From: Bruce Griffiths <[EMAIL PROTECTED]> Subject: Re: [time-nuts] sub cables Date: Fri, 02 May 2008 10:47:03 +1200 Message-ID: <[EMAIL PROTECTED]>
> Magnus Danielson wrote: > > From: Scott Mace <[EMAIL PROTECTED]> > > Subject: Re: [time-nuts] sub cables > > Date: Thu, 01 May 2008 16:30:43 -0500 > > Message-ID: <[EMAIL PROTECTED]> > > > > > >> 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. > >> > > > > Modern sub cables does not used a distributed line of EDFAs anymore. They > > use > > the entire cable length as an amplifier instead. If the laser is down, you > > can > > reach it and service it, since it sits on dry land anyways. > > > > I have an EDFA lying around my office desk. Never know when I need one. > > Uses a 250 mW 850 nm pumping laser. > > > > Cheers, > > Magnus > > > > > Magnus > > There is a limit to the cable length when using EDFAs above which a > regenerator is required. Certainly, unless you go soliton system. Also, long stretches of EDFA fibers is usually using dispersion compensation fibers, which provides an matching anti-group-delay to force the dispersed frequencies back into place and thus reshaping. The reshaping abilities have advanced significantly. EDFA also has an interesting shift in frequency for each amplification. There are now very long cables systems which is all optical from shore to shore such that any 3R is on shore and not wet. For instance, the TAT-14 cables is all-optical trans-atlantic. The PC-1 trans-pacific cable, a 21000 km run, is also all-optical. They are laying a new trans-pacific cable now, it should be ready just prior to the Being olympics. This is standard buissness now. Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
