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From: Didi on 7 Aug 2010 20:24 On Aug 8, 12:48 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> wrote: > On Sat, 7 Aug 2010 02:19:29 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >On Aug 7, 3:41 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> > >wrote: > >> On Fri, 6 Aug 2010 17:19:41 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >> >On Aug 7, 3:05 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> > >> >wrote: > >> >> On Fri, 6 Aug 2010 12:56:35 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >> >> >On Aug 6, 5:31 pm, "keith...(a)gmail.com" <keith...(a)gmail.com> wrote: > >> >> >> On Aug 6, 8:57 am, Didi <d...(a)tgi-sci.com> wrote: > > >> >> >> > On Aug 6, 3:13 pm, John Larkin > > >> >> >> > <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> > > ... > >> >> >> > > Most of our VME modules have a calibration connector and a relay per > >> >> >> > > channel, so our customer can switch every channel to a traceable > >> >> >> > > dvm/source and verify calibration before and after every test run, > >> >> >> > > without disconnecting field wiring. That works well with all the gear > >> >> >> > > in one rack, but would be very messy to attempt with distributed i/o. > > >> >> >> > Why do you say it would be messy? Replacing say 32 analog cables with > >> >> >> > a 10/100 Ethernet link should only make it easier from where I look > >> >> >> > at it (clearly not from the same point as you). I ask because I was > >> >> >> > asked recently about a tiny (50x100mm) ADC board with 16 inputs, > >> >> >> > to etherner, the motivation being cabling. > >> >> >> > [Nothing came out of it but then the inquiry was from Pakistan, either > >> >> >> > the floods got them or it was one of the so many "first ask then > >> >> >> > think" > >> >> >> > inquiries coming from these parts of the world :-) ]. > > >> >> >> It's messy because his traceable calibration reference is no longer > >> >> >> where the I/O is. > > >> >> >I guess that depends on the cable length then. If the analog cables > >> >> >have to > >> >> >be tens of meters just having the input connector handy for > >> >> >calibration > >> >> >is a poor decision, but if the cables are reasonably short digitizing > >> >> >locally makes no sense since the entire system is local. > > >> >> Reread what he's said. His calibration reference is muxed into each input. If > >> >> you distribute the input functions you have to distribute the calibration > >> >> signal as well, negating your advantage. > > >> >It certainly does not negate the advantage of having the _analog_ > >> >input > >> >cables an order of magnitude shorter. Having them that long will > >> >degrade the quality of the sampled signal, there is no reasonable > >> >way around that unless the signals are DC, perhaps. > > >> Ok, let me try this another way... How do you propose to do the muxing of > >> this traceable standard? Cable *it* around to each point. Place one at every > >> node? Of course it's a trade-off. > > >It is a trade-off indeed, it is just that I would have made it in > >favour > >of the acquired signal integrity rather than the calibrating signal > >source. > > That may be the right decision, maybe not. It certainly is not an obvious one > to make on a newsgroup, no less. Maybe. It would be the right decision if the added dynamic range buys you something you want to pay for. We don't know that in that particular case. > >One can do things about the latter (average multiple measurements > >etc.) > >which cannot be done with the input signal. > > Maybe. But it's not always possible to make a choice that simple. Making these choices can be difficult indeed. Things nowadays have moved a lot towards local sampling and digital communication, though. It is of course a matter of possessing the whole acquisition and networking technology under one hood, I know not everyone can have that. > ... I'm quite > sure John has considered the issue. Oh I am pretty sure myself John has done his considerations, of course. Dimiter ------------------------------------------------------ Dimiter Popoff Transgalactic Instruments http://www.tgi-sci.com ------------------------------------------------------ http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
From: krw on 7 Aug 2010 20:32 On Sat, 7 Aug 2010 17:24:25 -0700 (PDT), Didi <dp(a)tgi-sci.com> wrote: >On Aug 8, 12:48�am, "k...(a)att.bizzzzzzzzzzzz" ><k...(a)att.bizzzzzzzzzzzz> wrote: >> On Sat, 7 Aug 2010 02:19:29 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: >> >On Aug 7, 3:41�am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> >> >wrote: >> >> On Fri, 6 Aug 2010 17:19:41 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: >> >> >On Aug 7, 3:05�am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> >> >> >wrote: >> >> >> On Fri, 6 Aug 2010 12:56:35 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: >> >> >> >On Aug 6, 5:31�pm, "keith...(a)gmail.com" <keith...(a)gmail.com> wrote: >> >> >> >> On Aug 6, 8:57�am, Didi <d...(a)tgi-sci.com> wrote: >> >> >> >> >> > On Aug 6, 3:13�pm, John Larkin >> >> >> >> >> > <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> >> >> >> > > ... >> >> >> >> > > Most of our VME modules have a calibration connector and a relay per >> >> >> >> > > channel, so our customer can switch every channel to a traceable >> >> >> >> > > dvm/source and verify calibration before and after every test run, >> >> >> >> > > without disconnecting field wiring. That works well with all the gear >> >> >> >> > > in one rack, but would be very messy to attempt with distributed i/o. >> >> >> >> >> > Why do you say it would be messy? Replacing say 32 analog cables with >> >> >> >> > a 10/100 Ethernet link should only make it easier from where I look >> >> >> >> > at it (clearly not from the same point as you). I ask because I was >> >> >> >> > asked recently about a tiny (50x100mm) ADC board with 16 inputs, >> >> >> >> > to etherner, the motivation being cabling. >> >> >> >> > [Nothing came out of it but then the inquiry was from Pakistan, either >> >> >> >> > the floods got them or it was one of the so many "first ask then >> >> >> >> > think" >> >> >> >> > inquiries coming from these parts of the world :-) ]. >> >> >> >> >> It's messy because his traceable calibration reference is no longer >> >> >> >> where the �I/O is. >> >> >> >> >I guess that depends on the cable length then. If the analog cables >> >> >> >have to >> >> >> >be tens of meters just having the input connector handy for >> >> >> >calibration >> >> >> >is a poor decision, but if the cables are reasonably short digitizing >> >> >> >locally makes no sense since the entire system is local. >> >> >> >> Reread what he's said. �His calibration reference is muxed into each input. If >> >> >> you distribute the input functions you have to distribute the calibration >> >> >> signal as well, negating your advantage. � >> >> >> >It certainly does not negate the advantage of having the _analog_ >> >> >input >> >> >cables an order of magnitude shorter. Having them that long will >> >> >degrade the quality of the sampled signal, there is no reasonable >> >> >way around that unless the signals are DC, perhaps. >> >> >> Ok, let me try this another way... �How do you propose to do the muxing of >> >> this traceable standard? �Cable *it* around to each point. �Place one at every >> >> node? �Of course it's a trade-off. >> >> >It is a trade-off indeed, it is just that I would have made it in >> >favour >> >of the acquired signal integrity rather than the calibrating signal >> >source. >> >> That may be the right decision, maybe not. �It certainly is not an obvious one >> to make on a newsgroup, no less. > >Maybe. It would be the right decision if the added dynamic range >buys you something you want to pay for. We don't know that in that >particular case. Again, Captain Obvious sticks his neck out; "if it's a better solution, it might be better". >> >One can do things about the latter (average multiple measurements >> >etc.) >> >which cannot be done with the input signal. >> >> Maybe. �But it's not always possible to make a choice that simple. > >Making these choices can be difficult indeed. Things nowadays have >moved >a lot towards local sampling and digital communication, though. It is >of >course a matter of possessing the whole acquisition and networking >technology under one hood, I know not everyone can have that. Again, Captain Obvious makes an incredible statement. >> ... I'm quite >> sure John has considered the issue. > >Oh I am pretty sure myself John has done his considerations, of >course. ???
From: Didi on 7 Aug 2010 20:44 On Aug 8, 3:32 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> wrote: > On Sat, 7 Aug 2010 17:24:25 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >On Aug 8, 12:48 am, "k...(a)att.bizzzzzzzzzzzz" > ><k...(a)att.bizzzzzzzzzzzz> wrote: > >> On Sat, 7 Aug 2010 02:19:29 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >> >On Aug 7, 3:41 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> > >> >wrote: > >> >> On Fri, 6 Aug 2010 17:19:41 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >> >> >On Aug 7, 3:05 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> > >> >> >wrote: > >> >> >> On Fri, 6 Aug 2010 12:56:35 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >> >> >> >On Aug 6, 5:31 pm, "keith...(a)gmail.com" <keith...(a)gmail.com> wrote: > >> >> >> >> On Aug 6, 8:57 am, Didi <d...(a)tgi-sci.com> wrote: > > >> >> >> >> > On Aug 6, 3:13 pm, John Larkin > > >> >> >> >> > <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> >> > > ... > >> >> >> >> > > Most of our VME modules have a calibration connector and a relay per > >> >> >> >> > > channel, so our customer can switch every channel to a traceable > >> >> >> >> > > dvm/source and verify calibration before and after every test run, > >> >> >> >> > > without disconnecting field wiring. That works well with all the gear > >> >> >> >> > > in one rack, but would be very messy to attempt with distributed i/o. > > >> >> >> >> > Why do you say it would be messy? Replacing say 32 analog cables with > >> >> >> >> > a 10/100 Ethernet link should only make it easier from where I look > >> >> >> >> > at it (clearly not from the same point as you). I ask because I was > >> >> >> >> > asked recently about a tiny (50x100mm) ADC board with 16 inputs, > >> >> >> >> > to etherner, the motivation being cabling. > >> >> >> >> > [Nothing came out of it but then the inquiry was from Pakistan, either > >> >> >> >> > the floods got them or it was one of the so many "first ask then > >> >> >> >> > think" > >> >> >> >> > inquiries coming from these parts of the world :-) ]. > > >> >> >> >> It's messy because his traceable calibration reference is no longer > >> >> >> >> where the I/O is. > > >> >> >> >I guess that depends on the cable length then. If the analog cables > >> >> >> >have to > >> >> >> >be tens of meters just having the input connector handy for > >> >> >> >calibration > >> >> >> >is a poor decision, but if the cables are reasonably short digitizing > >> >> >> >locally makes no sense since the entire system is local. > > >> >> >> Reread what he's said. His calibration reference is muxed into each input. If > >> >> >> you distribute the input functions you have to distribute the calibration > >> >> >> signal as well, negating your advantage. > > >> >> >It certainly does not negate the advantage of having the _analog_ > >> >> >input > >> >> >cables an order of magnitude shorter. Having them that long will > >> >> >degrade the quality of the sampled signal, there is no reasonable > >> >> >way around that unless the signals are DC, perhaps. > > >> >> Ok, let me try this another way... How do you propose to do the muxing of > >> >> this traceable standard? Cable *it* around to each point. Place one at every > >> >> node? Of course it's a trade-off. > > >> >It is a trade-off indeed, it is just that I would have made it in > >> >favour > >> >of the acquired signal integrity rather than the calibrating signal > >> >source. > > >> That may be the right decision, maybe not. It certainly is not an obvious one > >> to make on a newsgroup, no less. > > >Maybe. It would be the right decision if the added dynamic range > >buys you something you want to pay for. We don't know that in that > >particular case. > > Again, Captain Obvious sticks his neck out; "if it's a better solution, it > might be better". Ah. I did not notice I was talking to AlwaysRight. Dimiter
From: krw on 7 Aug 2010 20:50 On Sat, 7 Aug 2010 17:44:53 -0700 (PDT), Didi <dp(a)tgi-sci.com> wrote: >On Aug 8, 3:32�am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> >wrote: >> On Sat, 7 Aug 2010 17:24:25 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: >> >On Aug 8, 12:48�am, "k...(a)att.bizzzzzzzzzzzz" >> ><k...(a)att.bizzzzzzzzzzzz> wrote: >> >> On Sat, 7 Aug 2010 02:19:29 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: >> >> >On Aug 7, 3:41�am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> >> >> >wrote: >> >> >> On Fri, 6 Aug 2010 17:19:41 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: >> >> >> >On Aug 7, 3:05�am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> >> >> >> >wrote: >> >> >> >> On Fri, 6 Aug 2010 12:56:35 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: >> >> >> >> >On Aug 6, 5:31�pm, "keith...(a)gmail.com" <keith...(a)gmail.com> wrote: >> >> >> >> >> On Aug 6, 8:57�am, Didi <d...(a)tgi-sci.com> wrote: >> >> >> >> >> >> > On Aug 6, 3:13�pm, John Larkin >> >> >> >> >> >> > <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> >> >> >> >> > > ... >> >> >> >> >> > > Most of our VME modules have a calibration connector and a relay per >> >> >> >> >> > > channel, so our customer can switch every channel to a traceable >> >> >> >> >> > > dvm/source and verify calibration before and after every test run, >> >> >> >> >> > > without disconnecting field wiring. That works well with all the gear >> >> >> >> >> > > in one rack, but would be very messy to attempt with distributed i/o. >> >> >> >> >> >> > Why do you say it would be messy? Replacing say 32 analog cables with >> >> >> >> >> > a 10/100 Ethernet link should only make it easier from where I look >> >> >> >> >> > at it (clearly not from the same point as you). I ask because I was >> >> >> >> >> > asked recently about a tiny (50x100mm) ADC board with 16 inputs, >> >> >> >> >> > to etherner, the motivation being cabling. >> >> >> >> >> > [Nothing came out of it but then the inquiry was from Pakistan, either >> >> >> >> >> > the floods got them or it was one of the so many "first ask then >> >> >> >> >> > think" >> >> >> >> >> > inquiries coming from these parts of the world :-) ]. >> >> >> >> >> >> It's messy because his traceable calibration reference is no longer >> >> >> >> >> where the �I/O is. >> >> >> >> >> >I guess that depends on the cable length then. If the analog cables >> >> >> >> >have to >> >> >> >> >be tens of meters just having the input connector handy for >> >> >> >> >calibration >> >> >> >> >is a poor decision, but if the cables are reasonably short digitizing >> >> >> >> >locally makes no sense since the entire system is local. >> >> >> >> >> Reread what he's said. �His calibration reference is muxed into each input. If >> >> >> >> you distribute the input functions you have to distribute the calibration >> >> >> >> signal as well, negating your advantage. � >> >> >> >> >It certainly does not negate the advantage of having the _analog_ >> >> >> >input >> >> >> >cables an order of magnitude shorter. Having them that long will >> >> >> >degrade the quality of the sampled signal, there is no reasonable >> >> >> >way around that unless the signals are DC, perhaps. >> >> >> >> Ok, let me try this another way... �How do you propose to do the muxing of >> >> >> this traceable standard? �Cable *it* around to each point. �Place one at every >> >> >> node? �Of course it's a trade-off. >> >> >> >It is a trade-off indeed, it is just that I would have made it in >> >> >favour >> >> >of the acquired signal integrity rather than the calibrating signal >> >> >source. >> >> >> That may be the right decision, maybe not. �It certainly is not an obvious one >> >> to make on a newsgroup, no less. >> >> >Maybe. It would be the right decision if the added dynamic range >> >buys you something you want to pay for. We don't know that in that >> >particular case. >> >> Again, Captain Obvious sticks his neck out; "if it's a better solution, it >> might be better". > >Ah. I did not notice I was talking to AlwaysRight. You were the one trying to tell John his business, then defending the position with tautologies that certainly deserved the Captain Obvious tag.
From: Didi on 7 Aug 2010 21:10
On Aug 8, 3:50 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> wrote: > On Sat, 7 Aug 2010 17:44:53 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >On Aug 8, 3:32 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> > >wrote: > >> On Sat, 7 Aug 2010 17:24:25 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >> >On Aug 8, 12:48 am, "k...(a)att.bizzzzzzzzzzzz" > >> ><k...(a)att.bizzzzzzzzzzzz> wrote: > >> >> On Sat, 7 Aug 2010 02:19:29 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >> >> >On Aug 7, 3:41 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> > >> >> >wrote: > >> >> >> On Fri, 6 Aug 2010 17:19:41 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >> >> >> >On Aug 7, 3:05 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> > >> >> >> >wrote: > >> >> >> >> On Fri, 6 Aug 2010 12:56:35 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: > >> >> >> >> >On Aug 6, 5:31 pm, "keith...(a)gmail.com" <keith...(a)gmail.com> wrote: > >> >> >> >> >> On Aug 6, 8:57 am, Didi <d...(a)tgi-sci.com> wrote: > > >> >> >> >> >> > On Aug 6, 3:13 pm, John Larkin > > >> >> >> >> >> > <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> >> >> > > ... > >> >> >> >> >> > > Most of our VME modules have a calibration connector and a relay per > >> >> >> >> >> > > channel, so our customer can switch every channel to a traceable > >> >> >> >> >> > > dvm/source and verify calibration before and after every test run, > >> >> >> >> >> > > without disconnecting field wiring. That works well with all the gear > >> >> >> >> >> > > in one rack, but would be very messy to attempt with distributed i/o. > > >> >> >> >> >> > Why do you say it would be messy? Replacing say 32 analog cables with > >> >> >> >> >> > a 10/100 Ethernet link should only make it easier from where I look > >> >> >> >> >> > at it (clearly not from the same point as you). I ask because I was > >> >> >> >> >> > asked recently about a tiny (50x100mm) ADC board with 16 inputs, > >> >> >> >> >> > to etherner, the motivation being cabling. > >> >> >> >> >> > [Nothing came out of it but then the inquiry was from Pakistan, either > >> >> >> >> >> > the floods got them or it was one of the so many "first ask then > >> >> >> >> >> > think" > >> >> >> >> >> > inquiries coming from these parts of the world :-) ]. > > >> >> >> >> >> It's messy because his traceable calibration reference is no longer > >> >> >> >> >> where the I/O is. > > >> >> >> >> >I guess that depends on the cable length then. If the analog cables > >> >> >> >> >have to > >> >> >> >> >be tens of meters just having the input connector handy for > >> >> >> >> >calibration > >> >> >> >> >is a poor decision, but if the cables are reasonably short digitizing > >> >> >> >> >locally makes no sense since the entire system is local. > > >> >> >> >> Reread what he's said. His calibration reference is muxed into each input. If > >> >> >> >> you distribute the input functions you have to distribute the calibration > >> >> >> >> signal as well, negating your advantage. > > >> >> >> >It certainly does not negate the advantage of having the _analog_ > >> >> >> >input > >> >> >> >cables an order of magnitude shorter. Having them that long will > >> >> >> >degrade the quality of the sampled signal, there is no reasonable > >> >> >> >way around that unless the signals are DC, perhaps. > > >> >> >> Ok, let me try this another way... How do you propose to do the muxing of > >> >> >> this traceable standard? Cable *it* around to each point. Place one at every > >> >> >> node? Of course it's a trade-off. > > >> >> >It is a trade-off indeed, it is just that I would have made it in > >> >> >favour > >> >> >of the acquired signal integrity rather than the calibrating signal > >> >> >source. > > >> >> That may be the right decision, maybe not. It certainly is not an obvious one > >> >> to make on a newsgroup, no less. > > >> >Maybe. It would be the right decision if the added dynamic range > >> >buys you something you want to pay for. We don't know that in that > >> >particular case. > > >> Again, Captain Obvious sticks his neck out; "if it's a better solution, it > >> might be better". > > >Ah. I did not notice I was talking to AlwaysRight. > > You were the one trying to tell John his business, then defending the position > with tautologies that certainly deserved the Captain Obvious tag. I was asking about his point of view. It happens that this sort of business is similar to mine, and the issue under discussion is certainly part of my business. And yes, I happen to have the acquisition _and_ networking technology under one hood, so I was curious what can be the reason for others not to move this way. He was not interested in answering which is something I can live with. Yet I was not after your "know better" general comments which asked for the "AlwaysRight" tag. Dimiter |