[ale] nanoseconds and milliseconds

[Derek Atkins]

Jim Kinney <jim.kinney at gmail.com> writes:

> At a prior work place, a latency induced failure appeared in a project. So a
> large wooden spool of fiber was acquired. By adding appropriate fiber
> crossover lines, it was possible to test latencies created by up to several km
> of fiber.

The speed of light can be measured as approximately 1ns per foot.  So
yeah, you can add "significant" delay to a transmission by adding fiber.

> Copper won't work that way as it requires a regeneration at 300m.

It actually still works, but you just need additional repeaters at
greater distances.  Moreover, IIRC the "speed" of transmission in copper
is slower than light in fiber due to the additional resistence of the
copper, so it's more like 1.25-1.5ns per foot.

-derek
-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
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