>
>> >>> >>>
>>>> >>>>> >>>>>
>>>>>> >>>>>>>
>>>>>>>> >>>>>>>>>
>>>>>>>>>> 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.
>>>>>>>>>>
>>>>>>>>>>>formatting link>>>>>>>>> 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 tried it, with a 50kHz-9GHz coupler. While it works, the absence of the incident step is merely confusing, and of course the coupler introduces some wiggles that can't be told apart from those of the DUT. In conclusion, I'll keep doing TDR the old way, without directional coupler.
Jeroen Belleman