[mythtv-users] Way OT: High-speed Data Service Delivery

Ian Clark mrrooster at gmail.com
Wed Aug 3 15:37:41 UTC 2011

On 13 July 2011 12:20, David Watkins <watkinshome at gmail.com> wrote:
>>>Sorry for diving in a bit here, and apologies for my ignorance, but
>>>surely the propagation speed over copper is approx the speed of light,
>>>and over fiber it /is/ the speed of light (in whatever medium the
>>>fibre is made of?)
>> The NVP (nominal velocity of propagation) for a copper pair is
>> typically in the order of 70% of the speed of light in a vacuum. When
>> testing copper cable, to get an accurate length you need to set the
>> NVP in the tester - either by using a manufacturers figure, or by
>> testing a sample of cable.
>> And for fibre, yes you are correct.
> ... which also happens to be approximately 70% of the speed of light
> in a vacuum.

Heh, forgot I asked this.

Cheers both of you, very informative. :)


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