[time-nuts] sub cables

Scott Mace smace at intt.net
Thu May 1 17:30:43 EDT 2008

A repeater or regen goes optical-electrical-optical.  I think you are
talking about an EDFA.  While it may pass light when it's down, one
has to take into account the optical budget of the span.


Poul-Henning Kamp wrote:
> In message <qsak149dee8iddn3u4826obrvtf0ssrpel at 4ax.com>, Neon John writes:
>> Now I'm curious how power is tapped off at each repeater point.  I understand
>> the daisychain architecture but I'm wondering about the details, what
>> components can withstand the intial high voltage surge as the cable is
>> charging and how the voltage drop at each repeater is maintained relatively
>> constant, even if the repeater fails and quits consuming power.
> It may be different these modern days, but it used to be that each
> repeater had a (power)resistor connected in series with the supply
> wires and the amplifier was connected across the resistor.
> If the amplifier disconnected, the resistor kept continuity, if the
> amplifier shorted, there would be continuity as well.
> In addition the resistor kept the electronics from getting too cold.
>> Also, is it true that an optical cable will keep working with a single
>> repeater failure, that the laser light will pass through unamplified?  Seems
>> like I read that somewhere but I'm not sure.
> Yes, that's the major benefit from the "erbium doped fiber repeater"
> design.  Google it for details.

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