Everett M. Greene wrote:>Why are new terms added to industry "discussions" without >properly defining them? I've been looking for a definition >of isochronous for the last few years and have never found >one. Now someone has added plesiochronous to this group's >discussions. > >It's been quite a number of years since streaming tape >drives were introduced (and have since died?). There never >was a definition of what streaming meant, but in that case >one could eventually determine that streaming meant not >start-stop, but it would have nice if someone had taken the >time to define what was meant. > >iso == the same (like isotope, atoms of the same tope :-) ) plesio == nearly (like plesiosaur, a creature that was almost a dinosaur) so Isochronous means following the same timing. The signals could be truly synchronous, or they might jitter around like crazy, but they follow the same long term timing. Plesiochronous means having pretty close timing. The commonest use of this term is in PCM telecoms. Muxes above E1 or T1 used to be all plesiochronous. The clock sources are designed to be no better than 50ppm, but the data format offers the elasticity to cope with 100ppm error. The E1s or T1s had to be plesiochronous. These systems have largely given way to synchronous muxing, using rhubidium clocks in telephone exchanges to keep everything in true sync. These terms are hardly obscure or hard to find on Google in less time that it took me to type this. I don't think streaming should have been too hard to figure out, either. I think you picked three of the most self-evident terms, in an industry littered with truly obscure terms. :-\ Regards, Steve
Arbitrary asynchronous (plesiochronous?) resampling in "real time"
Started by ●April 25, 2005
Reply by ●June 13, 20052005-06-13
Reply by ●June 13, 20052005-06-13
Everett M. Greene wrote:> Why are new terms added to industry "discussions" without > properly defining them? I've been looking for a definition > of isochronous for the last few years and have never found > one. Now someone has added plesiochronous to this group's > discussions. > > It's been quite a number of years since streaming tape > drives were introduced (and have since died?). There never > was a definition of what streaming meant, but in that case > one could eventually determine that streaming meant not > start-stop, but it would have nice if someone had taken the > time to define what was meant.The terms are part of the language, albeit a relatively recent part. Certainly Google will turn up definitions. I'll check the OED ... not in the 1933 supplement. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●June 14, 20052005-06-14
in article 20050613.7944A18.F196@mojaveg.iwvisp.com, Everett M. Greene at mojaveg@mojaveg.iwvisp.com wrote on 06/13/2005 21:00:> Why are new terms added to industry "discussions" without > properly defining them? I've been looking for a definition > of isochronous for the last few years and have never found > one. Now someone has added plesiochronous to this group's > discussions. > > It's been quite a number of years since streaming tape > drives were introduced (and have since died?). There never > was a definition of what streaming meant, but in that case > one could eventually determine that streaming meant not > start-stop, but it would have nice if someone had taken the > time to define what was meant.welcome to the wonderful world of Jargon. sometimes jargon helps us to precisely and concisely focus in on whatever it is we're discussing so as not to end up making the mistake about discussing or disagreeing about two different things. sometimes jargon is batted around for social reasons. i'm still trying to figure out what the difference between "plesiochronous" and "quasi-synchronous" is and, if there is no difference, why the need for a new term? -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."
Reply by ●June 14, 20052005-06-14
robert bristow-johnson wrote: ...> sometimes jargon is batted around for social reasons.See "shibboleth".> i'm still trying to figure out what the difference between "plesiochronous" > and "quasi-synchronous" is and, if there is no difference, why the need for > a new term?Strictly, "quasi synchronous" means "as if synchronous", which we take to mean "mostly behaves like synchronous, sort of". "Plesiosynchronous" means "nearly synchronous", which is not exactly the same thing. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●June 14, 20052005-06-14
> i'm still trying to figure out what the difference between "plesiochronous" > and "quasi-synchronous" is and, if there is no difference, why the need for > a new term?The impression I got was that plesiochronous was closer to being synchronous than quasi-synchronous, i.e. less drift, but I could be wrong. There really doesn't seem to be a need for a new term, yet we have it. Actually, in audio I've been dealing with "plesiochronous" systems for years without having/needing any word for them. You would just say the 2 systems have the same nominal sample rate but aren't locked together. It is the comms guys that seem to have popularized "plesiochronous" and now it is being used in audio as well.
Reply by ●June 14, 20052005-06-14
Everett M. Greene wrote:> ,,. Now someone has added plesiochronous to this group's > discussions.... I found these definitions on the web: plesiosynchronous - sipping a cosmopolitan on the beach while the cabana boy rubs oil on my back and the waves lap upon the shore. very pleasing synchronous activities for all the senses. "plesiosynchronous" is a phrase often uttered by Mexican sardines as a help to novice fishermen trying to bait them on a hook. Roughly translates to "Please, Yo, sinker on us". Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●June 14, 20052005-06-14
in article JeWdnUmc0YDNmDLfRVn-1g@rcn.net, Jerry Avins at jya@ieee.org wrote on 06/14/2005 12:26:> robert bristow-johnson wrote: > > ... > >> sometimes jargon is batted around for social reasons. > > See "shibboleth". > >> i'm still trying to figure out what the difference between "plesiochronous" >> and "quasi-synchronous" is and, if there is no difference, why the need for >> a new term? > > Strictly, "quasi synchronous" means "as if synchronous", which we take > to mean "mostly behaves like synchronous, sort of". "Plesiosynchronous" > means "nearly synchronous", which is not exactly the same thing.i wonder if i should change my term for musical notes (of a tonal nature and mostly harmonic) that are eligible for reproduction using true wavetable synthesis, from "quasi-periodic" to "plesio-periodic"? -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."
Reply by ●June 14, 20052005-06-14
robert bristow-johnson wrote:> in article JeWdnUmc0YDNmDLfRVn-1g@rcn.net, Jerry Avins at jya@ieee.org wrote > on 06/14/2005 12:26: > > >>robert bristow-johnson wrote: >> >>... >> >> >>>sometimes jargon is batted around for social reasons. >> >>See "shibboleth". >> >> >>>i'm still trying to figure out what the difference between "plesiochronous" >>>and "quasi-synchronous" is and, if there is no difference, why the need for >>>a new term? >> >>Strictly, "quasi synchronous" means "as if synchronous", which we take >>to mean "mostly behaves like synchronous, sort of". "Plesiosynchronous" >>means "nearly synchronous", which is not exactly the same thing. > > > i wonder if i should change my term for musical notes (of a tonal nature and > mostly harmonic) that are eligible for reproduction using true wavetable > synthesis, from "quasi-periodic" to "plesio-periodic"?That depends on whether the music dwives you quasi, or if you find it plesing. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●June 14, 20052005-06-14
"Jerry Avins" <jya@ieee.org> wrote in message news:W5WdnXxRAYBG8jLfRVn-tQ@rcn.net...> > That depends on whether the music dwives you quasi, or if you find it > plesing.Wow, that is bad! (I mean that in a good way.)
Reply by ●June 18, 20052005-06-18
"robert bristow-johnson" <rbj@audioimagination.com> wrote in message news:BED4C877.8475%rbj@audioimagination.com...> in article JeWdnUmc0YDNmDLfRVn-1g@rcn.net, Jerry Avins at jya@ieee.org > wrote > on 06/14/2005 12:26: > >> >>> i'm still trying to figure out what the difference between >>> "plesiochronous" >>> and "quasi-synchronous" is and, if there is no difference, why the need >>> for >>> a new term?Robert, The difference is you are mixing languages. Plesiochronus and synchronous have Greek roots. The "plesiochronous problem" has been around for a long time (even referred to by that name). It is the basic problem of synchronizing clocks around the world. Quasi comes from Latin. The word purests would hate to see a mixing of the languages when building new words. Of course we are in a world where computer people say "insert the media" when they are only going to insert a single solitary thing. It is a medium and not a media. And this is the same world where Nissan names a car the Maxima. Yeap, they gave a plural name to a singular object. I think more people should study some basic Greek and Latin, and if they don't, they should simply try to see if a word already exists before creating a bastard that adds yet another exception to the list of exceptions. My two cents worth. Clay p.s. period stems from Greek, so plesioperiodic would be more correct than quasiperiodic.>> >> Strictly, "quasi synchronous" means "as if synchronous", which we take >> to mean "mostly behaves like synchronous, sort of". "Plesiosynchronous" >> means "nearly synchronous", which is not exactly the same thing. > > i wonder if i should change my term for musical notes (of a tonal nature > and > mostly harmonic) that are eligible for reproduction using true wavetable > synthesis, from "quasi-periodic" to "plesio-periodic"? > > -- > > r b-j rbj@audioimagination.com > > "Imagination is more important than knowledge." > >
