[Physltest] [Phys-L] Re: pulse on a vertical rope

[Brian Whatcott <betwys1@SBCGLOBAL.NET>]

At 12:26 AM 1/3/2005, John D., you wrote:

>  >  But
> > later when the pulse goes back down the rope, it will mostly
> > reconstitute itself, thus explaining why experimentally (from the
> > previous reference I gave), up to 10 returns of the pulse were
> > observed.
>
> I've never done careful experiments on this system, but my intuition
> and analysis are screaming at me, saying that there is a wide class
> of pulses that will not reconstitute themselves -- especially for
> narrow square pulses on a long rope.

///

> Reflection from an impedance mismatch is not dissipative.  On the Smith
> chart, it shows up as a purely reactive impedance.


It's interesting to recall that one way of matching a line of one impedance
  to another of different characteristic impedance is to insert a section
  of smoothly varying impedance which matches each line at its ends.

This too is non-dissipative, and in the usual case, maintains narrow
  square pulses.


Brian Whatcott    Altus OK    Eureka!
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