On Friday, October 8, 2021 at 12:07:52 PM UTC-7, John Larkin wrote:> On Fri, 8 Oct 2021 12:02:25 -0500, amdx <am...@knology.net> wrote: > > >On 10/8/2021 11:18 AM, jla...@highlandsniptechnology.com wrote: > >> On Fri, 8 Oct 2021 10:05:15 -0500, amdx <am...@knology.net> wrote: > >> > >>> Here's a AT&T Labs archive video, showing an interesting machine used to > >>> demonstrate wave behavior. > >>> > >>> Shows open and shorted end, mismatched termination, matching line, > >>> wideband matching line etc.> >> Hilariously wrong.> An open transmission line does not invert the reflection. That's as > far as I watched it, so other stuff may be funny too.What does 'open' mean to you? Does it mean short-circuited, so voltage is nil, or does it mean open-circuited, so current is nil? In the acoustic case, 'open' means pressure is nil, but not displacement velocity, while 'closed' means velocity is nil, but not pressure. Now comes the money shot: are you thinking of the pressure, or the velocity, waveform in the acoustic case? And, are you comparing to the current, or the voltage waveform in the electrical case? Analogies require that you keep a consistent correspondence between systems. Discussing the analogy has little meaning without that discipline.
AT&T Labs wave behavior machine.
Started by ●October 8, 2021
Reply by ●October 9, 20212021-10-09
Reply by ●October 9, 20212021-10-09
On Fri, 8 Oct 2021 21:15:00 +0100, "Kevin Aylward" <kevinRemoveandReplaceATkevinaylward.co.uk> wrote:>wrote in message news:spr0mg1lu7qpq13asn2q2a4amao1jdpr51@4ax.com... > >On Fri, 8 Oct 2021 10:05:15 -0500, amdx <amdx@knology.net> wrote: > >>>Here's a AT&T Labs archive video, showing an interesting machine used to >>>demonstrate wave behavior. >> >>>Shows open and shorted end, mismatched termination, matching line, >>>wideband matching line etc. >> >> >Very cool. >> >>>> https://www.youtube.com/watch?v=DovunOxlY1k&t=297s >> >> Mikek > >>Hilariously wrong. > > >I agree he got it backwards with regard to the electrical line, he got the >analogy wrong...however...it was still a nice video.... > > > >-- Kevin Aylward > >http://www.anasoft.co.uk/ SuperSpice >http://www.kevinaylward.co.uk/ee/index.htmlHe's right if the txline graph is current. Maybe the Bell system did all their telecom measurements in amps? -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it.
Reply by ●October 10, 20212021-10-10
On Sat, 09 Oct 2021 11:48:53 -0700, jlarkin@highlandsniptechnology.com wrote:>On Fri, 8 Oct 2021 21:15:00 +0100, "Kevin Aylward" ><kevinRemoveandReplaceATkevinaylward.co.uk> wrote: > >>wrote in message news:spr0mg1lu7qpq13asn2q2a4amao1jdpr51@4ax.com... >> >>On Fri, 8 Oct 2021 10:05:15 -0500, amdx <amdx@knology.net> wrote: >> >>>>Here's a AT&T Labs archive video, showing an interesting machine used to >>>>demonstrate wave behavior. >>> >>>>Shows open and shorted end, mismatched termination, matching line, >>>>wideband matching line etc. >>> >>> >Very cool. >>> >>>>> https://www.youtube.com/watch?v=DovunOxlY1k&t=297s >>> >>> Mikek >> >>>Hilariously wrong. >> >> >>I agree he got it backwards with regard to the electrical line, he got the >>analogy wrong...however...it was still a nice video.... >> >> >> >>-- Kevin Aylward >> >>http://www.anasoft.co.uk/ SuperSpice >>http://www.kevinaylward.co.uk/ee/index.html > >He's right if the txline graph is current. Maybe the Bell system did >all their telecom measurements in amps?More like power I think... dBm for instance +++++ + + Father Brown. Great show ! boB
Reply by ●October 10, 20212021-10-10
On Saturday, October 9, 2021 at 2:49:01 PM UTC-4, jla...@highlandsniptechnology.com wrote:> On Fri, 8 Oct 2021 21:15:00 +0100, "Kevin Aylward" > <kevinRemoveandReplaceATkevinaylward.co.uk> wrote: > > >wrote in message news:spr0mg1lu7qpq13as...@4ax.com... > > > >On Fri, 8 Oct 2021 10:05:15 -0500, amdx <am...@knology.net> wrote: > > > >>>Here's a AT&T Labs archive video, showing an interesting machine used to > >>>demonstrate wave behavior. > >> > >>>Shows open and shorted end, mismatched termination, matching line, > >>>wideband matching line etc. > >> > >> >Very cool. > >> > >>>> https://www.youtube.com/watch?v=DovunOxlY1k&t=297s > >> > >> Mikek > > > >>Hilariously wrong. > > > > > >I agree he got it backwards with regard to the electrical line, he got the > >analogy wrong...however...it was still a nice video.... > > > > > > > >-- Kevin Aylward > > > >http://www.anasoft.co.uk/ SuperSpice > >http://www.kevinaylward.co.uk/ee/index.html > He's right if the txline graph is current. Maybe the Bell system did > all their telecom measurements in amps?If you actually pay attention to what he says, he states that he is talking about current. https://youtu.be/DovunOxlY1k?t=330 You just have to pay attention in class. -- Rick C. + Get 1,000 miles of free Supercharging + Tesla referral code - https://ts.la/richard11209
Reply by ●October 10, 20212021-10-10
On 10/8/2021 7:38 PM, amdx wrote:> On 10/8/2021 3:10 PM, Jeroen Belleman wrote: >> On 2021-10-08 21:07, John Larkin wrote: >>> On Fri, 8 Oct 2021 12:02:25 -0500, amdx <amdx@knology.net> wrote: >>> >>>> On 10/8/2021 11:18 AM, jlarkin@highlandsniptechnology.com wrote: >>>>> On Fri, 8 Oct 2021 10:05:15 -0500, amdx <amdx@knology.net> wrote: >>>>> >>>>>> Here's a AT&T Labs archive video, showing an interesting machine >>>>>> used to >>>>>> demonstrate wave behavior. >>>>>> >>>>>> Shows� open and shorted end, mismatched termination, matching line, >>>>>> wideband matching line etc. >>>>>> >>>>>> �� Very cool. >>>>>> >>>>>>> https://www.youtube.com/watch?v=DovunOxlY1k&t=297s >>>>>> ����������������������������� Mikek >>>>> Hilariously wrong. >>>>> >>>> � Hi John, if you are smart enough to call an AT&T Labs video, >>>> "Hilariously wrong" >>>> It seems like you could convey the information about where they are >>>> wrong. >>>> I doubt everything said in the video is wrong. >>>> ����������������������������� Mikek >>> >>> An open transmission line does not invert the reflection. That's as >>> far as I watched it, so other stuff may be funny too. >>> >> >> He's talking of current, not voltage. He says so a few times. >> >> Jeroen Belleman > > �So, it looks like John watched part of the video, saw one point that > he got wrong, > > then he goes on the label the whole video, "Hilariously wrong". > > � John, do you care to watch it and pick anything else apart. > > Or could you say, "I got it wrong, the demo device is pretty neat, and > the video was > > well planned before filming was started"? > > ������������������������������������������ MikekAlso, he mentioned inversion near the beginning when he was drawing and explaning the operation of the line. It was clear to me and appeared correct. Perhaps John can give us a time in the video to examine?
Reply by ●October 10, 20212021-10-10
On 10/8/2021 8:48 PM, jlarkin@highlandsniptechnology.com wrote:> On Fri, 08 Oct 2021 22:10:47 +0200, Jeroen Belleman > <jeroen@nospam.please> wrote: > >> On 2021-10-08 21:07, John Larkin wrote: >>> On Fri, 8 Oct 2021 12:02:25 -0500, amdx <amdx@knology.net> wrote: >>> >>>> On 10/8/2021 11:18 AM, jlarkin@highlandsniptechnology.com wrote: >>>>> On Fri, 8 Oct 2021 10:05:15 -0500, amdx <amdx@knology.net> wrote: >>>>> >>>>>> Here's a AT&T Labs archive video, showing an interesting machine used to >>>>>> demonstrate wave behavior. >>>>>> >>>>>> Shows open and shorted end, mismatched termination, matching line, >>>>>> wideband matching line etc. >>>>>> >>>>>> Very cool. >>>>>> >>>>>>> https://www.youtube.com/watch?v=DovunOxlY1k&t=297s >>>>>> Mikek >>>>> Hilariously wrong. >>>>> >>>> Hi John, if you are smart enough to call an AT&T Labs video, "Hilariously wrong" >>>> It seems like you could convey the information about where they are wrong. >>>> I doubt everything said in the video is wrong. >>>> Mikek >>> >>> An open transmission line does not invert the reflection. That's as >>> far as I watched it, so other stuff may be funny too. >>> >> >> He's talking of current, not voltage. He says so a few times. >> >> Jeroen Belleman > > Ok, let's change hilariously wrong to hilariously weird. >What's weird about it? You don't understand it?
Reply by ●October 10, 20212021-10-10
On 10/8/2021 10:05 AM, amdx wrote:> Here's a AT&T Labs archive video, showing an interesting machine used to > demonstrate wave behavior. > > Shows open and shorted end, mismatched termination, matching line, > wideband matching line etc. > > Very cool. > >> https://www.youtube.com/watch?v=DovunOxlY1k&t=297s > > MikekGreat video, Mikek. Thanks for the link.
Reply by ●October 10, 20212021-10-10
On Sun, 10 Oct 2021 02:20:32 -0500, John S <Sophi.2@invalid.org> wrote:>On 10/8/2021 8:48 PM, jlarkin@highlandsniptechnology.com wrote: >> On Fri, 08 Oct 2021 22:10:47 +0200, Jeroen Belleman >> <jeroen@nospam.please> wrote: >> >>> On 2021-10-08 21:07, John Larkin wrote: >>>> On Fri, 8 Oct 2021 12:02:25 -0500, amdx <amdx@knology.net> wrote: >>>> >>>>> On 10/8/2021 11:18 AM, jlarkin@highlandsniptechnology.com wrote: >>>>>> On Fri, 8 Oct 2021 10:05:15 -0500, amdx <amdx@knology.net> wrote: >>>>>> >>>>>>> Here's a AT&T Labs archive video, showing an interesting machine used to >>>>>>> demonstrate wave behavior. >>>>>>> >>>>>>> Shows open and shorted end, mismatched termination, matching line, >>>>>>> wideband matching line etc. >>>>>>> >>>>>>> Very cool. >>>>>>> >>>>>>>> https://www.youtube.com/watch?v=DovunOxlY1k&t=297s >>>>>>> Mikek >>>>>> Hilariously wrong. >>>>>> >>>>> Hi John, if you are smart enough to call an AT&T Labs video, "Hilariously wrong" >>>>> It seems like you could convey the information about where they are wrong. >>>>> I doubt everything said in the video is wrong. >>>>> Mikek >>>> >>>> An open transmission line does not invert the reflection. That's as >>>> far as I watched it, so other stuff may be funny too. >>>> >>> >>> He's talking of current, not voltage. He says so a few times. >>> >>> Jeroen Belleman >> >> Ok, let's change hilariously wrong to hilariously weird. >> > >What's weird about it? You don't understand it?I test transmission lines with oscilloscopes, not ammeters. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it.
Reply by ●October 10, 20212021-10-10
On 2021-10-10 17:58, jlarkin@highlandsniptechnology.com wrote:> On Sun, 10 Oct 2021 02:20:32 -0500, John S <Sophi.2@invalid.org> > wrote: > >> On 10/8/2021 8:48 PM, jlarkin@highlandsniptechnology.com wrote: >>> On Fri, 08 Oct 2021 22:10:47 +0200, Jeroen Belleman >>> <jeroen@nospam.please> wrote: >>> >>>> On 2021-10-08 21:07, John Larkin wrote: >>>>> On Fri, 8 Oct 2021 12:02:25 -0500, amdx <amdx@knology.net> wrote: >>>>> >>>>>> On 10/8/2021 11:18 AM, jlarkin@highlandsniptechnology.com wrote: >>>>>>> On Fri, 8 Oct 2021 10:05:15 -0500, amdx <amdx@knology.net> wrote: >>>>>>> >>>>>>>> Here's a AT&T Labs archive video, showing an interesting machine used to >>>>>>>> demonstrate wave behavior. >>>>>>>> >>>>>>>> Shows open and shorted end, mismatched termination, matching line, >>>>>>>> wideband matching line etc. >>>>>>>> >>>>>>>> Very cool. >>>>>>>> >>>>>>>>> https://www.youtube.com/watch?v=DovunOxlY1k&t=297s >>>>>>>> Mikek >>>>>>> Hilariously wrong. >>>>>>> >>>>>> Hi John, if you are smart enough to call an AT&T Labs video, "Hilariously wrong" >>>>>> It seems like you could convey the information about where they are wrong. >>>>>> I doubt everything said in the video is wrong. >>>>>> Mikek >>>>> >>>>> An open transmission line does not invert the reflection. That's as >>>>> far as I watched it, so other stuff may be funny too. >>>>> >>>> >>>> He's talking of current, not voltage. He says so a few times. >>>> >>>> Jeroen Belleman >>> >>> Ok, let's change hilariously wrong to hilariously weird. >>> >> >> What's weird about it? You don't understand it? > > I test transmission lines with oscilloscopes, not ammeters.I've been having thoughts about inserting a directional coupler between the pulse generator and the scope, so that it will show /only/ the reflection, not its superposition with the incident signal. I think I can make a coupler with the necessary bandwidth, a few tens of kHz up to 10 GHz or so. Would it be worth the trouble? Jeroen Belleman
Reply by ●October 10, 20212021-10-10
On Sat, 9 Oct 2021 21:53:34 -0700 (PDT), Rick C <gnuarm.deletethisbit@gmail.com> wrote:>On Saturday, October 9, 2021 at 2:49:01 PM UTC-4, jla...@highlandsniptechnology.com wrote: >> On Fri, 8 Oct 2021 21:15:00 +0100, "Kevin Aylward" >> <kevinRemoveandReplaceATkevinaylward.co.uk> wrote: >> >> >wrote in message news:spr0mg1lu7qpq13as...@4ax.com... >> > >> >On Fri, 8 Oct 2021 10:05:15 -0500, amdx <am...@knology.net> wrote: >> > >> >>>Here's a AT&T Labs archive video, showing an interesting machine used to >> >>>demonstrate wave behavior. >> >> >> >>>Shows open and shorted end, mismatched termination, matching line, >> >>>wideband matching line etc. >> >> >> >> >Very cool. >> >> >> >>>> https://www.youtube.com/watch?v=DovunOxlY1k&t=297s >> >> >> >> Mikek >> > >> >>Hilariously wrong. >> > >> > >> >I agree he got it backwards with regard to the electrical line, he got the >> >analogy wrong...however...it was still a nice video.... >> > >> >I would believe a Bell Labs video over most anybody on this newsgroup Might be a difference of presentation that isn't clear to some>> > >> >-- Kevin Aylward >> > >> >http://www.anasoft.co.uk/ SuperSpice >> >http://www.kevinaylward.co.uk/ee/index.html >> He's right if the txline graph is current. Maybe the Bell system did >> all their telecom measurements in amps? > >If you actually pay attention to what he says, he states that he is talking about current. > >https://youtu.be/DovunOxlY1k?t=330 > >You just have to pay attention in class.Bell Labs was good at all kinds of units of measurement. The Bel was useful too. In Munich at the museum of science, I saw George Ohm's original Fluke meter ! boB
