[time-nuts] Newbie questions

Hal Murray hmurray at megapathdsl.net
Wed Jan 6 07:48:50 UTC 2010

magnus at rubidium.dyndns.org said:
> This sounds fast. The normal taxiometer is at 66% of speed of ligth in
>  vaccum, which for 1 ns is about 3 dm so for the RG-59 that would be
> about 2 dm.

> Some cables reach 78%, but RG-58 and RG-59 is down at normal 66%. 

Sounds right.

My rule to thumb for back-of-envelope work is that a signal in fiber and good 
(but not nutty) coax goes 1 km while light in air/vacuum goes 1 mile.  In 
this context, "good" means foam rather than solid dielectric.

Light goes 1 ft/ns in air or 5000 ns per mile or 5 usec/mile.  In coax/fiber, 
that's 5 usec/km.

These are my opinions, not necessarily my employer's.  I hate spam.

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