[time-nuts] Why are 1PPS signals so skinny?

[Dave Martindale]

For what it's worth, that seems to be the standard way to distribute analog
video (composite or component).  A low-impedance voltage source with a gain
of 2 drives a bunch of outputs with an individual 75 ohm series resistor
for each output.  Each cable that is connected to an output has a parallel
75 ohm terminator at the far end.  Inputs are all high impedance.  The
result is cables properly terminated at both ends (no reflections), unity
gain overall (the driver gain of 2 compensates for the 2:1 voltage divider
due to the terminators, and the ability to daisy-chain through several
inputs.

- Dave

On Tue, May 15, 2012 at 6:02 PM, Hal Murray <hmurray at megapathdsl.net> wrote:

>
> It's not uncommon to use both source/series and end/parallel terminations.
>  The series terminator drops the signal level by 2 but minimizes
> reflections if you are working in a less than ideal setup.  It also
> provides a current limit on the driver in case something gets shorted.
>
>
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