate my BS filter. IMHO, whatever meaning it may have had in the past has now been distorted beyond usefulness.
Reply by ●October 4, 20052005-10-04
PCM refers to any situation where an analog signal is sampled and digitized by an A/D converter. Sampling and digitizing is ubiquitous in modern systems, and most engineers would simply refer to the signals at the output of an A/D converter as "digital" rather than "pulse code modulated". I think the term survives only because some textbook writers like to use it so they can cover the topic of A/D conversion under the general topic of "modulation". But to the average engineer A/D conversion and modulation are distinct functions, and seldom is the former thought of as a subset of the latter. Steve
Reply by ●October 4, 20052005-10-04
"Jerry Avins" <jya@ieee.org> wrote in message news:-4WdnWgXWtR1HNzeRVn-qg@rcn.net...> PCM stands for pulse code modulation. Can there be PCM without modulation? > Is it still PCM if the modulation carries more than one bit per symbol?These days, PCM is the name given to the common uncompressed representations of audio signals as bit sequences. Yes, I know that's silly, but that's the way it is.> Radium is confused (or a clever troll), but his ravings raise an > interesting question.On this topic, he's correct. The pedantry here is getting a bit overzealous by inferring the meaning of the acronym from its expansion, and then holding that up as a reason to ridicule someone who obviously has experience with the practical definition of the term. This is one of the most genuinely helpful groups on Usenet, but it has its vulgar moments. -- Matt
Reply by ●October 4, 20052005-10-04
Matt Timmermans wrote:> "Jerry Avins" <jya@ieee.org> wrote in message > news:-4WdnWgXWtR1HNzeRVn-qg@rcn.net... > >>PCM stands for pulse code modulation. Can there be PCM without modulation? >>Is it still PCM if the modulation carries more than one bit per symbol? > > > These days, PCM is the name given to the common uncompressed representations > of audio signals as bit sequences. Yes, I know that's silly, but that's the > way it is.If there's general agreement on the issue (there hardly seems to be), that's fine with me, but nobody told me about it. Can you cite any credible sources? (Credible is a step down from authoritative.) There was a time when many took "communist" to mean any individual who disagreed with the speaker's politics, but that didn't make it so. ... Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●October 4, 20052005-10-04
"Jerry Avins" <jya@ieee.org> wrote in message news:sMydnckE6OIQFN_eRVn-jg@rcn.net...> Matt Timmermans wrote: >> "Jerry Avins" <jya@ieee.org> wrote in message >> news:-4WdnWgXWtR1HNzeRVn-qg@rcn.net... >> >>>PCM stands for pulse code modulation. Can there be PCM without modulation? Is >>>it still PCM if the modulation carries more than one bit per symbol? >> >> >> These days, PCM is the name given to the common uncompressed representations >> of audio signals as bit sequences. Yes, I know that's silly, but that's the >> way it is. > > If there's general agreement on the issue (there hardly seems to be), that's > fine with me, but nobody told me about it. Can you cite any credible sources? > (Credible is a step down from authoritative.) There was a time when many took > "communist" to mean any individual who disagreed with the speaker's politics, > but that didn't make it so.I'm in agreement with Matt regarding the common use of PCM, at least in the consumer audio industry. The term "PCM" in exactly the sense Matt describes is used many times my home DVD player's documentation (JVC XV-SA600). Some examples: "There are some audio formats recorded on discs as shown below. . Linear PCM Uncompressed digital audio, the same format used on CDs and most studio masters." "DVD with 192/176.4/96/88.2 kHz, 16/22/24 bit linear PCM" In fact, the digital output is labeled "PCM/Stream" (stream is used to refer to Dolby Digital and other compressed/encoded formats). Here's another source: http://computing-dictionary.thefreedictionary.com/PCM I also found a number of references that refer to PCM as the more strict original definition such as http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci214284,00.html. It seems that it is context-dependent. If you are in telecomms or engineering theory, one definition is standard. In the consumer audio (and to some extent pro audio) area, Matt's/Radium's more colloquial usage is common.
Reply by ●October 4, 20052005-10-04
Jon Harris wrote:> "Jerry Avins" <jya@ieee.org> wrote in message > news:sMydnckE6OIQFN_eRVn-jg@rcn.net... > >>Matt Timmermans wrote: >> >>>"Jerry Avins" <jya@ieee.org> wrote in message >>>news:-4WdnWgXWtR1HNzeRVn-qg@rcn.net... >>> >>> >>>>PCM stands for pulse code modulation. Can there be PCM without modulation? Is >>>>it still PCM if the modulation carries more than one bit per symbol? >>> >>> >>>These days, PCM is the name given to the common uncompressed representations >>>of audio signals as bit sequences. Yes, I know that's silly, but that's the >>>way it is. >> >>If there's general agreement on the issue (there hardly seems to be), that's >>fine with me, but nobody told me about it. Can you cite any credible sources? >>(Credible is a step down from authoritative.) There was a time when many took >>"communist" to mean any individual who disagreed with the speaker's politics, >>but that didn't make it so. > > > I'm in agreement with Matt regarding the common use of PCM, at least in the > consumer audio industry. The term "PCM" in exactly the sense Matt describes is > used many times my home DVD player's documentation (JVC XV-SA600). Some > examples: > > "There are some audio formats recorded on discs as shown below. > . Linear PCM > Uncompressed digital audio, the same format used on CDs and most studio > masters." > > "DVD with 192/176.4/96/88.2 kHz, 16/22/24 bit linear PCM" > > In fact, the digital output is labeled "PCM/Stream" (stream is used to refer to > Dolby Digital and other compressed/encoded formats). > > Here's another source: > http://computing-dictionary.thefreedictionary.com/PCM > > I also found a number of references that refer to PCM as the more strict > original definition such as > http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci214284,00.html. > It seems that it is context-dependent. If you are in telecomms or engineering > theory, one definition is standard. In the consumer audio (and to some extent > pro audio) area, Matt's/Radium's more colloquial usage is common.Thanks. I believe in context, as my comments to Rune this morning in his OT thread make clear. I'll go with it on reading, but avoid it (except in its telcom sense) when making statements. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
