I think the OP is asking about whether it should account for chromatic dispersion or not. Intramodal dispersion may very well be a limit on your link even the power budget (as presented before) is fine. As Mikael said, I would stick to the specs from the manufacturer for that specific module, or rent an OTDR and make the measurements.
-- Evelio On Wed, Apr 22, 2015 at 1:51 PM, Baldur Norddahl <baldur.nordd...@gmail.com> wrote: > First: buy a power meter. They are really cheap and the only way to know > for sure how much signal you got. It will also tell you how much launch > power you have. The fiberstore modules are listed as 0 to +5 dBm launch > power - if you got lucky it might be +5 and if you got a lower end module > it might be close to 0. Obviously this makes a huge difference for how much > power you get on the other end. Also it is said that the laser will lose > power over time. > > Second you need to think in terms of power budget, not distance. So you got > 68 km and the module is rated for 80 km - but not all fiber is not born > equal. A power meter allows you to measure the true link loss. > > Third you did not tell what DWDM multiplexer you are using. A 44 channel > DWDM multiplexer from Fiberstore can have up to 4.5 dB insertion loss. You > might have two of those on your link for a total of 9 dB loss. Your 80 km > module has a 23 dB link budget, so this leaves you with 23-9 = 14 dB > budget. If your fiber has 0.25 dB loss per km, that is only 56 km. > > Regards, > > Baldur >
