[rescue] Fiber loop simulators?

[James Lockwood]

On Thu, 25 Apr 2002, George Adkins wrote:

> How about a little tiny box with a pair of ST mounts inside and a micrometer
> screw  for distracting the ferrules from one another in order to diminish the
> signal?
>
> or make a series of progressively darker glass windows that you could rotate
> in between them to "Dial A Distance"

This would factor in for attenuation, but not spread due to frequency.
Remember that even a "square wave" pulse is really a set of sine waves
after Fourier decomposition, and the speed of light in a medium varies
depending on its frequency.

Bottom line, your neat square waves:
   ___     ___     ___
  |   |   |   |   |   |
__|   |___|   |___|   |__

Get "smudged" after a few miles of fibre:
    _       _       _
  _/ \_   _/ \_   _/ \_
_/     \_/     \_/     \_

Bad ASCII representation, but you get the idea.

-James